Virologic investigations of free-living European bison (Bison bonasus) from the Bialowieza Primeval Forest,Poland

We conducted virologic investigations on postmortem specimens from 261 free-living European bison (Bison bonasus) from the Bialowieza Primeval Forest, Poland collected between 1990 and 2000. Fifty-four of 94 males had balanoposthitis; none of the 167 female bison examined had reproductive tract lesions. Peripheral blood, swabs, and various tissues were analyzed for bovine viruses as well as for viral DNA by bovine herpesvirus 1 (BoHV-1) and bovine herpesvirus 4 (BoHV-4) specific polymerase chain reaction (PCR) technique. An infectious bovine rhinotracheitis like BoHV-1 strain was isolated from the spleen of a female bison calf and additionally was detected by nested PCR from splenic tissue. None of the bison had significant antibody titers against BoHV-1, bovine herpesvirus 2, BoHV-4, caprine herpesvirus 1, cervid herpesvirus 1, or bovine viral diarrhea (BVD) virus-1. However, low antibody titers in two animals indicate that this European bison population has been exposed to BVD virus or BVD-like viruses and BoHV-2.     

A journey with T cells, primate/human retroviruses and other persisting human T-cell tropic viruses

A study of the growth of primate/human T cells led to mechanisms for temporary laboratory culture of these cells (discovery of interleukin-2) and also their continuous culture (by immortalization after infection with human T-cell lymphotropic virus type 1 or 2 (HTLV-1 or 2)). Cultures of lymphocytes also led us to isolate five persisting T-tropic viruses: 1. the Hall's Island strain of gibbon ape leukemia virus, 2. HTLV-1, 3. HTLV-2, 4. human immunodeficiency virus and 5. human herpes virus-6 (HHV-6). This report is a brief synopsis of the discoveries of the first human retroviruses, the HTLV.     

Duration of bluetongue viremia in experimentally infected American bison.

Six yearling American bison (Bison bison bison) bulls and one yearling ewe (Ovis aries) were inoculated intradermally and subcutaneously with 2 x 10(5) plaque forming units (pfu) of bluetongue (BT) virus serotype 11. Two uninoculated yearling bison bulls served as negative controls. Blood samples were collected for serology and virus isolation on 0, 4, 7, 11 and 14 days post-inoculation (dpi) and every 2 wk thereafter to 127 dpi. Every 4 wk a new ewe was inoculated with a pooled sample of whole blood from the six infected bison, and each sheep was monitored for 28 days for clinical signs of BT and seroconversion. Bluetongue viremia was detected in all six inoculated bison starting at 4 to 28 dpi and was no longer detectable from 42 dpi onward. Pooled blood samples collected at 28, 56, 84 and 112 dpi from the six infected bison were not infectious for sheep. The six infected bison seroconverted by 11 to 28 dpi on a competitive enzyme-linked immunosorbent assay and by 28 dpi on the serum neutralization test, and all remained seropositive thereafter. No clinical signs or lesions attributable to BT were observed in the infected bison or controls. There was evidence that a small amount of epizootic hemorrhagic disease virus type 2 had been present in the BT virus inoculum; reasons are given for concluding that this did not affect the results of the BT study.     

Necrobacillosis in free-living male European bison in Poland

In the Bialowieza Primeval Forest (Poland) a chronic disease of the external genital organs has been observed in free-living male European bison (Bison bonasus) since 1980. Investigations on this disease started in the late 1980s. The most striking findings are necrotic and ulcerative lesions of the prepuce and penis of bison aged from 6 mo to >10 yr. Histologic examination of tissue samples from the prepuce of six bison (9-mo- to 8-yr-old), and from the penis of two bison (3- and 8-yr-old), were characteristic of necrobacillosis. Masses of slender, Gram-negative, rod-like or filamentous bacteria occurred in necrotic tissue. At the periphery of necrotic tissue filamentous bacteria were often arranged in large clusters and strands that advanced towards healthy tissue. Immunolabeling and electron microscopy also suggest that these organisms are Fusobacterium sp.     

Identification of a common antigen of herpes simplex virus bovine herpes mammillitis virus, and B virus.

In immunoelectrophoretic analyses one common antigen was demonstrated in antigen preparations from herpes simplex virus types 1- and 2- (HSV-1 and HSV-2), bovine herpes mammillitis (BHM) virus-, and B virus-infected cells solubilized by Triton X-100. The antigen was also demonstrated in solubilized purified HSV-1 and BHM virus. The common antigen was identified as antigen 11 of HSV-1 or HSV-2. Differences were found in the polypeptide composition of the related antigens when isolated from the four different herpesviruses, but a glycopolypeptide with a molecular weight of 125,000 was present in each of the four different antigen preparations, indicating that this polypeptide carried the common antigenic determinants.     

Characterization of infertility and bovine leukemia virus infection in beef bulls on southwestern Louisiana coastal range

One hundred and twenty-six beef bulls on southwestern Louisiana coastal range were evaluated for breeding soundness. Samples were taken to determine the incidence of bovine leukemia virus (BLV) infection, and the prepuce was cultured for potential pathogens. A high incidence (47.6%) of questionable and unsatisfactory potential breeders resulted mainly from 37.0% of the bulls exhibiting high numbers of abnormal sperm cells in the semen. Only bulls in the 4-to 5-yr age group exhibited the expected incidence of normal spermiograms. Genital campylobacteriosis was not diagnosed but there was genital trichomoniasis in three of the seven herds. Hemophilus somnus , mycoplasma and ureaplasma were isolated from the prepuce of 13.3, 48.8 and 36.7% of the bulls, respectively. Isolation of these organisms from the prepuce did not appear to be associated with abnormal spermiograms. Of the bulls studied, 34.4% had positive AGID reactions for BLV. Bulls seropositive to BLV had an increased incidence of leukocyte counts that were above the normal range. There was no apparent relationship between BLV infection and abnormal spermiograms.     

The seasonal fertility of North American bison (Bison bison) bulls

The objective of this study was to determine the presence and magnitude of seasonal fluctuations in semen quality and other reproductive indices in bison bulls. Testicles from 288 commercially slaughtered bison bulls were collected monthly over a 1-year period. Carcass and testicle weight were determined and measurements of seminiferous tubule lumen, diameter, and epithelial thickness were made. Sperm cell morphology and defects were described and quantified using epididymal semen from each testicle. Twenty-one Plains (Bison bison bison) and Wood bison (Bison bison athabascae) breeding bulls, averaging 6.0 years of age (range 2.5-8.0), from three farms were selected for semen collection and evaluation on the basis of producer co-operation. Semen was collected by electro-ejaculation on four seasonal occasions during a 12-month period. Ejaculate quality was judged on the basis of volume, density, gross and individual motility, morphology, live/dead ratio, and concentration. Sperm cell morphologies were evaluated microscopically and classified according to criteria used for bovine semen. Fecal testosterone was measured at each semen collection using a commercial competitive binding radioimmunoassay. There was an increase in carcass weights over the study period and testis weights were moderately correlated (r=0.44) with carcass weights. However, mean testes weights were heavier (P<0.05) in the summer than in winter, spring, or fall periods. There were no differences in the proportion of normal and abnormal epididymal sperm between seasons but there were seasonal changes in the testicular parenchyma. Seminiferous tubule and lumen diameter, and epithelial thickness were greatest (P<0.05) in summer. Live bulls gained weight between April and November, but lost weight over the winter. Normal sperm cell percentages as well as individual sperm cell motility in electro-ejaculated sperm samples were higher (P<0.05) at the pre-breeding collection relative to other collections, but no change in sperm cell concentrations occurred over the study period. Fecal testosterone concentrations were highest at the pre-breeding period (June) but decreased (P<0.05) in each subsequent collection to reach their lowest levels in the April. While many changes in seen characteristics were not significant, overall results indicate the presence of some reproductive seasonality and increased testicular capacity in the summer breeding season. Bulls showing marginal semen quality in the winter but otherwise carrying desirable genetic traits may warrant another evaluation in late spring prior to being culled from a breeding program.     

Excretion of lumpy skin disease virus in bull semen

This work was done to establish the incidence and duration of excretion of lumpy skin disease virus (LSDV) in semen of experimentally infected susceptible bulls. Six serologically negative bulls 11-20 months of age were experimentally infected with a virulent field isolate (strain V248/93) of LSDV. Animals were observed for the development of clinical signs, blood was collected until day 90 after infection, and semen was collected every second day until day 18, then twice a week till day 63 and twice a month until three consecutive samples were negative when tested for LSDV by polymerase chain reaction (PCR). An aliquot of each sample which tested positive using PCR was inoculated onto cell monolayers for the recovery of virus. Two bulls developed severe lumpy skin disease (LSD), two bulls showed mild signs and two bulls showed a transient fever only. Multiple samples were positive on PCR from both of the severely affected bulls and one of the mildly affected bulls; between days 10 and 159, days 8 and 132, and days 10 and 21 respectively. Only one sample from each of the other three bulls was positive on PCR. Virus was only isolated from two samples from one of the severely affected bulls and from five semen samples from the other. This study confirmed the excretion of LSDV in bovine semen for prolonged periods, even when obvious clinical signs of the disease were no longer apparent.     

Papillomatosis in a European bison

Five European bison (Bison bonasus) from three European zoos were shipped to the Bukovské Vrchy Hills (Slovakia) in June 2004 and kept together in an acclimatization enclosure. The European bison were released into the wild in December 2004. At that time, papillomas were found at the medial canthus of the left eye of a 12-yr-old female bison. Cutaneous papillomatosis was confirmed histologically. Negative stain transmission electron microscopic examination revealed papillomavirus in the papillomas, and papillomavirus DNA also was detected using the polymerase chain reaction with FAP59 and FAP64 primers. The amplified 413 bp DNA sequence was identical to that of BAPV2 bovine papillomavirus. This paper is the first report of papillomatosis in European bison.     

Fecal androgens of bison bulls during the rut

The influence of sex hormones is a key proximate factor underlying male reproductive behavior in mammals. Effective conservation policies for the remaining purebred plains bison (Bison bison bison) herds require knowledge of the physiology underlying bison reproductive biology. We used fecal steroid analysis to characterize androgen levels in adult bison bulls before, during, and after the rut, and to examine androgen levels of bulls differing in reproductive status, age, and mating success. Fieldwork was carried out at the Fort Niobrara National Wildlife Refuge in north-central Nebraska. All adult bison in the herd were individually known by unique brands. Fecal samples were collected during 2003 from bulls during pre-rut (June), rut (July-August), and post-rut (September), and behavioral observations focused on reproductive status and mating success during the rut. Matched sample data indicated that androgen levels (ng/g feces) of bulls peaked during the rut, doubling from pre-rut to rut and then declining by 75% during post-rut. Dominant bulls that tended (guarded) cows maintained higher androgen levels than bulls that were not tending. There was a positive correlation between bull age (associated with mating success) and androgens, with higher androgen levels in prime-aged bulls compared with younger bulls. Nonetheless, there was no correlation between mating success (measured by number of copulations observed) and androgen level. This suggests that while androgens may provide the proximate motivation to compete for matings, other factors determine the mating success of bison bulls.     

Natural breeding with bulls experimentally infected with Neospora caninum failed to induce seroconversion in dams

Four bulls and 56 heifers seronegative to Neospora caninum were used to determine the feasibility of venereal transmission in bovine neosporosis under natural conditions. Bulls were experimentally infected with 10⁸ live N. caninum tachyzoites. Two of them with the Nc-1 isolate and the other two with the Nc-Spain-7 isolate. After 13 months of initial infection, each bull was re-infected with the same isolate and dose. The experiments were carried out from March to September during 2006 and 2007 where groups of cyclic heifers were naturally mated by the experimentally infected bulls. In year 2006, two bulls infected with different N. caninum isolate serviced 12 heifers each. In year 2007, the same bulls serviced the same heifers a second time (now primiparous) and six new heifers were also added to each group. In addition, the other two bulls serviced 10 additional heifers each. Experimental animals were monitored for 30 weeks and serum samples were collected weekly and fortnightly in years 2006 and 2007, respectively to evaluate the presence of specific antibodies to N. caninum. Experimentally infected bulls showed a significant increase of specific IgG antibodies from 13 (Nc-SP-7) and 21 (Nc-1) days post-infection. Serum IgG antibody responses of individual animals were similar in kinetics but slightly different in magnitude. Serum samples from heifers were all negative. Pregnant rates were 100% in heifers and 91% in primiparous animals. Calves did not show precolostral specific antibodies to N. caninum. Venereal transmission of bovine neosporosis under natural grazing conditions is unlikely to occur.     

Gene transfer in bovine blastocysts using replication-defective retroviral vectors packaged with gibbon ape leukemia virus envelopes

With this work we demonstrate that murine leukemia virus (MLV)-based replication-defective retroviral vectors encapsidated with Gibbon ape leukemia virus (GaLV) envelopes are significantly more infectious to bovine embryonic trachea (EBTr) cells than vectors encapsidated with murine xenotropic envelope proteins. In a test of internal promoter activity in an MLV retroviral vector, the rat β-actin promoter was shown to be better than the herpes simplex virus type 1 thymidine kinase (TK) and human cytomegalovirus (CMV) immediate early promoters for the expression of an E. coli β-galactosidase marker gene in bovine target cells. By co-culture of bovine blastocysts and virus-producing cells, or by culture of embryos in the medium harvested from virus-producing cells, we transferred the E. coli β-galactosidase gene into trophoblasts and also into inner cell mass (ICM) cells of a bovine embryo through the infection of the MLV-based replication-defective retroviruses encapsidated with GaLV envelope proteins. The infection was confirmed by the expression of the E. coli β-galactosidase gene under a β-actin internal promoter. In addition, co-culture of ICM cells with virus-producing cells resulted in differentiation of ICM cells into embryoid bodies expressing the marker genes. © 1993 Wiley-Liss, Inc.     

Serological evidence of herpesvirus infection in captive Asian elephants (Elephas maximus)

In mid 1988 a 3-yr-old Asian elephant (Elephas maximus) from a circus in Switzerland died following generalized manifestation of a herpesvirus infection. In an effort to determine prevalence of infection with the herpesvirus, and due to lack of a corresponding virus isolate, it was decided to evaluate contact animals and elephants from a second herd for antibody to bovine herpesvirus 1 (BHV1) and bovine herpesvirus 2 (BHV2). Of 15 sera tested four displayed low neutralizing antibody titers to BHV2. None of the sera neutralized BHV1. However, as evidenced by protein A-mediated immunoprecipitation of metabolically radio-labeled virus-infected and mock-infected cell antigens, followed by separation of precipitation products in SDS-polyacrylamide gels, the 15 sera precipitated multiple antigens from both viruses. Similar results were obtained when using BHV4 antigens. The extent of reaction was most distinct with respect to BHV2 antigens, less prominent with BHV1 antigens, and least with BHV4 antigens. The respective protein patterns, although less marked, matched well with those obtained with bovine reference sera. Additional evaluation of sera from six elephants from two zoos in the Federal Republic of Germany gave essentially identical results. It was concluded that at least one herpesvirus, immunologically related to BHV2, may be widely distributed among captive Asian elephants, and that this virus apparently does not cause overt disease in the majority of animals.     

Immune responses after oral inoculation of weanling bison or beef calves with a bison or cattle isolate of Mycobacterium avium subsp. paratuberculosis

Paratuberculosis is endemic in domestic and wild ruminants worldwide. We designed the following study to compare host immune responses and pathologic changes in beef calves and bison calves after challenge with either a cattle or bison (Bison bison) strain of Mycobacterium avium subsp. paratuberculosis. In the first part of the study, six bison and six beef calves were orally inoculated with a cattle isolate of M. avium subsp. paratuberculosis over a 2 wk period. In the second part, an additional six bison and six beef calves were similarly inoculated with a bison strain of M. avium subsp. paratuberculosis. Throughout each of the studies, blood and fecal samples were taken monthly for a 6 mo infection period. Tissue samples were obtained at necropsy for culture and histopathologic analyses. Results from this study demonstrated that bison calves were more susceptible to tissue colonization than beef calves after challenge with the cattle isolate and, conversely, that beef calves were more susceptible to the bison strain of M. avium subsp. paratuberculosis. Although lesions were minimal they were most apparent in the jejunum and distal ileum. Interferon-gamma (IFN-gamma) responses were noted in some calves by 1 mo postinoculation and were sustained longer in beef calves after challenge with the bison isolate. Antibody was not detected in either beef or bison calves during the 6 mo infection period. These results indicate that the host response to strains of M. avium subsp. paratuberculosis may differ between ruminant species.     

Serologic survey of white-tailed deer on Anticosti Island, Quebec for bovine herpesvirus 1, bovine viral diarrhea, and parainfluenza 3.

In 1985 unusual mortality was observed among the 3- to 4-yr-old white-tailed deer (Odocoileus virginianus) on Anticosti Island, Québec (Canada). A viral pathogen was suspected to be the cause of the deaths. Thus, a serologic survey for bovine herpesvirus 1 (BHV-1), bovine viral diarrhea (BVD) virus and parainfluenza-3 (PI-3) virus was conducted. We examined 396 deer sera from 1985. Results indicated that the high mortality mainly afflicted 3- to 4-yr-old deer. In 1985, 57% of deer sampled were seropositive for viral neutralizing antibodies against BHV-1. Prevalences decreased over the next 2 yr of the survey. Prevalence of antibodies against PI-3 virus, determined by hemagglutination inhibition test, remained high (82% to 84%) for the 3 yr period. No deer were seropositive for neutralizing antibodies against BVD virus during the survey period. Analysis of antibodies against BHV-1 and PI-3 viruses according to sex, age and antibody titers revealed that an epizootic BHV-1 infection occurred in 1985; PI-3 infection appears to be enzootic in Anticosti deer.     

Contraception of bison by GnRH vaccine: a possible means of decreasing transmission of brucellosis in bison

Preventing pregnancy in brucellosis-infected bison (Bison bison) provides a potential means of preventing transmission of disease. To determine whether a gonadotropin-releasing hormone (GnRH) vaccine was effective in reducing pregnancy in bison and to study the safety of injecting GnRH in pregnant bison, a study was conducted at the Idaho Fish and Game Wildlife Health Laboratory in Caldwell, Idaho (USA). Four pregnant and two nonpregnant female bison were given a single injection of GnRH vaccine, and five pregnant adult females were given a sham injection that contained only adjuvant. Three of the GnRH-vaccinated bison that were pregnant at the time of vaccination delivered healthy calves. One treated bison had dystocia that resulted in a dead calf. All control bison delivered healthy calves. After calving, females of both groups were exposed to two bulls. Treated bison were palpated 6 wk after exposure to the bulls, and blood was drawn for pregnancy-specific protein B analysis. The six treated bison were not pregnant. The sham-treated bison became pregnant and delivered viable calves. This study demonstrates that a single dose of GnRH vaccine is effective in preventing pregnancy in female bison for at least 1 yr.     

Characterization of Anaplasma marginale isolated from North American bison

Anaplasma marginale (Rickettsiales: Anaplasmataceae), a tick-borne pathogen of cattle, is endemic in tropical and subtropical regions of the world. Although serologic tests have identified American bison, Bison bison, as being infected with A. marginale, the present study was undertaken to confirm A. marginale infection and to characterize isolates obtained from naturally infected bison in the United States and Canada. Major surface protein (MSP1a and MSP4) sequences of bison isolates were characterized in comparison with New World cattle isolates. Blood from one U.S. bison was inoculated into a susceptible, splenectomized calf, which developed acute anaplasmosis, demonstrating infectivity of this A. marginale bison isolate for cattle. The results of this study showed that these A. marginale isolates obtained from bison were similar to ones from naturally infected cattle.