Intratesticular inoculation of avian leukosis virus (ALV) in chickens--production of neutralizing antibodies and lack of virus shedding into semen.

In order to investigate the possibility of producing transgenic chickens by injection of avian leukosis virus-based vectors into testis, we have analyzed the infection rate of testicular cells following inoculation of Rous-associated virus type 1 (RAV-1) into the gonads of adult and 1-wk-old brown leghorn males. Viroproduction, neutralizing antibody production, and vital DNA presence in testis, blood, muscle, and semen were analyzed at various times after infection. Inoculation of RAV-1 into the gonads of adult males resulted in a low level of viroproduction in testis and blood, followed by the appearance of neutralizing antibody 2 or 3 wk later. Neither viroproduction in semen nor viral DNA presence in sperm were detected even though the infected chickens were found to produce RAV-1 in testis. One week after intratesticular inoculation of 1-wk-old males with RAV-1, a high level of viroproduction was found in blood and testis, and viral DNA was detected in gonadal cells. Further, by 6 wk after inoculation, the production of virus decreased in all tissues, viral DNA could not longer be detected in the testis, and neutralizing antibodies appeared in blood. All together these data show that it is possible to infect testicular cells by direct inoculation of RAV-1 in the testis, and that the immune response of both adult and young chickens seems to reduce this infection. Moreover, no evidence of spermatozoa infection was found; this result suggests that RAV-1 inoculation into testis may not induce genetic transmission of virus, and consequently would not be useful in the production of transgenic chickens.