Infectious bronchitis virus in testicles and venereal transmission

Even though males represent only 8%-12% of the birds of a breeder flock, their role in infectious bronchitis virus (IBV) dissemination is largely unknown. We first assessed the effect of IBV replication in the chicken testes. Ten-week-old males were inoculated with Arkansas (Ark) or Massachusetts (Mass) IBV virulent strains. Seven days postinoculation (DPI) IBV RNA was detected in testicles of 100% of M41- and in 96% of Ark-infected males. Marginal nonsynonymous variation was detected in spike (S) gene of the predominant population of IBV replicating in the testes compared to the S gene of the predominant population of viruses prior to inoculation. IBV M41 and Ark were detected in spermatogonia and Sertoli cells of testicles of infected roosters by immunofluorescence, without evident histopathological changes. We next assessed venereal transmission of IBV by artificially inseminating 54-wk-old hens either with semen from IBV-infected roosters or with IBV suspended in naïve semen. IBV RNA was detected in the trachea of all hens inseminated with IBV-spiked semen and in 50% of hens inseminated with semen from IBV-infected males. The egg internal and external quality was negatively affected in hens inseminated with semen containing IBV. These results provide experimental evidence for IBV venereal transmission.