Isolation of acutely transforming subgroup J avian leukosis viruses that induce erythroblastosis and myelocytomatosis (vol 29, pg 327, 2000)

Avian leukosis virus of subgroup J (ALV-S), isolated in the late 1980s, pre dominantly causes myelocytic myeloid leukosis in meat-type chickens. In the past few years, we have observed the occurrence of lesions indicative of e rythroblastosis in ALV-J-infected flocks and, in this paper, we report the isolation of ALV-J strains from such flocks. Three of these isolates mere a cutely transforming viruses, as shown by their ability to transform bone ma rrow cell cultures, The bone marrow cultures transformed by these virus iso lates mere very similar to the myeloid cells transformed by the ALV-J strai n 966. However, the infection of meat-type chickens with these isolates eit her as embryos or as 1-day-old chicks resulted in the induction of erythrob lastosis as well as myelocytomatosis. Other histopathological changes obser ved in the inoculated birds included neoplastic lesions such as cholangioma and testicular cell tumour, and non-neoplastic lesions such as lymphomyelo id hyperplasia. This report demonstrates that highly oncogenic ALV-J, capab le of inducing a different spectrum of disease other than the widely report ed myelocytomatosis, could be established in naturally infected flocks.