Genetic analysis of E2 gene of human apillomavirus 23 derived from equine

human papillomavirus 23%horse%abortion%E2 gene%phylogenetic tree

To investigate the prevalence of HPV-23 in horses,our study designed specific primers and used PCR to detect 413 aborted fetal tissues of horses and 20 nasal swabs of horse workers.The E2 genes were sequenced,revealing 12 HPV-23 positive samples.Sequence analysis of E2 genes obtained in this study and the reference strains in GenBank were performed.A phylogenetic tree was constructed based on E2 genes of HPV-23 from human and horse-origin,and the genetic characteristics were analyzed.The results showed that Yili horses and Thoroughbred horses aborted fetal samples were positive for HPV-23,with a positive rate of 4.3%(2/46)and 9.3%(34/367),indicating that horse aborted fetuses carried HPV-23,which may cause abortion in horses.Nasal swab samples from workers were positive for HPV-23,with a positive rate of 60%(12/20).Sequence analysis showed that the E2 gene nucleotide and amino acids homology between the eight horse-origin and four human-origin HPV-23 identified in this study was 100%and shared 98.9%-99.2%nucleotide sequence identity with the E2 gene of two foreign human-origin HPV-23,suggesting that horse-origin HPV-23 may be derived from human.Based on the E2 genes,the phylogenetic tree showed that horse-origin and human-origin HPV-23 strains in our study and foreign strains of HPV-23 have a close genetic relationship in the Beta branch.Still,they were in different branches with EcPV,which further suggested that horse-origin HPV-23 might come from humans.In this study,HPV-23 was first detected in aborted fetal tissues of horses,suggesting that the virus may lead to abortion in horses,possibly human-origin HPV-23 infecting horses.These findings provide a reference for epidemiological studies of animal-origin HPV-23.