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Bulletin No. 27 - Summer 2007
VirologyPorcine Reproductive and Respiratory Syndrome (PRRS)
PESENTE P, REBONATO V, SANDRI G, GIOVANARDI D, RUFFONI LS, TORRIANI S
Phylogenetic analysis of ORF5 and ORF7 sequences of porcine reproductive and respiratory syndrome virus (PRRSV) from PRRS-positive Italian farms: A showcase for PRRSV epidemiology and its consequences on farm management.
Veterinary Microbiology, 2006, Volume 114, N°3-4, 214-224
A comprehensive analysis of phylogenetic, clinical and serological data was carried out by the authors in order to achieve a better overview of the epidemiological situation of porcine reproductive and respiratory syndrome virus (PRRSV) in Northern Italy and determine the impact of a recently developed gilt acclimatization program. This study included 27 PRRSV-positive pig herds, the phylogenetic trees were obtained analyzing 64 open reading frame 5 (ORF5) and 11 ORF7 sequences. The results of this study confirm a high variability among Italian isolates, but underline also an unexpected polymorphism for the ORF7 sequence, usually more conserved and consequently used as target in PRRSV PCR diagnostic tests suggesting that such assays may be updated to remain reliable. The spread of PRRSV in PRRSV-positive farms (sow herds, nursery sites and fattening units) was demonstrated to occur mainly through the introduction of animals infected with new variants of PRRSV and not to result from the evolution of a pre-existing variant. The acclimatization program evaluated in this paper gave inconsistent results, indicating that the compliance to rigorous biosecurity measures represents a critical point for the success of such an approach.
