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Buprenorphine hydrochloride (Bup-HCl) is a common injectable opioid analgesic. In ferrets, Bup-HCl must be administered every 8 to 12 h to maintain clinical efficacy. Extended-release analgesics offer multiple advantages, including reduced handling and injection frequency, improved compliance, and increased protection from end-of-dose failure. Although efficacy of extended-release buprenorphine formulations has been demonstrated in other species, their use in the domestic ferret has not been investigated. In this study, we evaluated the pharmacokinetics of a compounded polymeric formulation of buprenorphine (Bup-ER) and a pharmaceutical-grade, FDA-indexed liposomal suspension (Bup-XR). Two doses each of Bup-ER (0.12 and 0.2 mg/kg) and Bup-XR (0.2 and 0.6 mg/kg SC) were administered to young adult female ferrets and plasma concentrations were measured between 0 and 96 h ( n = 4 animals per timepoint). All doses of both drugs achieved therapeutic plasma levels by 30 min. Furthermore, high-dose Bup-XR maintained therapeutic levels for 72 h, followed by high-dose Bup-ER (less than 48 h), low-dose Bup-XR (24 h), and low-dose Bup-ER (less than 24 h). In this study, we also developed a pain scoring system and utilized this to compare analgesic efficacy between single high-dose Bup-XR (0.6 mg/kg SC) and a standard postoperative course of Bup-HCl (0.02 mg/kg SC every 10 to 12 h for 8 doses) after ovariohysterectomy. Ferrets receiving Bup-XR had significantly lower respiratory rate and posture scores in the first 24 h postoperatively than did those that received Bup-HCl and were less likely to react to palpation of the surgical incision. Of note, ferrets that received high-dose Bup-ER had a significantly higher incidence of injection site reactions than ferrets that received Bup-HCl ( P = 0.0137). This study demonstrates that a single dose of Bup-XR (0.6 mg/kg SC) is a safe and effective analgesic in female ferrets, with a duration of action up to 72 h and minimal side effects, offering a refinement to analgesia in this species.

SARS-CoV-2 infection of the upper airway and the subsequent immune response are early, critical factors in COVID-19 pathogenesis. By studying infection of human biopsies in vitro and in a hamster model in vivo, we demonstrated a transition in nasal tropism from olfactory to respiratory epithelium as the virus evolved. Analyzing each variant revealed that SARS-CoV-2 WA1 or Delta infect a proportion of olfactory neurons in addition to the primary target sustentacular cells. The Delta variant possessed broader cellular invasion capacity into the submucosa, while Omicron displayed enhanced nasal respiratory infection and longer retention in the sinonasal epithelium. The olfactory neuronal infection by WA1 and the subsequent olfactory bulb transport via axon were more pronounced in younger hosts. In addition, the observed viral clearance delay and phagocytic dysfunction in aged olfactory mucosa were accompanied by a decline of phagocytosis-related genes. Further, robust basal stem cell activation contributed to neuroepithelial regeneration and restored ACE2 expression postinfection. Together, our study characterized the nasal tropism of SARS-CoV-2 strains, immune clearance, and regeneration after infection. The shifting characteristics of viral infection at the airway portal provide insight into the variability of COVID-19 clinical features, particularly long COVID, and may suggest differing strategies for early local intervention.

The domestic ferret ( Mustela putorius furo ) is a common research model for infectious disease and behavioral studies. Ferrets are social animals that are commonly pair-housed. The United States has no species-specific regulatory standards for housing ferrets. Optimal enclosure dimensions have also not been investigated in this species, and cage sizes reported in the literature vary. Adequate space is an important animal welfare consideration, as smaller cages have been linked to increased incidence of stress- or boredom-related behaviors in some species. Here, we evaluated activity budget and space utilization in 2 different enclosure sizes for pair-housed female ferrets (n = 12). Single cages measured 78.7×78.7×45.7cm; double cages were comprised of 2 single cages connected by a short tunnel measuring 17.8 cm. Three pairs of ferrets were housed in each cage size and continuous video recordings were captured for 2 wk prior to crossover to the other cage size. The overall activity budget was similar between groups, with the predominant behavior being inactivity (89%). Stereotypic behaviors, such as cage biting or escape attempts, were infrequent (<0.1%) in both groups. Ferrets in double cages remained in the same cage as their partner 96% of the time, suggesting that social support is very valuable. Our results suggest that ferrets in both cage sizes experienced satisfactory welfare conditions. Our findings also suggest that while cage size is not the only determinant of conspecific aggression, larger cages may be an effective intervention to ameliorate aggression in certain ferrets based on signalment or behavioral history, with particular utility as a potential alternative to re-pairing or single-housing. This study provides valuable information to guide animal care and use programs regarding appropriate ferret housing.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a SARS-like coronavirus, continues to produce mounting infections and fatalities all over the world. Recent data point to SARS-CoV-2 viral infections in the human testis. As low testosterone levels are associated with SARS-CoV-2 viral infections in males and human Leydig cells are the main source of testosterone, we hypothesized that SARS-CoV-2 could infect human Leydig cells and impair their function. We successfully detected SARS-CoV-2 nucleocapsid in testicular Leydig cells of SARS-CoV-2-infected hamsters, providing evidence that Leydig cells can be infected with SARS-CoV-2. We then employed human Leydig-like cells (hLLCs) to show that the SARS-CoV-2 receptor angiotensin-converting enzyme 2 is highly expressed in hLLCs. Using a cell binding assay and a SARS-CoV-2 spike-pseudotyped viral vector (SARS-CoV-2 spike pseudovector), we showed that SARS-CoV-2 could enter hLLCs and increase testosterone production by hLLCs. We further combined the SARS-CoV-2 spike pseudovector system with pseudovector-based inhibition assays to show that SARS-CoV-2 enters hLLCs through pathways distinct from those of monkey kidney Vero E6 cells, a typical model used to study SARS-CoV-2 entry mechanisms. We finally revealed that neuropilin-1 and cathepsin B/L are expressed in hLLCs and human testes, raising the possibility that SARS-CoV-2 may enter hLLCs through these receptors or proteases. In conclusion, our study shows that SARS-CoV-2 can enter hLLCs through a distinct pathway and alter testosterone production.

Several vaccines have been introduced to combat the coronavirus infectious disease-2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Current SARS-CoV-2 vaccines include mRNA-containing lipid nanoparticles or adenoviral vectors that encode the SARS-CoV-2 Spike (S) protein of SARS-CoV-2, inactivated virus, or protein subunits. Despite growing success in worldwide vaccination efforts, additional capabilities may be needed in the future to address issues such as stability and storage requirements, need for vaccine boosters, desirability of different routes of administration, and emergence of SARS-CoV-2 variants such as the Delta variant. Here, we present a novel, well-characterized SARS-CoV-2 vaccine candidate based on extracellular vesicles (EVs) of Salmonella typhimurium that are decorated with the mammalian cell culture-derived Spike receptor-binding domain (RBD). RBD-conjugated outer membrane vesicles (RBD-OMVs) were used to immunize the golden Syrian hamster (Mesocricetus auratus) model of COVID-19. Intranasal immunization resulted in high titres of blood anti-RBD IgG as well as detectable mucosal responses. Neutralizing antibody activity against wild-type and Delta variants was evident in all vaccinated subjects. Upon challenge with live virus, hamsters immunized with RBD-OMV, but not animals immunized with unconjugated OMVs or a vehicle control, avoided body mass loss, had lower virus titres in bronchoalveolar lavage fluid, and experienced less severe lung pathology. Our results emphasize the value and versatility of OMV-based vaccine approaches., (© 2022 The Authors. Journal of Extracellular Vesicles published by Wiley Periodicals, LLC on behalf of the International Society for Extracellular Vesicles.)

To catalyze severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) research, including development of novel interventive and preventive strategies, the progression of disease was characterized in a robust coronavirus disease 2019 (COVID-19) animal model. In this model, male and female golden Syrian hamsters were inoculated intranasally with SARS-CoV-2 USA-WA1/2020. Groups of inoculated and mock-inoculated uninfected control animals were euthanized at 2, 4, 7, 14, and 28 days after inoculation to track multiple clinical, pathology, virology, and immunology outcomes. SARS-CoV-2-inoculated animals consistently lost body weight during the first week of infection, had higher lung weights at terminal time points, and developed lung consolidation per histopathology and quantitative image analysis measurements. High levels of infectious virus and viral RNA were reliably present in the respiratory tract at days 2 and 4 after inoculation, corresponding with widespread necrosis and inflammation. At day 7, when the presence of infectious virus was rare, interstitial and alveolar macrophage infiltrates and marked reparative epithelial responses (type II hyperplasia) dominated in the lung. These lesions resolved over time, with only residual epithelial repair evident by day 28 after inoculation. The use of quantitative approaches to measure cellular and morphologic alterations in the lung provides valuable outcome measures for developing therapeutic and preventive interventions for COVID-19 using the hamster COVID-19 model., (Copyright © 2022 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

IVC systems are marketed for improving the health and management of mouse colonies. The current study compared mouse reproductive performance and husbandry and environmental parameters among 3 high-density (HD) IVC rack systems (RS1, RS2, and RS3), which were present in separate but comparable rooms. Three breeding trios each of Swiss Webster (CFW) and BALB/c mice were placed in each rack ( n = 36 female, n = 18 male). Reproductive indices were measured for 3 breeding cycles over 2 generations; indices included time to parturition, litter size and pup weight, survivability, and interbirth interval. Over 18 wk, personnel used scoring systems to evaluate each RS daily to every other week according to cage dirtiness, need for spot changing, ease of cage changing, daily health checks, and cage wash processing. Macroenvironmental parameters (temperature, relative humidity, noise, total particulate matter) were measured weekly over 14 wks. Microenvironmental parameters (temperature, relative humidity, NH₃, CO₂, O₂) of 2 cages each of male and female CFW mice (4 mice/cage) on each RS were measured at 6 time points over 2 wks. RS1 had significantly smaller mean litter sizes of CFW mice (mean ± 1 SD, 6.5 ± 2.9 pups) as compared with both RS2 (9.5 ± 1.7 pups) and RS3 (9.3 ± 3.8 pups). RS1 scored as being significantly easier to process through the cage wash. RS2 had significantly lower room noise levels (46.0 ± 5.0 dBA) but higher humidity (58.6% ± 8.9%) as compared with both RS1 (43.7% ± 9.9%) and RS3 (46.0% ± 12.0%) over the 2-wk cycle, particularly at 8 and 12 d after cage change. In conclusion, in terms of mouse reproductive performance and husbandry and environmental parameters, each system had at least 1 advantage over the other 2. Therefore, various factors should be considered when choosing an IVC system for mice.

The significant advances made by the global scientific community during the COVID-19 pandemic, exemplified by the development of multiple SARS-CoV-2 vaccines in less than 1 y, were made possible in part because of animal research. Historically, animals have been used to study the characterization, treatment, and prevention of most of the major infectious disease outbreaks that humans have faced. From the advent of modern 'germ theory' prior to the 1918 Spanish Flu pandemic through the more recent Ebola and Zika virus outbreaks, research that uses animals has revealed or supported key discoveries in disease pathogenesis and therapy development, helping to save lives during crises. Here we summarize the role of animal research in past pandemic and epidemic response efforts, as well as current and future considerations for animal research in the context of infectious disease research.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), rapidly spread across the world in late 2019, leading to a pandemic. While SARS-CoV-2 infections predominately affect the respiratory system, severe infections can lead to renal and cardiac injury and even death. Due to its highly transmissible nature and severe health implications, animal models of SARS-CoV-2 are critical to developing novel therapeutics and preventatives. Syrian hamsters ( Mesocricetus auratus) are an ideal animal model of SARS-CoV-2 infections because they recapitulate many aspects of human infections. After inoculation with SARS-CoV-2, hamsters become moribund, lose weight, and show varying degrees of respiratory disease, lethargy, and ruffled fur. Histopathologically, their pulmonary lesions are consistent with human infections including interstitial to broncho-interstitial pneumonia, alveolar hemorrhage and edema, and granulocyte infiltration. Similar to humans, the duration of clinical signs and pulmonary pathology are short lived with rapid recovery by 14 d after infection. Immunocompromised hamsters develop more severe infections and mortality. Preclinical studies in hamsters have shown efficacy of therapeutics, including convalescent serum treatment, and preventatives, including vaccination, in limiting or preventing clinical disease. Although hamster studies have contributed greatly to our understanding of the pathogenesis and progression of disease after SARS-CoV-2 infection, additional studies are required to better characterize the effects of age, sex, and virus variants on clinical outcomes in hamsters. This review aims to describe key findings from studies of hamsters infected with SARS-CoV-2 and to highlight areas that need further investigation.

In the coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more severe outcomes are reported in males than in females, including hospitalizations and deaths. Animal models can provide an opportunity to mechanistically interrogate causes of sex differences in the pathogenesis of SARS-CoV-2. Adult male and female golden Syrian hamsters (8 to 10 weeks of age) were inoculated intranasally with 10 5 50% tissue culture infective dose (TCID 50 ) of SARS-CoV-2/USA-WA1/2020 and euthanized at several time points during the acute (i.e., virus actively replicating) and recovery (i.e., after the infectious virus has been cleared) phases of infection. There was no mortality, but infected male hamsters experienced greater morbidity, losing a greater percentage of body mass, developed more extensive pneumonia as noted on chest computed tomography, and recovered more slowly than females. Treatment of male hamsters with estradiol did not alter pulmonary damage. Virus titers in respiratory tissues, including nasal turbinates, trachea, and lungs, and pulmonary cytokine concentrations, including interferon-β (IFN-β) and tumor necrosis factor-α (TNF-α), were comparable between the sexes. However, during the recovery phase of infection, females mounted 2-fold greater IgM, IgG, and IgA responses against the receptor-binding domain of the spike protein (S-RBD) in both plasma and respiratory tissues. Female hamsters also had significantly greater IgG antibodies against whole-inactivated SARS-CoV-2 and mutant S-RBDs as well as virus-neutralizing antibodies in plasma. The development of an animal model to study COVID-19 sex differences will allow for a greater mechanistic understanding of the SARS-CoV-2-associated sex differences seen in the human population. IMPORTANCE Men experience more severe outcomes from coronavirus disease 2019 (COVID-19) than women. Golden Syrian hamsters were used to explore sex differences in the pathogenesis of a human isolate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). After inoculation, male hamsters experienced greater sickness, developed more severe lung pathology, and recovered more slowly than females. Sex differences in disease could not be reversed by estradiol treatment in males and were not explained by either virus replication kinetics or the concentrations of inflammatory cytokines in the lungs. During the recovery period, antiviral antibody responses in the respiratory tract and plasma, including to newly emerging SARS-CoV-2 variants, were greater in female than in male hamsters. Greater lung pathology during the acute phase combined with lower antiviral antibody responses during the recovery phase of infection in males than in females illustrate the utility of golden Syrian hamsters as a model to explore sex differences in the pathogenesis of SARS-CoV-2 and vaccine-induced immunity and protection.

Understanding how differences in animal husbandry practices affect the reproducibility of research results is critical. We sought to understand how different beddings might influence dietary obesity studies. We compared the effects of paper and corncob bedding on weight gain, metabolism, and gut microbiome (GM) of mice fed a high-fat diet (HFD) or a normal diet (ND) and evaluated effects on fecal and cecal microbiomes collected from these cohorts after euthanasia. Male C57BL/6J mice at 5 wk age were allowed to acclimate to the facility and the assigned bedding for one week before being placed on HFD or remaining on the ND for 12 wk. Fecal pellets and cecal samples were collected and frozen for batched 16S sequencing. Mice had similar body weight, visceral gonadal white adipose tissue (GWAT), subcutaneous inguinal white adipose tissue (IWAT), liver and spleen weights and metabolic changes regardless of the bedding type. Baseline microbiota differences were detected one week after bedding assignment. After 12 wk, the GM showed significant differences depending on both bedding and diet. The effects of the bedding were not significantly different between endpoint fecal and cecal GM, despite the inherent differences in microbiota in fecal and cecal samples. A correlation was detected between diet and the relative abundance of Bacteroidetes and Verrucomicrobia: Akkermansia . In conclusion, this study demonstrates the importance of considering bedding type when performing dietary experiments.

Studies of visual responses in isoflurane-anesthetized mice often use the sedative chlorprothixene to decrease the amount of isoflurane used because excessive isoflurane could adversely affect light-evoked responses. However, data are not available to justify the use of this nonpharmaceutical-grade chemical. The current study tested whether pharmaceutical-grade sedatives would be appropriate alternatives for imaging pupillary light reflexes. Male 15-wk-old mice were injected intraperitoneally with 1 mg/kg chlorprothixene, 5 mg/kg acepromazine, 10 mg/kg chlorpromazine, or saline. After anesthetic induction, anesthesia maintenance used 0.5% and 1% isoflurane for sedative- and saline-injected mice, respectively. A photostimulus (16.0 log photons cm -2 s -1 ; 470 nm) was presented to the right eye for 20 min, during which the left eye was imaged for consensual pupillary constriction and involuntary pupil drift. Time to immobilization, loss of righting reflex, physiologic parameters, gain of righting reflex, and degree of recovery were assessed also. The sedative groups were statistically indistinguishable for all measures. By contrast, pupillary drift occurred far more often in saline-treated mice than in the sedative groups. Furthermore, saline-treated mice took longer to reach maximal pupil constriction than all sedative groups and had lower heart rates compared with chlorpromazine- and chlorprothixene-sedated mice. Full recovery (as defined by purposeful movement, response to tactile stimuli, and full alertness) was not regularly achieved in any sedative group. In conclusion, at the doses tested, acepromazine and chlorpromazine are suitable pharmaceutical-grade alternatives to chlorprothixene for pupil imaging and conceivably other in vivo photoresponse measurements; however, given the lack of full recovery, lower dosages should be investigated further for use in survival procedures.

Mouse handling during cage changing and health evaluation has traditionally been performed by using forceps. This method was adopted as a biosecurity measure but can adversely affect employee ergonomics and rodent behavior. In this study, we evaluated alternative methods of rodent handling and their potential implications for efficiency, biosecurity, and animal welfare. Study groups included plastic cups, gloved hands, 2 methods of tunnel handling, and forceps. Evaluations included speed of cage change, ATP-based assessment of sanitization, and retrospective analysis of colony health and breeding data. The time to change 14 cages was significantly faster at each time point for the gloved hands and forceps groups as compared with the other methods. Overall speed did not increase significantly with each subsequent study week for any group. ATP levels after sanitization with hydrogen peroxide-peracetic acid mixture differed significantly between gloves and forceps. When ATP level was evaluated on a per-cm² basis, no significant difference between gloves and forceps was detected. Although tunnel and cup handling both increased the time for cage-changing, the tunnel served as both an indirect handling method and a shelter when left within the cage. Retrospective analysis revealed that breeding performance and colony health were similar among groups. Although efficiency is a concern for large-scale implementation of novel handling methods, the tunnel method may prove beneficial for sensitive strains or studies requiring indirect handling. In addition, using gloved hands to directly handle mice during cage changing is efficient and avoids the ergonomic strain associated with forceps. Precautions should be taken when handling mice with gloves, given that the increased contact area carries an increased load of organic debris. Changing gloves between rack sides or before proceeding to the animals belonging to a different investigator minimizes the potential for cross-contamination.

The Guide recommends sanitizing cage components, including microisolation cage tops (MCT), at a minimum of every 2 wk. Previously published data demonstrated that mouse MCT microbial loads do not increase until at least 2 wk and that sanitation can be delayed past 2 wk. How microbial loads differ on mouse compared with rat MCT, as well as across different ventilation systems, remains unclear. We hypothesized that MCT microbial loads would be higher in tops from rats compared with mice and would differ according to IVC ventilation system. We evaluated bacterial loads on MCT at serial time points to 90 d from static cages housing mice or rats and from rat and mouse cages on several ventilation systems (mice, 6; rats, 4). MCT were determined to have sufficiently elevated bacterial loads to necessitate changing based on either statistically significant changes in bacterial loads or values greater than 50 cfu. Across all ventilation systems, bacterial counts at 14 d were significantly higher on rat MCT compared with mouse MCT. Across the ventilation systems examined, rat MCT cfu remained similarly elevated from 14 d through 90 d. Mouse MCT total cfu were also stable across multiple ventilation systems yet remained lower than 50 cfu until at least 90 d. Patterns of bacterial species isolated from rat MCT were relatively consistent over time and ventilation system, whereas mice showed greater variability in both contexts. We found that 14 d is an appropriate sanitization time point for rat MCT, whereas the interval at which mouse MCT are cleaned can be extended to 90 d at least. Our data highlight interspecies differences in the accumulation of bacteria on MCT and that mouse MCT sanitation intervals for several housing systems can be extended beyond 14 d.

Between October 2016 and June 2017, a C57BL/6J mouse colony that was undergoing a pre- and perinatal methyl donor supplementation diet intervention to study the impact of parental nutrition on offspring susceptibility to disease was found to suffer from an epizootic of unexpected deaths. Necropsy revealed the presence of severe colitis, and further investigation linked these outbreak deaths to a Clostridium difficile strain of ribotype 027 that we term 16N203. C. difficile infection (CDI) is associated with antibiotic use in humans. Current murine models of CDI rely on antibiotic pretreatment to establish clinical phenotypes. In this report, the C. difficile outbreak occurs in F1 mice linked to alterations in the parental diet. The diagnosis of CDI in the affected mice was confirmed by cecal/colonic histopathology, the presence of C. difficile bacteria in fecal/colonic culture, and detection of C. difficile toxins. F1 mice from parents fed the methyl supplementation diet also had significantly reduced survival ( P < 0.0001) compared with F1 mice from parents fed the control diet. When we tested the 16N203 outbreak strain in an established mouse model of antibiotic-induced CDI, we confirmed that this strain is pathogenic. Our serendipitous observations from this spontaneous outbreak of C. difficile in association with a pre- and perinatal methyl donor diet suggest the important role that diet may play in host defense and CDI risk factors. IMPORTANCE Clostridium difficile infection (CDI) has become the leading cause of infectious diarrhea in hospitals worldwide, owing its preeminence to the emergence of hyperendemic strains, such as ribotype 027 (RT027). A major CDI risk factor is antibiotic exposure, which alters gut microbiota, resulting in the loss of colonization resistance. Current murine models of CDI also depend on pretreatment of animals with antibiotics to establish disease. The outbreak that we report here is unique in that the CDI occurred in mice with no antibiotic exposure and is associated with a pre- and perinatal methyl supplementation donor diet intervention study. Our investigation subsequently reveals that the outbreak strain that we term 16N203 is an RT027 strain, and this isolated strain is also pathogenic in an established murine model of CDI (with antibiotics). Our report of this spontaneous outbreak offers additional insight into the importance of environmental factors, such as diet, and CDI susceptibility., (Copyright © 2019 Mau et al.)

Research using laboratory animals has been revolutionized by the creation of humanized animal models, which are immunodeficient animals engrafted with human cells, tissues, or organs. These animal models provide the research community a unique and promising opportunity to mimic a wide variety of disease conditions in humans, from infectious disease to cancer. A vast majority of these models are humanized mice like those injected with human CD34+ hematopoietic stem cells and patient-derived xenografts. With this technology comes the need for the animal research enterprise to understand the inherent and potential risks, such as exposure to bloodborne pathogens, associated with the model development and research applications. Here, we review existing humanized animal models and provide recommendations for their safe use based on regulatory framework and literature. A risk assessment program-from handling the human material to its administration to animals and animal housing-is a necessary initial step in mitigating risks associated with the use of humanized animals in research. Ultimately, establishing institutional policies and guidelines to ensure personnel safety is a legal and ethical responsibility of the research institution as part of the occupational health and safety program and overall animal care and use program., (© The Author(s) 2018. Published by Oxford University Press on behalf of the National Academy of Sciences. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Viral vector research presents unique occupational health and safety challenges to institutions due to the rapid development of both in vivo and in vitro gene-editing technologies. Risks to human and animal health make it incumbent on institutions to appropriately evaluate viral vector usage in research on the basis of available information and governmental regulations and guidelines. Here we review the factors related to risk assessment regarding viral vector usage in animals and the relevant regulatory documents associated with this research, and we highlight the most commonly used viral vectors in research today. This review is particularly focused on the background, use in research and associated health and environmental risks related to adenoviral, adeno-associated viral, lentiviral, and herpesviral vectors.

The occupational health and safety program is an integral component of a comprehensive animal care and use program. It is important to mitigate the risk of exposures of animal care and research personnel to allergens and physical, chemical, radiologic, and biologic hazards during the conduct of various tasks. This need is especially true in infectious disease and biocontainment research. One aspect of the program is the provision of personal protective equipment (PPE). Commercially available PPE should be carefully evaluated based on their material composition and performance according to manufacturer data. To help institutions and end users by providing them guidance on choosing appropriate PPE, we here discuss the regulatory framework, device standards, and materials engineering for various PPE, including gloves, shoe covers, head caps, gowns, aprons, masks, hearing and eye protection devices, and respirators. Ultimately, the choice of appropriate PPE is based on the risk assessment, which should include consideration for personnel comfort, correct device fitting, and the containment level for the hazard used.

Estrogen supplementation is a key component of numerous mouse research models but can adversely affect the urinary system. The goal of this study was to develop a clinical scoring system and identify biomarkers of occult urinary tract lesions prior to the development of systemic illness in mice. Ovariectomized or sham-surgery SCID mice were implanted subcutaneously with a placebo pellet or one containing sustained-release estradiol (0.18 mg 60-d release 17β-estradiol). Mice were assessed twice weekly for 4 to 6 wk by using a clinical scoring system that included body condition, general activity, posture, hair coat, hydration, abdominal distension, urine staining of coat and skin, and ability to urinate. Samples were collected weekly for urinalysis, BUN, creatinine, and serum estradiol levels. Terminal samples were analyzed for histopathologic lesions. Compared with placebo controls, estradiolsupplemented mice had higher serum estradiol levels at weeks 2 and 3; significant differences in total clinical scores by the 3-wk time point; and in body condition, general activity, posture, hair coat, and urine staining scores by the 6-wk terminal time point. Urinary tract lesions included hydronephrosis, pyelonephritis, cystitis, and urolithiasis. All mice with urolithiasis had crystalluria, and 5 of the 6 mice with pyelonephritis or hydroureter had dilute urine (that is, specific gravity less than 1.030). However, these findings were not specific to mice with lesions. A total clinical score of 3.5 (maximum, 24) identified estradiol-supplemented mice with 83% specificity and 50% sensitivity, but no single clinical parameter, biomarker, or the total clinical score accurately predicted occult urinary tract lesions. Considering the lesions we observed, prudence is warranted when using pelleted sustained-release estradiol in mice, and important parameters to monitor for animal health include urine staining, body condition score, urine sediment, and urine specific gravity.

Seven male Hartley guinea pigs, 3 to 18 months old, died or had to be euthanized because of nonspecific clinical signs unresponsive to supportive treatment. Gross necropsy and histopathology findings in all animals included severe soft tissue calcification affecting the myocardium, kidneys, and occasionally the liver., (© The Author(s) 2014.)

Three breeding colonies of Myd88(-/-) mice had a history of significant morbidity and mortality. Although strain-specific poor reproductive performance might explain neonatal death and dystocia, mice were found dead or required euthanasia because of moribundity, distended abdomen, head tilt, and seizures. Histopathology results included bacteremia, placentitis, metritis, peritonitis with abscess formation, and suppurative meningoencephalitis. Intralesional gram-negative coccobacilli were present, often in extremely high number. Cultures of samples of the cardiac blood of a mouse and from water-bottle sipper tubes provided to some affected mice grew Pseudomonas aeruginosa. In addition, affected tissues from 2 mice and feces from a third tested PCR-positive for P. aeruginosa. Although the mice had received autoclaved reverse-osmosis-purified drinking water, we suspect that the mice were inoculated with P. aeruginosa through contaminated sipper tubes. Because of the deficiency in most of the Toll-like receptor signaling pathways, these Myd88(-/-) mice were unlikely to have developed competitive innate and adaptive immune responses, resulting in bacterial infections. These clinical cases underscore the importance of understanding how genotype, phenotype and environment affect animal health. Sound husbandry and experimental practices are needed to prevent the exposure of immuno-deficient mice to pathogens.

A 7-mo-old female New Zealand white rabbit presented with hemorrhage of the gingiva surrounding a loose lower right incisor. Antemortem conventional radiographs revealed only a small bone fragment adjacent to the left mandible's body. In light of a provisional diagnosis of mandibular fracture, the rabbit was euthanized. Postmortem radiographs of the disarticulated mandible demonstrated mandibular symphyseal fracture and comminuted fracture of the ramus and body of the left mandible. According to histopathology, the left submandibular salivary gland had necrotizing sialometaplasia, a nonneoplastic condition of the salivary glands that is caused by ischemic infarction. Although rabbits have been used as animal models of mandibular fracture and necrotizing sialometaplasia, no nonexperimental case of such conditions had been reported previously.

Endoluminal infusion and incubation of elastase with or without collagenase into the rabbit common carotid artery is an established model of arterial saccular aneurysm. The model mimics naturally occurring human cerebral aneurysms in many ways, including histologic and morphologic characteristics, hemodynamic pressures, and shear stresses. However, complications have been associated with the model. Here, we report 2 complications: 1) the first known case of iatrogenic laryngeal hemiplegia in a rabbit; and 2) histopathologically confirmed iatrogenic hippocampal and cerebellar infarcts (stroke). Finally, we present and review data from current literature on the morbidity and mortality associated with this model.

Cynomolgus (or longtailed) macaques (Macaca fascicularis) are used extensively as laboratory animals in biomedical research. Their use in Singapore, an emerging biomedical hub in Southeast Asia, is now increasing widely, with research subjects currently originating from Singapore, Vietnam, and Pulau Bintan, Indonesia. Limited data exist on the genetic and phenotypic polymorphisms and phylogenetic relationships of these groups, and the animals are used as research subjects without regard to potential differences or homogeneity. Here we characterize their phenotypes by using established primatology tools to detail morphometrics and pelage erythrism and saturation. Pelage analyses supported the Gloger rule, in which heavily pigmented forms predominate near the equator, with Singaporean and Bintan macaques having darker pelage than Vietnamese macaques. Morphometric variation patterns suggest a tendency toward insular dwarfism and correlate generally with the Bergmann rule, in which body mass increases with latitude and colder climate. Although the 3 populations all belong to the nominotypical subspecies M. f. fascicularis, phenotypic differences are evident and are valuable tools to analyze their phylogeographic history and phylogenetic relationships.

Background: A cynomolgus macaque (Macaca fascicularis) presented with decreased appetite, lethargy, ataxia, disorientation and visual impairment. It was used in a hepatitis B (HBV) study involving injections of HBV plasmid construct (450 microg) and aflatoxin B1 (25 microg/kg) in an effort to develop a model of liver cirrhosis and hepatocellular carcinoma., Methods: The case work-up included physical examination, including assessment of hydration, thoracic and abdominal radiographs and abdominal ultrasound. Clinical pathology included complete blood counts and tests for levels of plasma ammonia (NH(3)) and serum electrolytes, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, total bilirubin, and gamma-glutamyl transferase. Serum samples had also been serially tested for the presence of HBsAg, anti-HBc antibodies, HBV e-antigen, and HBV DNA. With a tentative diagnosis of hepatic encephalopathy, treatment with lactulose, antibiotics, and fluid therapy was initiated., Results: Clinical pathology and diagnostic imaging performed on the animal revealed no abnormalities except for the hyperammoniemia. Absence of HBV markers in the serum indicated unsuccessful inoculation. Not fully responding to therapeutic intervention, the animal was euthanized. Necropsy revealed fibrous peritoneal adhesions and an abscess in the cerebellopontine angle. Exudate culture indicated the presence of alpha-hemolytic streptococcus, Eubacterium lentum, and Bacteroides stercoris., Conclusions: Brain abscesses are uncommon in non-human primates. This case of cerebellar abscess is characterized by important features similar to that found in humans, including the presenting signs and the presence of the above-cultured bacteria.