Sequence analysis of the membrane protein gene and nucleocapsid gene of porcine reproductive and respiratory syndrome virus isolated from a swine herd in Hungary.

Porcine reproductive and respiratory syndrome virus (PRRSV) was isolated from blood samples taken at a pig farm in Hungary from pigs showing clinical signs of the disease. The virus (ABV 32) was identified as belonging to the European genotype by using type-specific monoclonal antibodies. This was confirmed by comparing the sequence of the membrane protein gene (ORF 6) and the nucleocapsid gene (ORF 7) with the American VR2332 and the European LV genotype reference strain, respectively. Analysis of the amino acid sequence of the ORF 6 and ORF 7 of ABV 32 revealed five amino acid changes in both ORFs when compared with LV, of which two changes in ORF 7 were only found in the Spanish isolates. Additionally, the ORF 7 sequence was compared with corresponding sequences of a total of 21 other European strains. Phylogenetic analysis using the PHYLIP package confirmed the close relationship between the Hungarian and the Spanish isolates. Of all the isolates analysed, ABV 32 and LV were the least related.