Current identification and surveillance practices for PRRSV involves a few selected U.S. veterinary diagnostic laboratories performing quantitative RT-PCR and ORF5 nucleotide sequencing followed by restriction fragment length polymorphism, a process that typically takes two weeks or more. Therefore there is a substantial need for faster surveillance programs coupled with next generation detection methods to rapidly identify and track genomic changes in PRRSV for animal health preparedness for future outbreaks. For this project we constructed a novel microarray platform that is designed to rapidly and specifically identify and differentiate all known strains of PRRSV, including novel or emerging isolates encoding a high degree of genetic variability compared to known isolates. Because this microarray platform emphasizes multiple key regions encompassing the entire PRRSV genome it has increased sensitivity and the ability to track genetic variability. Our results indicate that this platform successfully identified and distinguished the genetic variability of four genetically divergent PRRSV isolates in cell culture samples. Additionally, our data demonstrates that the PRRSV microarray has a 10 to 1000 times improved sensitivity or increased limit of detection compared to currently deployed quantitative RT-PCR. We have also demonstrated this array platform successfully identified and differentiated PRRSV using antemortem clinical samples (nasal swab and serum) collected from pigs infected with a Chinese highly pathogenic PRRSV isolate and bacterial cocktail consisting of Streptococcus suis, Haemophilus parasuis, and Actinobacillus suis. This data demonstrates that the PRRSV microarray is a sensitive and specific tool that is able to quickly identify novel or emerging strains of PRRSV in clinical samples containing multiple swine pathogens.
Tracy L. Nicholson, Ph.D.
National Animal Disease Center, ARS, USDA
P.O. Box 70
1920 Dayton Ave.
Ames, Iowa 50010