Avian sarcoma leukosis virus is characterized by a wide range of tumors, the most common of which are lymphomas.

Lymphoid leukosis is the most common form of this disease and with typical presentation of gradual onset, persistent low mortality, and neoplasia of the bursa.

[6] Lymphoid leukosis was eradicated in primary breeders in the 1980s and 1990s which dramatically reduced the incidence of the disease in commercial laying hens.

Layers, broilers, local chicken breeds, and even mallards may still become infected, and there are currently no available vaccines to combat the virus.

Since ASLV uses distinct cellular receptors to gain entry into cells, it has proven useful for understanding the early events in retroviral infection.

[5] ASLV is divided into six subgroups, labelled A through E and J, each having a different antigenicity due to variances in viral envelope glycoproteins.

[citation needed] Viral glycoprotein-receptor interactions are required to initiate membrane fusion of the virus and cell.

The surface glycoproteins for subgroups A-E are almost identical and include the conservation of all cysteine amino acid residues.

[11] In chicken chromosomes, three autosomal loci, t-va, t-vb, and t-vc, have been identified which control cell susceptibility of the ASLV virus subgroups A, B, and C respectively.

ASLV and some RSVs also contain the env gene, which encodes a precursor polyprotein that assembles in the endoplasmic reticulum.