Small ruminant lentivirus (SRLV) infections are widespread in Poland and circulation of subtypes A1, A12, A13, B1 and B2 was detected. The present work aimed at extending previous study based on the analysis of a larger number of animals from single-species flocks. Animals were selected for genetic analysis based on serological reactivity towards a range of recombinant antigens derived from Gag and Env viral proteins. Phylogenetic analysis revealed the existence of subtypes B2 and A12 in both goats and sheep and subtypes A1 and B1 in goats only. In addition, two novel subtypes, A16 and A17, were found in goats. Co-infections with strains belonging to different subtypes within A and B groups were detected in 1 sheep and 4 goats originating from four flocks. Although the reactivity of serum samples towards the recombinant antigens confirmed immunological relatedness between Gag epitopes of different subtypes and the cross-reactive nature of Gag antibodies, eleven serum samples failed to react with antigens representing all subtypes detected up-to-date in Poland, highlighting the limitations of the serological diagnosis. These data showed the complex nature of SRLV subtypes circulating in sheep and goats in Poland and the need for improving SRLV-related diagnostic capacity.

Porcine epidemic diarrhea virus (PEDV), a member of the Coronaviridae family, is the etiological agent of an acute and devastating enteric disease that causes moderate-to-high mortality in suckling piglets. The accurate and early detection of PEDV infection is essential for the prevention and control of the spread of the disease. Many molecular assays have been developed for the detection of PEDV, including reverse-transcription polymerase chain reaction (RT-PCR), real-time RT-PCR (qRT-PCR) and loop-mediated isothermal amplification assays. Additionally, several serological methods have been developed and are widely used for the detection of antibodies against PEDV. Some of them, such as the immunochromatography assay, can generate results very quickly and in field conditions. Molecular assays detect viral RNA in clinical samples rapidly, and with high sensitivity and specificity. Serological assays can determine prior immune exposure to PEDV, can be used to monitor the efficacy of vaccination strategies and may help to predict the duration of immunity in piglets. However, they are less sensitive than nucleic acid-based detection methods. Sanger and next-generation sequencing (NGS) allow the analysis of PEDV cDNA or RNA sequences, and thus, provide highly specific results. Furthermore, NGS based on nonspecific DNA cleavage in clustered regularly interspaced short palindromic repeats (CRISPR)–Cas systems promise major advances in the diagnosis of PEDV infection. The objective of this paper was to summarize the current serological and molecular PEDV assays, highlight their diagnostic performance and emphasize the advantages and drawbacks of the application of individual tests.

Introduction: Maedi-visna virus and caprine arthritis encephalitis virus are two closely related lentiviruses which cause multisystemic, progressive and persistent infection in goats and sheep. Because these viruses frequently cross the species barrier, they are considered to be one genetic group called small-ruminant lentiviruses (SRLV). They have in vivo tropism mainly for monocytes and macrophages and organ tropism with unknown mechanisms. Typical clinical signs are pneumonia in sheep, arthritis in goats, and mastitis in both species. Infection with SRLV cannot currently be treated or prevented, and control programmes are the only approaches to avoiding its spread. These programmes rely mainly on annual serological testing and elimination of positive animals. However, the high genetic and antigenic variability of SRLV complicate their early and definitive diagnosis. The objective of this review is to summarise the current knowledge of SRLV genetic variation and its implications for tropism, the development of diagnostic tests and vaccines and the effectiveness of control and eradication programmes. Material and Methods: Subject literature was selected from the PubMed and the Google Scholar databases. Results: The high genetic diversity of SRLV affects the performance of diagnostic tools and therefore control programmes. For the early and definitive diagnosis of SRLV infection, a combination of serological and molecular tests is suggested. Testing by PCR can also be considered for sub-yearling animals. There are still significant gaps in our knowledge of the epidemiology, immunology and biology of SRLV and their impact on animal production and welfare. Conclusion: This information may aid selection of the most effective SRLV spread reduction measures.

Small-ruminant lentivirus (SRLV) infections are widespread in Poland, and circulation of subtypes A1, A12, A13, A16, A17, B1 and B2 has been documented. The aim of this study was to characterize the SRLV strains circulating in sheep and goats in mixed flocks in the Malopolska region, where the highest seroprevalence has been detected. Phylogenetic analysis revealed that most of the isolates from sheep belonged to subtype A13, suggesting that this subtype may be predominant in the Malopolska region. Furthermore, the existence of a new subtype, tentatively designated as A18, was described for the first time. This work extends the current knowledge on the distribution of SRLV subtypes in sheep and goats in Poland and provides further information on the genetic diversity of SRLV. The new data are important for both epidemiological studies and eradication programs and provide insight into the evolution of SRLV.

Porcine transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) are swine coronaviruses belonging to the genus Alphacoronavirus in the family Coronaviridae. To date, there are no reports on the prevalence and genetic characterization of these viruses in domestic pigs from Poland. In this study, 828 serum samples were tested by TGEV/PRCV immunoassay to estimate TGEV and PRCV seroprevalence, while 277 nasal swabs and 221 stool samples were tested by real-time PCR to detect viral RNA. Our results revealed that 2.2% (95% CI 1.2, 3.2) of serum samples were positive for anti-TGEV antibodies, while 12.2% (95% CI 9.8, 14.4) of samples were positive for anti-PRCV antibodies. 2.5% (95% CI 1.5, 2.6) and 5.2% (95% CI 3.7, 6.7) of serum samples were inconclusive for TGEV and PRCV, respectively. RNA of TGEV was not detected in any of the tested samples, while PRCV RNA was detected in 6.22% of samples. Genetic and phylogenetic analysis revealed that all Polish PRCV strains were closely related to European and Korean PRCV strains than to American strains. Some of the Polish PRCV strains have a 672 nt deletion at the same position at the 5’ end of the S gene as other European and Korean PRCV strains, suggesting that they originated from the same precursor. Other Polish PRCV strains had a 690 nt deletion that differed in size and location from any of the known PRCV strains. This may suggest that these Polish PRCVs may have originated from different ancestor. Furthermore, the Polish PRCV strains showed some unique changes in their sequences, which may reflect their evolution. This study is the first report on the prevalence of TGEV/PRCV in pigs from Poland. In addition, this is the first report on the genetic characterization of Polish PRCV strains, which provide new information on PRCV heterogeneity.

Transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) are enveloped, single-stranded RNA viruses belonging to the genus Alphacoronavirus in the family Coronaviridae. PRCV, a TGEV mutant with a spike(S) gene deletion, exhibits altered tissue tropism. TGEV replicates mainly in the intestines and causes severe diarrhea and high mortality in piglets, whereas PRCV replicates mainly in the respiratory tract. PRCV causes mild or subclinical respiratory infections but may contribute to respiratory disease syndrome in pigs infected with other respiratory pathogens. As PRCV and TGEV continuously evolve, monitoring these viruses is important for disease prevention and control. In this review, we provide updated information on the prevalence and genetic characteristics of TGEV/PRCV and their phylogenetic relationships. We also discuss the impact of mutations, deletions and recombination on the virulence and tissue tropism of TGEV/PRCV and highlight the possible zoonotic potential of these viruses.