Comparative Immune Efficacy of Native Inactivated and Attenuated Vaccines for Porcine Reproductive and Respiratory Syndrome Virus over 2 Consecutive Years

摘要

The primary objective of this study was to evaluation the immune efficacy of native inactivated vaccine against porcine reproductive and respiratory syndrome virus. The experimental design included 60 gilts and 9 boars equal distribution in two farms free of antibody for PRRSV at the beginning of the experiment for two consecutive months. These gilts and boars were randomly assigned to three treatment groups equally designated as groupsⅠ～Ⅲ. GroupⅠwas inoculated intramuscularly with RespPRRSV/Repro vaccine. Group Ⅱ was inoculated intramuscularly with native multivalent inactivated vaccine. Group Ⅲ was sham-inoculated intramuscularly with saline as control. Gilts and boars were inoculated again at six months intervals during the consecutive 2 years. The neonatal piglets of three groups were inoculated the same vaccine as their parents one week before weaning (piglets were 25 days). Then antibody anti-PRRSV was detected in sera obtained from gilts, boars and piglets. Biological tissue samples were collected from the recently deceased or sacrificed pigs which presented with similar PRRS symptoms. Virus isolation and viral RNA using RT-nPCR were carried through in collected tissue samples, sera and semen. Productive performances of pigs were also evaluated in this project. The results showed all the indexes in groupⅡwere very similar to that of groupⅠexcept the virus isolation and viral RNA detection. Control group had more virus isolates and viral RNA detection than inoculated groups. The rate of piglets surviving, born dead and postnatal deaths and fattening differed significantly (P<(0.05)) between experiment groups and control. This was implied that pigs inoculated with native inactivated vaccine had the similarity immune efficacy to that of pigs inoculated attenuated vaccine. This is the first large-scale to evaluation the immune efficacy of native multivalent inactivated vaccine against PRRSV in field trial. Inoculating native inactivated multivalent vaccine is also an effective measure to prevent PRRS in Shanghai pig farms and this can reduce the risk of vaccine virus shedding because of inoculating the attenuated vaccine.