The advantage of enzyme-linked immunosorbent assay (ELISA) as a method of microbiological monitoring for rat virus (RV).

An enzyme-linked immunosorbent assay (ELISA) was tested to detect antibodies against rat virus (RV). The purified ELISA antigens were prepared from rat embryonic cells infected with RV-13 (prototype strain) and UT-2 (Japanese isolate), respectively. Western blotting analysis confirmed that both of these antigens had three structural polypeptides (81 K, 61 K, and 59 K). Eleven laboratory and wild rat colonies in Japan were tested for rat virus contamination, serologically. No significant differences in the sero-positive ratio and the distributions of ELISA titers were demonstrated in the ELISA, using antigens from RV-13 and UT-2. ELISA was more sensitive and specific for detecting antibodies against RV from rat serum rather than hemagglutination inhibition (HI) test. This study also confirmed that the RV contaminated widely in colonies of laboratory and wild rats in Japan, and suggested that RV would have to be checked during the microbiological monitoring of laboratory rats.     

Diagnosis of murine infections in relation to test methods employed

Comparative investigations of Sendai virus, pneumonia virus of mice (PVM), mouse encephalomyelitis virus (mouse polio), minute virus of mice (MVM), and reovirus type 3 (Reo 3) infected murine colonies revealed a 30% higher incidence of positive sera when enzyme-linked immunosorbent assay (ELISA) was employed instead of hemagglutination inhibition (HI) tests. Equivalent sensitivity as in the ELISA was obtained when the same sera were investigated by indirect immunofluorescence (IF) tests. The virus purification techniques described resulted in highly suitable antigens for all indirect ELISA established. Since IIF requires no purified antigens, this test is recommended as an alternative to ELISA as well as to HI and complement fixation (CF) tests for laboratories lacking the necessary equipment for high speed centrifugation. A high incidence of false positive HI reactions was found particularly in Reo 3 routine serology. An updated survey of seromonitoring showed that European murine colonies appeared to be infected far less with Reo 3 if ELISA or IIF tests were employed. During 1982-1984, only 13% of the mouse colonies screened possessed Reo 3 positive sera whereas no natural Reo 3 infection was found in rat colonies. Mouse hepatitis virus (MHV) and the coronaviruses of rats exhibited the highest incidence in murine colonies. A total of 60% of mouse and 41% of rat colonies were found to be infected by these viruses. In comparison with earlier serological surveys, the relative incidence of other murine infections was similar. Antibodies against Bacillus piliformis (Tyzzer's disease) were detected by the IIF test in 41% of the rat colonies screened.     

Serological survey of virus infection among wild house mice (Mus domesticus) in the UK

The serological prevalence of 13 murine viruses was surveyed among 103 wild-caught and 51 captive-bred house mice (Mus domesticus), originating from several trapping locations in northwest England, using blood samples obtained during routine health screening of an established wild mouse colony. A high proportion of recently caught wild mice were seropositive for mouse hepatitis virus (86%), mouse cytomegalovirus (79%), mouse thymic virus (78%), mouse adenovirus (68%), mouse parvovirus (59%) and minute virus of mice (41%). Seroprevalences of lymphocytic choriomeningitis virus (LCMV), orthopoxvirus, reovirus-3 and murid herpesvirus 4 (MuHV-4, also called murine gamma-herpesvirus [MHV-68]) were low (3-13%), and no animals were seropositive to Sendai virus, pneumonia virus or polyomavirus. Seroprevalence in wild-caught animals that had been in captivity for over six months was generally consistent with the range found in recently caught wild animals, while seroprevalence was generally much lower in captive-bred mice despite no attempt to prevent viral spread. A notable exception to this was LCMV, which appeared to have spread efficiently through the captive population (both captive-bred and wild-caught animals). Given the known viral life cycles in laboratory mice, it appears that viral persistence in the host was an important contributing factor in the spread of infection in captivity.     

Antibodies to ruminant alpha-herpesviruses and pestiviruses in Norwegian cervids

A serologic survey revealed that Norwegian populations of free-ranging reindeer (Rangifer tarandus tarandus), roe deer (Capreolus capreolus), red deer (Cervus elaphus), and moose (Alces alces) have been exposed to alpha-herpesviruses and pestiviruses. A total of 3,796 serum samples collected during the period 1993-2000 were tested in a neutralization test for antibodies against bovine herpesvirus 1 (BHV-1) or cervid herpesvirus 2 (CerHV-2), and 3,897 samples were tested by a neutralization test and/or enzyme-linked immunosorbent assay for antibodies against bovine viral diarrhea virus (BVDV). Antibodies against alpha-herpesvirus were found in 28.5% of reindeer, 3.0% of roe deer, and 0.5% of red deer, while all moose samples were negative. In reindeer, the prevalence of seropositive animals increased with age and was higher in males than females. Antibodies against BVDV were detected in 12.3% of roe deer, 4.2% of reindeer, 2.0% of moose and 1.1% of red deer. The results indicate that both alpha-herpesvirus and pestivirus are endemic in reindeer and pestivirus is endemic in roe deer in Norway. The viruses may be specific cervid strains. Seropositive red deer and moose may have become exposed as a result of contact with other ruminant species.     

Prevalence of antibodies to Sendai virus and rotavirus in laboratory rabbits

One hundred and sixty rabbit sera from 10 breeding colonies and 13 laboratory colonies were tested for antibodies to Sendai virus and rotavirus by enzyme-linked immunosorbent assay (ELISA). Antibodies were detected to Sendai virus in 53% and to rotavirus in 81%, indicating the prevalence of these viral infections in laboratory rabbit colonies.     

Ten-year long monitoring of laboratory mouse and rat colonies in French facilities: a retrospective study

From 1988 to 1997, a total of 69 mouse colonies and 36 rat colonies were examined for the presence of antibodies to 14 indigenous viruses of mice and rats. Among mouse viruses, high positivity rates were observed with mouse hepatitis virus (MHV), Theiler's encephalomyelitis virus (THEMV), minute virus of mice (MVM), Sendai virus and pneumonia virus of mice (PVM); the prevalence rates were high in rats with Khilam's rat virus (KRV), THEMV, Toolan's H-1 virus, Sendai virus, Parker's rat coronavirus (RCV/SDA) and PVM. During the last decade, the prevalence of some agents such as MHV, Sendai virus, THEMV, PVM and MVM has apparently decreased although they were still present in 1997 (except for PVM). Another point is the constant increase of colonies found free of viruses through this decade, demonstrating the efforts of the French research community to increase the quality of hygiene in laboratory animals.     

A serological survey on 15 murine pathogens in mice and rats

A serological survey for 15 murine pathogens was performed on 269 mouse sera collected from 21 conventional and 12 barrier colonies, and on 376 rat sera collected from 21 conventional and 23 barrier colonies. Animals having an antibody against at least one of the antigens were contained in 81.0% of conventional and 16.7% of barrier mouse colonies and also in 81.0% of conventional and 43.5% of barrier rat colonies. Main contaminants were mouse hepatitis virus and Sendai virus in mice, and Sendai virus and pneumonia virus of mice in rats. Results also indicated that antibodies to Toolan's H-1, minute virus of mice and PVM were positive in mice from a considerable number of colonies and those to Kilham rat virus, Mycoplasma pulmonis and Toolan's H-1 were sometimes detected in rats, suggesting prevalences of these pathogens in mice and rats in Japan.     

Simultaneous serodetection of major rat infectious pathogens by a multiplex immunochromatographic assay

Rapid and simple serologic tests that require only a small amount of blood without the euthanization of animals are valuable for microbial control in colonies of laboratory animals. In this study, we developed a multiplex immunochromatographic assay (ICA) for detection of antibodies to Sendai virus (also known as hemagglutinating virus of Japan), hantavirus, and sialodacryoadenitis virus, which are causative agents of major infectious diseases in rats. For this assay, an ICA strip was placed into a microtube containing 150 µl PBS and either 0.75 µl of rat serum or 1.5 µl of whole blood. Binding antibodies were visualized by using anti-rat IgG antibody-conjugated colloidal gold. Under these conditions, the multiplex ICA simultaneously and specifically detected antibodies to multiple antigens. Positive serum samples for each infectious disease were used to evaluate the sensitivity and specificity of the multiplex ICA. The sensitivities of the multiplex ICA for Sendai virus, hantavirus, and sialodacryoadenitis virus were 100%, 100%, and 81%, respectively. No nonspecific reactions were observed in any of the 52 positive sera against heterologous antigens. In addition, 10 samples of uninfected sera did not show any bands except for the control line. These observations indicate high specificity of the multiplex ICA. Moreover, the multiplex ICA could be applied to diluted blood. These results indicate that the multiplex ICA is appropriate for rapid and simple serological testing of laboratory rats.     

Seromonitoring of laboratory mouse and rat colonies for common murine pathogens (author's transl)]

During a period from 1973 to 1978, 392 and 225 lots including 12,232 mouse and 8,044 rat individual sera, respectively, were examined for antibodies to murine hepatitis virus, Sendai virus, Bordetella bronchiseptica, Mycoplasma pulmonis, Tyzzer agents, Salmonella typhimurium and Corynebacterium kutscheri. Of mouse lots 94.5% and 39.3% from breeder and user colonies, respectively, were negative for all antibodies examined as well as 31.6% and 17.2% of rat breeder and user colonies, respectively. Among positive lots from mouse users, high positivity rates were seen with Senai virus (47.6%), M. pulmonis (19.0%), and murine hepatitis virus (JHM : 18.2%, MHV : 31.0%), while the rates were high in rat user lots with Sendai virus (24.4%), B. bronchiseptica (39.3%) M. pulmonis (12.5%), murine coronaviruses (JHM : 19.0%, MHV-2 : 28.0%) and tyzzer agents (MSK : 19.6%, RT : 17.9%). These pathogenes with high positivities should be monitored indispensably as a quality control of laboratory mice and rats.     

Ten years-long survey on pathogen status of mouse and rat breeding colonies

Eleven pathogens including P. aeruginosa, Salmonella spp., E. coli O115a, c: K(B), P. pneumotropica, B. bronchiseptica, C. kutscheri, Tyzzer's organism, M. pulmonis, Sendai virus, MHV and Syphacia spp. were surveyed in 217 mouse and rat breeding colonies during 1972-1981. In conventional animals, P. pneumotropica and/or Syphacia spp. were detected in nearly 90% of 89 mouse and 64 rat colonies. Sendai virus, M. pulmonis, P. aeruginosa and MHV were positive in 51.7 to 23.6% of the colonies, and Tyzzer's organism, B. bronchiseptica and probably SDA virus were also detected in more than 10% of the rat colonies. Salmonella spp., E. coli O115a, c: K(B) and C. kutscheri were found in a few colonies. In SPF animals, P. aeruginosa was isolated from about one third of 33 mouse and 31 rat colonies, and P. aeruginosa was isolated from about one third of 33 mouse and 31 rat colonies, and P. pneumotropica was also positive in 3 rat colonies. Infection rates of P. pneumotropica, M. pulmonis, Sendai virus and Syphacia spp. were usually higher than 40% of animals sampled from colonies contaminated with them. Accidental contaminations of SPF colonies were usually caused by P. pneumotropica and Syphacia spp.     

Antibodies to selected viral disease agents in wild boars from the Czech Republic

Blood samples were collected from wild boar (Sus scrofa) shot during the hunting season from 1999 to 2005 in the Czech Republic. Sera were tested by enzyme-linked immunosorbent assay for the presence of antibodies against classical swine fever virus (CSFV), swine vesicular disease virus (SVDV), Aujeszky's disease virus (ADV), and bovine viral diarrhea virus (BVDV). Indirect fluorescence antibody test was used for detection of antibodies against porcine circovirus type 2 (PCV-2) and transmissible gastroenteritis virus (TGEV). Antibodies against ADV, BVDV, PCV-2, and TGEV were detected in 30% (101 of 338), 1% (2 of 352), 43% (57 of 134), and 1% (1 of 134) of wild boars, respectively. Sera of 6,471 and 362 tested wild boars were negative for the presence of antibodies against CSFV and SVDV, respectively. This is the first survey of TGEV antibodies in wild boars and the first serologic survey of viral diseases in wild boars in the Czech Republic. Wild boars in the Czech Republic may act as a potential reservoir of ADV and thus have a role in the epidemiology of this disease.     

Polymorphism of the major histocompatibility locus in the wild Norway rat

Specific alloantisera against the eight Ag-B groups found in inbred strains of rats were capable of reacting with all wild Norway rats (Rattus norvegicus) tested. Absorption studies, antisera production, and progeny testing involving wild rats showed that the antigenic specificities detected in the wild rat population were similar, if not identical, to the Ag-B antigens present in inbred strains. Xenoantisera prepared in rabbits against rat erythrocyte antigens (Ag-C1 and/or C2) reacted with erythrocytes from each wild rat tested. Progeny testing involving these erythrocyte antigens was identical to that observed in inbred strains. The restricted genetic polymorphism of theAg-B alleles in the wild rat population suggests that the functional and evolutionary significance of the major histocompatibility complex in the rat may not depend upon a high degree of genetic variability.     

Leptospira antibodies in wild boars (<Emphasis Type="Italic">Sus scrofa</Emphasis>) in Slovenia

Serum samples collected from 437 shot wild boars (Sus scrofa) were tested for the presence of antibodies against Leptospira interrogans sensu lato in wild boar in Slovenia. Assessment of leptospira-specific antibodies was performed by microscopic agglutination test. Antibodies against at least one of the pathogenic serovars were detected in 200 (45.8%) sera. From 200 positive samples, 100 samples (50%) had positive titre against a single serovar, while 100 (50%) samples had positive titres against two or more serovars. The most frequently detected antibodies were those against serovar Tarassovi. This investigation confirmed the presence of different pathogenic serovars in wild boar across Slovenia. It can be concluded that wild boars are natural reservoirs of at least some of the leptospiral serovars that represent a potential source of leptospirosis for other wild and domestic animals, as well as for humans.     

Increased Biodiversity in the Environment Improves the Humoral Response of Rats

Previous studies have compared the immune systems of wild and of laboratory rodents in an effort to determine how laboratory rodents differ from their naturally occurring relatives. This comparison serves as an indicator of what sorts of changes might exist between modern humans living in Western culture compared to our hunter-gatherer ancestors. However, immunological experiments on wild-caught animals are difficult and potentially confounded by increased levels of stress in the captive animals. In this study, the humoral immune responses of laboratory rats in a traditional laboratory environment and in an environment with enriched biodiversity were examined following immunization with a panel of antigens. Biodiversity enrichment included colonization of the laboratory animals with helminths and co-housing the laboratory animals with wild-caught rats. Increased biodiversity did not apparently affect the IgE response to peanut antigens following immunization with those antigens. However, animals housed in the enriched biodiversity setting demonstrated an increased mean humoral response to T-independent and T-dependent antigens and increased levels of “natural” antibodies directed at a xenogeneic protein and at an autologous tissue extract that were not used as immunogens.     

Prevalence of naturally occurring viral infections, Mycoplasma pulmonis and Clostridium piliforme in laboratory rodents in Western Europe screened from 2000 to 2003

In this report prevalence rates of rodent viruses in laboratory animals are presented based on routine serological screening of mouse and rat colonies from European institutes. The prevalences found during the period 2000-2003 are compared with those reported for 1981-1984 and 1990-1993. It is shown that some infections were eliminated from laboratory animal colonies (e.g. K-virus and polyomavirus) by taking preventative measures whereas other infections such as mouse hepatitis virus and parvoviruses remained at a high rate. Further decreases in prevalence rates in the last 10 years were found for infections such as pneumonia virus of mice, reovirus type 3, Sendai virus, sialodacryoadenitis/rat coronavirus and Mycoplasma pulmonis. The introduction of new detection methods showed that mouse parvovirus and rat parvovirus, both members of the Parvoviridae family, remain a major threat to laboratory mice and rats. Guinea pig cytomegalovirus and para-influenza virus appeared to be the most prevalent agents among laboratory guinea pigs. The importance of a standardized, up-to-date screening programme is discussed.     

Effects of hantaviral infection on survival, growth and fertility in wild rat (Rattus norvegicus) populations of Baltimore, Maryland

Survival, growth rates, body size and fertility of wild caught Norway rats (Rattus norvegicus), infected and uninfected with a Hantavirus (antigenically related to Seoul virus), were compared. No differences were found in the survival of seronegative versus seropositive rats, as measured by mark-recapture experiments. Growth rates, as measured by weight gain but not by increased body length, were slower in seropositive, sexually mature (greater than 200 g) rats, although no differences in the ultimate body size of infected versus uninfected rats were found. No differences in external measures of sexual maturity, or in embryo counts or testes sizes, were found for infected versus uninfected rats. We conclude that hantaviral infections have little or no impact on demographic processes in Norway rat populations.     

Serosurvey of free-ranging Amur tigers in the Russian Far East

Wild Amur tigers (Panthera tigris altaica, n=44) from the Russian Far East were tested for antibodies to feline leukemia virus, feline corona virus (FCoV), feline immunodeficiency virus, feline parvovirus (FPV), canine distemper virus (CDV), Toxoplasma gondii, and Bartonella henselae. Antibodies to FCoV, CDV, FPV, and T. gondii were detected in 43, 15, 68, and 42% of tigers, respectively. No differences were detected in antibody prevalence estimates between tigers captured as part of a research program and those captured to mitigate human-tiger conflicts. Domestic dogs (Canis familiaris) were tested as a potential source for CDV; 16% were vaccinated against CDV and 58% of unvaccinated dogs were antibody positive for CDV. A high percentage of tigers were exposed to potential pathogens that could affect the survival of this species. We recommend continued monitoring of wild tigers throughout Asia, development of standardized sampling and postmortem examination procedures, and additional research to better understand potential domestic and wild animal sources for these pathogens.     

Litter sex ratio variation in laboratory colonies of two geographically distinct strains of the root vole Microtus oeconomus

Litter sex ratio at birth was studied in two laboratory colonies of root voles Microtus oeconomus originating from northern and southern Norway, respectively Sex ratio was female biased in the northern (57% females), but not in the southern colony Sex seemed to be binomially distributed within litters of both colonies, and did not show consistent relationships with mother weight, litter size, parity or number of generations bred in the laboratory Both colonies originated from populations exhibiting cyclic population dynamics in the wild Thus different demography as such is unable to explain the difference in sex ratio between the two laboratory colonies Social organization has been shown to differ between the two strains of root voles both in the field and in the laboratory, but it is yet unclear whether this factor is related to the sex ratio difference documented in this laboratory study     

Serological survey of herpesvirus infections in wild ruminants of France and Belgium

The presence of antibodies against bovine herpesvirus 1 (BHV-1), bovid herpesvirus 6 (BHV-6), herpesvirus of Cervidae type 1 (HVC-1), reindeer herpesvirus, bovine herpesvirus 2 (BHV-2) and bovid herpesvirus 4 (BHV-4) was investigated in wild ruminants of France and Belgium between 1981 and 1986. There were no animals serologically positive for BHV-4. Antibodies against BHV-2 were demonstrated in roe deer (Cervus capreolus) (less than 1%) and chamois (Rupicapra rupicapra) (1%) in France. Animals seropositive to the four related viruses (BHV-1, BHV-6, HVC-1, reindeer herpesvirus) were detected in red deer (Cervus elaphus) in France and Belgium (1% and 11%, respectively), in roe deer (less than 1%) from France, in chamois (4%) in France and in ibex (Capra ibex) (4%) from France. The presence of antibodies against HVC-1, especially in red deer from Belgium, may suggest that wild ruminants in continental Europe are now infected with this virus, which previously has been isolated only in Scotland.