Evaluation of Presence of MHC Class II Susceptible and Resistant Alleles to Oncovirus in Seropositive and Seronegative Holstein- Frisian Dairy Cattle in Iran

Bovine leukemia virus (BLV) is an exogenous C- type oncovirus in the Retroviridae family. This virus is an important model for human T-cell leukemia virus type 1 infection because they shared molecular and biological features. The BOLA- DRB3.2 gene is a part of the major histocompatibility complex (MHC) class II in cattle and its association with susceptibility and/or resistance to development of different forms of BLV infection has been confirmed. One hundred and ninety six blood samples from Holstein- Frisian cattle of two different dairy farms were taken in this research. The alleles’ typing was carried out using polymerase chain reaction and restriction fragment length polymorphism (PCR- RFLP). The association between the BOLA- DRB 3.2 alleles and oncovirus infection profile was determined by odds ratio. In native population the frequency of BOLA- DRB3.2 alleles 11 and 28 (resistant alleles to oncovirus infection) were 2%. The frequency of BOLA- DRB 3.2* alleles 22, 24 and 8 (susceptible alleles to oncovirus infection) were 8%, 6% and 6%, respectively. In Holstein dairy cows the frequency of BOLA- DRB3.2* alleles 6 and 12 showed significant association with susceptibility to oncovirus infection (OR= 1.034; P< 0.02 and OR= 1.028; P< 0037).