Sequences near the 5' long terminal repeat of avian leukosis viruses determine the ability to induce osteopetrosis.

Avian leukosis virus (ALV)-induced osteopetrosis is associated with the accumulation of unintegrated viral DNA in osteoblasts. Viruses constructed from the DNAs of an osteopetrosis-inducing ALV (Br21) and a non-osteopetrosis-inducing ALV (RAV-0) have been used to test for the role of viral genes in the induction of osteopetrosis. Our results map osteopetrotic potential to a 1,400-base-pair region near the 5' long terminal repeat. This region contains signals for the splicing, translation, and packaging of viral RNAs and coding sequences for the gag proteins p19 and p10 and the N terminus of p27.