BackgroundThe incidence of reported cases of equine herpesvirus myeloencephalopathy (EHM) caused by infection with neuropathogenic strains of equine herpesvirus 1 (EHV-1) has markedly increased over the last decade in many Western countries. The purpose of this study was to estimate the prevalence of the neuropathogenic (G2254) and non-neuropathogenic (A2254) variants of EHV-1 among isolates associated with abortions in Polish stud farms.ResultsThe results of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing were consistent, and showed that two out of 64 abortions (3.1%) were induced by the neuropathogenic genotype G2254. All remaining 18 EHV-1 positive abortion cases (28.1%) were caused by the non-neuropathogenic genotype A2254.ConclusionsMost of the abortions in mares in Poland from 1999 to 2012 were associated with non-neuropathogenic strains of EHV-1. However, the presented data indicate that the neuropathogenic genotype of the virus is also present in Polish stud farms. Such a presence suggests that the future emergence of EHM in Poland is probable.

To determine the occurrence of bovine herpesvirus 1 (BoHV-1) related alphaherpesvirus infections in cervids, 1194 serum samples of wild ruminants originating from 59 forest districts of Poland were tested with IBR gB ELISA and virus neutralization test (VNT) against BoHV-1 and cervid herpesvirus 1 (CvHV-1). The seroprevalence differed significantly between free-living and captive cervids (P<0.001) with a total of 89 out of 498 (17.9%) and 268 out of 696 (38.5%) seropositive animals in each type of population. In free-ranging cervids, the highest seroprevalence was found among red deer (25.6%) and in fallow deer (23.1%), while it was the lowest in roe deer (1.7%). The seroprevalence varied at the district level between 0 and 100% with the mean value of 17.4% (95% CI:10.1-24.0). Additionally, seroprevalence was associated with afforestation (χ=7.5; P=0.006) and to some degree with the mean of cattle density in province (χ=7.0; P=0.08). The mean antibody titre against CvHV-1 in VNT (161.8; 95%CI: 146.0-177.6) has been significantly higher (P<0.0001) than the mean titre of BoHV-1 antibodies (10.1; 95%CI: 8.9-11.4). The results showed that BoHV-1 related alphaherpesvirus infections are present in population of free-ranging and farmed cervids in Poland. Based on the VNT results and considering the low susceptibility of red deer to BoHV-1, it seems that the dominant alphaherpesvirus circulating in wild ruminants is most likely CvHV-1 and therefore it is rather unlikely that deer in Poland could play any role as a reservoir of BoHV-1 for cattle.

In late 2022 and early 2023, SARS-CoV-2 infections were detected on three mink farms in Poland situated within a few km from each other. Whole-genome sequencing of the viruses on two of the farms showed that they were related to a virus identified in humans in the same region 2 years before (B.1.1.307 lineage). Many mutations were found, including in the S protein typical of adaptations to the mink host. The origin of the virus remains to be determined.

Introduction Many countries have reported severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infections in mink, and transmission back to humans has raised the concern of novel variants emerging in these animals. The monitoring system on Polish mink farms detected SARS-CoV-2 infection first in January 2021 and has been kept in place since then. Material and Methods Oral swab samples collected between February 2021 and March 2022 from 11,853 mink from 594 farms in different regions of Poland were screened molecularly for SARS-CoV-2. Isolates from those with the highest loads of viral genetic material from positive farms were sequenced and phylogenetically analysed. Serological studies were also carried out for one positive farm in order to follow the antibody response after infection. Results SARS-CoV-2 RNA was detected in mink on 11 farms in 8 out of 16 Polish administrative regions. Whole genome sequences were obtained for 19 SARS-CoV-2 strains from 10 out of 11 positive farms. These genomes belonged to four different variants of concern (VOC) – VOC-Gamma (20B), VOC-Delta (21J), VOC-Alpha (20I) and VOC-Omicron (21L) – and seven different Pango lineages – B.1.1.464, B.1.1.7, AY.43, AY.122, AY.126, B.1.617.2 and BA.2. One of the nucleotide and amino acid mutations specific for persistent strains found in the analysed samples was the Y453F host adaptation mutation. Serological testing of blood samples revealed a high rate of seroprevalence on the single mink farm studied. Conclusion Farmed mink are highly susceptible to infection with SARS-CoV-2 of different lineages, including Omicron BA.2 VOC. As these infections were asymptomatic, mink may become an unnoticeable virus reservoir generating new variants potentially threatening human health. Therefore, real-time monitoring of mink is extremely important in the context of the One Health approach.

Coronaviruses are extremely susceptible to genetic changes due to the characteristic features of the genome structure, life cycle and environmental pressure. Their remarkable variability means that they can infect many different species of animals and cause different disease symptoms. Moreover, in some situations, coronaviruses might be transmitted across species. Although they are commonly found in farm, companion and wild animals, causing clinical and sometimes serious signs resulting in significant economic losses, not all of them have been classified by the World Organization for Animal Health (OIE) as hazardous and included on the list of notifiable diseases. Currently, only three diseases caused by coronaviruses are on the OIE list of notifiable terrestrial and aquatic animal diseases. However, none of these three entails any administrative measures. The emergence of the SARS-CoV-2 infections that have caused the COVID-19 pandemic in humans has proved that the occurrence and variability of coronaviruses is highly underestimated in the animal reservoir and reminded us of the critical importance of the One Health approach. Therefore, domestic and wild animals should be intensively monitored, both to broaden our knowledge of the viruses circulating among them and to understand the mechanisms of the emergence of viruses of relevance to animal and human health.