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Bulletin No. 18 - Spring 2004
SIPASPorcine Reproductive and Respiratory Syndrome (PRRS)
PESENTE P, GIOVANARDI D, SPERATI RL, SANGRI GP, CAMPAGNARI E
Reinfezione di suini con ceppo omologo ed eterologo del virus della sindrome riproduttiva e respiratoria del suino (PRRSV): aspetti pratici - (Reinfection with homologous and heterologous porcine reproductive and respiratory virus strains: practical
Società Italiana di Patologia ed Allevamento dei Suini - Proceedings, 2004, 281-288
Initially PRRSV-negative pigs of 21 days of age were intramuscularly inoculated with a strain of PRRSV (strain A). Animals were monitored for clinical signs, the presence of PRRSV in blood and in oropharyngeal scrapings by nested-PCR and immune response by ELISA. When the scrapings resulted negative (at 105 days p.i.), pigs were inoculated again with the same strain (Day 140) and two weeks later (Day 154) with an heterologous strain (strain B). Following re-infection with the homologous strain, none of the pigs showed clinical signs suggesting that protection against an homologous strain lasts at least 140 days. Only one pig was still viremic 7 days after challenge, none of them showed any secondary antibody response. Following challenge with the heterologous strain, no clinical was observed but viremia was prolonged and a significant seroconversion occurred in all animals which can then excrete this heterologous strain of PRRSV. The response to an heterologous strain is clearly different from that to the homologous strain.
