An RNA viral infection of hamster testes and uteri resulting in orchitis and effects on fertility and reproduction.

A pantropic, attenuated RNA virus [TC83 strain of Venezuelan encephalitis (VE) virus] grew in hamster testes after intratesticular inoculation. Virus did not grow in testes after subcutaneous injection nor in uninoculated testes after unilateral testicular injection. Although viremia disappeared within 6 days when virus-neutralizing antibodies appeared in serum, viral growth in testes continued for 2-3 weeks after intratesticular inoculation. Virus also persisted for 12 days in testes of hamsters immunized 4 weeks previous to intratesticular inoculation. Thus, there seemed to be a barrier between germinal epithelium and blood to early virus-neutralizing antibodies which developed within 2-4 weeks of infection. Cytonecrosis, inflammation, depression in the number of germinal cells, atrophy, fibrosis and eventual sterility occurred with viral growth in testes of normal hamsters, but no histopathology other than atrophy and aspermia was seen in epididymides. Similar changes occurred in testes of some previously immunized hamsters. Virus antigen was found in diploid, but not haploid germinal cells, and virus (either attenuated or virulent VE) did not adsorb to or grow in sperm maintained in vitro. Males with infected testes and virus in the epididymis remained fertile for about 2 weeks after inoculation. Virus was only occasionally transferred to the uterus-vagina of normal females by copulation with males with infected testes, and only rarely did such females become infected. Usually, pregnancy developed and progressed normally, and no convincing transfer of virus to progeny occurred. In normal female hamsters inoculated intrauterinely or subcutaneously, virus did not reach higher concentrations in uteri than in blood, virus disappeared concurrently in both and no histopathology developed in uteri. However, infection of females by intrauterine inoculation of attenuated VE virus 2 hours before mating prevented pregnancy whereas intrauterine inoculation of saline or an adenovirus did not.