REPLICATION OF EQUID HERPESVIRUS-1 (EHV-1) IN THE TESTES AND EPIDIDYMIDES OF PONIES AND VENEREAL SHEDDING OF INFECTIOUS VIRUS

Six Welsh Mountain pony colts were infected intranasally with the Ab4 isolate of EHV-1. Clinical and virological monitoring demonstrated mil d upper respiratory tract disease, with nasal shedding of virus and es tablishment of a cell-associated viraemia. Detailed pathological exami nation of the urogenital tract was performed post mortem on days 4-9 p ost-infection (PI). EHV-1 was isolated from the epididymis on day 8 an d the testis on day 9 PI, with viral replication in endothelial cells of these organs and an associated necrotizing vasculitis and thrombosi s. Productive viral infection of germinal epithelium was not observed. In a further study, three Welsh Mountain pony stallions were infected intranasally with Ab4, which again resulted in mild upper respiratory tract disease and the establishment of a cell-associated viraemia. Se men samples were collected up to day 60 PI. Two stallions showed a dec rease in the proportion of morphologically normal sperm. Significant n umbers of inflammatory cells were observed in the sperm-rich fraction of ejaculates collected from one stallion between days 16 and 28 PI; i nfectious virus was recovered from the semen of this animal between da ys 17 and 25 PI, after the cessation of viraemia. The affected stallio n appeared clinically normal over the period of venereal EHV-1 sheddin g. (C) 1996 W.B. Saunders Company Limited