Heterogeneity of Czech isolates of the causative agent of the porcine reproductive and respiratory syndrome (PRRSV)
2001
Valicek, L. | Psikal, I. | Indik, S. | Rodak, L. | Smid, B. (Vyzkumny Ustav Veterinarniho Lekarstvi, Brno (Czech Republic))
The first identification of PRRSV in the Czech Republic in 1994 was followed by isolation in cell cultures of another seven strains. All the local isolates belong to the European genotype, they show genetic heterogeneity and genetically different strains were isolated even in the same herd. Phylogenetic analyses, based on nucleotide sequences of three PRRSV genes (ORF7, ORF6, ORF5) have classified two genetically variable Czech strains (CAPM V-501, V-503) as a separate subgroup differing from the reference strain Lelystad, most of the European isolates, and the American genotype as demonstrated by RT-PCR and assays using the monoclonal antibody JP24 reacting with the nucleocapsid protein. Long-term passaging of the strain CAPM V-502 in the cell line MARC 145 (n=152) resulted in ion mutations in the ORG5 genome. Heterogeneity and variability of PRRSV complicate both laboratory diagnostic and vaccination-based herd clearance programmes.
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