PMID- 10510038 OWN - NLM STAT- MEDLINE DCOM- 19991025 LR - 20190831 IS - 0378-1135 (Print) IS - 0378-1135 (Linking) VI - 68 IP - 3-4 DP - 1999 Aug 31 TI - Heterologous challenge with porcine reproductive and respiratory syndrome (PRRS) vaccine virus: no evidence of reactivation of previous European-type PRRS virus infection. PG - 187-95 AB - In Denmark, a porcine reproductive and respiratory syndrome virus (PRRSV) control programme, comprising vaccination of seropositive herds with a live American type PRRSV vaccine, was started in 1996. In several of these herds, spread of vaccine virus from vaccinated 3-18 week old pigs to non-vaccinated sows was demonstrated by the isolation of vaccine virus from fetuses and stillborn piglets. Surprisingly, sows infected with the American type vaccine strain consistently exhibited significantly stronger serological responses towards European type PRRSV than American type PRRSV. In order to elucidate whether the unexpectedly strong serological reaction towards European-type PRRSV in American type PRRSV infected sows was due to a booster reaction, or reactivation of an unrecognized, latent infection in the sows with European type PRRSV, a challenge study with the vaccine was carried out. In this study, the stronger serological response towards European type PRRSV than towards American type PRRSV was reproduced, and reactivation of the previous natural infection with European PRRSV could neither be demonstrated by virus isolation nor by RT-PCR. So, the increase in antibody titers towards European PRRSV in previously European PRRSV infected pigs after challenge with the vaccine strain seems to be the result of a boosting effect on the immune system, induced by the heterologous vaccine PRRSV strain. FAU - Botner, A AU - Botner A AD - Danish Veterinary Institute for Virus Research, Lindholm, Kalvehave. ab@vetvirus.dk FAU - Nielsen, J AU - Nielsen J FAU - Oleksiewicz, M B AU - Oleksiewicz MB FAU - Storgaard, T AU - Storgaard T LA - eng PT - Journal Article PL - Netherlands TA - Vet Microbiol JT - Veterinary microbiology JID - 7705469 RN - 0 (RNA, Viral) RN - 0 (Vaccines, Attenuated) RN - 0 (Viral Vaccines) SB - IM MH - Animals MH - Cells, Cultured MH - Enzyme-Linked Immunosorbent Assay/veterinary MH - Europe MH - Female MH - Immunoenzyme Techniques/veterinary MH - Lung/virology MH - Palatine Tonsil/virology MH - Porcine Reproductive and Respiratory Syndrome/*immunology MH - Porcine respiratory and reproductive syndrome virus/*immunology/isolation & purification/pathogenicity MH - Pregnancy MH - RNA, Viral/analysis/blood MH - Random Allocation MH - Recurrence MH - Reverse Transcriptase Polymerase Chain Reaction/veterinary MH - Specific Pathogen-Free Organisms MH - Swine MH - United States MH - Vaccination/veterinary MH - Vaccines, Attenuated/administration & dosage/immunology MH - Viral Vaccines/administration & dosage/*immunology EDAT- 1999/10/06 00:00 MHDA- 1999/10/06 00:01 CRDT- 1999/10/06 00:00 PHST- 1999/10/06 00:00 [pubmed] PHST- 1999/10/06 00:01 [medline] PHST- 1999/10/06 00:00 [entrez] AID - S0378-1135(99)00053-X [pii] AID - 10.1016/s0378-1135(99)00053-x [doi] PST - ppublish SO - Vet Microbiol. 1999 Aug 31;68(3-4):187-95. doi: 10.1016/s0378-1135(99)00053-x.