LESIONS IN THE REPRODUCTIVE-TRACT OF BOARS EXPERIMENTALLY INFECTED WITH PORCINE RUBULAVIRUS

''Blue eye'' disease of pigs in Mexico is caused by porcine rubulaviru s and characterized by infertility in sows and boars, nervous signs in young pigs, and corneal opacity in pigs of all ages. The pathogenesis of reproductive tract lesions in rubulavirus-infected boars has not p reviously been investigated. In a first experiment, four 9-month-old b oars were inoculated with porcine rubulavirus and killed 5, 15, 30 or 45 days post-inoculation (pi). In a second experiment, four similar bo ars were inoculated with the same virus and two animals were killed on each of days 70 and 80 pi. Swelling of the head of the epididymis dev eloped in all inoculated boars at approximately day 15 pi. Reduced spe rmatozoan motility and concentration were detected in semen samples co llected from one boar from day 21 pi. At post-mortem examination, nodu les were seen in the head of the epididymis of the boars killed 15, 30 or 45 days pi and the right testis of the pig killed 30 days pi was a trophic. Corresponding histopathological epididymal alterations includ ed formation of spermatic granulomas and vacuolar degeneration of duct ular epithelium. These lesions were associated with mononuclear cell i nfiltration and interstitial fibroplasia. Degeneration of seminiferous tubules and interstitial mononuclear cell infiltration were seen in t he atrophic testis of the pig killed 30 days pi. There was fibrosis of the head of the epididymis in all boars killed 70 or 80 days pi and o ne of these animals also had right testicular atrophy associated with degeneration of seminiferous tubules, lymphocytic infiltration and gia nt cell formation. Porcine rubulavirus antigen was detected by immunof luorescence labelling in the head of the epididymis of the pigs killed 15, 30 or 45 days pi and in one animal killed on day 70 pi. These res ults indicate that porcine rubulavirus can cause severe epididymo-orch itis and reduced semen quality in sexually mature boars. (C) 1997 W.B. Saunders Company Limited.