Safety and immunogenicity of a gE/gI/TK gene deleted pseudorabies virus variant expressing the E2 protein of classical swine fever virus in pigs.
Classical swine fever (CSF) and pseudorabies (PR) are both major infectious diseases of pigs, causing enormous economic losses to the swine industry in many countries. A marker vaccine that enables differentiation of infected from vaccinated animals (DIVA) is highly desirable for control and eradication of these two diseases in endemic areas. Since late 2011, PR outbreaks have been frequently reported in many Bartha K61 vaccinated pig farms in China. It has been demonstrated that a pseudorabies virus (PRV) variant with altered antigenicity and increased pathogenicity was responsible for the outbreaks. Previously, we showed that rPRVTJ delgE/gI/TK, a gE/gI/TK deleted PRV variant, was safe for susceptible animals and provided a complete protection against lethal PRV variant challenge, indicating that rPRVTJ delgE/gI/TK can be used as an attractive vaccine vector. To develop a safe bivalent vaccine against CSF and PR, we generated a recombinant virus rPRVTJ delgE/gI/TK E2 expressing the E2 protein of classical swine fever virus (CSFV) based on rPRVTJ delgE/gI/TK and evaluated its safety and immunogenicity in pigs. The results indicated that pigs (n=5) immunized with rPRVTJ delgE/gI/TK E2 of different doses did not exhibit clinical signs or viral shedding following immunization, the immunized pigs produced anti PRV or anti CSFV neutralizing antibodies and the pigs immunized with 10(6) or 10(5) TCID50 rPRVTJ delgE/gI/TK E2 were completely protected against the lethal challenge with either CSFV Shimen strain or variant PRV TJ strain. These findings suggest that rPRVTJ delgE/gI/TK E2 is a promising bivalent DIVA vaccine candidate against CSFV and PRV coinfections.
Immunology letters