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RNA Virus Diversity, Cross-Species Transmission, and Molecular Constraints in Two Closely Related Rat Species.

Viral infection involves co-evolution with hosts, yet the molecular determinants that constrain viral cross-species transmission remain poorly understood. Here, we established conspecific and heterospecific co-housing models for two closely related rat species, Rattus norvegicus (RN) and Rattus tanezumi (RT), both maintained in laboratory settings for over 10 generations, together with wild-caught RT individuals. Using meta-transcriptomic sequencing and population genomic analyses, we compared their RNA virus profiles and investigated the potential molecular constraints on cross-species viral transmission. From 63 rats, we characterized an extensive RNA virome comprising more than 600 viruses, including 7 zoonotic viruses, 29 viruses with cross-species transmission potential, and 335 novel viruses. Notably, the prevalence of Seoul orthohantavirus (SEOV) was significantly higher in RN than in RT. Population genomic analysis revealed that RN exhibited higher heterozygosity in Itgb3 (the gene encoding the SEOV receptor, β3-integrin) and Tlr7 (the gene encoding the receptor for viral ssRNA, Toll-like receptor 7) compared to RT. These genetic variations likely represent the molecular determinants responsible for the differential susceptibility to SEOV between the two species. Our findings clarify the diversity and prevalence of RNA viruses in closely related rodent species and highlight host genetic barriers that may influence zoonotic spillover risk.

Animals↗

Overview of marker vaccine and differential diagnostic test technology.

Recent advances in molecular biology, immunology, microbiology, genetics and microbial pathogenesis have lead to the development of a wide variety of new approaches for developing safer and more effective vaccines based on designs such as subunit vaccines, gene deleted vaccines, live vectored vaccines, and DNA mediated vaccines. Technology tools can be as basic as identifying naturally occurring strains with deletions that support differentiating infected from vaccinated animal (DIVA) needs or be based on higher technology developments such as improved protein expression and purification methods, transgenic plant- and plant virus-based antigen production, and novel adjuvants that target specific immune responses. These new approaches, when applied to the development of marker vaccines and companion diagnostic test kits hold tremendous potential for developing improved tools for eradication and control programs. Marker vaccines and companion diagnostic test kits must meet the established licensing requirements for purity, potency, safety and efficacy. Efficacy claims are based on evaluation of the level of protection demonstrated in host animal trials and may range from "prevents infection with (a specific agent)", to "for use as an aid in the reduction of disease due to (a specific agent)." The differences in claims and recommendations are a function of the variation in protection elicited by various vaccines. For designing effective eradication programs, vaccine efficacy characteristics such as for reducing susceptibility to infections and spread of infections must be well defined; similarly, diagnostic test performance characteristics (efficacy) must be determined. In addition to data to support efficacy claims, it is imperative that safety of production and use of vaccines be evaluated. During the design of marker vaccines and diagnostic tests, it is important to consider the application of appropriate technologies to improve the safety of these products. Use of recombinant technologies for production of vaccines and/or diagnostic test antigens can reduce the biosafety concerns during production and during use, including human exposure to zoonotic pathogens during production and use, and potential spread of foreign animal disease agents due to loss of biocontainment. In addition, vaccines may induce adverse reactions. It is important to determine the frequency of adverse events and to reduce the likelihood of induction of adverse reactions through proper design.

Animals↗

Veterinary use of antimicrobials and emergence of resistance in zoonotic and sentinel bacteria in the EU.

Antimicrobials are essential for treatment of sick animals, but even if used correctly, may eventually lead to antimicrobial resistance. While this represents a potential hazard to humans, the great majority of resistant human pathogens, especially the more important ones, are unrelated to animal sources. A survey of informed medical opinion suggested that of the human antimicrobial resistance problem, <4% was seen as potentially linked to animal sources. This proportion related largely to zoonotic bacteria which by definition have the capacity to carry resistance between species, although the evidence for resulting harm remains limited. A recent study compared resistance among chicken, pig and cattle isolates of Salmonella spp., Campylobacter spp. and Escherichia coli from a series of EU countries. When tested against antimicrobial agents, this survey showed variation of resistance between countries, between hosts and between organisms. Such variation may give insight into preferred methods of antimicrobial administration or disease control, but it is clear that the epidemiology of antimicrobial resistance induction and dissemination in animals remains complex and is yet to be fully understood.

Animals↗

Discrimination of Francisella tularensis subspecies using surface enhanced laser desorption ionization mass spectrometry and multivariate data analysis.

Francisella tularensis causes the zoonotic disease tularemia, and is considered a potential bioterrorist agent due to its extremely low infection dose and potential for airborne transmission. Presently, F. tularensis is divided into four subspecies; tularensis, holarctica, mediasiatica and novicida. Phenotypic discrimination of the closely related subspecies with traditional methods is difficult and tedious. Furthermore, the results may be vague and they often need to be complemented with virulence tests in animals. Here, we have used surface enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS) to discriminate between the four subspecies of F. tularensis. The method is based on the differential binding of protein subsets to chemically modified surfaces. Bacterial thermolysates were added to anionic, cationic, and copper ion-loaded immobilized metal affinity SELDI chip surfaces. After binding, washing, and SELDI-TOF-MS different protein profiles were obtained. The spectra generated from the different surfaces were then used to characterize each bacterial strain. The results showed that the method was reproducible, with an average intensity variation of 21%, and that the mass precision was good (300-450 ppm). Moreover, in subsequent cluster analysis and principal component analysis (PCA) data for the analyzed Francisella strains grouped according to the recognized subspecies. Partial least squares-discriminant analysis (PLS-DA) of the protein profiles also identified proteins that differed between the strains. Thus, the protein profiling approach based on SELDI-TOF-MS holds great promise for rapid high-resolution phenotypic identification of bacteria.

Animals↗

A systematic review and meta-analysis to estimate the global prevalence of leptospirosis in sheep.

Leptospirosis in sheep is a zoonotic concern considering sheep may act as potential reservoirs for Leptospira spp. infection to humans. This study aimed to estimate the pooled prevalence of leptospirosis in sheep worldwide. A comprehensive literature search was conducted across databases following PRISMA guidelines. Meta-analyses were performed using a random effect model in R software (version 4.3.1) to calculate pooled prevalence with 95% confidence intervals (CI). Subgroup analyses were performed based on prevalence types, diagnostic methods and continental regions to explore sources of heterogeneity. A total of 138 studies comprising 54,174 samples and 10,299 positive detections were included in this study. The global pooled prevalence of leptospirosis in sheep was 15.69% (95% CI: 12.69-19.25) with overall heterogeneity (I2) 98%. The prediction interval ranged from 1.09% to 75.91%, indicating wide inter-study variability. The seroprevalence was 16.16% (95% CI: 12.91-20.04) and infection prevalence was 12.98% (95% CI: 8.07-20.22), showing no significant difference (P&#xa0;=&#xa0;0.40). In addition, the prevalence of leptospirosis in sheep differed significantly across diagnostic methods and continents (P&#xa0;<&#xa0;0.01), indicating substantial variation influenced by both methodological and geographical factors. The funnel plot revealed marked asymmetry, suggesting potential publication bias which was confirmed by Egger's regression test (P&#xa0;<&#xa0;0.01). In conclusion, leptospirosis is widely prevalent in sheep globally, with marked geographical and methodological heterogeneity. These findings highlight the epidemiological importance of sheep in leptospirosis transmission and underscore the need for improved surveillance, standardized diagnostic approaches, and targeted control strategies within a One Health framework.

Animals↗

An outbreak of methicillin-resistant Staphylococcus aureus skin infections resulting from horse to human transmission in a veterinary hospital.

There are increasing reports of methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization in horses and evidence that MRSA can be transmitted between horses and humans. The objective of this study was to investigate reports of skin infection in personnel working with a foal with community-associated MRSA colonization and subsequent infection. Clinical diagnostic specimens were collected from individuals reporting skin lesions following contact with the affected foal. Nasal and groin screening swabs were collected from other veterinary personnel that attended a voluntary screening clinic. MRSA skin infections were identified in three neonatal intensive care unit personnel. Nasal colonization was subsequently identified in 10/103 (9.7%) other veterinary hospital personnel. Isolates were indistinguishable by pulsed field gel electrophoresis, classified as Canadian epidemic MRSA-5, possessed SCCmecIV, were negative for the Panton-Valentine leukocidin and were multidrug resistant. Transmission to veterinary personnel despite short-term contact with standard protective barriers highlights the potential importance of MRSA as an emerging zoonotic pathogen, and indicates that further evaluation of interspecies transmission of MRSA and means to prevent zoonotic infection are required.

Adult↗

Antibodies against Gag are diagnostic markers for feline foamy virus infections while Env and Bet reactivity is undetectable in a substantial fraction of infected cats.

Spumaretroviruses or foamy viruses constitute a distinct subfamily of retroviruses. The biology of foamy viruses within the authentic host, their mode of transmission, and disease potential in the authentic host or after zoonotic transmission into human or other species are almost unknown. Using feline foamy virus (FFV) as model system, we established modular enzyme-linked immunosorbent assays (ELISA) suited to determine feline IgG and IgM antibody responses against structural and non-structural FFV proteins. We validated the ELISAs with standard reference sera. In 99 cats admitted to a Swiss veterinary hospital, overall FFV Gag antibody prevalence was 36%, reactivity against Env and the non-structural protein Bet each was about 25%, and 19% of the sera were directed against all three FFV antigens. With one exception, all Bet- and/or Env-positive sera were also positive for Gag. In this small epidemiological pilot study, FFV antibodies were not significantly associated with clinical disease.

Animals↗

Is there immunity to Schistosoma japonicum?

The Oriental schistosome, Schistosoma japonicum, unlike the other two major schistosomes that infect humans (S. mansoni and S. haematobium), is a zoonotic species. The transmission dynamics and the potential effects of host-related regulatory factors, including immunity, are likely to be distinct for this parasite. Here, Allen Ross and collaborators from Australia, China and the Philippines discuss recently published and established epidemiological and laboratory data bearing on anti-infection immunity to Asian schistosomiasis, and contrast these findings with the emerging picture of development of anti-infection immunity against the African schistosomes. Implications for vaccines and other control strategies for schistosomiasis japonica are also discussed.

Adolescent↗

A relapsing fever group spirochete transmitted by Ixodes scapularis ticks.

A species of Borrelia spirochetes previously unknown from North America has been found to be transmitted by Ixodes scapularis ticks. Infected ticks are positive for Borrelia spp. by DFA test but negative for Borrelia burgdorferi by polymerase chain reaction (PCR) using species-specific primers for 16S rDNA, outer surface protein A, outer surface protein C, and flagellin genes. A 1,347-bp portion of 16S rDNA was amplified from a pool of infected nymphs, sequenced, and compared with the homologous fragment from 26 other species of Borrelia. The analysis showed 4.6% pairwise difference from B. burgdorferi, with the closest relative being Borrelia miyamotoi (99.3% similarity) reported from Ixodes persulcatus in Japan. Phylogenetic analysis showed the unknown Borrelia to cluster with relapsing fever group spirochetes rather than with Lyme disease spirochetes. A 764-bp fragment of the flagellin gene was also compared with the homologous fragment from 24 other Borrelia species. The flagellin sequence of B. burgdorferi was 19.5% different from the unknown Borrelia and showed 98.6% similarity with B. miyamotoi. A pair of PCR primers specifically designed to amplify a 219-bp fragment of the flagellin gene from this spirochete was used to survey field-collected I. scapularis nymphs from five northeastern states (Connecticut, Rhode Island, New York, New Jersey, and Maryland). Positive results were obtained in 1.9-2.5% of 712 nymphs sampled from four states but in none of 162 ticks collected from Maryland. Transovarial transmission was demonstrated by PCR of larval progeny from infected females with filial infection rates ranging from 6% to 73%. Transstadial passage occurred from larvae through adults. Vertebrate infection was demonstrated by feeding infected nymphs on Peromyscus leucopus mice and recovering the organism from uninfected xenodiagnostic larvae fed 7-21 days later. Considering the frequency of contact between I. scapularis and humans, further work is needed to determine the potential public health significance of yet another zoonotic agent transmitted by this tick species.

Animals↗

Parasitic zoonoses; public health and veterinary perspectives.

The importance of parasitic zoonoses continues to increase on both local and global scales as interactions between people and animals become more frequent through global travel, intensification of agriculture, habitat devastation, and changes in world trade patterns. A current and real threat is the potential for a deliberate introduction of a zoonotic disease through the prospect of bioterrorism. Parasitic zoonoses represent significant problems in public health, animal agriculture and conservation, and the meat industry. There is an urgent need for integration of medical and veterinary services, continuous disease surveillance in both humans and animals, the teaching of zoonoses to medical doctors, and intensified research on zoonotic agents and diseases. The convergence of both public health and veterinary services currently represents a real challenge for managing zoonotic diseases.

Animals↗

Production of herpes B virus recombinant glycoproteins and evaluation of their diagnostic potential.

B virus (cercopithecine herpesvirus 1) is the only deadly alphaherpesvirus that is zoonotically transmissible from macaques to humans. The detection of humoral immune responses is the method of choice for the rapid identification of B virus-infected animals. We evaluated the diagnostic potential of recombinant B virus glycoproteins for the detection of immunoglobulin G (IgG) antibodies in monkey and human sera. Glycoproteins B, C, and E and secreted (sgG) and membrane-associated (mgG) segments of glycoprotein G (gG) were expressed in the baculovirus expression system, while gD was expressed in CHO cells. We developed recombinant protein-based IgG enzyme-linked immunosorbent assays (ELISAs) and compared their diagnostic efficacies by using B virus antibody-negative (n = 40) and -positive (n = 75) macaque sera identified by a whole antigen-based ELISA and Western blotting. The diagnostic sensitivities of the gB-, gC-, gD-, and mgG-ELISAs were 100, 97.3, 88.0, and 80.0%, respectively. The specificities of the gB-, gC-, and gD-ELISAs and of the mgG-ELISA were 100 and 97.5%, respectively. In contrast, the sensitivities and specificities of sgG- and gE-ELISAs were low, suggesting that sgG and gE are less effective diagnostic antigens. Sera from nonmacaque monkeys cross-reacted with gB, gC, and gD, and only baboon sera reacted weakly with mgG. Human herpes simplex virus type 1 (HSV-1)- and HSV-2-positive sera pools reacted with gB and gD, whereas sera from B virus-infected individuals reacted with all four antigens. These data indicate that gB, gC, gD, and mgG have a high diagnostic potential for B virus serodiagnosis in macaques, whereas mgG may be a valuable antigen for discrimination between antibodies induced by B virus and those induced by other, closely related alphaherpesviruses, including HSV-1 and -2.

Animals↗

Viral zoonoses in Europe.

A number of new virus infections have emerged or re-emerged during the past 15 years. Some viruses are spreading to new areas along with climate and environmental changes. The majority of these infections are transmitted from animals to humans, and thus called zoonoses. Zoonotic viruses are, as compared to human-only viruses, much more difficult to eradicate. Infections by several of these viruses may lead to high mortality and also attract attention because they are potential bio-weapons. This review will focus on zoonotic virus infections occurring in Europe.

Animals↗

Histologic and molecular diagnosis of tularemia: a potential bioterrorism agent endemic to North America.

Francisella tularensis (FT), a zoonotic bacterium that causes tularemia, has received attention as a possible bioterrorism threat. We developed a PCR assay for use in fixed, processed tissues, which are safer to handle and allow archival testing. PCR analysis for a 211-bp fragment of the FT lipoprotein gene was performed on tissues from 16 cases of tularemia. In all, 14/15 cases with intact DNA (93%) were positive for FT by PCR. Frequent histologic findings in PCR-positive tissues included irregular microabscesses and granulomas in liver, spleen, kidney, and lymph nodes, and necrotizing pneumonia. Unusual cases featuring suppurative leptomeningitis and gastrointestinal ulcers were also seen. As this disease is endemic in North America, and has been identified as a potential bioterroristic threat, awareness of the clinicopathologic spectrum of disease and available detection methods is increasingly important. This PCR assay, the first designed for use in processed tissues, is an excellent method for diagnosis of tularemia.

Adolescent↗

Detection and molecular characterization of foamy viruses in Central African chimpanzees of the Pan troglodytes troglodytes and Pan troglodytes vellerosus subspecies.

BACKGROUND: Foamy viruses are exogenous retroviruses that are highly endemic in non-human primates (NHPs). Recent studies, mainly performed in North America, indicated frequent simian foamy virus (SFV) infection in persons occupationally exposed to NHPs. This zoonotic infection was demonstrated mainly after bites by chimpanzees [Pan troglodytes (P. t.)] of the West African P. t. verus subspecies in primatology centers or zoos in the USA. METHODS: We studied 32 chimpanzees from the Central African subspecies P. t. troglodytes and P. t. vellerosus, originating from Cameroon (29 cases) or Gabon (3 cases). We screened first plasma or sera of the animals with a Western blot detecting the SFVs Gag doublet proteins. Then, we performed two nested polymerase chain reactions (PCRs) amplifying a fragment of the integrase and LTR regions and, finally, we made phylogenetical analyses on the sequences obtained from the integrase PCR products. RESULTS: By serological and/or molecular assays, we detected foamy viruses (FVs) infection in 14 chimpanzees. Sequence comparison and phylogenetic analyses of a 425 bp fragment of the integrase gene obtained for 10 of the 14 positive apes, demonstrated a wide diversity of new FVs strains that belong phylogenetically either to the P. t. troglodytes or P. t. vellerosus foamy viral clade. CONCLUSIONS: This study shows that chimpanzees living in these areas of Central Africa are infected by several specific foamy viruses. This raises, in such regions, the potential risk of a human retroviral infection of zoonotic origin linked to chimpanzees contacts, as already exemplified for STLV-1 and SIV infections.

Amino Acid Sequence↗

Use of Rift Valley Fever Virus Expressing NanoLuc Luciferase for the Assessment of Neutralizing Antibodies and Antivirals.

Rift Valley fever (RVF) is an arboviral zoonotic disease affecting many African countries with the potential to spread to other geographical areas. In this chapter we describe the use of a replication-competent recombinant (r)RVFV expressing NanoLuc Luciferase (Nluc) for in vitro studies. The determination of parameters such as neutralizing antibodies in serum samples, or the antiviral activity of drugs is usually carried out using standard assays based on the assessment of cytopathic effect on cell cultures. The use of a virus encoding a traceable reporter protein allows to correlate the presence or absence of infection with the detection of the product in the infected cultures, thus tracking the level of RVFV infection in an objective, quantitative manner. In addition to this quantitative measurement of results, our protocol offers two other advantages, such as a shorter time to read, given that 48&#xa0;h post-infection the production of the reporter protein is enough to give an accurate result, and the use of an attenuated virus, which reduces the risk of exposure.

Rift Valley fever virus↗

Predicting the emergence of human hantavirus disease using a combination of viral dynamics and rodent demographic patterns.

The paper proposes a model explaining the spatial variation in incidence of nephropathia epidemica in Europe. We take into account the rodent dynamic features and the replicative dynamics of the virus in animals, high in the acute phase of newly infected animals and low in the subsequent chronic phase. The model revealed that only vole populations with multi-annual fluctuations allow for simultaneously high numbers of infected rodents and high proportions of those rodents in the acute excretion phase during the culminating phase of population build-up. This leads to a brief peak in exceptionally high concentrations of virus in the environment, and thereby, to human exposure. Such a mechanism suggests that a slight ecological disturbance in animal-parasite systems could result in the emergence of human diseases. Thus, the potential risk for public health due to several zoonotic diseases may be greater than previously believed, based solely on the distribution of human cases.

Animals↗

Echinococcus multilocularis.

PURPOSE OF REVIEW: Echinococcus multilocularis is a tapeworm of foxes that may cause a zoonotic infection resulting in a highly pathogenic and potentially fatal chronic liver infestation called human alveolar echinococcosis. Radical liver resection currently offers the only potential cure. Although alveolar echinococcosis is a rare parasitic disease that is restricted to transmission in the northern hemisphere, the parasite is geographically widespread being distributed from Alaska, across Canada and north central USA, through northern Europe and Eurasia to Japan. The present review summarizes the background to this helminthic infection and recent contributions in areas of pathology, diagnosis, treatment and transmission. RECENT FINDINGS: Concern is growing in Europe that the prevalence and distribution of E. multilocularis in red foxes has increased significantly in the last 10-15 years. A retrospective analysis revealed >550 cases of human alveolar echinococcosis diagnosed between 1982-2000, with the majority in France, Germany and Switzerland. Human prevalence rates >3% occur in central northwest China and the disease is of public health concern in northern Japan. Improvements in immunodiagnosis with native and recombinant antigens have enabled more accurate confirmation of hepatic image findings, while development of in-vitro culture of metacestode tissues provides a useful model for screening new anti-alveolar echinococcosis drugs as alternatives to albendazole and surgery. Recombinant molecules from the oncosphere and metacestode stages have shown potential as vaccine candidates. New tools of coproantigen and copro-DNA detection for vulpine infections have proved highly beneficial in epidemiological and transmission ecology studies, as has a landscape ecology approach to develop risk models for communities in endemic areas. SUMMARY: It is possible that human AE will become an emergent zoonosis in some regions of Europe and Eurasia. Improvements in diagnostic and treatment approaches are being investigated. Further understanding of host immune responses will aid in characterization of disease pathology. Control of E. multilocularis in its natural cycles will be difficult due to the involvement of wild animal hosts, however use of anthelminthic baits and dosing of domestic dogs may reduce transmission at local scales.

Animals↗

Enterotoxigenic potential of Staphylococcus intermedius.

Staphylococcal food poisoning (SFP) caused by enterotoxigenic staphylococci is one of the main food-borne diseases. In contrast to Staphylococcus aureus, a systematic screening for the enterotoxins has not yet been performed on the genomic level for the coagulase-positive species S. intermedius. Therefore, the enterotoxigenic potential of 281 different veterinary (canine, n = 247; equine, n = 23; feline, n = 9; other, n = 2) and 11 human isolates of S. intermedius was tested by using a multiplex PCR DNA-enzyme immunoassay system targeting the staphylococcal enterotoxin genes sea, seb, sec, sed, and see. Molecular results were compared by in vitro testing of enterotoxin production by two immunoassays. A total of 33 (11.3%) S. intermedius isolates, including 31 (12.6%) canine isolates, 1 equine isolate, and 1 human isolate, tested positive for the sec gene. In vitro production of the respective enterotoxins was detected in 30 (90.9%) of these isolates by using immunological tests. In contrast, none of 65 veterinary specimen-derived isolates additionally tested and comprising 13 (sub)species of coagulase-negative staphylococci were found to be enterotoxigenic. This study shows on both molecular and immunological levels that a substantial number of S. intermedius isolates harbor the potential for enterotoxin production. Since evidence for noninvasive zoonotic transmission of S. intermedius from animal hosts to humans has been documented, an enterotoxigenic role of this microorganism in SFP via contamination of food products may be assumed.

Animals↗