Chicken Infectious Anaemia Virus
Karel A. Schat
from: Avian Virology: Current Research and Future Trends (Edited by: Siba K. Samal). Caister Academic Press, U.K. (2019) Pages: 249-282.
Chicken anaemia virus (CAV) is the only member of the genus Gyrovirus of the family Anelloviridae. It has a single-stranded, covalently linked circular DNA genome of 2.3 kb coding for three viral proteins (VP). VP1 forms the capsid and is the only protein in the virus particles. VP2 has multiple functions, which are essential for the formation of the virus particles. VP3 causes apoptosis in vitro and in vivo. VP3, also known as Apoptin, is investigated as a potential anticancer treatment for human tumors. The promoter/enhancer region resembles oestrogen response elements and transcription can be activated by oestrogen and repressed by chicken ovalbumin upstream promoter transcription factor 1. Viral DNA can remain present in the gonads of chickens with or without virus-neutralizing (VN) antibodies. Transfer of viral DNA through the embryo can occur independently of the presence of VN antibodies. Infection of 1-day-old chicks without maternal antibodies causes apoptosis of the haematopoietic cells in the bone marrow and thymocytes in the thymus cortex causing anemia and immunosuppression. Infection after 2 to 3 weeks of age does not cause clinical disease but may cause subclinical immunosuppression. Vaccination of pullets between 9 and 15 weeks of age prevents clinical disease in newly hatched chickens by the transfer of maternal antibodies read more ...