First detection and characterisation of porcine hemagglutinating encephalomyelitis virus in the Czech Republic

Porcine hemagglutinating encephalomyelitis virus (PHEV) is a highly neurovirulent coronavirus that invades the central nervous system in piglets. The incidence of PHEV among pigs in many countries is rising, and the economic losses to the pig industry may be significant. Serological studies suggest that PHEV is spread worldwide. However, no surveillance has been carried out in the Czech Republic. In this study, eight pig farms were screened for the presence of members of the Coronaviridae family with the use of reverse transcription PCR. A collection of 123 faecal samples and 151 nasal swabs from domestic pigs were analysed. In PHEV-positive samples, almost the complete coding sequence of the nucleocapsid gene was amplified and the acquired sequences were compared to those of geographically dispersed PHEV strains; phylogenetic analyses were also performed. PHEV was present in 7.9% of nasal swabs taken from different age categories of pigs. No other swine coronaviruses were detected. The amino acid sequence of the Czech PHEV strains showed 95.8-98.1% similarity to other PHEV reference strains in GenBank. PHEV strains collected from animals on the same farm were identical; however, strains from different farms have only exhibited only 96.7-98.7% amino acid sequence identity. Our study demonstrates the presence of PHEV in pigs in the Czech Republic. The Czech PHEV strains were evolutionarily closest to the Belgium strain VW572.