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Bulletin No. 19 - Fall 2004
18th IPVS Congress, Hamburg, Germany, 2004Porcine Reproductive and Respiratory Syndrome (PRRS)
LABARQUE G, VAN GUCHT S, VAN REETH K, DREXLER C, NAUWYNCK H, PENSAERT M
Impact of genetic diversity of European-type porcine reproductive and respiratory syndrome virus strains on vaccine efficacy
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:33
To date, three clusters of European PRRSV isolates have been identified namely the Lelystad, the Danish and the Italian clusters. In this study, PRRSV-negative conventional pigs were vaccinated with a European-type vaccine belonging to the Lelystad cluster (Porcilis?PRRS, Intervet NV) and subsequently challenged either with a Lelystad strain or an Italian strain and compared to non-vaccinated controls which were also inoculated with either one or the other strain. PRRSV titers were determined in broncho-alveolar lavage (BAL) fluids and sera. While in the Lelystad-challenged pigs the virus was not present in neither BAL fluids nor sera, in the Italian-challenged pigs the virus was detected in both of them. Virus titers were anyway lower in these vaccinated pigs when compared to the control pigs. Therefore the vaccine efficacy does depend on the genetic and antigenic similarity between the vaccine and the challenge strain. A close monitoring of PRRSV strains is necessary to guarantee that PRRSV vaccines provide an acceptable level of protection in the field.
