Avian leukosis virus (ALV) is a retrovirus that belongs to the family Retroviridae and the genus Alpharetrovirus. It primarily infects birds, especially poultry species, causing a series of diseases collectively known as avian leukosis. ALV can be further classified into various subgroups, including A, B, C, D, E, J, K, L, and N, based on their viral envelope antigens.
The virus primarily targets and infects the lymphoid system, including the bone marrow, bursa of Fabricius, and thymus, which play a crucial role in the bird's immune system. As a result, ALV can lead to significant immunosuppression among infected birds, making them more susceptible to other pathogens and contributing to increased mortality rates. It can also cause tumors in various organs such as the liver, spleen, kidneys, and gonads, leading to reduced production performance, reproductive disorders, and economic losses in affected flocks.
Avian leukosis virus is highly contagious and can be transmitted vertically from infected hens to their offspring via the egg, or horizontally through direct contact with infected bird secretions, such as saliva, feces, and nasal discharge. ALV does not pose a significant risk to human health and is specific to avian species.
Prevention and control measures for avian leukosis virus include strict biosecurity practices, such as isolating and regularly testing new birds before introducing them to a flock, thorough disinfection of equipment and facilities, and the use of ALV-free poultry breeding stock. Vaccination programs against ALV have also been developed to reduce the incidence and impact of the disease in commercial poultry production.
