Abstract
BACKGROUND: Avian leukosis virus (ALV) is one of the main causes of tumour development within the poultry industry in China. The subgroup J avian leukosis viruses (ALV-J), which induce erythroblastosis and myelocytomatosis, have the greatest pathogenicity and transmission ability within this class of viruses. ALV can be transmitted both horizontally and vertically; however, the effects of ALV infection in chickens-especially roosters-during the propagation, on future generations is not clear. Knowing the role of the cock in the transmission of ALV from generation to generation might contribute to the eradication programs for ALV. RESULTS: The results showed that two hens inseminated with ALV-J-positive semen developed temporary antibody responses to ALV-J at 4-5 weeks post insemination. The p27 antigen was detected in cloacal swabs of six hens, and in 3 of 26 egg albumens at 1-6 weeks after insemination. Moreover, no viremia was detected at 6 weeks after insemination even when virus isolation had been conducted six times at weekly intervals for each of the 12 females. However, ALV-J was isolated from 1 of their 34 progeny chicks at 1 week of age, and its gp85 had 98.4%-99.2% sequence identity with the gp85 of ALV-J isolated from semen samples of the six cocks. CONCLUSIONS: Our findings indicated that females that were late horizontally infected with ALV-J by artificial insemination might transmit the virus to progeny through eggs, which amounts to vertical transmission.