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Introduction. In some species, the population structure of pathogenic bacteria is clonal. However, the mechanisms that determine the predominance and persistence of specific bacterial lineages of group C Streptococcus remain poorly understood. In Brazil, a previous study revealed the predominance of two main lineages of Streptococcus dysgalactiae subsp. equisimilis (SDSE). Aim. The aim of this study was to assess the virulence and fitness advantages that might explain the predominance of these SDSE lineages for a long period of time. Methodology. emm typing was determined by DNA sequencing. Adhesion and invasion tests were performed using human bronchial epithelial cells (16HBE14o-). Biofilm formation was tested on glass surfaces and the presence of virulence genes was assessed by PCR. Additionally, virulence was studied using Caenorhabditis elegans models and competitive fitness was analysed in murine models. Results. The predominant lineages A and B were mostly typed as emm stC839 and stC6979, respectively. Notably, these lineages exhibited a superior ability to adhere and invade airway cells. Furthermore, the dominant lineages were more prone to induce aversive olfactory learning and more likely to kill C. elegans. In the competitive fitness assays, they also showed increased adaptability. Consistent with the increased virulence observed in the ex vivo and in vivo models, the predominant lineages A and B showed a higher number of virulence-associated genes and a superior ability to accumulate biofilm. Conclusion. These results suggest strongly that this predominance did not occur randomly but rather was due to adaptive mechanisms that culminated in increased colonization and other bacterial properties that might confer increased bacteria–host adaptability to cause disease.

BACKGROUND The high demand for adequate material for the gold standard reverse transcription real-time polymerase chain reaction (RT-qPCR)-based diagnosis imposed by the Coronavirus disease 2019 (COVID-19) pandemic, combined with the inherent contamination risks for healthcare workers during nasopharyngeal swab (NP) sample collection and the discomfort it causes patients, brought the need to identify alternative specimens suitable for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). OBJECTIVES The aim of this work was to compare saliva and gingival fluid swabs to NP swabs as specimens for RT-qPCR-based SARS-CoV-2 diagnosis. METHODS We compared gingival fluid swabs (n = 158) and saliva (n = 207) to the rayon-tipped NP swabs obtained from mild-symptomatic and asymptomatic subjects as specimens for RT-qPCR for SARS-CoV-2 detection. FINDINGS When compared to NP swabs, gingival fluid swabs had a concordance rate of 15.4% among positive samples, zero among inconclusive, and 100% among negative ones. For saliva samples, the concordance rate was 67.6% among positive samples, 42.9% among inconclusive, and 96.8% among negative ones. However, the concordance rate between saliva and NP swabs was higher (96.9%) within samples with lower cycle threshold (Ct) values (Ct > 10 ≤ 25). MAIN CONCLUSIONS Our data suggests that whereas gingival fluid swabs are not substitutes for NP swabs, saliva might be considered whenever NP swabs are not available or recommended.

Vaccines are a recommended strategy for controlling influenza A infections in humans and animals. Here, we describe the effects of hydrostatic pressure on the structure, morphology and functional characteristics of avian influenza A H3N8 virus. The effect of hydrostatic pressure for 3 h on H3N8 virus revealed that the particles were resistant to this condition, and the virus displayed only a discrete conformational change. We found that pressure of 3 kbar applied for 6 h was able to inhibit haemagglutination and infectivity while virus replication was no longer observed, suggesting that full virus inactivation occurred at this point. However, the neuraminidase activity was not affected at this approach suggesting the maintenance of neutralizing antibody epitopes in this key antigen. Our data bring important information for the area of structural virology of enveloped particles and support the idea of applying pressure-induced inactivation as a tool for vaccine production.

Background Avian influenza A viruses can cross naturally into mammals and cause severe diseases, as observed for H5N1. The high lethality of human infections causes major concerns about the real risk of a possible pandemic of severe diseases to which human susceptibility may be high and universal. High hydrostatic pressure (HHP) is a valuable tool for studies regarding the folding of proteins and the assembly of macromolecular structures such as viruses; furthermore, HHP has already been demonstrated to promote viral inactivation. Methods Here, we investigated the structural stability of avian and human influenza viruses using spectroscopic and light-scattering techniques. We found that both particles have similar structural stabilities and that HHP promotes structural changes. Results HHP induced slight structural changes to both human and avian influenza viruses, and these changes were largely reversible when the pressure returned to its initial level. The spectroscopic data showed that H3N2 was more pressure-sensitive than H3N8. Structural changes did not predict changes in protein function, as H3N2 fusion activity was not affected, while H3N8 fusion activity drastically decreased. The fusion activity of H1N1 was also strongly affected by HHP. In all cases, HHP caused inactivation of the different influenza viruses. Conclusions HHP may be a useful tool for vaccine development, as it induces minor and reversible structural changes that may be associated with partial preservation of viral biological activities and may potentiate their immunogenic response while abolishing their infectivity. We also confirmed that, although pressure does not promote drastic changes in viral particle structure, it can distinctly affect viral fusion activity.

Background: Influenza affects thousands of people worldwide every year, motivating the development of new therapies. In this work, the effects of two homeopathic preparations (influenza biotherapies and thymulin) were chosen following two different rationales: isotherapy and endo-isotherapy models. The homeopathic effects were evaluated individually considering the inflammatory and behavioral responses against influenza virus antigen were studied in BALB/c mice.Methods: Male adult mice were treated orally and blindly for 21 days with highly diluted influenza virus or with thymulin, and were divided in two sets of experiments. The first series of experiments aimed to describe their behavior, using an open field (OF) device. In the second series, mice were challenged subcutaneously with influenza hemagglutinin antigen (7 μg/200 μl) at day 21. At day 42, behavior and inflammation response were evaluated.Results: No behavioral changes were seen in OF tests at any time point after treatments. Flow cytometry and morphometry revealed significant changes in T and B cell balance after influenza antigen challenge, varying according to treatment.Conclusion: The results show that both homeopathic treatments induced subtle changes in acquired immune anti-viral response regulation. A deeper understanding of the mechanism could elucidate their possible use in influenza epidemiological situations.

Aims: To determine the frequency of viral pathogens causing upper respiratory tract infections in non-hospitalized, symptomatic adults in the city of Rio de Janeiro. Methods: Respiratory samples (nasal/throat swabs) were collected between August 2010 and November 2012 and real time PCR was used to detect different viral pathogens. Results: Viruses were detected in 32.1% (43/134) of samples from 101 patients. Specifically, 9% (12/134) were positive for HBoV, 8.2% (11/134) were positive for HAdV, 5.2% (7/134) were positive for HRV, and 1.5% (2/134) were positive for FLUBV or HMPV, as single infections. HRSV-A, HPIV-3, and HCoV-HKU1 were detected in one (0.75%) sample each. Co-infections were detected in 4.8% (6/134) of the samples. Peaks of viral infections were observed in March, April, May, August, and October. However, positive samples were detected all year round. Only 23.3% (10/43) of the positive samples were collected from patients with febrile illness. Conclusion: Results presented in this report suggest that respiratory viral infections are largely under diagnosed in immunocompetent adults. Although the majority of young adult infections are not life-threatening they may impose a significant burden, especially in developing countries since these individuals represent a large fraction of the working force. Keywords: Respiratory infection, Viral infection, Viral diagnosis, Epidemiology

Background: Influenza viruses cause highly contagious acute respiratory illnesses with significant mortality, especially among young children, elderly people, and individuals with serious medical conditions. This encourages the development of new treatments for humanflu. Biotherapies aredilutedsolutionsprepared from biological products compounded following homeopathic procedures. Objectives: To develop a biotherapy prepared from the infectious influenza A virus (A/ Aichi/2/68 H3N2) and to verify its in vitro response. Methods: The ultradiluted influenza virus solution was prepared in the homeopathic dilution 30dH, it was termed Influenzinum RC. The cellular alterations induced by this preparation were analyzed by optical and electron microscopy, MTT and neutral red assays.Glycolyticmetabolism(PFK-1) wasstudiedbyspectrophotometricassay.Additionally, the production of tumor necrosis factor-a (TNF-a) by J774.G8 macrophage cells was quantified by ELISA before and after infection with H3N2 influenza virus and treatment. Results: Influenzinum RC did not cause cytotoxic effects but induced morphological alterations in MadineDarby canine kidney (MDCK) cells. After 30 days, a significant increase (p < 0.05) in mitosis rate was detected compared to control. MDCK mitochondrial activity was changed after treatment for 10 and 30 days. Treatment significantlydiminished(p

Universidade Federal do Rio de Janeiro. Faculdade de Farm?cia. Departamento de Medicamentos. Rio de Janeiro, RJ, Brazil / Instituto Federal do Rio de Janeiro. Rio de Janeiro, RJ, Brazil. Universidade Federal do Rio de Janeiro. Faculdade de Farm?cia. Departamento de Medicamentos. Rio de Janeiro, RJ, Brazil. Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de G?es. Rio de Janeiro, RJ, Brazil. Instituto Roberto Costa. Rio de Janeiro, RJ, Brazil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Ananindeua, PA, Brasil. Funda??o Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brazil. Universidade Federal do Rio de Janeiro. Instituto de Microbiologia Professor Paulo de G?es. Rio de Janeiro, RJ, Brazil. Universidade Federal do Rio de Janeiro. Faculdade de Farm?cia. Departamento de Medicamentos. Rio de Janeiro, RJ, Brazil. Background: Influenza and its complications are common at all ages, especially in children. Vaccines and anti-influenza drugs aim to prevent it. Preventative approaches with favorable risk profiles should be considered for flu, particularly since the evidence of the efficacy of anti-viral drugs is debated. Methods: This pragmatic clinical trial was conducted in the Brazilian Public Health System in Petr?polis (BPHSP) with children aged from 1 to 5 years old. The medications used were mainly selected based on in vitro experiments (InfluBio), and in successful qualitative clinical experiences (Homeopathic Complex). Following informed parental consent, subjects were randomly distributed, in a blind manner, to three experimental groups: Homeopathic Complex, Placebo, and InfluBio. BPHSP health agents collected flu and acute respiratory infection symptomatic episodes monthly following the established protocol. The number of these episodes was registered in one year (2009?2010). Results: Out of the 600 children recruited, 445 (74.17%) completed the study (149: Homeopathic complex; 151: Placebo; 145: InfluBio). The number of flu and acute respiratory infection symptomatic episodes detected in this clinical trial was low; however, it was different between homeopathic groups and placebo (p < 0.001). In the first year post-intervention, 46/151 (30.5%) of children in the placebo group developed 3 or more flu and acute respiratory infection episodes, while there was no episode in the group of 149 children who used Homeopathic Complex, and only 1 episode in the group of 145 (1%) children who received InfluBio. Conclusion: These results suggested that the use of homeopathic medicines minimized the number of flu and acute respiratory infection symptomatic episodes in children, signalizing that the homeopathic prophylactic potential should be investigated in further studies.

Influenza viruses are common agents of flu outbreaks, epidemics, and pandemics that have occurred through the centuries. Prevention and control of flu are of great clinical importance, since they cause serious damage to health, with a consequent impact on quality of life and economy of a country. Resistance against the current drugs justifies the development of new anti-influenza molecules. Flavonoids exhibit significant activity against flu through their anti-inflammatory and antiviral properties. The profile of these molecules makes them particularly promising as therapeutic agents against flu.This review focus on the activity of flavonoids on different influenza virus targets as well as their use in patented pharmaceutical formulations. Twenty-one patents of these compounds for prophylaxis and treatment of influenza infection are discussed.The H1N1 influenza pandemic in 2009 resulted in a significant increase in the number of patents claiming pharmaceutical formulations for prophylaxis and treatment of flu. The research advances on flavonoids showing anti-influenza activity and the efforts made by researchers and industries consolidate the interest on new alternatives for the therapy of an infectious disease that represents a serious public health problem throughout the world.

Influenza virus infections are a serious global health threat, particularly in light of newly emerging strains, such as the avian virus H5N1. In this study, a sample of avian influenza A virus subtype H3N8 inactivated by high hydrostatic pressure was used as a vaccine. Our goal was to study pressurized virus preparations for their ability to induce an immunogenic and protective response when using mice as an animal model. Here, Balb/c mice were treated through the intranasal route with three doses of pressurized virus. After vaccination, the mice were challenged and monitored for virus-specific antibodies (ELISA and neutralization assay), clinical symptoms and death. After immunization, there was an increase of IgG1 and IgG2a in sera and IgA in nasal lavages, which indicated that the serum antibodies were showing neutralizing ability. The viral neutralization assay demonstrated that the produced antibodies were neutralizing. After the challenge, the control group (immunized with saline) showed all measured clinical signs of disease (weight loss, ruffled fur, lethargy and huddling). The vaccinated animals did not develop any clinical signs. The results reveal that the animals were able to produce a satisfactory humoral response after vaccination and protected against the challenge. Our work reaffirms the use of hydrostatic pressure as a means for developing low-cost viral vaccines with good immune response.

Variant samples from the three genotypes of erythroviruses have already been detected using sequencing as methodology for analysis. This study aimed to investigate the efficacy of single-stranded conformation polymorphism (SSCP) analysis and heteroduplex mobility assay (HMA) as methodologies to detect human erythrovirus variants, using their VP1 unique region sequences. Clinical samples and plasmids of PVBAUA, A6, LaLi, V9Gh3051, and D91.1 erythrovirus variants as prototypes of the three genotypes were used. SSCP analysis was able to distinguish all divergences among the plasmids, including the two mutation points between LaLi and A6 plasmids that led to distinct electrophoresis mobility patterns. Although HMA analysis was unabled to detect two mutation points between LaLi and A6, it enabled the differentiation among all other plasmids that revealed specific electrophoresis patterns, with high-enough sensibility to detect 1.5% nucleotide substitutions. When 57 clinical samples were analyzed, 33 of them presented an identical pattern to PVBAUA by HMA and SSCP analyses, two of them were sequenced and presented an identical sequence in relation to PVBAUA. Another pattern was found for 21 samples. Among these, two samples were sequenced, revealing one mutation point in relation to PVBAUA, while each one of the three remaining samples presented a distinct pattern, showing two or three mutations in relation to PVBAUA by sequencing. HMA and SSCP analyses were suggested as methodologies suited for detecting genetic mutations of human erythroviruses in developing countries because of their practicability and minor costs for reagents and equipment.

Influenza viruses pose a serious global health threat, particularly in light of newly emerging strains, such as the avian influenza H5N1 and H7N9 viruses. Vaccination remains the primary method for preventing acquiring influenza or for avoiding developing serious complications related to the disease. Vaccinations based on inactivated split virus vaccines or on chemically inactivated whole virus have some important drawbacks, including changes in the immunogenic properties of the virus. To induce a greater mucosal immune response, intranasally administered vaccines are highly desired as they not only prevent disease but can also block the infection at its primary site. To avoid these drawbacks, hydrostatic pressure has been used as a potential method for viral inactivation and vaccine production. In this study, we show that hydrostatic pressure inactivates the avian influenza A H3N8 virus, while still maintaining hemagglutinin and neuraminidase functionalities. Challenged vaccinated animals showed no disease signs (ruffled fur, lethargy, weight loss, and huddling). Similarly, these animals showed less Evans Blue dye leakage and lower cell counts in their bronchoalveolar lavage fluid compared with the challenged non-vaccinated group. We found that the whole inactivated particles were capable of generating a neutralizing antibody response in serum, and IgA was also found in nasal mucosa and feces. After the vaccination and challenge we observed Th1/Th2 cytokine secretion with a prevalence of IFN-γ. Our data indicate that the animals present a satisfactory immune response after vaccination and are protected against infection. Our results may pave the way for the development of a novel pressure-based vaccine against influenza virus.

In this study were analyzed 526 sera; the patients aged from two days to 65 years old presenting exanthema, which was the most frequent symptom observed, besides fever, adenomegaly, and arthralgia. These sera were negative by enzyme-linked immunosorbent assay (IgM-ELISA) for either rubella (495), toxoplasma (41), cytomegalovirus (12), measles (40), dengue (56), and they were submitted to nested polymerase chain reaction (PCR) for B19 DNA and commercial IgM-ELISA for B19. In 39 abortion cases, IgM or DNA were not detected, therefore they were not took into account for analysis. Specific DNA and IgM were detected respectively in 71 (14.5%) and IgM in 62 (12.7%) sera from 487 sera analyzed. IgM and DNA were simultaneously detected in 43 (8.8%), while agreement among the results by PCR and IgM-ELISA was observed in 440 (90.4%). The sera were collected from January 1999 to December 2000, most of them in 1999 (325), during winter and spring. The major number of clinical cases was observed in the age group from one to ten years old. IgM or DNA were detected in 23 from 51 municipal districts of the state of Rio de Janeiro, where the samples were collected.

The expression of sialoglycoconjugates in Fonsecaea pedrosoi conidia, mycelia, and sclerotic cells was analyzed using influenza A and C virus strains, sialidase treatment, and lectin binding. Conidium and mycelium whole cells were recognized by Limax flavus (LFA), Maackia amurensis (MAA), and Sambucus nigra (SNA) lectins, denoting the presence of surface sialoglycoconjugates containing alpha 2,3- and alpha 2,6-sialylgalactosyl sequences. Sialidase-treated conidia reacted more intensively with peanut agglutinin (PNA), confirming the occurrence of sialyl-galactosyl linkages. Conidial cells agglutinated in the presence of influenza A and C virus strains, which confirmed the results obtained from lectin-binding experiments and revealed the presence of sialoglycoconjugates bearing 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac(2)) surface structures. Western blotting analysis with peroxidase-labeled LFA demonstrated the occurrence of sialylglycoproteins in protein extracts from conidia and mycelia, with molecular masses corresponding to 56 and 40 kDa. An additional band of 77 kDa was detected in conidial extracts, suggesting an association between sialic acid expression and morphogenesis. Synthesis of sialic acids was correlated with sialidase expression, since both conidial and mycelial morphological stages presented secreted and cell-associated enzyme activity. Sialoglycoconjugates were not detected in F. pedrosoi sclerotic cells from in vitro and in vivo sources, which also do not express sialidase activity. The surface sialyl residues in F. pedrosoi are apparently involved in the fungal interaction with immune effector cells, since sialidase-treated conidia were less resistant to phagocytosis by human neutrophils from healthy individuals. These findings suggest that sialic acid expression in F. pedrosoi varies according to the morphological transition and may protect infecting propagules against immune destruction by host cells.

Neuraminidase (NA) of influenza A (H3N2) viruses was characterized after purification by gel filtration and proteolytic treatment, using the X-31 variant strain that is a reassortment between the influenza A/Victoria/3/75 (responsible for the 1975 pandemic) and the influenza A/PR/8/34 virus samples, as a model. In the purification process, NA heads, that is the spike responsible for the virus sialidase activity, were purified by filtration through a Bio-Gel polyacrylamide column. The enzyme activity was determined by periodic acid/thiobarbituric acid assay and high-performance thin-layer chromatography. The sialidase showed preference for the α-2,3-linkage over the α-2,6-linkage of sialyllactoses (Km of 1.8 and 5.2 × 10–4M, respectively) at pH 5.2. The enzyme acted on natural and synthetic substrates at different hydrolysis rates, as well as on human erythrocytes (A group, Rh+) and yeast (Candida albicans) cells. The active NA produced by gel filtration was characterized by different parameters of its sialidase activity, also showing to be a suitable tool for the identification of natural sialocompounds and for the screening of antisialidase drugs to treat influenza virus infections.

Cryptococcus neoformans is a fungal pathogen associated with systemic mycoses in up to 10% of AIDS patients. C. neoformans yeasts express sialic acids on the cell wall, where they play an anti-phagocytic role, and may represent a virulence factor at the initial phase of infection. Since the nature of the sialic acid-carrying components is undefined in C. neoformans, our aim in the present work was to identify sialylated molecules in this fungus and study the sialylation process. C. neoformans yeast forms were cultivated in a chemically defined medium free of sialic acids, to search for autologous sialylglycoconjugates. Sialylated glycolipids were not detected. Two glycoproteins with molecular masses of 38 and 67 kDa were recognized by Sambucus nigra agglutinin, an alpha2,6-sialic acid-specific lectin. The 67 kDa glycoprotein also interacted with Influenza C virus, but not with Limax flavus agglutinin, suggesting the presence of the 9-O-acetylated sialic acid derivative as a constituent of the oligosaccharide chains. A partially purified protein fraction from cryptococcal yeast forms was able to transfer sialic acid from CMP-Neu5Ac to both N-(acetyl-1-(14)C)-lactosamine and asialofetuin. Additional evidence for a sialyltransferase in C. neoformans was obtained through the reactivity of fungal proteins with rabbit anti-rat alpha2,6 sialyltransferase polyclonal antibody. Our results indicate that sialic acids in C. neoformans are linked to glycoproteins, which are sialylated by the action of a fungal sialyltransferase. This is the first demonstration of this biosynthetic step in pathogenic fungi.

Heteroduplex mobility assay, single-stranded conformation polymorphism and nucleotide sequencing were utilised to genotype human parvovirus B19 samples from Brazil and Paraguay. Ninety-seven serum samples were collected from individuals presenting with abortion or erythema infectiosum, arthropathies, severe anaemia and transient aplastic crisis; two additional skin samples were collected by biopsy. After the procedure, all clinical samples were classified as genotype 1.

SUMMARY Paramyxoviruses and avian influenza viruses are present worldwide, and wild birds are known natural reservoirs of these viruses. This study monitored the circulation of these viruses in migratory and resident coastal birds captured in the state of Rio de Janeiro, Brazil. In total, 494 birds were trapped, and their fecal samples were collected and inoculated into embryonated chicken eggs. The allantoic fluids were evaluated using a hemagglutination test and PCR amplification of the genes of the M and L proteins of influenza A virus and paramyxovirus, respectively. Avian paramyxovirus was detected in 5 (1.01%) of the birds. The majority of these viruses were isolated from migratory birds classified into the order Charadriiformes (families Scolopacidae and Charadriidae). Four samples were characterized as avian paramyxovirus serotype-2 (APMV-2) by a hemagglutination inhibition test. These results reinforce the importance of continuous surveillance of wild species in Brazil.

Asymptomatic influenza virus infections in pigs are frequent and the lack of measures for controlling viral spread facilitates the circulation of different virus strains between pigs. The goal of this study was to demonstrate the circulation of influenza A virus strains among asymptomatic piglets in an abattoir in Brazil and discuss the potential public health impacts. Tracheal samples (n = 330) were collected from asymptomatic animals by a veterinarian that also performed visual lung tissue examinations. No slaughtered animals presented with any noticeable macroscopic signs of influenza infection following examination of lung tissues. Samples were then analysed by reverse transcription-polymerase chain reaction that resulted in the identification of 30 (9%) influenza A positive samples. The presence of asymptomatic pig infections suggested that these animals could facilitate virus dissemination and act as a source of infection for the herd, thereby enabling the emergence of influenza outbreaks associated with significant economic losses. Furthermore, the continuous exposure of the farm and abattoir workers to the virus increases the risk for interspecies transmission. Monitoring measures of swine influenza virus infections and vaccination and monitoring of employees for influenza infection should also be considered. In addition regulatory agencies should consider the public health ramifications regarding the potential zoonotic viral transmission between humans and pigs.

Whole inactivated vaccines (WIVs) possess greater immunogenicity than split or subunit vaccines, and recent studies have demonstrated that WIVs with preserved fusogenic activity are more protective than non-fusogenic WIVs. In this work, we describe the inactivation of human influenza virus X-31 by high hydrostatic pressure (HHP) and analyze the effects on the structure by spectroscopic measurements, light scattering, and electron microscopy. We also investigated the effects of HHP on the glycoprotein activity and fusogenic activity of the viral particles. The electron microscopy data showed pore formation on the viral envelope, but the general morphology was preserved, and small variations were seen in the particle structure. The activity of hemagglutinin (HA) during the process of binding and fusion was affected in a time-dependent manner, but neuraminidase (NA) activity was not affected. Infectious activity ceased after 3 hours of pressurization, and mice were protected from infection after being vaccinated. Our results revealed full viral inactivation with overall preservation of viral structure and maintenance of fusogenic activity, thereby conferring protection against infection. A strong response consisting of serum immunoglobulin IgG1, IgG2a, and serum and mucosal IgA was also detected after vaccination. Thus, our data strongly suggest that applying hydrostatic pressure may be an effective method for developing new vaccines against influenza A as well as other viruses.

Five extracts from A. brasiliana, obtained through different procedures, showed anti-HSV activity. The best activity was detected in a fraction (B) that was obtained from the crude cold aqueous extract on Sephadex G15. Fraction B showed low cellular toxicity and inhibition from 32.4% to 99.9% at concentrations from 6.2 to 50.0 μg/mL, exhibiting a therapeutic index of 32. Fractions obtained on Sephadex G100 and reversed-phase column also showed considerable inhibition. Fraction B did not show any virucidal activity, however, its inhibitory activity was revealed during the later stages of the virus replication cycle. This fraction showed activity on DNA synthesis of infected cells.

Studies were done to evaluate comparatively the traditional HA assay and a more recently introduced lectin-neuraminidase (LN) methodologyin search of a simple and sensitive assay for virus detection during laboratorial diagnosis. The results proved the value of LN assay as a sensitive methodologyfor detection of virus particles, presenting results at least equal to those obtained by HA (hemagglutination) assay, with significant values of accumulated frequencies for LN/HA factors (ratios between LN and HA titers) higher than two. The accumulated values of frequencies for LN/HA factors as high as four were very significant, 72.7 (per cent) for influenzavirus and 60.7 (per cent) for Newcastle disease virus (NDV), moreover accumulated frequencies for LN/HA factors even as high as 32 were due to influenzavirus (45.4 per cent) and NDV (7.2 per cent) samples. After the storage period, most of those concentraded samples that even did not present HA titers could be detected through LN assay, demonstrating a lower threshold for virus detection.

The present study had the objective of evaluating the pathogenic potential of the genetically related strains of Streptococcus agalactiae no. 80427 (human origin) and no. 87159 (bovine origin), and comparing the results with two other strains isolated from bovine mastitis (no. 87244) and invasive human infection (no. 90356), with no genetic or epidemiologic relationship between them or with the first 2 isolates. Virulence genes hylB (hyaluronidase) and lmb (laminin-binding protein) were detected in the 4 strains, and genes bac (beta protein) and bca (alpha protein) were only detected in human strains. The protein profile obtained using SDS-PAGE did not indicate any differences between the 4 strains. No significant difference was detected between human and bovine strains in the assays of adherence to and invasion of 16HBe cells, as well as in the resistance assay for intracellular bacterial survival in macrophages. However, the strain 87159 exhibited a greater survival in the killing test with whole human blood and was more virulent in newborn mice than the 80427 strain. The strain 87244 was not virulent in mice. These data suggest that isolates of human and bovine origins may express similar virulence attributes, leading to a possible, however limited, dissemination.

A atividade sialidásica do vírus influenza tem uma atividade essencial sobre glicoproteínas celulares, permitindo a disseminação de infecções virais por prevenir a auto-agregação entre partículas virais e a re-ligação vírus-célula. Duas amostras variantes purificadas de vírus influenza A/Memphis/102/72 (H3N2), reconhecidas por sua atividade de ligação a receptores apresentando estruturas como a2,6 ou a2,3-sialilactose, foram analisadas por sua atividade sialidásica sobre diferentes substratos naturais e artificiais. A amostra M1/5 mostrou maior atividade sialidásica sobre fetuína (D.O.=0,226), MPN (D.O.=0,110) e eritrócitos humanos (10.240 unidades hemaglutinantes/ml), enquanto a atividade da amostra M1/5HS8 foi expressa por D.O.=0,129, D.O.=0,065 e 2.560 unidades hemaglutinantes/ml quando usados, respectivamente, fetuína, MPN e eritrócitos humanos como substratos. Contudo a amostra M1/5HS8 exibiu uma atividade sialidásica mais significativa sobre mucina quando comparada à amostra M1/5; a atividade enzimática da primeira amostra foi responsável pela liberação de 3,5 nmol de ácidos siálicos livres, enquanto a última produziu 16,5 nmol de ácidos siálicos livres.

Vaccinal and wild strains of Newcastle Disease virus (NDV) were analyzed for cell receptor binding and fusogenic biological properties associated with their HN (hemagglutinin-neuraminidase) and F (fusion protein) surface structures respectively. The evaluation of the biological activities of HN and F was carried out respectively by determination of hemagglutinating titers and hemolysis percentages, using erythrocytes from various animal origins at different pH values. Significant differences in hemagglutination titers for some strains of NDV were detected, when interacting with goose, sheep, guinea-pig and human "O" group erythrocytes at neutral pH. Diversity of hemolysis percentages was observed between different NDV strains at acid pH. These analysis were developed to evaluate particular aspects of the actual influence of the receptor specificity and pH on the receptor binding and fusogenic processes of Newcastle Disease viruses.

Sialic acids from sialoglycoconjugates present at the cell surface of Cryptococcus neoformans yeast forms were analyzed by high-performance thin-layer chromatography, binding of influenza A and C virus strains, enzymatic treatment, and flow cytofluorimetry with fluorescein isothiocyanate-labeled lectins. C. neoformans yeast forms grown in a chemically defined medium contain N-acetylneuraminic acid and its 9-O-acetylated derivative. A density of 3 x 10(6) residues of sialic acid per cell was found in C. neoformans. Sialic acids in cryptococcal cells are glycosidically linked to galactopyranosyl units as inferred from the increased reactivity of neuraminidase-treated yeasts with peanut agglutinin. N-Acetylneuraminic acids are alpha-2,6 and alpha-2,3 linked, as indicated by using virus strains M1/5 and M1/5 HS8, respectively, as agglutination probes. The alpha-2,6 linkage markedly predominated. These findings were essentially confirmed by the interaction of cryptococcal cells with the lectins Sambucus nigra agglutinin and Maackia amurensis agglutinin. We also investigated whether the sialyl residues present in C. neoformans are involved in the fungal interaction with a cationic solid-phase substrate and with mouse resident macrophages. Adhesion of yeast cells to poly-L-lysine was mediated, in part, by sialic acid residues, since the number of adherent cells was markedly reduced after treatment with bacterial neuraminidase. The enzymatic removal of sialic acids also made C. neoformans yeast cells more susceptible to endocytosis by macrophages. The results show that sialic acids are components of the cryptococcal cell surface that contribute to its negative charge and protect yeast forms against phagocytosis.