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Bulletin No. 19 - Fall 2004
18th IPVS Congress, Hamburg, Germany, 2004Porcine Reproductive and Respiratory Syndrome (PRRS)
PESCH S, OHLINGER VF
Differential diagnosis of PRRS field virus strains and modified live vaccines in Europe
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:35
The nucleotide sequence of the ORF5 of 120 European PRRSV isolates was determined and compared to that of Porcilis®PRRS modified live vaccine (MLV). Sequencing is a necessary step to differentiate field PRRSV strains from Porcilis®PRRS MLV due to their genetic similarity. Field strains were shown to share 79.5-96% homology with Porcilis?PRRS MLV while Porcilis®PRRS MLV-derived strains were shown to have 99.2-100% homology. Single site mutations in Porcilis®PRRS MLV were demonstrated to often occur resulting sometimes in a modification of the amino acid sequence. The use of modified live virus vaccine is thus strongly associated with the risk of genetic drift.
