Isolation and Identification of an Attenuated Strain of Pseudorabies Virus

A strain pseudorabies virus named LY strain was isolated from pigs in Liaoyang.The virus isolate was purified by plaque technique on CEF monolayer with the titer of 10 7 29 TCID 50 /mL.Virus neutralization(VN) test showed that the isolate could be neutralized by PRV positive serum.Envelope and peplomers were observed on the surface of the virus under electron microscope.With the special primer,the gD gene about 1 240 bp was obtained by PCR.The virus isolate was pathogenic to 3 days mice and safe to rabbits and neonatal pigs.The neonatal pigs inoculated with different doses (10 0,10 -1 ,10 -2 mL) of the isolate showed no clinical signs when challenged with virulents train of PRV after a 14 day vaccination.Weaned pigs acquired high titer maternal antibodies from vaccinated sows and could be protected against PRV infection.Antibody to the isolate was detected from the vaccinated pigs.According to the above results,it was suggested that the virus isolate might be an attenuated PRV virus with good protection against virulent strain of PRV.