Necrobacillosis in free-living male European bison in Poland

Increased Parasitic Load in Captive-Released European Bison (Bison bonasus) has Important Implications for Reintroduction Programs

Captive-bred animals, widely used in reintroduction programmes, are often immunologically naïve and more susceptible to pathogens. We analysed infection of invasive blood-sucking nematode Ashworthius sidemi in captive-bred European bison (Bison bonasus) released to the wild in the Białowieża Forest (Poland). Mean A. sidemi infection intensity of released bison (29,137 nematodes) was over threefold higher than in wild bison (8756). It indicates a rapid acquisition and increase in the infection intensity in previously dewormed bison released from captivity. Thus, reintroduction programmes should consider the impact of pathogens and involve controlled exposure of captive animals to specific parasites prior to release.

Seroprevalence and risk factors for selected respiratory and reproductive tract pathogen exposure in European bison (Bison bonasus) in Poland

After the complete extinction from the wild of European bison (Bison bonasus) at the beginning of the twentieth century, the worldwide species population was restored to approximately 5500 individuals, with the species however remaining endangered. Despite numerous studies on the ecology and genetics of European bison, the threats of infectious diseases have been largely unexamined. The aim of this study was to screen the exposure of the world's largest population of European bison to the pathogens, which may influence the condition and development of the endangered species. A total of 240 free-ranging and captive European bison from eight main Polish populations sampled were tested for the presence of specific antibodies against ten different viruses, bacteria or protozoan. The samples were collected from chemically immobilized, selectively culled or found dead animals. Based on serology, the exposure to bovine viral diarrhea virus (BVDV), bovine herpesvirus type 1 (BoHV-1), Mycoplasma and Brucella spp. was determined as rather accidental. Using gamma-interferon assay followed by Mycobacterium tuberculosis subs. caprae detection in tissues, diagnosis of bovine tuberculosis was made for 6 out of 78 (7.7%) bison from one captive herd. The highest seroprevalence was found for bovine adenovirus type 3 (BAdV-3) -60.2% and bovine parainfluenza type 3 (PIV-3) -34.0%, while the antibodies against bovine respiratory syncytial virus (BRSV), Toxoplasma gondii and Leptospira spp. were found in 10.4%, 10.4% and 8.7% of samples, respectively. In the multivariable statistical analysis using generalized linear mixed models (GLMMS), the risk factors for PIV-3 seropositivity included population type (free-living/captive), age and health status (apparently healthy/eliminated due to the poor condition). Higher risk of BAdV-3 seropositive result was observed in free-living female European bison. The high BAdV-3 and PIV-3 seroprevalences may suggest involvement of these pathogens in the most frequently observed respiratory disorders in European bison. Moreover, this is the first study demonstrating BAdV-3 exposure in the species.

Phenotypic characteristics and virulence genotypes of Trueperella (Arcanobacterium) pyogenes strains isolated from European bison (Bison bonasus)

Trueperella (Arcanobacterium) pyogenes is an opportunistic animal pathogen, which in European bison is associated with different suppurative infections mainly of the urogenital tract. Little is known about the virulence of this bacterium and about the pathogenesis of infections. The main objective of this study was to determine phenotypic properties and virulence genotypes of the twenty-five T. pyogenes strains isolated from lesions in various tissues of free-living European bison. Classical bacteriological methods were used for phenotypic characterization. Genes encoding seven known and putative virulence factors of T. pyogenes were detected by PCR technique. Analysis of 16S rDNA partial sequences was performed to establish phylogenetic relationships of the isolated strains. All isolates showed typical morphological features of T. pyogenes and variable biochemical activity. Most of them displayed a strong positive effect in synergistic CAMP test. For all isolates the 16S rRNA gene partial sequence was identical to that of the T. pyogenes reference strain. All isolates carried the plo and fimA genes, while the nanH, nanP, cbpA, fimC and fimG genes were present in 40, 44, 12, 88 and 24% of the isolates, respectively. The T. pyogenes strains isolated from European bison represented various phenotypes and virulence genotypes, but there was no association between the investigated properties of the bacteria and the type of anatomopathological lesions from which they were isolated. These results indicate that the studied virulence factors of T. pyogenes are not significant determinants of the localization and type of infection caused by this bacterium.

MHC-DRB3 variation in a free-living population of the European bison, Bison bonasus

MHC genes play a crucial role in pathogen recognition and are the most polymorphic genes in vertebrates. Loss of variation in these genes in bottlenecked species is thought to put their survival at risk. We examined variation at the MHC II DRB3 locus in the European bison, Bison bonasus, a species that has undergone an extreme bottleneck: the current population originated from only 12 founders. We also tested for the association of DRB3 genes with the incidence of posthitis, a disease affecting the reproductive organs of bulls and posing a new threat to the survival of the species. We found very limited MHC diversity, with only four alleles segregating in a sample of 172 individuals from a free-ranging Białowieza population. The alleles were highly divergent and revealed the hallmark of positive selection acting on them in the past, that is, a significant excess of nonsynonymous substitutions. This excess was concentrated in putative antigen-binding sites, suggesting that selection was driven by pathogens. However, we did not observe departures from Hardy-Weinberg equilibrium, an indicator of strong ongoing selection. Neither have we found a significant association between DRB3 alleles or genotypes and susceptibility to posthitis. Alleles conferring resistance to males may have been lost during the extreme bottleneck the species had undergone.

Arcanobacterium bialowiezense sp. nov. and Arcanobacterium bonasi sp. nov., isolated from the prepuce of European bison bulls (Bison bonasus) suffering from balanoposthitis, and emended description of the genus Arcanobacterium Collins et al. 1983

A taxonomic study was performed on 13 bacterial strains isolated from preputial swabs of European bison (Bison bonasus) bulls suffering from balanoposthitis. The isolates were Gram-positive, non-motile, facultatively anaerobic, diphtheroid-shaped cells. Based on biochemical profiles and BOX-PCR-generated genomic fingerprints, the isolates were grouped into two clusters represented by four and nine strains, respectively. Strains 1(W3/01)T and 2(W106/04)T, selected as representatives of the two clusters, shared 97·2 % 16S rRNA gene sequence similarity. The highest gene sequence similarities found (95·5–96·4 %) were to Arcanobacterium pyogenes DSM 20630T and Arcanobacterium bernardiae DSM 9152T, demonstrating that the novel strains are members of the genus Arcanobacterium, but are not members of a recognized species. The polar lipid profiles of the two novel strains displayed the major characteristics also found in A. pyogenes DSM 20630T and Arcanobacterium haemolyticum DSM 20595T. Detection of a quinone system with MK-10(H4) as the predominant compound confirmed phylogenetic relatedness of the novel strains to A. pyogenes and separated them from the type species of the genus, A. haemolyticum, which contains MK-9(H4) as the predominant quinone. Results from DNA–DNA hybridizations clearly demonstrated that strains 1(W3/01)T and 2(W106/04)T represent separate species. Based on these data, two novel species of the genus Arcanobacterium are described, for which the names Arcanobacterium bialowiezense sp. nov. [type strain 1(W3/01)T=DSM 17162T=NCTC 13354T] and Arcanobacterium bonasi sp. nov. [type strain 2(W106/04)T=DSM 17163T=NCTC 13355T] are proposed.

Fusobacteriosis in captive wild-caught pronghorns (Antilocapra americana)

An outbreak of Fusobacterium necrophorum-induced septicemia occurred in a group of 40 captive wild-caught pronghorns (Antilocapra americana). Primary pododermatitis or necrotic stomatitis progressed to produce fatal septicemia with metastatic lesions in the forestomachs, lung, liver, and cecum in 38 of the animals. Two remaining animals were euthanatized because of chronic pododermatitis. Housing the animals in a pasture previously used by bovids and heavy rains with persistence of ground water pools in the pasture were contributing factors in the pathogenesis of this outbreak.