Prevalence of coronaviruses in European bison (Bison bonasus) in Poland

Abstract

Coronaviruses have been confirmed to infect a variety of species, but only one case of associated winter dysentery of European bison has been described. The study aimed to analyze the prevalence, and define the impact on the species conservation, the source of coronavirus infection, and the role of the European bison in the transmission of the pathogen in Poland. Molecular and serological screening was performed on 409 European bison from 6 free-ranging and 14 captive herds over the period of 6 years (2017-2023). Presence of coronavirus was confirmed in one nasal swab by pancoronavirus RT-PCR and in 3 nasal swab samples by bovine coronavirus (BCoV) specific real time RT-PCR. The detected virus showed high (> 98%) homology in both RdRp and Spike genes to BCoV strains characterised recently in Polish cattle and strains isolated from wild cervids in Italy. Antibodies specific to BCoV were found in 6.4% of tested samples, all originating from free-ranging animals. Seroprevalence was higher in adult animals over 5 years of age (p = 0.0015) and in females (p = 0.09). Our results suggest that European bison play only a limited role as reservoirs of bovine-like coronaviruses. Although the most probable source of infections in the European bison population in Poland is cattle, other wild ruminants could also be involved. In addition, the zoonotic potential of bovine coronaviruses is quite low.

Keywords: BCoV; Coronaviruses; European bison; PCR; Sanger sequencing; Seroprevalence.

Figure 1

Phylogenetic relationship of selected members of Betacoronavirus genus infecting wild,related domestic mammals, and human. Country of origin and year of detection of selected strains are included in the brackets. Three subgenus are distinguished: Embecovirus (green), Sarbecovirus (red) and Marbecovirus (blue). Phylogenetic tree was constructed by neighbour-joining method based on the RdRp gene sequences of coronaviruses available in GenBank, using MEGA11 software.

Figure 2

Map of the free-ranging populations (light grey silhouette) and enclosures (dark grey silhouette), where tested European bison originated from. Two non-existing in 2022 captive herds: Kiermusy (M) and Smardzewice (N) were sampled between 2018 and 2021 (M) and in 2018 (N), that is, until they were closed down. Seropositive herds were red framed, while red virus sign indicated locations where coronavirus infected individuals were detected. The size of the silhouette on the map corresponds approximately to the herd /population size.

Figure 3

Neighbour-joining phylogenetic tree was constructed using a 601-nucleotide-long fragment of the gene encoding the spike protein of Betacoronaviruses with Human coronavirus HCoV OC43 used as an outgroup . Sequence acquired in this study is marked by black square. In brackets the European (GIIb) phylogenetic group as described by Shin et al. 2022 was distinguished. Data about the country of origin, date of sample collection and hosts are included next to the name of each strain.

Figure 4

Neighbour-joining phylogenetic tree was constructed using a 432 nucleotide-long fragment of the gene encoding the RNA-dependent RNA polymerase (RdRp) of Betacoronaviruses with Human coronavirus SARS-CoV-2 used as an outgroup . Sequence acquired in this study is marked by a black square. In brackets 3 subgena of the Betacoronavirus genus were distinguished. Data about the country of origin, date of sample collection, and hosts are included next to the name of each strain.

Figure 5

The local polynomial smoothed line represents BCoV seroprevalence by European bison age.