Neuropathogenic Equid Herpesvirus 1 involving in horse respiratory disease outbreak, north Xinjiang, China, 2021-2023

Background: Equid herpesvirus 1 (EHV-1) is one of important viral pathogens that frequently cause respiratory disease in horse cross the worldwide. Until now, no information on EHV-1 presents in Chinese horse respiratory disease. An acute respiratory disease outbreak in horse population of north Xinjiang between April 2021 and May 2023. Results: : qPCR detection revealed the presence of EHV-1 in all samples as the possible cause of all respiratory disease, although EHV-4, EHV-2 and EHV-5 were also found to circulate in a small portion of samples. Three EHV-1 strains, caused respiratory disease in horses, were successfully isolated. Furthermore, the full ORF33 sequences comparison and phylogenetic analysis indicated that indicated that the isolates could have been origin from EHV-1 trains detected in Yili horse abortions. In addition, based on the predicted ORF30 nucleotide sequence, it was found that all the strains carried a guanine at the 2254 nucleotide position (aspartic acid at position 752 of the viral DNA polymerase) and were, therefore, identified as neuropathogenic strains. Conclusion: This study is the first one that establishes EHV-1 as the cause of respiratory disease in horses, of China. Further characterization of the ORF30 sequences revealed that all the EHV-1 strains from the study carried the neuropathogenic genotype. Totally, neuropathogenic EHV-1 infection in China’s horse population should be concerned because the virus detected in both respiratory disease and abortions.