DIFFERENTIATION OF NORTH-AMERICAN AND EUROPEAN PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS GENOTYPES BY IN-SITU HYBRIDIZATION

Non-radioactive probes that can detect specifically North American and European isolates of porcine reproductive and respiratory syndrome vi rus (PRRSV) in formalin-fixed paraffin-embedded tissues by in situ hyb ridization were developed. These probes allow the differentiation betw een North American and European genotypes of the PRRS virus as well as the detection of both genotypes. Two amplified cDNA products generate d by polymerase chain reaction (PCR), one from the cDNA of the Canadia n PRRSV LHVA-93-3 isolate and the second one from the European Lelysta d isolate, and labelled with digoxigenin were utilized as probes. The LHVA-93-3 derived probe was found to detect Canadian and USA PRRSV iso lates in infected cells, while the Lelystad derived probe hybridized o nly with European isolates. The specificity of both probes was also de monstrated on formalin-fixed tissues collected from PRRSV infected pig s. Furthermore, by combining the LHVA-93-3 (North American) probe and the Lelystad (European) probe, successful detection of both PRRSV geno types in fixed tissues could be achieved. (C) 1997 Elsevier Science B. V.