Detection of porcine reproductive and respiratory syndrome virus in semen and serum of boars during the first six days after inoculation

Results: Serum samples became PCR-positive before semen samples. During the first 6 days after inoculation, serum was PRRSV-positive in 36 of 40 boars, and semen was PRRSV-positive in four of 40 boars. Median time to detection was 36 and 48 hours for nested PCR and Taqman PCR, respectively. Results were inconsistent when a positive semen sample was pooled with negative semen. Elevated rectal temperature was not associated with PCRpositive serum or semen results. Implications: Under the conditions of this study, PCR is more sensitive and detects PRRSV-infected boars earlier in serum than in semen. Pooling of positive semen samples provides variable PCR results. Rectal temperatures are not correlated with PCR-positive results. Sampling techniques are needed to more easily obtain serum samples for PCR from boars once or twice weekly at the time of semen collection.