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Considering that vaccination against smallpox with live vaccinia virus led to serious adverse effects in some cases, the WHO, after declaration of the global eradication of smallpox in 1980, strongly recommended to discontinue the vaccination in all countries. This led to the loss of immunity against not only smallpox but also other zoonotic orthopoxvirus infections in humans over the past years. An increasing number of human infections with zoonotic orthopoxviruses and, first of all, monkeypox, force us to reconsider a possible re-emergence of smallpox or a similar disease as a result of natural evolution of these viruses. The review contains a brief analysis of the results of studies on genomic organization and evolution of human pathogenic orthopoxviruses, development of modern methods for diagnosis, vaccination, and chemotherapy of smallpox, monkeypox, and other zoonotic human orthopoxvirus infections. [ABSTRACT FROM AUTHOR]

Monkeypox virus is a member of the Orthopoxvirus genus and the Poxviridae family. Orthopoxviruses are among the most intricate animal viruses. The pathogenicity of human monkeypox infection has been emphasized in response to its recent emergence in non‐endemic countries and the threat of bioterrorism. It is always necessary to take appropriate precautions in exposure to emerging or re‐emerging infections. Here, we focus on the current state of the human monkeypox infection outbreak, research & development of immune responses, and clinical interventions to prevent and treat the human monkeypox virus and other human poxviruses. [ABSTRACT FROM AUTHOR]

Smallpox eradication and lack of adequate animal model for smallpox infection underlies a necessity to assess immunogenic and protective properties of genetic engineering-created live attenuated smallpox vaccines in several animal models of orthopoxviral infections. Here we compared immunogenic and protective properties of the recombinant vaccinia virus (VACV) LIVP-GFP intradermally (i.d.) inoculated to mice, guinea pigs and rabbits. LIVP-GFP immunization in all animal species was applied at dose of 2 × 104 or 2 × 106 PFU. Control animals were injected with saline. Blood sampling was performed on day 28 after virus LIVP-GFP or saline inoculation. Blood samples were taken intravitally from the retro-orbital venous sinus in mice, heart in guinea pigs or marginal ear vein in rabbits. Serum samples were isolated by precipitating blood cells via centrifugation. The serum anti-VACV IgG titers were determined by ELISA. On day 30 post-immunization animals were intranasally challenged with lethal dose of host specific orthopoxvirus species. Mice were infected by cowpox virus (CPXV) strain GRI-90 at dose 68 LD50, guinea pigs – by VACV GPA at dose 56 LD50, rabbits — by VACV HB-92 at dose 100 LD50. All animals in control group died afterwards, whereas all animals immunized by attenuated recombinant virus LIVP-GFP at dose 2 × 106 PFU survived. In case of the LIVP-GFP immunization at dose 2 × 104 PFU, 88% of mice, 67% of rabbits and 50% of guinea pigs survived after being challenged with species-specific CPXV, VACV HB-92, and VACV GPA. ELISA data for the blood serum samples revealed a correlation between level of VACV-specific antibodies and level of protection in animal species. Based on the data obtained, it could be concluded that all three “animal–orthopoxvirus” models allow to provide with a proper evaluation of immunogenicity and protectiveness for generated modern attenuated vaccines against smallpox and other orthopoxviral human infections. Upon that, it was shown that BALB/c mouse strain was the most convenient investigational host species.

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Monkeypox is caused by a sylvatic, double-stranded DNA zoonotic virus. Since 1 January 2022, monkeypox cases have been reported to WHO from 106 Member States across six WHO regions, and as of 2 October 2022, a total of 68,900 confirmed cases, including 25 deaths, occurred. Here, by using a whole genome approach, we perform a genetic and phylodynamic survey of the monkeypox virus Clade IIb B.1, which is the lineage causing the current multi-country outbreak. Results suggest that outbreaks seem to be isolated and localized in several epidemic clusters with geographic consistency. Currently, monkeypox appears to be a virus with a flattened genetic variability in terms of evolutionary path, with a very slow rate of growth in the population size. This scenario confirms that the monkeypox virus lacks the evolutionary advantage, given by the high level of mutation rate, which is very strong in RNA viruses. Of course, constant genome-based monitoring must be performed over time in order to detect the change in its genetic composition, if any. [ABSTRACT FROM AUTHOR]

Human monkeypox is caused by Monkeypox virus (MPXV), an Orthopoxvirus, previously rare in the United States (1). The first U.S. case of monkeypox during the current outbreak was identified on May 17, 2022 (2). As of September 28, 2022, a total of 25,341 monkeypox cases have been reported in the United States.* The outbreak has disproportionately affected gay, bisexual, and other men who have sex with men (MSM) (3). JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic), administered subcutaneously as a 2-dose (0.5 mL per dose) series with doses administered 4 weeks apart, was approved by the Food and Drug Administration (FDA) in 2019 to prevent smallpox and monkeypox infection (4). U.S. distribution of JYNNEOS vaccine as postexposure prophylaxis (PEP) for persons with known exposures to MPXV began in May 2022. A U.S. national vaccination strategy† for expanded PEP, announced on June 28, 2022, recommended subcutaneous vaccination of persons with known or presumed exposure to MPXV, broadening vaccination eligibility. FDA emergency use authorization (EUA) of intradermal administration of 0.1 mL of JYNNEOS on August 9, 2022, increased vaccine supply (5). As of September 28, 2022, most vaccine has been administered as PEP or expanded PEP. Because of the limited amount of time that has elapsed since administration of initial vaccine doses, as of September 28, 2022, relatively few persons in the current outbreak have completed the recommended 2-dose series.§ To examine the incidence of monkeypox among persons who were unvaccinated and those who had received ≥1 JYNNEOS vaccine dose, 5,402 reported monkeypox cases occurring among males¶ aged 18-49 years during July 31-September 3, 2022, were analyzed by vaccination status across 32 U.S. jurisdictions.** Average monkeypox incidence (cases per 100,000) among unvaccinated persons was 14.3 (95% CI = 5.0-41.0) times that among persons who received 1 dose of JYNNEOS vaccine ≥14 days earlier. Monitoring monkeypox incidence by vaccination status in timely surveillance data might provide early indications of vaccine-related protection that can be confirmed through other well-controlled vaccine effectiveness studies. This early finding suggests that a single dose of JYNNEOS vaccine provides some protection against monkeypox infection. The degree and durability of such protection is unknown, and it is recommended that people who are eligible for monkeypox vaccination receive the complete 2-dose series. [ABSTRACT FROM AUTHOR]

Poxviruses are double-stranded DNA viruses with several members displaying restricted host ranges. They are genetically stable with low nucleotide mutation rates compared to other viruses, due to the poxviral high-fidelity DNA polymerase. Despite the low accumulation of mutations per replication cycle, poxvirus genomes can recombine with each other to generate genetically rearranged viruses through recombination, a process directly associated with replication and the aforementioned DNA polymerase. Orthopoxvirus replication is intimately tethered to high frequencies of homologous recombination between co-infecting viruses, duplicated sequences of the same virus, and plasmid DNA transfected into poxvirus-infected cells. Unfortunately, the effect of these genomic alterations on the cellular context for all poxviruses across the family Poxviridae remains elusive. However, emerging sequence data on currently circulating and archived poxviruses, such as the genera orthopoxviruses and capripoxviruses, display a wide degree of divergence. This genetic variability cannot be explained by clonality or genetic drift alone, but are probably a result of significant genomic alterations, such as homologous recombination, gene loss and gain, or gene duplications as the major selection forces acting on viral progeny. The objective of this review is to cross-sectionally overview the currently available findings on natural and laboratory observations of recombination in orthopoxviruses, capripoxviruses, and leporipoxviruses, as well as the possible mechanisms involved. Overall, the reviewed available evidence allows us to conclude that the current state of knowledge is limited in terms of the relevance of genetic variations across even a genus of poxviruses as well as fundamental features governing and precipitating intrinsic gene flow and recombination events. [ABSTRACT FROM AUTHOR]

The monkeypox virus (MPXV) is the cause of a zoonotic infection similar to smallpox. Although it is endemic to Africa, it has recently begun to circulate in other parts of the world. In July 2022, the World Health Organization declared monkeypox an international public health emergency. This review aims to provide an overview of this neglected zoonotic pathogen. MPXV circulates as two distinct clades, the Central African and West African, with case fatality rates of 10.6% and 3.6%, respectively. The risk of infection is greater for those who work with animals or infected individuals. The virus' entry into the human body provokes both natural and acquired immunity. Although natural killer cells, CD4 + T cells, and CD8 + T cells play an essential role in eradicating MPXV, there is still a gap in the understanding of the host immune response to the virus. Currently, there are no specific therapeutic guidelines for treating monkeypox; however, some antiviral drugs such as tecovirimat and cidofovir may help to abate the severity of the disease. The use of nonpharmaceutical interventions and immunization can reduce the risk of infection. Increased surveillance and identification of monkeypox cases are crucial to understand the constantly shifting epidemiology of this resurging and intimidating disease. The present review provides a detailed perspective on the emergence and circulation of MPXV in human populations, infection risks, human immune response, disease diagnosis and prevention strategies, and future implications, and highlights the importance of the research community engaging more with this disease for an effective global response. [ABSTRACT FROM AUTHOR]

The aim of the study was to develop a sensitive and fast immunochemical test for the detection of orthopoxviruses (OPXV) in the “point of care” format.Materials and methods. The analyses were performed in cultured crude and purifed preparations of vaccinia virus, cowpoxvirus, rabbitpoxvirus and ectromelia virus, as well as in the blood and tissue suspensions of infected mice and rabbits. OPXV-antigen was detected by one-stage and two-stage protocols of dot-immunoassay based on flat protein arrays using rabbit polyclonal antibodies as capture and detection reagents.Results and discussion. The results show that the detection limit of OPXV is inversely related to the degree of their purifcation. The one-stage (rapid) protocol is specifc and allows detecting OPXV in crude culture samples of the virus and in clinical samples in the range of 104–103 PFU/ml within 39 minutes. Rapid dot-immunoassay can be applied to detect or exclude the presence of a viral threat in samples and can be useful in various aspects of biosafety provision. The simplicity of the one-stage protocol, the possibility to visually account the results and easy interpretation of the results allow the rapid test to be used in the “point of care” format.

• Mpox has triggered a demand for quality-assured MPXV PCR-diagnostic capabilities. • External Quality Assessment (EQA) is key to establish new diagnostic portfolios. • Performance levels in OPXV diagnostics increased compared to data from the 2000s. • One-third-of datasets were generated by OPXV-generic assays only. • Broader EQA participation is desirable for capacity build in developing countries. Diagnostic capabilities and correspondent External Quality Assessments (EQA) are key for outbreak preparedness. To support diagnostic facilities with a quality assessment of newly established monkeypox virus (MPXV) molecular diagnostic workflows, Quality Control for Molecular Diagnostics (QCMD) and the Bundeswehr Institute of Microbiology (IMB) piloted an international EQA study conducting four challenges from autumn 2022 to summer 2023 during the global mpox outbreak. To assess the performance (sensitivity/specificity) of molecular assays used by diagnostic laboratories. Inactivated EQA panels were prepared and distributed containing seven samples of clade Ia and clade IIb MPXV strains at different viral concentrations, two specificity controls with other zoonotic orthopoxviruses (vaccinia and cowpox virus) and a negative control. Assessment was based on reported qualitative testing results. In this outbreak-related EQA study, a total of 192 laboratories from 37 countries reported 346 qualitative datasets. Overall, core samples were correctly detected by approximately 92 % of participants in all four challenges. While sensitivity performance was acceptable in at least 90 % of datasets correctly reported even for educational MPXV-positive samples with low viral concentration [102 genome equivalents (GE)/mL], several laboratories reported the educational specificity controls as false positives or were unable to differentiate MPXV from related orthopoxviruses. Mpox is now a globally occurring infection with a demand for quality-assured diagnostic capabilities. The newly established EQA scheme presented here, offers a multi-purpose panel for orthopoxviruses with a focus on MPXV which will continue to ensure diagnostic quality in clinical settings with up-to-date sample panels. [ABSTRACT FROM AUTHOR]

Monkeypox, once a rare zoonotic disease, has been endemic to some African countries since its original identification among humans in 1970. Since then, cases in non-endemic regions have been linked to returning travelers or those who had contact with transported animals. The causative agent, Monkeypox virus, belongs to Orthopoxviruses, the same family as Variola—the causative organism for smallpox. Although most monkeypox outbreaks until recently were linked to zoonotic transmission, secondary human–human transmission in smallpox-unvaccinated individuals was observed in a small proportion of overall cases. Smallpox was declared to be eradicated in 1980, and since its eradication, Monkeypox virus has been the most significant poxvirus to cause human disease. The 2022 monkeypox outbreak marks a significant paradigm shift in the human and poxvirus association, with new modes of transmission and concerns of viral evolution and entrenchment as a sexually transmitted disease. Monkeypox clinically resembles smallpox but is far milder. At this time, there are no approved therapies for monkeypox, and antiviral agents effective against smallpox are being utilized. Additionally, preventive strategies being utilized include smallpox vaccinations such as JYNNEOS and ACAM2000. In this narrative review, we discuss the virology, epidemiology, transmission, clinical manifestations, diagnosis, management, and prevention strategies associated with monkeypox. [ABSTRACT FROM AUTHOR]

This review provides a brief history of the impacts that a human-specific Orthopoxvirus (OPXV), Variola virus, had on mankind, recalls how critical vaccination was for the eradication of this disease, and discusses the consequences of discontinuing vaccination against OPXV. One of these consequences is the emergence of zoonotic OPXV diseases, including Monkeypox virus (MPXV). The focus of this manuscript is to compare pathology associated with zoonotic OPXV infection in veterinary species and in humans. Efficient recognition of poxvirus lesions and other, more subtle signs of disease in multiple species is critical to prevent further spread of poxvirus infections. Additionally included are a synopsis of the pathology observed in animal models of MPXV infection, the recent spread of MPXV among humans, and a discussion of the potential for this virus to persist in Europe and the Americas. [ABSTRACT FROM AUTHOR]

As part of public health preparedness for infectious disease threats, CDC collaborates with other U.S. public health officials to ensure that the Laboratory Response Network (LRN) has diagnostic tools to detect Orthopoxviruses, the genus that includes Variola virus, the causative agent of smallpox. LRN is a network of state and local public health, federal, U.S. Department of Defense (DOD), veterinary, food, and environmental testing laboratories. CDC developed, and the Food and Drug Administration (FDA) granted 510(k) clearance* for the Non-variola Orthopoxvirus Real-time PCR Primer and Probe Set (non-variola Orthopoxvirus [NVO] assay), a polymerase chain reaction (PCR) diagnostic test to detect NVO. On May 17, 2022, CDC was contacted by the Massachusetts Department of Public Health (DPH) regarding a suspected case of monkeypox, a disease caused by the Orthopoxvirus Monkeypox virus. Specimens were collected and tested by the Massachusetts DPH public health laboratory with LRN testing capability using the NVO assay. Nationwide, 68 LRN laboratories had capacity to test approximately 8,000 NVO tests per week during June. During May 17-June 30, LRN laboratories tested 2,009 specimens from suspected monkeypox cases. Among those, 730 (36.3%) specimens from 395 patients were positive for NVO. NVO-positive specimens from 159 persons were confirmed by CDC to be monkeypox; final characterization is pending for 236. Prompt identification of persons with infection allowed rapid response to the outbreak, including isolation and treatment of patients, administration of vaccines, and other public health action. To further facilitate access to testing and increase convenience for providers and patients by using existing provider-laboratory relationships, CDC and LRN are supporting five large commercial laboratories with a national footprint (Aegis Science, LabCorp, Mayo Clinic Laboratories, Quest Diagnostics, and Sonic Healthcare) to establish NVO testing capacity of 10,000 specimens per week per laboratory. On July 6, 2022, the first commercial laboratory began accepting specimens for NVO testing based on clinician orders. [ABSTRACT FROM AUTHOR]

Background and Objective: The recent multi-country outbreak of human monkeypox (HMPX) in non-endemic regions poses an emerging public health concern. University students in health schools/faculties represent a core knowledgeable group that can be helpful to study from a public health point of view. As future healthcare workers, assessment of their knowledge and attitude towards emerging zoonotic viral infections can be helpful to assess their taught material and courses with potential improvement if gaps in knowledge were identified. Therefore, we aimed to evaluate the level of HMPX knowledge, conspiracy beliefs regarding emerging virus infections, as well as their associated determinants among university students studying Medicine, Nursing, Dentistry, Pharmacy, Medical Laboratory Sciences, and Rehabilitation in Jordanian health schools/faculties. In addition, we sought to evaluate the correlation between HMPX knowledge and the extent of holding conspiracy beliefs regarding emerging viral infection. Materials and Methods: A convenient sample of university students was obtained through an electronic survey distributed in late May 2022 using the chain-referral approach. Assessment of HMPX knowledge and general attitude towards emerging virus infections was based on survey items adopted from previously published literature. Results: The study sample comprised 615 students with a mean age of 20 years and a majority of females (432, 70.2%) and medical students (n = 351, 57.1%). Out of eleven monkeypox knowledge items, three were identified correctly by >70% of the respondents. Only 26.2% of the respondents (n = 161) knew that vaccination to prevent monkeypox is available. Age was significantly associated with better HMPX knowledge for a majority of items. Older age, females, and affiliation to non-medical schools/faculties were associated with harboring higher levels of conspiracy beliefs regarding emerging virus infections. Our data also indicate that lower levels of HMPX knowledge were associated with higher levels of conspiracy beliefs. Conclusion: The current study pointed to generally unsatisfactory levels of knowledge regarding the emerging HMPX among university students in Jordanian health schools/faculties. Conspiracy beliefs regarding emerging virus infections were widely prevalent, and its potential detrimental impact on health behavior should be evaluated in future studies. [ABSTRACT FROM AUTHOR]

There are several possible reasons for the return of smallpox as an endemic disease. For example, the possibility of maintaining smallpox virus in an active state in the corpses of the dead, buried in permafrost regions, or the evolutionary changes of orthopoxviruses with the appearance of more virulent strains. Since the eradication of smallpox, the requirements for smallpox vaccines have changed, leading to a change in the principles of smallpox vaccination. The purpose of the study is to review the evolution of means and principles of smallpox vaccination. For almost 200 years four generations of vaccine preparations have been developed. The first ones were the dermovaccines, i.e. the virus-containing detritus of calfskin. Then, chicken-embryo-skin cell cultures were used as a substrate for virus accumulation. The third generation were the vaccines based on vaccine strains at-tenuated by various methods. Fourth, DNA vaccines and subunit recombinant vaccines. One of the main contemporary principles of smallpox vaccination is safety (limited use of the vaccines of first and second generations, the development of next generations of vaccines, means and schemes of safe vaccination) while maintaining the requirements of efficiency equal to the existing vaccines. The replacement of epidemiologically tested vaccines with the third and fourth- generation drugs necessitated a comparative assessment of the protective efficacy and safety of new vaccines. It may be useful to carry out two-stage vaccination using inactivated or new safe nonreplicating the third and fourth generation vaccines at the first stage.

The purpose of this review is to give an up-to-date, thorough, and timely overview of monkeypox (Mpox), a severe infectious viral disease. Furthermore, this review provides an up-to-date treatment option for Mpox. The monkeypox virus (MPXV) has remained the most virulent poxvirus for humans since the elimination of smallpox approximately 41 years ago, with distribution mainly in central and west Africa. Mpox in humans is a zoonotically transferred disease that results in symptoms like those of smallpox. It had spread throughout west and central Africa when it was first diagnosed in the Republic of Congo in 1970. Mpox has become a major threat to global health security, necessitating a quick response by virologists, veterinarians, public health professionals, doctors, and researchers to create high-efficiency diagnostic tests, vaccinations, antivirals, and other infection control techniques. The emergence of epidemics outside of Africa emphasizes the disease’s global significance. A better understanding of Mpox’s dynamic epidemiology may be attained by increased surveillance and identification of cases.

Orthopoxviruses (OPVs), including the causative agents of smallpox and mpox have led to devastating outbreaks in human populations worldwide. However, the discontinuation of smallpox vaccination, which also provides cross-protection against related OPVs, has diminished global immunity to OPVs more broadly. We apply machine learning models incorporating both host ecological and viral genomic features to predict likely reservoirs of OPVs. We demonstrate that incorporating viral genomic features in addition to host ecological traits enhanced the accuracy of potential OPV host predictions, highlighting the importance of host-virus molecular interactions in predicting potential host species. We identify hotspots for geographic regions rich with potential OPV hosts in parts of southeast Asia, equatorial Africa, and the Amazon, revealing high overlap between regions predicted to have a high number of potential OPV host species and those with the lowest smallpox vaccination coverage, indicating a heightened risk for the emergence or establishment of zoonotic OPVs. Our findings can be used to target wildlife surveillance, particularly related to concerns about mpox establishment beyond its historical range., Competing Interests: Competing Interest Statement: The authors declare no competing interest.

Monkeypox virus (MPXV) has recently caused a global disease outbreak in humans. Differences in the neutralizing antibody response to vaccination vs. MPXV infection remain poorly understood. Here, we examined the neutralization of MPXV and VACV by sera from a cohort of convalescent and vaccinated individuals at 1- and 8-months post-exposure. Convalescent individuals displayed higher neutralizing antibody titers against MPXV than vaccinated and MPXV-naïve persons at one-month post-exposure. Neutralizing antibody titers had waned significantly in both groups at 8 months. This study suggests additional vaccine strategies are needed to elicit a durable humoral response and prevent breakthrough infections., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Poxviruses are dsDNA viruses infecting a wide range of cell types, where they need to contend with multiple host antiviral pathways, including DNA and RNA sensing. Accordingly, poxviruses encode a variety of immune antagonists, most of which are expressed early during infection from within virus cores before uncoating and genome release take place. Amongst these antagonists, the poxvirus immune nuclease (poxin) counteracts the cyclic 2'3'-GMP-AMP (2'3'-cGAMP) synthase (cGAS)/stimulator of interferon genes DNA sensing pathway by degrading the immunomodulatory cyclic dinucleotide 2'3'-cGAMP, the product of activated cGAS. Here, we use poxviruses engineered to lack poxin to investigate how virus infection triggers the activation of STING and its downstream transcription factor interferon-responsive factor 3 (IRF3). Our results demonstrate that poxin-deficient vaccinia virus (VACV) and ectromelia virus (ECTV) induce IRF3 activation in primary fibroblasts and differentiated macrophages, although to a lower extent in VACV compared to ECTV. In fibroblasts, IRF3 activation was detectable at 10 h post-infection (hpi) and was abolished by the DNA replication inhibitor cytosine arabinoside (AraC), indicating that the sensing was mediated by replicated genomes. In macrophages, IRF3 activation was detectable at 4 hpi, and this was not affected by AraC, suggesting that the sensing in this cell type was induced by genomes released from incoming virions. In agreement with this, macrophages expressing short hairpin RNA (shRNA) against the virus uncoating factor D5 showed reduced IRF3 activation upon infection. Collectively, our data show that the viral genome is sensed by cGAS prior to and during genome replication, but immune activation downstream of it is effectively suppressed by poxin. Our data also support the model where virus uncoating acts as an immune evasion strategy to simultaneously cloak the viral genome and allow the expression of early immune antagonists.

INTRODUCTION. Vaccination against smallpox was discontinued in 1980 following the success of the World Health Organization’s Smallpox Eradication Programme. Consequently, more than half of the current world population lacks immunity to orthopoxviruses pathogenic to humans. Since 2022, several countries have been reporting outbreaks of mpox (previously known as monkeypox), which necessitates developing new small molecules active against orthopoxviruses.AIM. The aim was to evaluate the safety and tolerability of NIOCH-14, a Russian anti-smallpox medicinal product, after oral administration in a phase I clinical trial.MATERIALS AND METHODS. The clinical trial was conducted in 90 healthy volunteers at the Federal State budgetary Institution of Healthcare ‘Medical and Sanitary Unit No. 163 of the Federal Medical and Biological Agency’ in accordance with Protocol No. NIOCH-01/20 ‘An open, simple, randomised study of the safety, tolerability, pharmacokinetics of NIOCH-14 in volunteers aged 18–50 years in parallel groups’. Investigators used a standard set of clinical, laboratory, and instrument-based testing methods. The clinical trial included six experimental groups of 15 subjects each. Groups 1, 2, and 3 received NIOCH-14 as a single oral dose of 200, 600, and 1200 mg, respectively. Groups 4, 5, and 6 received NIOCH-14 at daily oral doses of 200, 600, and 1200 mg/day, respectively, for 6 days.RESULTS. After single and repeated administration of NIOCH-14 at doses of 200, 600, and 1200 mg to volunteers, the study did not demonstrate any changes in the blood test results (erythrocyte, leucocyte, platelet, and differential leucocyte counts; haemoglobin levels; erythrocyte sedimentation rate values; alanine transaminase, aspartate transaminase, and alkaline phosphatase activity levels; total protein, total bilirubin, glucose, creatinine, urea, and C-reactive protein levels; prothrombin time ratios; thymol turbidity). Similarly, the urinalysis results remained unaltered throughout the entire observation period. No adverse events were observed in volunteers receiving NIOCH-14 at all single doses or repeated doses of 200 and 600 mg. One volunteer receiving the investigational medicinal product at a repeated dose of 1200 mg/day experienced transient epigastric pain on days 2 and 5.CONCLUSIONS. The physical examination, haematology, blood chemistry, and urinalysis results did not reveal any pathological changes in healthy volunteers. The investigational medicinal product, formulated as hard gelatin capsules containing 200 mg of NIOCH-14 and excipients, demonstrated a favourable safety and tolerability profile.REGISTRATION. This clinical trial is registered at ClinicalTrials.gov (NCT05976100).

Since May 2022, the multi-country outbreak of monkeypox (mpox) has raised a great concern worldwide. Early detection of mpox virus infection is recognized as an efficient way to prevent mpox transmission. Mpox specific detection methods reported up to now are based on the SNPs among mpox virus and other orthopoxviruses. We have therefore developed a real-time PCR based mpox detection method targeting mpox virus specific sequences (N3R and B18Rplus). We have also optimized an orthopoxvirus detection system which targets the highly conserved E9L and D6R genes. The mpox and orthopoxvirus real-time PCR assays have a high sensitivity (1 copy/reaction) and specificity. Mpox viral DNA and clinical samples from mpox patients are detected with the mpox detection system. Furthermore, we have established a multiplex real-time PCR detection system allowing simultaneous and efficient detection of mpox and orthopoxvirus infections. • A new mpox detection method based on mpox virus specific sequences. • The mpox and orthopoxvirus real-time PCR assays have a high sensitivity (1 copy/reaction). • New multiplex real-time PCR system allows simultaneous and efficient detection of mpox and orthopoxvirus infections. [ABSTRACT FROM AUTHOR]

Different kinds of media spiked with monkeypox virus (MPXV) were subjected to heat inactivation at different temperatures for various periods of time. The results showed that MPXV was inactivated in less than 5 min at 70 °C and less than 15 min at 60 °C, with no difference between viruses from the West African and Central African clades. The present findings could help laboratory workers to manipulate MPXV in optimal biosafety conditions and improve their protocols. [ABSTRACT FROM AUTHOR]

Introduction. The abolition of smallpox vaccination has led to the disappearance of population immunity to pox viruses. However, the threat of infection by pathogenic orthopoxviruses persists and determines the need to develop sensitive and operational methods for indicating pathogens. Objectives and purposes. Development of a sensitive, fast and easy-to-use immunochemical test for the detection of orthopoxviruses in the «point of care» format. Material and methods. We used preparations of cultural vaccinia virus (VV) with varying degrees of purification, polyclonal antibodies from hyperimmune rabbit serum, and equipment from a previously developed autonomous kit for dot-immunoassay on flat protein arrays. Results and discussion. It has been established that rabbit polyclonal antibodies can be used in a single-stage dotanalysis, both as a capture agent immobilized on a substrate and as a detection reagent bound with colloidal gold particles. It is shown that the effectiveness of the detection of VV is inversely related to the degree of purification of viruses from sub-viral structures. The sensitivity of the rapid detection of viruses in a crude preparation was about 30 times higher than in pure viral material. The increase in sensitivity, presumably, occurs due to binding to the capture antibodies of subviral structures, which form large aggregates of sensitized gold particles. The test does not detect cross-reactions with heterogeneous viruses (measles, rubella and chickenpox) that cause exantematous diseases. Conclusion. The one-stage variant of the dot-immunoassay reduces the analysis time to 40 minutes and improves the detection sensitivity of orthopoxviruses in crude viral preparations to the range of 105-104 PFU / ml. Full makeup, ease of analysis and the ability to visually accounting for results allow the test to be used outside of laboratories.

The review contains a brief analysis of the results of investigations conducted during 40 years after smallpox eradication and directed to study genomic organization and evolution of variola virus (VARV) and development of modern diagnostics, vaccines and chemotherapies of smallpox and other zoonotic orthopoxviral infections of humans. Taking into account that smallpox vaccination in several cases had adverse side effects, WHO recommended ceasing this vaccination after 1980 in all countries of the world. The result of this decision is that the mankind lost the collective immunity not only to smallpox, but also to other zoonotic orthopoxvirus infections. The ever more frequently recorded human cases of zoonotic orthopoxvirus infections force to renew consideration of the problem of possible smallpox reemergence resulting from natural evolution of these viruses. Analysis of the available archive data on smallpox epidemics, the history of ancient civilizations, and the newest data on the evolutionary relationship of orthopoxviruses has allowed us to hypothesize that VARV could have repeatedly reemerged via evolutionary changes in a zoonotic ancestor virus and then disappeared because of insufficient population size of isolated ancient civilizations. Only the historically last smallpox pandemic continued for a long time and was contained and stopped in the 20th century thanks to the joint efforts of medics and scientists from many countries under the aegis of WHO. Thus, there is no fundamental prohibition on potential reemergence of smallpox or a similar human disease in future in the course of natural evolution of the currently existing zoonotic orthopoxviruses. Correspondingly, it is of the utmost importance to develop and widely adopt state-of-the-art methods for efficient and rapid species-specific diagnosis of all orthopoxvirus species pathogenic for humans, VARV included. It is also most important to develop new safe methods for prevention and therapy of human orthopoxvirus infections.

The aim of the work was an experimental evaluation of the characteristics of the kit for the rapid immunochemical detection of orthopoxviruses (OPV). The kit is based on the method of one-stage dot-immunoassay on flat protein arrays using gold conjugates and a silver developer. Rabbit polyclonal antibodies against the vaccinia virus were used as capture and detection reagents. The sensitivity of detection of OPV and the specificity of the analysis were assessed using culture crude preparations (monkeypox virus, vaccinia virus, rabbitpox virus, cowpox virus, and ectromelia virus), a suspension from a crust from a human vaccination site as well as blood and tissue suspensions of infected rabbits. It has been shown that the assay using the kit makes it possible to detect OPV within 36 min at a temperature of 18–40 °C in unpurified culture samples of the virus and clinical samples in the range of 103–104 PFU/mL. Tests of the kit did not reveal cross-reactivity with uninfected cell cultures and viral pathogens of exanthematous infections (measles, rubella and chicken pox). The kit can be used to detect or exclude the presence of a virus threat in samples and can be useful in various aspects of biosecurity. The simplicity of analysis, the possibility of visual accounting the and interpretation of the results make it possible to use the test in laboratories with a high level of biological protection and in out-of-laboratory conditions.

Alkaloid-like angular 6/6/5/6-annulated pyrano[4,3-b]pyrroles (pretazettine analogs) contain chemically labile groups that can react with water at room temperature. Their antiviral activity against Vaccinia virus and their tendency to hydrolysis were investigated. Compounds that were more resistant to hydrolysis exhibited the greatest antiviral activity. [ABSTRACT FROM AUTHOR]

Orthopoxviruses produce two antigenically distinct infectious enveloped virions termed intracellular mature virions and extracellular virions (EV). EV have an additional membrane compared to intracellular mature virions due to a wrapping process at the trans-Golgi network and are required for cell-to-cell spread and pathogenesis. Specific to the EV membrane are a number of proteins highly conserved among orthopoxviruses, including F13, which is required for the efficient wrapping of intracellular mature virions to produce EV and which plays a role in EV entry. The distantly related molluscipoxvirus, molluscum contagiosum virus, is predicted to encode several vaccinia virus homologs of EV-specific proteins, including the homolog of F13L, MC021L. To study the function of MC021, we replaced the F13L open reading frame in vaccinia virus with an epitope-tagged version of MC021L. The resulting virus (vMC021L-HA) had a small-plaque phenotype compared to vF13L-HA but larger than vF13L. The localization of MC021-HA was markedly different from that of F13-HA in infected cells, but MC021-HA was still incorporated in the EV membrane. Similar to F13-HA, MC021-HA was capable of interacting with both A33 and B5. Although MC021-HA expression did not fully restore plaque size, vMC021L-HA produced amounts of EV similar to those produced by vF13L-HA, suggesting that MC021 retained some of the functionality of F13. Further analysis revealed that EV produced from vMC021L-HA exhibit a marked reduction in target cell binding and an increase in dissolution, both of which correlated with a small-plaque phenotype. [ABSTRACT FROM AUTHOR]

Introduction: The global eradication of smallpox and abandonment of mandatory smallpox vaccination has led to an increased proportion of the population who are immunologically naïve to infections caused by Orthopoxviruses (OPV). Aim: To present the different courses of OPV infection in children and to highlight the diagnostic difficulties in their differentiation from the other inflammatory processes. Material and methods: We retrospectively evaluated the medical documentation of 5 children with OPV infection. Clinical diagnosis of OPV infection was based on evaluation of animal contact and skin symptoms, characterised by either a single ulcer or disseminated lesions. In all five cases, blood samples and skin swabs were collected from the lesion(s) to identify specific OPV DNA fragments (Vgf, b9R and D11L genes) using PCR. Results: Two children presented with high fever, a single ulcer on the skin and local lymphadenopathy. The three other patients were in good general health and their skin lesions presented as a disseminated vesicular rash. Using the Vgf gene as the target for PCR, OPV infection was confirmed in material collected from skin lesions of all children and in blood samples of 4 children. The B9R and d11L genes tested positive in the skin material of 2 children and blood samples of 2 children. All analysed patients presented a history of ineffective antibiotic therapy. Conclusions: In the case of unclear necrotising skin lesions in children, the primary diagnosis always includes bacterial dermatitis. However, if the patient has come into contact with animals, diagnosis of OPV infection should also be considered. [ABSTRACT FROM AUTHOR]

Orthopoxviruses (OPXVs) are an increasing threat to human health due to the growing population of OPXV-naive individuals after the discontinuation of routine smallpox vaccination. Antiviral drugs that are effective as postexposure treatments against variola virus (the causative agent of smallpox) or other OPXVs are critical in the event of an OPXV outbreak or exposure. The only US Food and Drug Administration-approved drug to treat smallpox, Tecovirimat (ST-246), exerts its antiviral effect by inhibiting extracellular virus (EV) formation, thereby preventing cell–cell and long-distance spread. We and others have previously demonstrated that host Golgi-associated retrograde proteins play an important role in monkeypox virus (MPXV) and vaccinia virus (VACV) EV formation. Inhibition of the retrograde pathway by small molecules such as Retro-2 has been shown to decrease VACV infection in vitro and to a lesser extent in vivo. To identify more potent inhibitors of the retrograde pathway, we screened a large panel of compounds containing a benzodiazepine scaffold like that of Retro-1, against VACV infection. We found that a subset of these compounds displayed better anti-VACV activity, causing a reduction in EV particle formation and viral spread compared to Retro-1. PA104 emerged as the most potent analog, inhibiting 90% viral spread at 1.3 μM with a high selectivity index. In addition, PA104 strongly inhibited two distinct ST-246-resistant viruses, demonstrating its potential benefit for use in combination therapy with ST-246. These data and further characterizations of the specific protein targets and in vivo efficacy of PA104 may have important implications for the design of effective antivirals against OPXV. [ABSTRACT FROM AUTHOR]

Orthopoxviruses produce two, antigenically distinct, infectious enveloped virions termed intracellular mature virions and extracellular virions. Extracellular virions are required for cell- to-cell spread and pathogenesis. Specific to the extracellular virion membrane, glycoproteins A33, A34, and B5 are highly conserved among orthopoxviruses and have roles during extracellular virion formation and subsequent infection. B5 is dependent on an interaction with either A33 or A34 for localization to the site of intracellular envelopment and incorporation into the envelope of released extracellular virions. In this report we show that an interaction between A33 and A34 can be detected in infected cells. Furthermore, we show that a three-protein complex between A33, A34, and B5 forms in the ER that disassociates post ER export. Finally, immunofluorescence reveals that co-expression of all three glycoproteins results in their localization to a juxtanuclear region that is presumably the site of intracellular envelopment. These results demonstrate the existence of two previously unidentified interactions; one between A33 and A34 and another simultaneous interaction between all three of the glycoproteins. Furthermore, these results indicate that interactions amongst A33, A34, and B5 are vital for proper intracellular trafficking and subcellular localization. [ABSTRACT FROM AUTHOR]

The monkeypox (Mpox) virus has raised significant concerns given its recent spread with an increasing number of confirmed cases worldwide. In this study, we evaluated the performance of a laboratory developed test (LDT) using BioGX Xfree hMPXV/OPXV reagents for the qualitative detection of non-variola Orthopoxviruses and Mpox virus DNA, in swabs from human pustular or vesicular rash specimens. Analytical and clinical testing analysis were carried out on two different platforms: the BD MAX™ System (BD Diagnostics) and the new pixl.16 Real-Time PCR Platform (BioGX), using a synthetic Mpox virus DNA (ATCC VR-3270SD) and residual clinical samples previously identified with an EUA approved Mpox real-time PCR assay. In the end, the Xfree hMPXV/OPXV LDT proved to be a sensitive, specific, and reproducible test for the detection of Mpox on both platforms evaluated with the pixl.16 having an advantage of a small footprint and providing faster TAT facilitated by an extraction-free workflow. [ABSTRACT FROM AUTHOR]

The vaccinia virus (VACV) has been used for prophylactic immunization against smallpox for many decades. However, the VACV-based vaccine had been highly reactogenic. Therefore, after the eradication of smallpox, the World Health Organization in 1980 recommended that vaccination against this infection be discontinued. As a result, there has been a rise in the occurrence of orthopoxvirus infections in humans in recent years, with the most severe being the 2022 monkeypox epidemic that reached all continents. Thus, it is crucial to address the pressing matter of developing safe and highly immunogenic vaccines for new generations to combat orthopoxvirus infections. In a previous study, we created a LAD strain by modifying the LIVP (L) VACV strain, which is used as a first-generation smallpox vaccine in Russia. This modification involved introducing mutations in the A34R gene to enhance extracellular virion production and deleting the A35R gene to counteract the antibody response to the viral infection. In this study, a strain LADA was created with an additional deletion in the DNA of the LAD strain ati gene. This ati gene directs the production of a major non-virion immunogen. The findings indicate that the LADA VACV variant exhibits lower levels of reactogenicity in BALB/c mice during intranasal infection, as compared to the original L strain. Following intradermal immunization with a 105 PFU dose, both the LAD and LADA strains were found to induce a significantly enhanced cellular immune response in mice when compared to the L strain. At the same time, the highest level of virus-specific IFN-γ producing cells for the LAD variant was detected on the 7 th day post-immunization (dpi), whereas for LADA, it was observed on 14 dpi. The LAD and LADA strains induced significantly elevated levels of VACV-specific IgG compared to the original L strain, particularly between 28 and 56 dpi. The vaccinated mice were intranasally infected with the cowpox virus at a dose of 460 LD 50 to assess the protective immunity at 62 dpi. The LADA virus conferred complete protection to mice, with the LAD strain providing 70% protection and the parent strain L offering protection to only 60% of the animals., (Copyright ® 2024 National Research University Higher School of Economics.)

Objective: To describe varicella cases in Tshuapa Province of the Democratic Republic of the Congo identified during monkeypox surveillance.Methods: Demographic, clinical and epidemiological data were collected from each suspected monkeypox case 2009-2014. Samples were tested by PCR for both Orthopoxviruses and varicella-zoster virus (VZV); a subset of VZV-positive samples was genotyped. We defined a varicella case as a rash illness with laboratory-confirmed VZV.Results: There were 366 varicella cases were identified; 66% were ≤19 years old. Most patients had non-typical varicella rash with lesions reported as the same size and stage of evolution (86%), deep and profound (91%), on palms of hands and/or soles of feet (86%) and not itchy (49%). Many had non-typical signs and symptoms, such as lymphadenopathy (70%) and sensitivity to light (23%). A higher proportion of persons aged ≥20 years than persons aged ≤19 years had ≥50 lesions (79% vs. 65%, P = 0.007) and were bedridden (15% vs. 9%, P = 0.056). All VZV isolates genotyped from 79 varicella cases were clade 5. During the surveillance period, one possible VZV-related death occurred in a 7-year-old child.Conclusions: A large proportion of patients presented with non-typical varicella rash and clinical signs and symptoms, highlighting challenges identifying varicella in an area with endemic monkeypox. Continued surveillance and laboratory diagnosis will help in rapid identification and control of both monkeypox and varicella and improve our understanding of varicella epidemiology in Africa. [ABSTRACT FROM AUTHOR]

Orthopoxviruses (OPXVs) have a broad host range in mammalian cells, but Chinese hamster ovary (CHO) cells are non-permissive for vaccinia virus (VACV). Here, we revealed a species-specific difference in host restriction factor SAMD9L as the cause for the restriction and identified orthopoxvirus CP77 as a unique inhibitor capable of antagonizing Chinese hamster SAMD9L (chSAMD9L). Two known VACV inhibitors of SAMD9 and SAMD9L (SAMD9&L), K1 and C7, can bind human and mouse SAMD9&L, but neither can bind chSAMD9L. CRISPR-Cas9 knockout of chSAMD9L from CHO cells removed the restriction for VACV, while ectopic expression of chSAMD9L imposed the restriction for VACV in a human cell line, demonstrating that chSAMD9L is a potent restriction factor for VACV. Contrary to K1 and C7, cowpox virus CP77 can bind chSAMD9L and rescue VACV replication in cells expressing chSAMD9L, indicating that CP77 is yet another SAMD9L inhibitor but has a unique specificity for chSAMD9L. Binding studies showed that the N-terminal 382 amino acids of CP77 were sufficient for binding chSAMD9L and that both K1 and CP77 target a common internal region of SAMD9L. Growth studies with nearly all OPXV species showed that the ability of OPXVs in antagonizing chSAMD9L correlates with CP77 gene status and that a functional CP77 ortholog was maintained in many OPXVs, including monkeypox virus. Our data suggest that species-specific difference in rodent SAMD9L poses a barrier for cross-species OPXV infection and that OPXVs have evolved three SAMD9&L inhibitors with different specificities to overcome this barrier. IMPORTANCE: Several OPXV species, including monkeypox virus and cowpox virus, cause zoonotic infection in humans. They are believed to use wild rodents as the reservoir or intermediate hosts, but the host or viral factors that are important for OPXV host range in rodents are unknown. Here, we showed that the abortive replication of several OPXV species in a Chinese hamster cell line was caused by a species-specific difference in the host antiviral factor SAMD9L, suggesting that SAMD9L divergence in different rodent species poses a barrier for cross-species OPXV infection. While the Chinese hamster SAMD9L could not be inhibited by two previously identified OPXV inhibitors of human and mouse SAMD9&L, it can be inhibited by cowpox virus CP77, indicating that OPXVs encode three SAMD9&L inhibitors with different specificity. Our data suggest that OPXV host range in broad rodent species depends on three SAMD9&L inhibitors with different specificities. [ABSTRACT FROM AUTHOR]

In response to the 2022 outbreak of mpox driven by unprecedented human-to-human monkeypox virus (MPXV) transmission, we designed BNT166, aiming to create a highly immunogenic, safe, accessible, and scalable next-generation vaccine against MPXV and related orthopoxviruses. To address the multiple viral forms and increase the breadth of immune response, two candidate multivalent mRNA vaccines were evaluated pre-clinically: a quadrivalent vaccine (BNT166a; encoding the MPXV antigens A35, B6, M1, H3) and a trivalent vaccine (BNT166c; without H3). Both candidates induced robust T cell responses and IgG antibodies in mice, including neutralizing antibodies to both MPXV and vaccinia virus. In challenge studies, BNT166a and BNT166c provided complete protection from vaccinia, clade I, and clade IIb MPXV. Furthermore, immunization with BNT166a was 100% effective at preventing death and at suppressing lesions in a lethal clade I MPXV challenge in cynomolgus macaques. These findings support the clinical evaluation of BNT166, now underway (NCT05988203). [Display omitted] • BNT166 is a multivalent mRNA orthopoxvirus vaccine encoding MPXV antigens A35, B6, M1, H3 • It elicits robust antibody and T cell responses to EV and MV antigens • Immunization protects mice from VACV, clade I and IIb MPXV, and NHPs from clade I MPXV • Clinical evaluation of BNT166 safety and immunogenicity is ongoing (NCT05988203) In 2022–2023, unprecedented outbreaks of clades I and IIb monkeypox virus driven by human-to-human transmission demonstrated a need for rapidly scalable and deployable vaccines against orthopoxviruses. BNT166 is a multivalent mpox mRNA vaccine that shows efficacy in multiple preclinical models, supporting its further study in clinical trials. [ABSTRACT FROM AUTHOR]

Objective of the study is to develop and validate the method for species-specific detection of cowpox virus (CPV). Materials and methods. Utilized were oligonucleotide primers and fluorescence-labeled probes for genus-specific detection of orthopoxviruses (OPV) and species-specific detection of cowpox and ectromelia viruses (EV). Pairs of fluorescent dyes and corresponding fluorescence extinguishers were embodied into probes in accordance with their specificity: OPV-specific probe contained FAM/BHQ1 pair, CPVspecific probe – JOE/BHQ1, and EV-specific – Cy5/BHQ3. For evaluation of sensitivity and specificity of the method for species-specific detection of CPV, investigated were samples of 68 different strains of orthopoxviruses. Results and conclusions. Implemented was complex approach to species-specific detection of CPV using multiplex real-time PCR variant for simultaneous multilocus detection on the basis of three independent target genes of CPV, to genus-specific detection for the exclusion of false-negative results, and additional oligonucleotide primers and probes, providing for specific detection of EV, aimed at the exclusion of false-positive results.

Monkeypox is a zoonotic disease caused by monkeypox virus (MPXV), which is a member of orthopoxvirus genus. The reemergence of MPXV in 2017 (at Bayelsa state) after 39 years of no reported case in Nigeria, and the export of travelers’ monkeypox (MPX) from Nigeria to other parts of the world, in 2018 and 2019, respectively, have raised concern that MPXV may have emerged to occupy the ecological and immunological niche vacated by smallpox virus. This review X-rays the current state of knowledge pertaining the infection biology, epidemiology, and evolution of MPXV in Nigeria and worldwide, especially with regard to the human, cellular, and viral factors that modulate the virus transmission dynamics, infection, and its maintenance in nature. This paper also elucidates the role of recombination, gene loss and gene gain in MPXV evolution, chronicles the role of signaling in MPXV infection, and reviews the current therapeutic options available for the treatment and prevention of MPX. Additionally, genome-wide phylogenetic analysis was undertaken, and we show that MPXV isolates from recent 2017 outbreak in Nigeria were monophyletic with the isolate exported to Israel from Nigeria but do not share the most recent common ancestor with isolates obtained from earlier outbreaks, in 1971 and 1978, respectively. Finally, the review highlighted gaps in knowledge particularly the non-identification of a definitive reservoir host animal for MPXV and proposed future research endeavors to address the unresolved questions.

Buffalopox virus (BPXV) is the cause of buffalopox, which was recognized by the FAO/WHO Joint Expert Committee on Zoonosis as an important zoonotic disease. Buffalopox was first described in India, later in other countries, and has become an emerging contagious viral zoonotic disease infecting milkers with high morbidity among affected domestic buffalo and cattle. BPXV is a member of the genus Orthopoxvirus and a close variant of the vaccinia virus (VACV). Recent genome data show that BPXV shares a most recent common ancestor of VACV Lister strain, which had been used for inoculating buffalo calves to produce a Smallpox vaccine. Over time, VACV evolved into BPXV by establishing itself in buffaloes to be increasingly pathogenic to this host and to make infections in cattle and humans. Together with the current pandemic of SARS-COV2/COVID 19, BPXV infections illustrate how vulnerable the human population is to the emergence and re-emergence of viral pathogens from unsuspected sources. In view that majority of the world population are not vaccinated against smallpox and are most vulnerable in the event of its re-emergence, reviewing and understanding the biology of vaccinia-like viruses are necessary for developing a new generation of safer smallpox vaccines in the smallpox-free world.

Camelpox virus is the causative agent of Camelpox, a highly contagious disease of camels. A high passage Camelpox virus strain has previously been reported to contain several genes which more closely resemble Vaccinia, a virus species with no known natural host, encompassing various strains that show high inter-strain genomic variation. In this study, we demonstrate that yet another high passage, live attenuated vaccine, comprising a different strain of Camelpox virus, contains genomic sequences that match a differing strain of Vaccinia virus. These results are discussed in the context of hypotheses put forward to explain the unknown origins of Vaccinia virus, suggesting further studies to elucidate evolutionary trajectories of Orthopoxviruses through passaging. [ABSTRACT FROM AUTHOR]

Live viral vaccines elicit protective, long-lived humoral immunity, but the underlying mechanisms through which this occurs are not fully elucidated. Generation of affinity matured, long-lived protective antibody responses involve close interactions between T follicular helper (TFH) cells, germinal center (GC) B cells, and T follicular regulatory (TFR) cells. We postulated that escalating concentrations of antigens from replicating viruses or live vaccines, spread through the hematogenous route, are essential for the induction and maintenance of long-lived protective antibody responses. Using replicating and poorly replicating or nonreplicating orthopox and influenza A viruses, we show that the magnitude of TFH cell, GC B cell, and neutralizing antibody responses is directly related to virus replicative capacity. Further, we have identified that both lymphoid and circulating TFH:TFR cell ratios during the peak GC response can be used as an early predictor of protective, long-lived antibody response induction. Finally, administration of poorly or nonreplicating viruses to allow hematogenous spread generates significantly stronger TFH:TFR ratios and robust TFH, GC B cell and neutralizing antibody responses. [ABSTRACT FROM AUTHOR]

Double‐stranded RNA‐activated protein kinase R (PKR) is an important and rapidly evolving antiviral kinase. Most poxviruses contain two distinct PKR inhibitors, called E3 and K3 in vaccinia virus (VACV), the prototypic orthopoxvirus. E3 prevents PKR homodimerization by binding double‐stranded RNA, while K3 acts as a pseudosubstrate inhibitor by binding directly to activated PKR and thereby inhibiting interaction with its substrate eIF2α. In our study here, we analyzed E3 and K3 orthologs from the phylogenetically distinct capripoxviruses (CaPVs), which include lumpy skin disease virus, sheeppox virus, and goatpox virus. Whereas the sheeppox virus E3 ortholog did not substantially inhibit PKR, all three CaPV K3 orthologs showed species‐specific inhibition of PKR, with strong inhibition of sheep, goat, and human PKR but only weak inhibition of cow and mouse PKR. In contrast, VACV K3 strongly inhibited cow and mouse PKR but not sheep, goat, or human PKR. Infection of cell lines from the respective species with engineered VACV strains that contained different K3 orthologs showed a good correlation of PKR inhibition with virus replication and eIF2α phosphorylation. Our results show that K3 orthologs can have dramatically different effects on PKR of different species and indicate that effective PKR inhibition by K3 orthologs is crucial for virus replication. Even closely related viruses can display dramatic differences in their host range and virulence; however, the molecular mechanisms underlying these differences are poorly understood. This study shows that an antiviral host protein (PKR) is inhibited by poxvirus proteins in both a host‐ and virus‐specific fashion. Effective PKR inhibition correlated with virus replication in cell lines from many different species, including aberrant hosts such as humans. These data suggest that evolving resistance against one viral antagonist may come at the price of making PKR more sensitive to more distantly related PKR inhibitors in a so‐far‐unpredictable manner. [ABSTRACT FROM AUTHOR]

Ectromelia virus (ECTV) is an orthopoxvirus that productively replicates in dendritic cells (DCs), but its influence on the microtubule (MT) cytoskeleton in DCs is not known. Here, we show that ECTV infection of primary murine granulocyte-macrophage colony stimulating factor-derived bone marrow cells (GM-BM) downregulates numerous genes engaged in MT cytoskeleton organization and dynamics. In infected cells, the MT cytoskeleton undergoes dramatic rearrangement and relaxation, accompanied by disappearance of the microtubule organizing centre (MTOC) and increased acetylation and stabilization of MTs, which are exploited by progeny virions for intracellular transport. This indicates a strong ability of ECTV to subvert the MT cytoskeleton of highly specialized immune cells. [ABSTRACT FROM AUTHOR]

Even nearly forty years after the eradication of smallpox, members of the Poxviridae family continue to be the focus of an increasing number of studies. Among these studies, prominently stands vaccinia virus, an orthopoxvirus that is associated with bovine vaccinia outbreaks. Although more frequently associated with infections in cattle and humans, the host range of vaccinia virus is not restricted only to these hosts. There are several instances of molecular and serological evidence of circulation of vaccinia virus among wildlife species. In addition, viral isolation has confirmed a broad spectrum of vaccinia virus hosts. In this report, we provide a brief update on the host range of Brazilian vaccinia virus, and present a case description of an outbreak in domestic buffalo calves from Northeastern Brazil that corroborates previous serological and molecular studies. Furthermore, in the present study, vaccinia virus has been isolated for the first time in buffaloes, and referred to as vaccinia virus Pernambuco (VACV-PE). Phylogenetic reconstruction was based on A56R clustered VACV-PE with vaccinia virus isolates belonging to group 1 Brazilian vaccinia virus. Furthermore, the vaccinia virus genome was detected in the milk of a lactating cow, which thereby revealed a pathway for future studies on the possible impact of vaccinia virus on buffalo milk and milk products. Taken together, these results provide the first description of clinical disease caused by vaccinia virus in buffaloes in South America. They also raise new questions about the chain of transmission of this virus. [ABSTRACT FROM AUTHOR]

Orthopoxviruses (OPVs) have broad host range infecting a variety of species along with gene‐specific determinants. Several genes including haemagglutinin (HA) are used for differentiation of OPVs. Among poxviruses, OPVs are sole members encoding HA protein as part of extracellular enveloped virion membrane. Camelpox virus (CMLV) causes an important contagious disease affecting mainly young camels, endemic to Indian subcontinent, Africa and the Middle East. This study describes the sequence features and phylogenetic analysis of HA gene (homologue of VACV A56R) of Indian CMLV isolates. Comparative analysis of CMLV HA gene revealed conserved nature within CMLVs but considerable variability was observed between various species of OPVs. Most Indian CMLV isolates showed 99.5%–100% and 96.3%–100% identity, at nucleotide (nt) and amino acid (aa) levels respectively, among themselves and with CMLV‐M96 strain. Importantly, Indian CMLV strains along with CMLV‐M96 showed deletion of seven nucleotides resulting in frameshift mutation at C‐terminus of HA protein. Phylogenetic analysis displayed distinct clustering among CMLVs which might point to the circulation of diverse CMLV strains in nature. Despite different host specificity of OPVs, comparative sequence analysis of HA protein showed highly conserved N‐terminal Ig V‐set functional domain with tandem repeats. Understanding of molecular diversity of CMLVs and structural domains of HA protein will help in the elucidation of molecular mechanisms for immune evasion and design of novel antivirals for OPVs. [ABSTRACT FROM AUTHOR]