RESUMO
Bovine leukemia virus (BLV) is a retrovirus that infects cattle and is associated with an increase in secondary infections. The objective of this study was to analyze the effect of BLV infection on cell viability, apoptosis and morphology of a bovine mammary epithelial cell line (MAC-T), as well as Toll like receptors (TLR) and cytokine mRNA expression. Our findings show that BLV infection causes late syncytium formation, a decrease in cell viability, downregulation of the anti-apoptotic gene Bcl-2, and an increase in TLR9 mRNA expression. Moreover, we analyzed how this stably infected cell line respond to the exposure to Staphylococcus aureus (S. aureus), a pathogen known to cause chronic mastitis. In the presence of S. aureus, MAC-T BLV cells had decreased viability and decreased Bcl-2 and TLR2 mRNA expression. The results suggest that mammary epithelial cells infected with BLV have altered the apoptotic and immune pathways, probably affecting their response to bacteria and favoring the development of mastitis.
Assuntos
Células Epiteliais/virologia , Interações Hospedeiro-Patógeno , Vírus da Leucemia Bovina/fisiologia , Animais , Apoptose/genética , Biomarcadores , Bovinos , Linhagem Celular , Proliferação de Células , Sobrevivência Celular , Citocinas/metabolismo , Efeito Citopatogênico Viral , Leucose Enzoótica Bovina/metabolismo , Leucose Enzoótica Bovina/virologia , Células Epiteliais/metabolismo , Feminino , Glândulas Mamárias Animais/metabolismo , Glândulas Mamárias Animais/virologia , Mastite Bovina/metabolismo , Mastite Bovina/virologia , Receptores Toll-Like/metabolismoRESUMO
Bovine leukemia virus (BLV)-infected cattle were classified by their proviral load into low and high proviral load profiles (LPL and HPL, respectively). Blood from these animals was used to infect sheep to obtain multiple identical copies of integrated provirus. An env fragment of BLV was amplified from all infected sheep and sequenced. The sequences that were obtained were compared to already published BLV genome sequence, resulting in three clusters. Mutations could not be attributed to the passage of provirus from cattle to sheep and subsequent amplification and sequencing. The description of two different proviral load profiles, the association of the BoLA-DRB3.2 0902 allele with the LPL profile, the availability of complete BLV sequences, and the comparison of a variable region of the env gene from carefully characterized cattle are still not enough to explain the presence of animals in every herd that are resistant to BLV dissemination.
