Xia SL1, Xiang GT1, Lei JL1, Du M1, Wang Y1, Zhou M1, Liu Y1, Ji S1, Wang YL1, Luo Y1, Sun Y2, Qiu HJ3

Vet Microbiol. 2016 Nov 30;196:50-54

Abstract

Classical swine fever (CSF) is an economically important disease caused by Classical swine fever virus (CSFV). In order to eradicate CSF, many marker vaccines that allow differentiation of infected from vaccinated animals (DIVA) have been developed. In our previous studies, a DIVA CSF vaccine rAdV-SFV-E2 has been demonstrated to completely protect pigs against lethal CSFV challenge. In the context of risk assessments for an emergency vaccination scenario, the question has been raised whether preexisting maternally derived antibodies (MDAs) interfere with the efficacy of the vaccine. In this study, six groups of piglets (n=5), with or without anti-C-strain or anti-rAdV-SFV-E2 MDAs, were immunized twice with 106 TCID50 rAdV-SFV-E2 and challenged with the CSFV Shimen strain. Clinical signs, CSFV-specific antibodies, viremia and pathological and histopathological changes were monitored. The results showed that the vaccinated piglets, either with or without MDAs directed against C-strain (about 67% blocking rate) or rAdV-SFV-E2 (about 50% blocking rate) were completely protected; however, the mock-vaccinated piglets displayed severe CSF-typical clinical symptoms, viremia, pathological/histopathological changes and deaths (5/5). These findings demonstrate that the MDAs to either rAdV-SFV-E2 or C-strain do not interfere with the efficacy of rAdV-SFV-E2, which highlights the great potential of the vaccine for control and eradication of CSF.