Natural pathogens of laboratory mice, rats, and rabbits and their effects on research

Experimental colonization with H. hepaticus, S. aureus and R. pneumotropicus does not influence the metabolic response to high-fat diet or incretin-analogues in wildtype SOPF mice

OBJECTIVES

We here assessed whether typical pathogens of laboratory mice affect the development of diet-induced obesity and glucose intolerance, and whether colonization affects the efficacy of the GLP-1R agonist liraglutide and of the GLP-1/GIP co-agonist MAR709 to treat obesity and diabetes.

METHODS

Male C57BL/6J mice were experimentally infected with Helicobacter hepaticus, Rodentibacter pneumotropicus and Staphylococcus aureus and compared to a group of uninfected specific and opportunistic pathogen free (SOPF) mice. The development of diet-induced obesity and glucose intolerance was monitored over a period of 26 weeks. To study the influence of pathogens on drug treatment, mice were then subjected for 6 days daily treatment with either the GLP-1 receptor agonist liraglutide or the GLP-1/GIP co-agonist MAR709.

RESULTS

Colonized mice did not differ from SOPF controls regarding HFD-induced body weight gain, food intake, body composition, glycemic control, or responsiveness to treatment with liraglutide or the GLP-1/GIP co-agonist MAR709.

CONCLUSIONS

We conclude that the occurrence of H. hepaticus, R. pneumotropicus and S. aureus does neither affect the development of diet-induced obesity or type 2 diabetes, nor the efficacy of GLP-1-based drugs to decrease body weight and to improve glucose control in mice.

Pathologists' perspective on the study design, analysis, and interpretation of proliferative lesions in a lifetime rodent carcinogenicity bioassay of sucralose

Sucralose, a sugar substitute first approved for use in 1991, is a non-caloric sweetener regulated globally as a food additive. Based on numerous experimental animal studies (dating to the 1980s) and human epidemiology studies, international health agencies have determined that sucralose is safe when consumed as intended. A single lifetime rodent carcinogenicity bioassay conducted by the Ramazzini Institute (RI) reported that mice fed diets containing sucralose develop hematopoietic neoplasia, but controversy continues regarding the validity and relevance of these data for predicting health effects in humans. The present paper addresses the controversy by providing the perspective of experienced pathologists on sucralose-related animal toxicity and carcinogenicity data generally, and the RI carcinogenicity bioassay findings specifically, using results from publicly available papers and international regulatory authority decisions. In the authors' view, flaws in the design, methodology, data evaluation, and reporting of the RI carcinogenicity bioassay for sucralose diminish the value of the data as evidence that this agent represents a carcinogenic hazard to humans. This limitation will remain until the RI bioassay is repeated under Good Laboratory Practices and the design, data, and accuracy of the pathology diagnoses and interpretations are reviewed by qualified pathologists with experience in evaluating potential chemically-induced carcinogenic hazards.

Amino acid restriction, aging, and longevity: an update

Various so-called dietary restriction paradigms have shown promise for extending health and life. All such paradigms rely on ad libitum (hereafter ad lib) feeding, something virtually never employed in animals whose long-term health we value, either as a control or, except for food restriction itself, for both control and treatment arms of the experiment. Even though the mechanism(s) remain only vaguely understood, compared to ad lib-fed animals a host of dietary manipulations, including calorie restriction, low protein, methionine, branched-chain amino acids, and even low isoleucine have demonstrable health benefits in laboratory species in a standard laboratory environment. The remaining challenge is to determine whether these health benefits remain in more realistic environments and how they interact with other health enhancing treatments such as exercise or emerging geroprotective drugs. Here we review the current state of the field of amino acid restriction on longevity of animal models and evaluate its translational potential.

Sterility testing of germ-free mouse colonies

In biomedical research, germ-free and gnotobiotic mouse models enable the mechanistic investigation of microbiota-host interactions and their role on (patho)physiology. Throughout any gnotobiotic experiment, standardized and periodic microbiological testing of defined gnotobiotic housing conditions is a key requirement. Here, we review basic principles of germ-free isolator technology, the suitability of various sterilization methods, and the use of sterility testing methods to monitor germ-free mouse colonies. We also discuss their effectiveness and limitations, and share the experience with protocols used in our facility. In addition, possible sources of isolator contamination are discussed and an overview of reported contaminants is provided.

Zebrafish-based platform for emerging bio-contaminants and virus inactivation research

Emerging bio-contaminants such as viruses have affected health and environment settings of every country. Viruses are the minuscule entities resulting in severe contagious diseases like SARS, MERS, Ebola, and avian influenza. Recent epidemic like the SARS-CoV-2, the virus has undergone mutations strengthen them and allowing to escape from the remedies. Comprehensive knowledge of viruses is essential for the development of targeted therapeutic and vaccination treatments. Animal models mimicking human biology like non-human primates, rats, mice, and rabbits offer competitive advantage to assess risk of viral infections, chemical toxins, nanoparticles, and microbes. However, their economic maintenance has always been an issue. Furthermore, the redundancy of experimental results due to aforementioned aspects is also in examine. Hence, exploration for the alternative animal models is crucial for risk assessments. The current review examines zebrafish traits and explores the possibilities to monitor emerging bio-contaminants. Additionally, a comprehensive picture of the bio contaminant and virus particle invasion and abatement mechanisms in zebrafish and human cells is presented. Moreover, a zebrafish model to investigate the emerging viruses such as coronaviridae and poxviridae has been suggested.

The role of viruses in human acute appendicitis: a systematic literature review

BACKGROUND

There have been debates about the human appendix function, and while previous research suggested it might be a vestigial organ with no functional significance, recent studies have pointed out that it might have an important role in the immune system. Acute appendicitis (AA) is a common cause of emergency abdominal surgery in the world. Some epidemiologic investigations have found an association between appendicitis and viral infections. In this study, we have reviewed systematically articles to discover viral infections that cause appendicitis and find any possible correlations between the two.

METHODS

This systematic review was performed by searching among electronic databases including Web of Science, PubMed, Scopus, and EMBASE on viruses and appendicitis topics.

RESULTS

Conducted search leads to 983 results in all databases after the duplicate removal and screening by title, abstract, and full-text based on inclusion criteria lead to 19 studies. There were several assays to detect the viruses, which are thought to be AA causative agents. RT-PCR and immunoassays were the mainstay methods to detect the probable cause.

CONCLUSION

Investigations suggested that some viruses including measles virus (MV), influenza virus, dengue fever virus (DFV), human immunodeficiency virus (HIV), human herpesviruses, rotavirus, and adenovirus are associated with acute appendicitis. Despite the available reports, the specific mechanisms behind the relationship between acute appendicitis and viral infections are yet to be understood. Therefore, further investigations are necessary to find out the pathogenesis and pathophysiology of viral complications in appendicitis.

Experience of eradicating parasites of laboratory rats in conventional vivarium

The purpose of the research is to test different dehelminthization schemes of laboratory rats infected with cestodes Rodentolepis nana and nematodes Syphacia muris and evaluate the significance of combined environment disinfection measures. The practical experience of eradication (helminth eradication) in animals in a conventional vivarium was described.Materials and methods. Experiments were conducted to study the efficacy of anthelmintics and administration schemes against cestode and nematode infections in laboratory rats. In the first experiment, praziquantel was used at a dose of 10 mg/kg to treat rats infected with R. nana. In the second experiment, the comparative efficacy of fenbendazole, albendazole, and pyrantel was evaluated against syphaciosis at the recommended dosages of 20, 10, and 12.5 mg/kg, respectively. Each drug was given orally, individually, twice with an interval of 7 days. The third experiment tested different schemes for treating syphaciosis with fenbendazole. One group of rats was given the drug orally individually using an esophageal tube at a dose of 20 mg/kg once a day for 7 consecutive days. Other groups were given fenbendazole daily with food for 7 days (150 mg fenbendazole per 1 kg of food). In all three experiments, all animals were divided into groups, and their cells underwent a complex of additional disinfection measures, and those kept in cages without disinfection.Results and discussion. Praziquantel showed 100% efficacy at a single dose of 10 mg/kg in R. nana therapy. In animals without additional disinfection procedures, cestode eggs were again recorded starting from day 14 after the drug administration. In the group of animals with disinfection measures, pathogens were not detected during the experiment. Double administration of fenbendazole, albendazole and pyrantel in the recommended dosages against syphaciosis did not result in eradicated nematodes in the animals. The disinfection did not affect the obtained results. Fenbendazole administered daily for 7 days ensured helminth eradication in animals. However, on day 7 after the therapy, Syphacia sp. eggs were again found in the groups that received the drug individually intragastrically through a tube, regardless of whether their cells were disinfected. The animals that received fenbendazole with food and were regularly disinfested remained free from nematodes throughout the experiment until the additional disinfection measures were cancelled. In the absence of disinfection, released helminth eggs were recorded on day 14 after therapy.

Redox Biomarkers Assessment after Oral Administration of Wine Extract and Grape Stem Extract in Rats and Mice

Wine and by-products of the winemaking process, such as grape stems, are rich in bioactive polyphenolic compounds that might be beneficial for animal and human health. In recent years, the administration of dietary polyphenols with strong antioxidant and cytoprotective properties has constituted an emerging line of research interest toward disease prevention. However, in scientific literature, only a limited number of studies have investigated the safety and the toxicological risks of polyphenolic compounds in vivo. Based on the above, the purpose of the present study was two-fold: first, to examine the effects of oral administration of a grape stem extract, derived from the Greek red wine Mavrodaphne, on mice redox biomarkers; and second, to investigate the biological effects of oral administration of a wine extract, derived from the emblematic Greek red wine Xinomavro, on rats. Toward this purpose, body weight, growth rate, hematological, biochemical, and histopathological parameters, as well as a panel of redox biomarkers, were examined. According to our results, the administration of Mavrodaphne grape stem extract in mice induced alterations in redox homeostasis, preventing mice from the adverse effects of lipid peroxidation. Contrariwise, the administration of Xinomavro wine extract induced both beneficial and harmful outcomes on rat redox status determined by the examined tissue. Collectively, our study reports that the Mavrodaphne grape stem extract, a serious pollutant when disposed in environmental matrices, is an important source of bioactive polyphenolic compounds that could protect from oxidative damage and improve animal and human health. Finally, the Xinomavro wine extract exerts tissue-specific changes in redox balance, which are indicative of the complexity that characterizes the biological systems.

Health Monitoring for Laboratory Salamanders

Laboratory animal health monitoring programs are necessary to protect animal health and welfare, the validity of experimental data, and human health against zoonotic infections. Health monitoring programs should be designed based on a risk assessment and knowledge about the biology and transmission of salamander pathogens. Both traditional and molecular diagnostic platforms are available for salamanders, and they provide complementary information. A comprehensive approach to health monitoring leverages the advantages of multiple platforms to provide a more complete picture of colony health and pathogen status. This chapter presents key considerations in the design and implementation of a colony health monitoring program for laboratory salamanders, including protocols for necropsy and sample collection.

Pathologists' perspective on the study design, analysis, and interpretation of proliferative lesions in lifetime and prenatal rodent carcinogenicity bioassays of aspartame

Aspartame, an artificial sweetener commonly used as a sugar substitute, is currently authorized for use in more than 100 countries. Hundreds of studies, conducted in various countries dating back to the 1970s, have shown that aspartame is safe at real-world exposure levels. Furthermore, multiple human epidemiology studies have provided no indication that consumption of aspartame induces cancer. Given the continued controversy surrounding the Ramazzini Institute's (RI) studies suggesting that aspartame is a carcinogenic hazard in rodents and evaluation by the International Agency for Research on Cancer, this report aims to provide the perspective of experienced pathologists on publicly available pathology data regarding purported proliferative lesions in liver, lung, lymphoid organs, and mammary gland as well as their implications for human risk assessment as reported for three lifetime rodent carcinogenicity bioassays of aspartame conducted at the RI. In the authors' view, flaws in the design, methodology and reporting of the RI aspartame studies limit the utility of the data sets as evidence that this agent represents a carcinogenic hazard. Therefore, all three RI studies, and particularly the accuracy of their pathology diagnoses and interpretations, should be rigorously reviewed by qualified and experienced veterinary toxicologic pathologists in assessing aspartame's carcinogenic risk.

Reporting quality in preclinical animal experimental research in 2009 and 2018: A nationwide systematic investigation

Lack of translation and irreproducibility challenge preclinical animal research. Insufficient reporting methodologies to safeguard study quality is part of the reason. This nationwide study investigates the reporting prevalence of these methodologies and scrutinizes the reported information’s level of detail. Publications were from two time periods to convey any reporting progress and had at least one author affiliated to a Danish University. We retrieved all relevant animal experimental studies using a predefined research protocol and a systematic search. A random sampling of 250 studies from 2009 and 2018 led to 500 publications in total. Reporting of measures known to impact study results estimates were assessed. Part I discloses a simplified two-level scoring “yes/no” to identify the presence of reporting. Part II demonstrates an additional three-level scoring to analyze the reported information’s level of detail. Overall reporting prevalence is low, although minor improvements are noted. Reporting of randomization increased from 24.0% in 2009 to 40.8% in 2018, blinded experiment conduct from 2.4% to 4.4%, blinded outcome assessment from 23.6% to 38.0%, and sample size calculation from 3.2% to 14.0%. Poor reporting of details is striking with reporting of the random allocation method to groups being only 1.2% in 2009 and 6.0% in 2018. Reporting of sample size calculation method was 2.4% in 2009 and 7.6% in 2018. Only conflict-of-interest statements reporting increased from 37.6% in 2009 to 90.4%. Measures safeguarding study quality are poorly reported in publications affiliated with Danish research institutions. Only a modest improvement was noted during the period 2009–2018, and the lack of details urgently prompts institutional strategies to accelerate this. We suggest thorough teaching in designing, conducting and reporting animal studies. Education in systematic review methodology should be implemented in this training and will increase motivation and behavior working towards quality improvements in science.

Molecular characterization of Cryptosporidium spp., Enterocytozoon bieneusi and Giardia duodenalis in laboratory rodents in China

Cryptosporidium spp., Enterocytozoon bieneusi and Giardia duodenalis are significant zoonotic intestinal pathogens that can cause gastrointestinal symptoms such as diarrhea and induce a host immune response. A total of 1237 fecal samples were collected from laboratory rodents (rats, mice and guinea pigs) from four different locations in China to investigate the infection rates and molecular characterization of these pathogens on experimental animals. Genomic DNA was extracted from each sample, and PCR amplifications were done. Overall, the Cryptosporidium spp. infection rate was 3.8% (47/1237). Four known Cryptosporidium species were identified, namely C. parvum, C. muris, C. tyzzeri and C. homai, the three former being zoonotic species. The overall E. bieneusi infection rate was 3.0% (37/1237). Seven known E. bieneusi genotypes, namely S7, BEB6, J, Henan-IV, CHG10, D and WL6, were detected by sequence analysis. Among these, genotypes D, Henan-IV and CHG10 have a high zoonotic risk. Giardia duodenalis was not detected at any of the three loci (SSU rRNA, bg and gdh) after PCR amplification. This study provides basic data for these pathogens in laboratory rodents in China and lays the foundation for their prevention and control in laboratory animals.

First Report of ‘Candidatus Mycoplasma haematomacacae’ in Laboratory-Kept Rhesus Monkeys (Macaca mulatta) Maintained in Rio de Janeiro, Brazil

Simple Summary

Health assessment in animals used in research studies are essential, since only animals that present no diseases are considered suitable for these purposes. In laboratory kept animals, a bacterium that infects red blood cells, named hemotropic Mycoplasma (also called hemoplasmas), has been described as problem for research studies. Different hemoplasma species have been detected infecting monkeys from Brazil. However, the occurrence of these bacteria in monkeys maintained in laboratory in Brazil have never been described. Accordingly, this study aimed: (1) to screen laboratory-kept rhesus monkeys for hemoplasmas; (2) to verify if any of the hemoplasma-positive animals demonstrate a decrease in their red blood cells counts; and (3) to investigate the genetic diversity of hemoplasma species in monkeys from Brazil. Five out of eight (62.5%) rhesus monkeys tested positive for hemoplasmas using a technique that detects DNA from these bacteria in monkey’s blood. Further analysis demonstrated that rhesus monkeys were infected by a species named ‘Candidatus Mycoplasma haematomacacae’ that had already been described occurring in monkeys from Japan and USA. Although no decreases on red blood cells count were perceived in rhesus monkeys evaluated herein, future studies are needed to elucidate if ‘Ca. M. haematomacacae’ is a problem for research studies that use rhesus monkeys.

Abstract

Health monitoring programs in animals used as experimental models are essential, since only disease-free subjects are considered suitable for research purposes. In laboratory-kept animals, hemoplasmas have been described as an important confounding variable. Different hemoplasma species have been detected infecting non-human primates (NHP) from Brazil. However, the occurrence of hemoplasma species in laboratory-kept NHP in Brazil has not-yet been assessed. Accordingly, this study aimed (i) to screen laboratory-kept rhesus monkeys for hemoplasmas, (ii) to verify if any of the hemoplasma-positive animals demonstrate hematological abnormalities, and (iii) to assess the genotype diversity of hemoplasma species in NHP from Brazil. Five out of eight (62.5%; 95% CI: 3.05–8.63) rhesus monkeys tested positive for hemotropic Mycoplasma spp. by PCR. Sequencing, phylogenetic, distance, and genotype diversity analyses of partial 16S rRNA gene demonstrate that rhesus monkeys were infected by ‘Candidatus Mycoplasma haematomacacae’ (formerly ‘Candidatus Mycoplasma haemomacaque’). Assessments of partial 16S rRNA diversity of hemoplasma species in NHP suggest that at least four genetically diverse groups may occur in Brazil. Although no hematological abnormalities were demonstrated in rhesus monkeys evaluated herein, future studies are needed to elucidate the influence of ‘Ca. M. haematomacacae’ as a confounding variable on research studies.

Why serology just is not enough: Strategic parvovirus risk assessment using a novel qPCR assay

Health monitoring of laboratory rodents not only improves animal health but also enhances the validity of animal experiments. In particular, infections of laboratory animals with murine parvoviruses influence biomedical research data. Despite strict barrier housing, prevalence remains high in animal facilities, leading to increased risk of parvovirus introduction after the import of contaminated mice. Unfortunately, hygienic rederivation can be challenging, since gametes often contain residual virus material. Consequently, the process has to be closely monitored with highly sensitive diagnostic methods to verify parvovirus decontamination of the rederived progeny. However, diagnostic sensitivity of traditional methods is often low and requires testing of large animal cohorts. Therefore, we aimed to develop a powerful quantitative real-time polymerase chain reaction (qPCR) assay for the fast and reliable detection of murine parvoviruses in different sample materials. We validated the assay within an infection experiment and systematically analysed various animal-derived and environmental sample materials. We further developed a strategic risk assessment procedure for parvovirus monitoring after embryo transfer. Our novel qPCR assay reliably detected parvovirus DNA in a broad variety of sample materials, with environmental samples dominating in the acute phase of infection, whereas animal-derived samples were more suitable to detect low virus loads in the chronic phase. Here, the assay served as a highly sensitive screening method for parvovirus contamination in mouse colonies, requiring significantly lower sample sizes than traditional methods like conventional PCR and serology. Thus, the use of our novel qPCR assay substantially improves parvovirus diagnostics, enhancing research validity according to the 6Rs.

Research-Relevant Conditions and Pathology of Laboratory Mice, Rats, Gerbils, Guinea Pigs, Hamsters, Naked Mole Rats, and Rabbits

Animals are valuable resources in biomedical research in investigations of biological processes, disease pathogenesis, therapeutic interventions, safety, toxicity, and carcinogenicity. Interpretation of data from animals requires knowledge not only of the processes or diseases (pathophysiology) under study but also recognition of spontaneous conditions and background lesions (pathology) that can influence or confound the study results. Species, strain/stock, sex, age, anatomy, physiology, spontaneous diseases (noninfectious and infectious), and neoplasia impact experimental results and interpretation as well as animal welfare. This review and the references selected aim to provide a pathology resource for researchers, pathologists, and veterinary personnel who strive to achieve research rigor and validity and must understand the spectrum of "normal" and expected conditions to accurately identify research-relevant experimental phenotypes as well as unusual illness, pathology, or other conditions that can compromise studies involving laboratory mice, rats, gerbils, guinea pigs, hamsters, naked mole rats, and rabbits.

Rag2 Deficiency Enhances Susceptibility to Systemic Mouse Adenovirus Type 1 Infection

Introduction

Recombination-activating gene (Rag) 1 and Rag2, which are essential in V(D)J recombination, play a crucial role in B- and T-cell maturation.

Method

We investigated the effects of Rag2 deficiency in clustered regularly interspaced short palindromic repeats/Cas9-mediated FVB-Rag2 knockout (KO) and wild-type (WT) mice infected with mouse adenovirus type 1 (MAV-1) via the intranasal route.

Results

MAV-1 infection caused more severe histopathological changes in FVB-Rag2 KO mice than in WT mice. FVB-Rag2 KO mice exhibited moderate to severe inflammation on day 4 and severe inflammation on day 8 post infection. In contrast, WT mice showed mild inflammation on day 4 and mild to severe inflammation on day 8 post infection, including interstitial pneumonia and inflammatory cell infiltration in the lungs and liver. Viral loads in the spleen and kidneys were significantly higher in FVB-Rag2 KO mice than in WT mice on day 8 post infection. Levels of cytokines and chemokines, including macrophage inflammatory protein-1α, induced protein 10, interferon (IFN)-α, IFN-γ, and tumor necrosis factor alpha, were upregulated in the spleens of FVB-Rag2 KO mice compared with those of WT mice. The upregulation of several cytokines occurred concurrently with the histopathological changes. MAV-1 infection induced more severe systemic infection in FVB-Rag2 KO mice than in WT mice.

Conclusion

In mice, Rag2 deficiency induces inflammatory cell recruitment via the upregulation of cytokine and chemokine levels. The MAV-1 infection model can be utilized to assess the efficacy and safety of therapeutic agents for human adenoviral diseases.

Microbiological survey of Korean mouse facilities from 2014 to 2019

We surveyed mouse microbiological contamination rates by testing rates for common contaminants using serological, culture, and parasitological methods. A total of 21,292 experimentally housed mice from 206 animal facilities, including hospitals, universities, companies, and research institutes, were tested over a 6-year period from 2014 to 2019. The most commonly found contaminants were various species of nonpathogenic protozoa (47.2%). The most common pathogenic bacteria were Staphylococcus aureus (21.2%), Pasteurella pneumotropica (12.5%), and Pseudomonas aeruginosa (5.8%). Mouse hepatitis virus (6.1%) was detected, but no other viral or bacterial pathogens were found. These results establish that the main pathogens that currently contaminate mouse facilities in Korea are opportunistic pathogens and that contamination with important pathogens, such as those in Categories B or C, has decreased.

Radiant catalytic ionization improves the microbiological status of rodent facilities without affecting the prooxidative status of mice

The main microbial contaminants of rooms in which laboratory rodents are housed are bacteria and fungi. Restriction of microbial growth to below threshold levels requires the application of various sophisticated antimicrobial techniques that must be effective and safe for the animals. Some of the most commonly used techniques, including chemical disinfection, ventilation, filtration, sterilization and radiation, are not always sufficiently effective. The aim of the current study was to evaluate the efficacy of a modern technique (i.e. radiant catalytic ionization (RCI)) on the microbiological status of an animal care facility, and the health of the mice housed therein. The experiment, conducted over seven days, compared an experimental room with an RCI system permanently turned on with a negative control room. At the completion of the experiment, the number of bacteria in the RCI room air and on its walls was lower than that in the control room (p < 0.01 in both cases). Values of the basic prooxidative parameter, thiobarbituric acid reactive substances concentration, in tissues of mice from the RCI room were within allowed boundaries. Hence, application of an RCI system proved to be an ideal technique to ensure high hygienic standards in animal rooms without any adverse effects on the animals housed therein.

Deaths Due to Mixed Infections with Passalurus ambiguus, Eimeria spp. and Cyniclomyces guttulatus in an Industrial Rabbit Farm in Greece

Domestic rabbits are commercially farmed for their meat whilst gastrointestinal diseases can hinder their production. Passalurusambiguus and Eimeria spp. are two common rabbit intestinal parasites that can cause diarrhoea, among other symptoms, and in severe cases, death. C. guttulatus is a commensal yeast of the rabbits’ stomach that is considered apathogenic but can worsen symptoms in rabbits suffering from coccidiosis. In the present case report, we describe an outbreak of deaths in three different age groups (A: lactating does, B: 58 days old and C: 80 days old) in an industrial rabbit farm in Greece. Symptoms included depression, diarrhoea, inappetence, weight loss, dehydration and ruffled furs. Using a faecal flotation technique, sick rabbits were found to be moderately to heavily infected with P. ambiguus, Eimeria spp. and C. guttulatus. Treatment with fenbendazole and oregano oil combined with hygiene control measures successfully controlled the infections and resolved clinical symptoms. A faecal flotation method or other reliable diagnostic technique should be used regularly in industrial rabbit farms to screen for gastrointestinal parasitic infections. Early diagnosis and control will help to maintain production levels and, therefore, limit financial losses for the farmer while ensuring animal welfare.

A New Antifungal-Loaded Sol-Gel Can Prevent Candida albicans Prosthetic Joint Infection

Fungal PJI is one of the most feared complications after arthroplasty. Although a rare finding, its high associated morbidity and mortality makes it an important object of study. The most frequent species causing fungal PJI is C. albicans. New technology to treat this type of PJI involves organic-inorganic sol-gels loaded with antifungals, as proposed in this study, in which anidulafungin is associated with organophosphates. This study aimed to evaluate the efficacy of an anidulafungin-loaded organic-inorganic sol-gel in preventing prosthetic joint infection (PJI), caused by Candida albicans using an in vivo murine model that evaluates many different variables. Fifty percent (3/6) of mice in the C. albicans-infected, non-coated, chemical-polished (CP)-implant group had positive culture and 100% of the animals in the C. albicans-infected, anidulafungin-loaded, sol-gel coated (CP + A)-implant group had a negative culture (0/6) (p = 0.023). Taking the microbiology and pathology results into account, 54.5% (6/11) of C. albicans-infected CP-implant mice were diagnosed with a PJI, whilst only 9.1% (1/11) of C. albicans-infected CP + A-implant mice were PJI-positive (p = 0.011). No differences were observed between the bone mineral content and bone mineral density of noninfected CP and noninfected CP + A (p = 0.835, and p = 0.181, respectively). No histological or histochemical differences were found in the tissue area occupied by the implant among CP and CP + A. Only 2 of the 6 behavioural variables evaluated exhibited changes during the study: limping and piloerection. In conclusion, the anidulafungin-loaded sol-gel coating showed an excellent antifungal response in vivo and can prevent PJI due to C. albicans in this experimental model.

Health Monitoring of Laboratory Rodent Colonies-Talking about (R)evolution

The health monitoring of laboratory rodents is essential for ensuring animal health and standardization in biomedical research. Progress in housing, gnotobiotic derivation, and hygienic monitoring programs led to enormous improvement of the microbiological quality of laboratory animals. While traditional health monitoring and pathogen detection methods still serve as powerful tools for the diagnostics of common animal diseases, molecular methods develop rapidly and not only improve test sensitivities but also allow high throughput analyses of various sample types. Concurrently, to the progress in pathogen detection and elimination, the research community becomes increasingly aware of the striking influence of microbiome compositions in laboratory animals, affecting disease phenotypes and the scientific value of research data. As repeated re-derivation cycles and strict barrier husbandry of laboratory rodents resulted in a limited diversity of the animals' gut microbiome, future monitoring approaches will have to reform-aiming at enhancing the validity of animal experiments. This review will recapitulate common health monitoring concepts and, moreover, outline strategies and measures on coping with microbiome variation in order to increase reproducibility, replicability and generalizability.

Behavioral and Reproductive Effects of Environmental Enrichment and Pseudoloma neurophilia infection on Adult Zebrafish (Danio rerio)

Recent studies have shown beneficial effects of environmental enrichment (EE) for zebrafish, while infection of zebrafish with the common pathogen Pseudoloma neurophilia has negative effects. This study investigates the effects of P. neurophilia infection and EE in housing and breeding tanks on measures of behavior, growth, and reproduction. Zebrafish were socially housed and were either infected, P. neurophilia-infected (PNI) (n = 12 tanks), or SPF for P. neurophilia (SPF) (n = 24 tanks). Fish were housed with or without EE, which consisted of placing plastic plants in the tanks; sprigs from plants were placed in half of the breeding tanks for half of breedings, alternating breeding tanks without EE weekly. Behavioral testing included the Novel Tank Diving Test (NTT) and Light/Dark Preference Test (LDT) conducted prior to breeding. At the end of the study, biometric data were collected. Histopathology and molecular analysis for common diseases in fish confirmed that SPF fish remained SPF and that fish from all PNI tanks were infected. PNI fish produced significantly fewer eggs and had lower body weights and lengths than did SPF fish. Fish with EE had longer body lengths, than did fish without EE, and male fish had longer body lengths than female fish. The biometric results and reproductive measures show that SPF fish exhibited better growth and suggest that EE in housing tanks could improve fish growth. The behavioral test results were inconclusive regard- ing whether infection status or EE altered anxiety-like behavior. Our results support other recent studies showing negative effects of P. neurophilia infection on zebrafish.

Animal models of cough

Cough is a vital airway reflex that keeps the respiratory tract wisely protected. It is also a sign of many diseases of the respiratory system and it may become a disease in its own right. Even though the efficacy of antitussive compounds is extensively studied in animal models with promising results, the treatment of pathological cough in humans is insufficient at the moment. The limited translational potential of animal models used to study cough causes, mechanisms and possible therapeutic targets stems from multiple sources. First of all, cough induced in the laboratory by mechanical or chemical stimuli is far from natural cough present in human disease. The main objective of this review is to provide a comprehensive summary of animal models currently used in cough research and to address their advantages and disadvantages. We also want to encourage cough researchers to call for precision is research by addressing the sex bias which has existed in basic cough research for decades and discuss the role of specific pathogen-free (SPF) animals.

Clinical and molecular aspects of veterinary coronaviruses

Coronaviruses are a large group of RNA viruses that infect a wide range of animal species. The replication strategy of coronaviruses involves recombination and mutation events that lead to the possibility of cross-species transmission. The high plasticity of the viral receptor due to a continuous modification of the host species habitat may be the cause of cross-species transmission that can turn into a threat to other species including the human population. The successive emergence of highly pathogenic coronaviruses such as the Severe Acute Respiratory Syndrome (SARS) in 2003, the Middle East Respiratory Syndrome Coronavirus in 2012, and the recent SARS-CoV-2 has incentivized a number of studies on the molecular basis of the coronavirus and its pathogenesis. The high degree of interrelatedness between humans and wild and domestic animals and the modification of animal habitats by human urbanization, has favored new viral spreads. Hence, knowledge on the main clinical signs of coronavirus infection in the different hosts and the distinctive molecular characteristics of each coronavirus is essential to prevent the emergence of new coronavirus diseases. The coronavirus infections routinely studied in veterinary medicine must be properly recognized and diagnosed not only to prevent animal disease but also to promote public health.

Isolation of Streptococcus cuniculi from corneal lesion in laboratory-raised mice

Corneal lesions appearing as white mass beneath intact epithelium, with ocular discharge in one mouse, was observed in a batch of laboratory-raised BALB/c mice (n=9 of 56). The affected mice remained active, well-groomed and had normal appetite. Isolates recovered from swab cultures of the external and internal contents of the eye had partial 16S rRNA gene sequence of 99.1% similarity to Streptococcus cuniculi. No previous report of S. cuniculi infection in laboratory rodents has been presented. The isolate was susceptible to all antibiotics tested. We suggest S. cuniculi is an opportunistic bacteria in laboratory mice but are uncertain of its source. Our findings revealed that S. cuniculi is able to colonize laboratory mice and should be considered when mice present with eye lesion or ocular discharge.

Coupling between tolerance and resistance for two related Eimeria parasite species

Resistance (host capacity to reduce parasite burden) and tolerance (host capacity to reduce impact on its health for a given parasite burden) manifest two different lines of defense. Tolerance can be independent from resistance, traded off against it, or the two can be positively correlated because of redundancy in underlying (immune) processes. We here tested whether this coupling between tolerance and resistance could differ upon infection with closely related parasite species. We tested this in experimental infections with two parasite species of the genus Eimeria. We measured proxies for resistance (the (inverse of) number of parasite transmission stages (oocysts) per gram of feces at the day of maximal shedding) and tolerance (the slope of maximum relative weight loss compared to day of infection on number of oocysts per gram of feces at the day of maximal shedding for each host strain) in four inbred mouse strains and four groups of F1 hybrids belonging to two mouse subspecies, Mus musculus domesticus and Mus musculus musculus. We found a negative correlation between resistance and tolerance against Eimeria falciformis, while the two are uncoupled against Eimeria ferrisi. We conclude that resistance and tolerance against the first parasite species might be traded off, but evolve more independently in different mouse genotypes against the latter. We argue that evolution of the host immune defenses can be studied largely irrespective of parasite isolates if resistance-tolerance coupling is absent or weak (E. ferrisi) but host-parasite coevolution is more likely observable and best studied in a system with negatively correlated tolerance and resistance (E. falciformis).

The Role of Feed in Aquatic Laboratory Animal Nutrition and the Potential Impact on Animal Models and Study Reproducibility

Feed plays a central role in the physiological development of terrestrial and aquatic animals. Historically, the feeding practice of aquatic research species derived from aquaculture, farmed, or ornamental trades. These diets are highly variable, with limited quality control, and have been typically selected to provide the fastest growth or highest fecundity. These variations of quality and composition of diets may affect animal/colony health and can introduce confounding experimental variables into animal-based studies that impact research reproducibility.

Effects of Pseudoloma neurophilia infection on the brain transcriptome in zebrafish (Danio rerio)

Laboratory zebrafish are commonly infected with the intracellular, brain-infecting microsporidian parasite Pseudoloma neurophilia. Chronic P. neurophilia infections induce inflammation in meninges, brain and spinal cord, and have been suggested to affect neural functions since parasite clusters reside inside neurons. However, underlying neural and immunological mechanisms associated with infection have not been explored. Utilizing RNA-sequencing analysis, we found that P. neurophilia infection upregulated 175 and downregulated 45 genes in the zebrafish brain, compared to uninfected controls. Four biological pathways were enriched by the parasite, all of which were associated with immune function. In addition, 14 gene ontology (GO) terms were enriched, eight of which were associated with immune responses and five with circadian rhythm. Surprisingly, no differentially expressed genes or enriched pathways were specific for nervous system function. Upregulated immune-related genes indicate that the host generally show a pro-inflammatory immune response to infection. On the other hand, we found a general downregulation of immune response genes associated with anti-pathogen functions, suggesting an immune evasion strategy by the parasite. The results reported here provide important information on host-parasite interaction and highlight possible pathways for complex effects of parasite infections on zebrafish phenotypes.

Toxicity of a methotrexate metronomic schedule in Wistar rats

Metronomic chemotherapy is a relevant strategy that uses low doses of antineoplastic drugs for sustained periods to control tumor growth, an alternative frequently utilized in veterinary patients. This work aimed to evaluate the toxic effects of a metronomic oral dose of methotrexate (MTX) for 45 days in tumor-free Wistar rats when compared with control animals. Clinical alterations, body weight, food, and water intake were monitored daily, and bone marrow suppression, hematological, biochemical, and histopathological analyses were performed at three points (days 30, 45, and 60). MTX-treated animals did not demonstrate severe systemic involvement. At 30 days, compared with control animals, MTX-treated animals showed significant leukocytosis (11.9 ± 2.3 vs. 7.8 ± 0.2 10⁶/μL; P < .05) and augmentation of immature myeloid populations from bone marrow (9.0 ± 0.8 vs. 6.5 ± 1.5%; P < .05), and at 60 days, treated animals showed significant neutrophilia (35.0 ± 11.0 vs. 23.00 ± 3.0%; P < .05), depletion of bone marrow lymphocytes (8.2 ± 0.7 vs. 11.5 ± 1.9%; P < .05), and immature myeloid populations (7.2 ± 0.7 vs. 8.3 ± 0.6%; P < .05). At a histopathological level, splenic hypoplasia and respiratory inflammatory lesions were significant when compared with control animals, presenting mild to moderate myelotoxicity, immune suppression, and associated clinical compromise that persisted beyond treatment withdrawal. This suggested that MTX metronomic toxicity should not be neglected owing to the observed residual side-effects and special care should be taken regarding myelosuppression.

Reporting animal research: Explanation and elaboration for the ARRIVE guidelines 2.0

Improving the reproducibility of biomedical research is a major challenge. Transparent and accurate reporting is vital to this process; it allows readers to assess the reliability of the findings and repeat or build upon the work of other researchers. The ARRIVE guidelines (Animal Research: Reporting In Vivo Experiments) were developed in 2010 to help authors and journals identify the minimum information necessary to report in publications describing in vivo experiments. Despite widespread endorsement by the scientific community, the impact of ARRIVE on the transparency of reporting in animal research publications has been limited. We have revised the ARRIVE guidelines to update them and facilitate their use in practice. The revised guidelines are published alongside this paper. This explanation and elaboration document was developed as part of the revision. It provides further information about each of the 21 items in ARRIVE 2.0, including the rationale and supporting evidence for their inclusion in the guidelines, elaboration of details to report, and examples of good reporting from the published literature. This document also covers advice and best practice in the design and conduct of animal studies to support researchers in improving standards from the start of the experimental design process through to publication.

Behavioural effects of the common brain-infecting parasite Pseudoloma neurophilia in laboratory zebrafish (Danio rerio)

Research conducted on model organisms may be biased due to undetected pathogen infections. Recently, screening studies discovered high prevalence of the microsporidium Pseudoloma neurophilia in zebrafish (Danio rerio) facilities. This spore-forming unicellular parasite aggregates in brain regions associated with motor function and anxiety, and despite its high occurrence little is known about how sub-clinical infection affects behaviour. Here, we assessed how P. neurophilia infection alters the zebrafish´s response to four commonly used neurobehavioral tests, namely: mirror biting, open field, light/dark preference and social preference, used to quantify aggression, exploration, anxiety, and sociability. Although sociability and aggression remained unaltered, infected hosts exhibited reduced activity, elevated rates of freezing behaviour, and sex-specific effects on exploration. These results indicate that caution is warranted in the interpretation of zebrafish behaviour, particularly since in most cases infection status is unknown. This highlights the importance of comprehensive monitoring procedures to detect sub-clinical infections in laboratory animals.

Room Decontamination Using Ionized Hydrogen Peroxide Fog and Mist Reduces Hatching Rates of Syphacia obvelata Ova

This study evaluated the efficacy of ionized hydrogen peroxide (iHP) fog and mist for environmental and surface decontaminationof Syphacia obvelata ova in rodent rooms. Ova were collected by perianal tape impression from S. obvelata infectedmice. In experiment 1, ova were exposed to iHP using a whole-room fogging decontamination system with a 15 min initialfog application cycle in unoccupied rodent rooms. Ova were removed from the fogged environment after a 15 min, 30 min, 90min, or 240 min iHP exposure time. In experiment 2, a second cohort of ova were exposed to iHP using the whole-room foggingdecontamination system. Ova were removed after 3, 4 or 6 continuous fog application cycles with 45 min dwelling timebetween each cycle and 15 h dwelling time for the last time point. In experiment 3, a third set of ova was exposed to an iHPsurface misting unit with 1, 2, or 3 iHP mist applications. A 7 min contact time followed each application. After exposure, ovawere incubated in a hatching medium for 6 h. Control ova were maintained at room temperature without iHP exposure beforeincubation in the hatching medium. After incubation, the number of ova hatched was assessed by microscopic examination.For experiment 1, results ranged from 46% to 57% of exposed ova hatched. For experiment 2, results ranged from 43% to 49%of ova hatched. For experiment 3, 37% to 46% of exposed ova hatched. Conversely, for the control groups above 80% of ovahatched for all 3 experiments. These data suggest that exposure to iHP fog and mist has variable effectiveness in reducingviability of S. obvelata ova at the time points tracked. Further studies are needed to identify iHP exposures that will furtherreduce or eliminate the hatching of rodent pinworm ova.

Efficacy data of halogenated phenazine and quinoline agents and an NH125 analogue to veterinary mycoplasmas

BACKGROUND

Mycoplasmas primarily cause respiratory or urogenital tract infections impacting avian, bovine, canine, caprine, murine, and reptilian hosts. In animal husbandry, mycoplasmas cause reduced feed-conversion, decreased egg production, arthritis, hypogalactia or agalactia, increased condemnations, culling, and mortality in some cases. Antibiotics reduce transmission and mitigate clinical signs; however, concerning levels of antibiotic resistance in Mycoplasma gallisepticum and M. capricolum isolates exist. To address these issues, we evaluated the minimum inhibitory concentrations (MICs) of halogenated phenazine and quinoline compounds, an N-arylated NH125 analogue, and triclosan against six representative veterinary mycoplasmas via microbroth or agar dilution methods. Thereafter, we evaluated the minimum bactericidal concentration (MBC) of efficacious drugs.

RESULTS

We identified several compounds with MICs ≤25 μM against M. pulmonis (n = 5), M. capricolum (n = 4), M. gallisepticum (n = 3), M. alligatoris (n = 3), M. agassizii (n = 2), and M. canis (n = 1). An N-arylated NH125 analogue, compound 21, served as the most efficacious, having a MIC ≤25 μM against all mycoplasmas tested, followed by two quinolines, nitroxoline (compound 12) and compound 20, which were effective against four and three mycoplasma type strains, respectively. Nitroxoline exhibited bactericidal activity among all susceptible mycoplasmas, and compound 21 exhibited bactericidal activity when the MBC was able to be determined.

CONCLUSIONS

These findings highlight a number of promising agents from novel drug classes with potential applications to treat veterinary mycoplasma infections and present the opportunity to evaluate preliminary pharmacokinetic indices using M. pulmonis in rodents as an animal model of human infection.

Antidiabetic effect of Cordia morelosana, chemical and pharmacological studies

ETHNOPHARMACOLOGICAL IMPORTANCE

CORDIA MORELOSANA: Standley (Boraginaceae) is commonly used in folk medicine for the treatment of diarrhoea, kidney inflammation, diabetes, lung pain, bronchitis, asthma, hoarseness, cough and fever.

AIM

Current work was conducted to develop a bio-guided isolation of antidiabetic compounds from ethanolic extract of Cordia morelosana (EECm).

MATERIAL AND METHODS

The phytochemical bio-guided study was conducted by successive chromatographic techniques, and isolated compounds were characterized by 1D and 2D-NMR experiments. The in vivo antihyperglycemic and antidiabetic activities of EECm (100 mg/kg), and methyl rosmarinate (MR, 50 mg/kg) were determined on normoglycemic and diabetic murine models. Additionally, the in vitro activity was conducted to determine α-glucosidase inhibitory effect, and PPARs, GLUT4 and FATP expression on 3T3-L1 cells by RT-PCR. Acute and sub-chronic toxicological studies for EECm were conducted on rats, following the OECD guidelines (No. 420 and 407).

RESULTS

EECm promotes significant α-glucosidase inhibition (55.6%) at 1 mg/kg respect to the control. Also, EECm (100 mg/kg) showed significant antihyperglycemic effect on oral glucose tolerance test (OGTT), and in non-insulin dependent type 2 diabetes (NIDD) model, had antidiabetic activity (p < 0.001) compared to controls. The bio-guided isolation allowed to obtain four known compounds described as rosmarinic acid (RA), methyl rosmarinate (MR), nicotiflorine and 1-O-methyl-scyllo-inositol. On the other hand, MR showed significant antidiabetic and anthiyperglycemic activities (p < 0.05), and overexpression of PPARγ, PPARα, GLUT-4 and FATP than control. Docking studies were conducted with PPARγ and PPARα, showing interesting binding mode profile on those targets. Finally, EECm displayed a LD₅₀ > 2000 mg/kg and sub-chronic toxicological study reveals no toxic signs in animals tested compared to control.

CONCLUSION

EECm showed significant antihyperglycemic and antidiabetic actions being RA and MR the main antidiabetic metabolites.

The Impact of Age and Sex on Mouse Models of Melioidosis

Mouse models have been used to generate critical data for many infectious diseases. In the case of Burkholderia pseudomallei, mouse models have been invaluable for bacterial pathogenesis studies as well as for testing novel medical countermeasures including both vaccines and therapeutics. Mouse models of melioidosis have also provided a possible way forward to better understand the chronicity associated with this infection, as it appears that BALB/c mice develop an acute infection with B. pseudomallei, whereas the C57BL/6 model is potentially more suggestive of a chronic infection. Several unanswered questions, however, persist around this model. In particular, little attention has been paid to the effect of age or sex on the disease outcome in these animal models. In this report, we determined the LD₅₀ of the B. pseudomallei K96243 strain in both female and male BALB/c and C57BL/6 mice in three distinct age groups. Our data demonstrated a modest increase in susceptibility associated with sex in this model, and we documented important histopathological differences associated with the reproductive systems of each sex. There was a statistically significant inverse correlation between age and susceptibility. The older mice, in most cases, were more susceptible to the infection. Additionally, our retrospective analyses suggested that the impact of animal supplier on disease outcome in mice may be minimal. These observations were consistent regardless of whether the mice were injected with bacteria intraperitoneally or if they were exposed to aerosolized bacteria. All of these factors should be considered when designing experiments using mouse models of melioidosis.

The Impact of Pseudoloma neurophilia Infection on Body Condition of Zebrafish

The zebrafish is a widely used animal model in biomedical research. Despite this, pathogens continue to be common in laboratory zebrafish. It is important to determine and describe the pathophysiology of cryptic infections on zebrafish to elucidate the impacts on experimental endpoints. Body condition is a basic measurement used experimentally and in health monitoring of animals. We exposed three wild-type zebrafish strains: AB, WIK, and 5D to Pseudoloma neurophilia. After 8 weeks postexposure, we individually imaged and processed fish for histology. Morphometric analysis was performed on images and an index of body condition was calculated based on the ratio of length/width from the dorsal aspect. Histological sections from each fish were examined to establish sex, severity of infection, and tissue distribution. We observed a significant decrease in body condition in female fish that was not observed in males. In addition, we observed a negative correlation between the total gonadal area of P. neurophilia exposed females and unexposed controls. These results illustrate the sex-specific impacts of a common chronic pathogen on zebrafish health and a commonly used experimental endpoint, further supporting the establishment of rigorous health monitoring programs in laboratory zebrafish colonies that include screening for chronic infectious diseases.

Electrochemical virus detections with nanobiosensors

Infectious diseases are caused from pathogens, which need a reliable and fast diagnosis. Today, expert personnel and centralized laboratories are needed to afford much time in diagnosing diseases caused from pathogens.

Recent progress in electrochemical studies shows that biosensors are very simple, accurate, precise, and cheap at virus detection, for which researchers find great interest in this field. The clinical levels of these pathogens can be easily analyzed with proposed biosensors. Their working principle is based on affinity between antibody and antigen in body fluids. The progress still continues on these biosensors for accurate, rapid, reliable sensors in future.

Medical Management and Diagnostic Approaches

This chapter reviews the basic principles of medical management of rat colonies and diagnostic approaches to detect infectious diseases of rats. As is the case with all other species, rats are susceptible to a variety of injuries and diseases that can cause distress, morbidity, or mortality. Any facility that houses rats must develop monitoring programs designed to rapidly identify health-related problems so they can be communicated to appropriate veterinary or animal care personnel to be resolved. These programs generally consist of multiple components, some of which are directed toward individual animals and others that assess the health status of rat populations as a whole. Topics include individual animal monitoring and care, signs of illness and distress, colony health management, components of microbiological monitoring programs, including agents commonly targeted and sentinel programs, quarantine, biological material screening, diagnostic testing methodologies, including culture, serology, molecular diagnostic and histopathology, test profiles and interpretation, management of disease outbreaks, and treatment and prevention strategies for infectious agents.

Rats and Mice

This chapter provides an overview of the natural history, anatomy, physiology, clinical examination, common diseases, and treatment of rats (Rattus norvegicus) and mice (Mus musculus) in the context of veterinary medicine. Guidelines for the care and feeding of rats and mice can provide owners with information to help prevent disease in their pets. Useful techniques for restraint, clinical examination, and diagnostic sample collection are provided to aid veterinarians in thorough evaluation of these small rodents. Common diseases and treatments are discussed separately for each species, organized by organ system. Zoonotic diseases are also discussed to provide guidance for rat and mouse pet owners.

Impact of TCR Diversity on the Development of Transplanted or Chemically Induced Tumors

Burnet postulated that the diversity of T-cell receptors (TCR) allows T cells to protect against the development of cancers that display antigens with a similar, seemingly endless diversity. To test this hypothesis, we developed a strategy in which a single breeding pair of mice gives rise to four groups of sibling mice. Three of the four groups had a similar number of CD8⁺ T cells, but TCR diversity was either broad, significantly reduced, or absent when expressing only one type of TCR. The fourth group had no T cells. All mice shared the same housing, and, therefore, their microbial environment was similar. Only slight differences in the intestinal flora were observed under these conditions. An undisturbed broad TCR repertoire was required for the rejection of inoculated cancers displaying the natural antigenic heterogeneity of primary tumors, whereas even one type of TCR was sufficient to protect against artificial cancers stably expressing cognate antigens. The three groups of mice with limited or no TCR repertoire showed an increased risk of developing primary tumors after chemical induction. However, the risk of early death or morbidity in these cohorts of mice was significantly higher than in mice with a diverse TCR repertoire, and it remains unknown whether mice with reduced TCR diversity, who died early without cancer, would have developed tumors with higher, lower, or equal probability after induction. Together, TCR diversity seems crucial to overcome the natural genetic instability of cancers and their antigenic heterogeneity, which impacts the design of cellular therapies.

Cancer Treatment Goes Viral: Using Viral Proteins to Induce Tumour-Specific Cell Death

Cell death is a tightly regulated process which can be exploited in cancer treatment to drive the killing of the tumour. Several conventional cancer therapies including chemotherapeutic agents target pathways involved in cell death, yet they often fail due to the lack of selectivity they have for tumour cells over healthy cells. Over the past decade, research has demonstrated the existence of numerous proteins which have an intrinsic tumour-specific toxicity, several of which originate from viruses. These tumour-selective viral proteins, although from distinct backgrounds, have several similar and interesting properties. Though the mechanism(s) of action of these proteins are not fully understood, it is possible that they can manipulate several cell death modes in cancer exemplifying the intricate interplay between these pathways. This review will discuss our current knowledge on the topic and outstanding questions, as well as deliberate the potential for viral proteins to progress into the clinic as successful cancer therapeutics.

Polymicrobial abscess following ovariectomy in a mouse

Background

Ovariectomy is a common procedure in laboratory rodents used to create a post-menopausal state. Complications including post-surgical abscess are rarely reported, but merit consideration for the health and safety of experimental animals.

Case presentation

A female C57/black6 mouse was ovariectomized as part of a cohort study. At Day 14 post-surgery, she developed a visible swelling on the right side, which 7 days later increased in size over 24 h, leading to euthanasia of the animal. Gross pathology was consistent with abscess. A core of necrotic tissue was present in the uterine horn. Abscess fluid and affected tissue were collected for Gram stain and bacteriological culture. The abscess core and fluid yielded three distinct types of bacterial colonies identified by 16S ribosomal RNA sequencing as Streptococcus acidominimus, Pasteurella caecimuris, and a novel species in the genus Gemella.

Conclusions

This is the first report of polymicrobial abscess in a rodent as a complication of ovariectomy, and the first description of a novel Gemella species for which we have proposed the epithet Gemella muriseptica. This presentation represents a potential complication of ovariectomy in laboratory animals.

Nonabsorbable Suture Knot on the Tendon Affects Rotator Cuff Healing: A Comparative Study of the Knots on Tendon and Bone in a Rat Model of Rotator Cuff Tear

BACKGROUND

Nonabsorbable suture knots are usually used to link the tendon and bone during rotator cuff repair surgery. There are many variations in the arthroscopic knot-tying technique; however, the location of suture knot placement for rotator cuff healing has rarely been studied.

HYPOTHESIS

The authors compared the rotator cuff healing between knots tied on tendon and bone in a rotator cuff tear rat model. It has been hypothesized that knots can cause chronic inflammation and create the weakest link between tendon and bone, thus affecting rotator cuff healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

Bilateral supraspinatus tenotomy and rotator cuff repair at the greater tuberosity were performed on 24 Wistar rats. Nonabsorbable surgical suture knots were made on the right supraspinatus tendon tissue and left humerus inferior to the greater tuberosity, respectively. Twelve rats each were sacrificed at 3 and 9 weeks. Six of the 12 rats were used for biomechanical testing and the remaining 6 for histologic evaluation.

RESULTS

The surgical knots placed on the bursal side of the tendon migrated to the articular side, as noted on gross observation in 22 of 24 samples. The knots on the tendon group showed significantly inferior tendon-bone integration and significantly inferior biomechanical results in terms of maximum load to failure and stiffness. An obvious chronic foreign body inflammatory reaction was found in the knots on the tendon group at 3 and 9 weeks. Furthermore, inferior bone-tendon interface regeneration and weakest link formation were obtained in the knots on the tendon group compared with those on the bone group.

CONCLUSION

Nonabsorbable suture knots placed on the tendon migrate to the articular side, causing chronic inflammation and weakening tendon-bone healing, which may explain some retears after rotator cuff repair.

CLINICAL RELEVANCE

The present animal study suggests that it is not recommended in clinical practice to make several bulky nonabsorbable suture knots on the rotator cuff tendon during rotator cuff repair surgery. It may be better to tie the knots at the bone side or do knotless repair.

Combining fish and environmental PCR for diagnostics of diseased laboratory zebrafish in recirculating systems

Precise knowledge of the health status of experimental fish is crucial to obtain high scientific and ethical standards in biomedical research. In addition to the use of sentinel fish, the examination of diseased fish is a fundamental part of all health monitoring concepts. PCR assays offer excellent sensitivity and the ability to test a broad variety of pathogenic agents in different sample types. Recently, it was shown that analysis of environmental samples such as water, sludge or detritus from static tanks can complement PCR analysis of fish and is actually more reliable for certain pathogens. In our study, we investigated whether the analysis of filtered water mixed with detritus of tanks including fish showing clinical signs of illness is suitable to complement health monitoring programs in recirculating systems. The obtained data indicate that pathogens such as Pseudoloma neurophilia or Myxidium streisingeri were exclusively or mainly found in fish, while mycobacteria were predominantly present in environmental samples. A combination of both sample types seems to be required for the detection of a broad range of infectious agents in zebrafish colonies using real-time PCR technology.

Interferon Control of Neurotropic Viral Infections

Interferons (IFNs) comprise a pleiotropic family of signaling molecules that are often the first line of defense against viral infection. Inflammatory responses induced by IFN are generally well tolerated during peripheral infections; yet, the same degree of inflammation during infection of the central nervous system (CNS) could be catastrophic. Thus, IFN responses must be modified within the CNS to ensure host survival. In this review, we discuss emerging principles highlighting unique aspects of antiviral effects of IFN protection following neurotropic viral infection, chiefly using new techniques in rodent models. Evaluation of these unique responses provides insights into how the immune system eradicates or controls pathogens, while avoiding host damage. Defining these principles may have direct impact on the development of novel clinical approaches.

The devil is in the details-Host disease and co-infections are associated with zoonotic pathogen carriage in Norway rats (Rattus norvegicus)

Traditionally, zoonotic pathogen ecology studies in wildlife have focused on the interplay among hosts, their demographic characteristics and their pathogens. But pathogen ecology is also influenced by factors that traverse the hierarchical scale of biological organization, ranging from within-host factors at the molecular, cellular and organ levels, all the way to the host population within a larger environment. The influence of host disease and co-infections on zoonotic pathogen carriage in hosts is important because these factors may be key to a more holistic understanding of pathogen ecology in wildlife hosts, which are a major source of emerging infectious diseases in humans. Using wild Norway rats (Rattus norvegicus) as a model species, the purpose of this study was to investigate how host disease and co-infections impact the carriage of zoonotic pathogens. Following a systematic trap and removal study, we tested the rats for the presence of two potentially zoonotic bacterial pathogens (Bartonella tribocorum and Leptospira interrogans) and assessed them for host disease not attributable to these bacteria (i.e., nematode parasites, and macroscopic and microscopic lesions). We fitted multilevel multivariable logistic regression models with pathogen status as the outcome, lesions and parasites as predictor variables and city block as a random effect. Rats had significantly increased odds of being infected with B. tribocorum if they had a concurrent nematode infection in one or more organ systems. Rats with bite wounds, any macroscopic lesion, cardiomyopathy or tracheitis had significantly increased odds of being infected with L. interrogans. These results suggest that host disease may have an important role in the ecology and epidemiology of rat-associated zoonotic pathogens. Our multiscale approach to assessing complex intrahost factors in relation to zoonotic pathogen carriage may be applicable to future studies in rats and other wildlife hosts.

Seroprevalence of Rodent Pathogens in Wild Rats from the Island of St. Kitts, West Indies

Simple Summary

The role of rodents in the transmission of many diseases is widely known. Wild rats abundant in urban environments may transmit diseases to humans and other animals, including laboratory rodents used for biomedical research in research facilities, possibly compromising research data. In order to gather information about the various diseases present around such facilities, it is important to conduct routine surveillance of wild rodents in the area. In this pilot study, we surveyed 22 captured wild rats (Rattus norvegicus and Rattus rattus) from the Caribbean island of St. Kitts for 19 microorganisms. Information gained from such surveillance data would be beneficial in assessing regional public health risks and when implementing routine laboratory rodent health monitoring protocols.

Abstract

A pilot seroprevalence study was conducted to document exposure to selected pathogens in wild rats inhabiting the Caribbean island of St. Kitts. Serum samples collected from 22 captured wild rats (Rattus norvegicus and Rattus rattus) were tested for the presence of antibodies to various rodent pathogens using a rat MFI2 serology panel. The samples were positive for cilia-associated respiratory bacillus (13/22; 59.1%), Clostridium piliforme (4/22; 18.2%), Mycoplasma pulmonis (4/22; 18.2%), Pneumocystis carinii (1/22; 4.5%), mouse adenovirus type 2 (16/22; 72.7%), Kilham rat virus (15/22; 68.2%), reovirus type 3 (9/22; 40.9%), rat parvovirus (4/22; 18.2%), rat minute virus (4/22; 18.2%), rat theilovirus (2/22; 9.1%), and infectious diarrhea of infant rats strain of group B rotavirus (rat rotavirus) (1/22; 4.5%). This study provides the first evidence of exposure to various rodent pathogens in wild rats on the island of St. Kitts. Periodic pathogen surveillance in the wild rat population would be beneficial in assessing potential regional zoonotic risks as well as in enhancing the current knowledge when implementing routine animal health monitoring protocols in facilities with laboratory rodent colonies.