SEMEN CHANGES IN BOARS AFTER EXPERIMENTAL-INFECTION WITH PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME (PRRS) VIRUS

Eleven boars seronegative to porcine reproductive and respiratory synd rome virus (PRRSV) were trained for semen collection: five boars were inoculated intranasally with 6x10(6)TCID(50)/ml of PRRSV (Group A); fo ur boars were inoculated intranasally with 6x10(4)TCDD(50)/ml (Group B ); and two boars were used as uninfected control (Group C). Semen samp les were collected at 7-d intervals from 49 d prior to experimental in oculation with PRRSV to 70 d after inoculation, and were examined for sperm volume, sperm concentration, sperm morphology, sperm motility an d for the presence of PRRSV. The infection in boars was demonstrated b y the reisolation of PRRSV from the serum of all inoculated boars. Rec tal temperatures and general health of the boars were clinically norma l throughout the trial. Differences were observed in the quality of se men collected from boars after experimental infection with PRRSV. This infection induced a significant decrease in sperm motility and in spe rmatozoa with normal acrosomes. Of the semen Samples tested for virus isolation in swine alveolar macrophages PRRSV was only isolated in 1 b oar from Group B. The virus was detected in an additional semen sample in Group A by the production of an antibody titer in a biological ass ay. All attempts to detect PRRSV by RT-PCR in semen samples were unsuc cessful. Nevertheless, from our study it is possible to suggest that t he PRRSV can occasionally be transmitted in the semen during the initi al phase of the disease.