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☆

Short communication. Differentiation of Type-I Porcine Reproductive and Respiratory Syndrome Virus vaccines and field strains by restriction fragment length polymorphism analysis

“…2). A similar result has been previously reported between Porcilis PRRS® strain and field isolates showing close phylogenetic relationships (Pesente et al, 2006). However, the digestion of RT-PCR products of isolates that shared the RFLP pattern 2 when cut with ItaI with a second restriction enzyme, AccI, rendered different patterns indicating that those field isolates are different from the vaccine strain.…”

Successful elimination of PRRS virus from an infected farrow-to-finish herd by vaccination

“…The resulting cDNA was subjected to amplification of the ORF5 gene of PRRS virus. Amplification of ORF5 for sequencing was performed using a nested PCR assay with previously described primers (Pesente et al 2006). Gel-purified PCR products were sequenced (Macrogene, the Netherlands).…”

Porcine Herd Health Management Practices for the Control of PRRSV Infection

“…Gilt introduction in breeding population is the key for PRRS control, consisting of 3 periods: the isolation period, the acclimatization period, and the recovery period (Pesente et al, 2006;Vashisht et al, 2008). The length of each period may range from 30 to 60 days, depending on the age of the replacement animal, the PRRS history of intra and inter farms, and the type and size of farm.…”

“…This method has inherent risks and requires thoughtful application and high quality control standards (Zimmerman et al, 2006). Consistent acclimatization of incoming breeding stock to PRRSV results in: a) the stabilization of clinical signs, b) the production of PRRSV negative piglets at weaning, c) the prevention of PRRSV outbreaks associated with endemic PRRSV strains, d) the development of specific immunity to the homologous herd strains, and e) the improvement of production parameters (Pesente et al, 2006;Vashisht et al, 2008). It is generally accepted that early exposure (2-4 months of age) can result in the protection of the exposed animals and the introduction of the replacement animals at a time when shedding has stopped.…”

“…Increasing titers of PRRSV specific antibody demonstrated by rising ELISA S/P ratios in a group of infected animals can also indicate PRRSV infection. Finally, sequencing of PRRSV isolates followed by phylogenetic analysis is a powerful tool to monitor the spread of virus intra and inter farms and allows a fuller understanding of the success or failure of the control programme (Pesente et al, 2006). The ELISA in all of its current forms is the best practical diagnostic method to detect exposure events and confirm vaccinations, but it is not a reliable indicator of protection against PRRSV.…”