Biological characterization of a recombinant pseudorabies virus

Abstract

In a previous study we obtained and characterized in vitro a novel pseudorabies virus (PRV) variant named gIp2 with a TK, gI/gE, 11k and 28k negative phenotype and a duplication of PK gene. The main objective of the present study was to determine the safety and efficacy, as a vaccine candidate, of this recombinant PRV. For this purpose, we used 24 PRV seronegative three weeks old piglets that were divided into five groups of treatment. Piglets of groups A and B were immunized twice with 10E6.5 and 10E5.5 TCID sub(50) of gIp2, respectively; pigs of group C were vaccinated twice with MLV vaccine Auskipra GN and pigs of groups D and E were not immunized and served as infected and uninfected controls, respectively. Four weeks after the second immunization pigs of groups A, B, C and D were challenged by intranasal inoculation of 106 TCID sub(50) of the wildtype NIA-3 strain of PRV. No adverse reactions or clinical signs were observed in any group after immunization, indicating that the application of up to 10 times the conventional dose included in a commercial vaccine (i.e. 10E5.5 TCID sub(50)) of gIp2 was safe in piglets. Additionally, the inoculation of gIp2 induced an immune response able to provide clinical and virological protection against pseudorabies virus after challenge. In conclusion, the use of gIp2 in piglets as a vaccine virus is safe and induces an immunity comparable to that exerted by commercially available vaccines.