γδ⁺T-Lymphocyte Cytotoxicity against Envelope-Expressing Target Cells Is Unique to the Alymphocytic State of Bovine Leukemia Virus Infection in the Natural Host

Toll-like receptors, IFN-γ and IL-12 expression in bovine leukemia virus-infected animals with low or high proviral load

“…γδ + T lymphocytes play a crucial role against intracellular pathogens, linking innate and specific immune responses (Baldwin and Telfer, 2015;Pollock and Welsh, 2002), and even a subpopulation of them can act as immune regulatory cells (Hoek et al, 2009). Concerning BLV, Lundberg et al reported that the non-PL state in most infected cattle correlates with larger proportion of γδ + T cells exhibiting more efficient cytotoxic activity against antigens of the viral envelope, without interaction with molecules of the MHC (Lundberg and Splitter, 2000). The increased levels of IFN-γ in LPL cattle detected in our research, together with other findings from the literature (Usui et al, 2007), might suggest that γδ + T lymphocytes are involved in the cellular immune response against replication of BLV.…”

Bovine leukemia virus: A major silent threat to proper immune responses in cattle

“…At the same time, AL cultures had significantly reduced CD8+ T cells compared to both PL and uninfected cattle. To demonstrate the role of ␥␦+ T cells, Lundberg and Splitter (2000) added them to cultures of both autologous fibroblasts and D17 cells expressing BLV Env. Only ␥␦+ T cells from AL cattle showed significantly increased lysis of antigen-expressing cells and lysis of D17 cells, demonstrating that lysis can occur in both an MHC-restricted and MHC-unrestricted manner (Lundberg and Splitter, 2000).…”

“…To demonstrate the role of ␥␦+ T cells, Lundberg and Splitter (2000) added them to cultures of both autologous fibroblasts and D17 cells expressing BLV Env. Only ␥␦+ T cells from AL cattle showed significantly increased lysis of antigen-expressing cells and lysis of D17 cells, demonstrating that lysis can occur in both an MHC-restricted and MHC-unrestricted manner (Lundberg and Splitter, 2000). Although BLV antigens will stimulate perforin release from CD8+ cells in BLV+ animals (Florins et al, 2009), the importance of ␥␦+ T cells during the AL stage of EBL may be a result of the suppression of CD8+ cell activation, although this would not explain the lack of ␥␦+ cytotoxicity in PL cattle.…”

Cell dynamics and immune response to BLV infection: a unifying model

“…Almost concomitantly to the early seroconversion period, cytotoxic T-lymphocytes (CTL) specific for Tax and Envelope epitopes appear in the peripheral blood (39,40). Compared to humans, a peculiarity of cattle is that gammadelta T-lymphocytes are major players in this cytotoxic response (41). BLV infection also triggers both a virusdependent and a virus-independent CD4 helper T cell response (42)(43)(44).…”