Identification and antigenic variation of new epidemiology of pseudorabies virus from swine

Abstract

An epidemic disease characterized by neurologic symptoms and death in neonatal piglets occurred in many large scale pig farms of mainland China since 2011.To investigate the causative agent of the disease,the gE of pseudorabies virus(PRV) was amplified by PCR from the brain tissues of dead piglets and the results showed that PRVs were found in all detected farms.Sequence alignments of gE indicated that gE genes from 14 farms of 5 provinces in 2012 were highly homologous and they were all belong to a relatively independent sub-branch in phylogenetic analysis.In addition,the isolated PRV named HeN1 was able to cause itch and death in experimentally infected mice and the LD50 of PRV HeN1 isolate was 102.37 TCID50 which was significantly lower than that of virulent PRV Shuangcheng strain(103.83 TCID50).Furthermore,the cross-neutralization tests indicated that the serum from Bartha k61 vaccine strain inoculated pigs had low neutralizing effect to the PRV HeN1 isolate,but serum from HeN1 inoculated pigs had higher neutralizing effect to both of the viruses.In conclusion,we speculated that the prevalence of PRVs might have antigenic variation to some extent since 2011.