Lymphocyte proliferation and apoptosis of lymphocyte subpopulations in bovine leukemia virus-infected dairy cows with high and low proviral load

Abstract

Bovine leukemia virus (BLV) is one of the most important virus in dairy cattle. The infection behavior follows what we call the iceberg phenomenon: 60% of infected animals do not show clinical signs; 30% develop persistent lymphocytosis (PL); and the remaining 10%, die due to lymphosarcoma. BLV transmission depends on infected cell exchange and thus, proviral load is determinant. Understanding the mechanisms by which cattle governs the control of viral dissemination will be desirable for designing effective therapeutic or preventive strategies for BLV. The development of high proviral load (HPL) or low proviral load (LPL) might be associated to genetic factors and humoral immune responses, however cellular responses are not fully described. It is known that BLV affects cellular homeostasis: proliferation and apoptosis. It is also known that the BLV tropism is directed towards B lymphocytes, and that lymphocytotic animals have elevated amounts of these cells. Usually, when an animal is infected by BLV, the B markers that increase are CD21, CD5 and CD11b. This increase could be related to the modulation of apoptosis in these cells. This is the first work in which animals infected with BLV are classified according to their proviral load and the subpopulations of B and T lymphocytes are evaluated in terms of their percentage in peripheral blood and its stage of apoptosis and viability. PBMCs from HPL animals proliferated more than LPL and non-infected animals. CD11b + /CD5 + lymphocytes in LPL animals presented greater early and late apoptosis than HPL animals and cells of HPL animals had increased viability than LPL animals. Our results confirm that BLV alters the mechanism of apoptosis and proliferation of infected cells.

Prostaglandin E2–Induced Immune Exhaustion and Enhancement of Antiviral Effects by Anti–PD-L1 Antibody Combined with COX-2 Inhibitor in Bovine Leukemia Virus Infection

“…The production capacity of PGE 2 was higher in CD14 + cells than in CD21 + cells, suggesting that CD14 + cells are the main source of PGE 2 . However, in the late stage of BLV infection, the number of circulating B lymphocytes is dramatically increased (34), and our immunohistochemical staining results clearly revealed PGE 2 production by tumor B cells in cattle with EBL. Thus, B cells may also contribute to or act as the main source of PGE 2 production in the late stage of BLV infection.…”

Immune response in nonspecific mastitis: What can it tell us?

“…In agreement with our results, T cells, especially CD8 + T cells, recruitment has been previously reported during IMI (Soltys and Quinn, 1999;Tassi et al, 2013). An increased number of γδ T cells, mainly represented here by CD4 − CD8 − T cells (Nieto Farias et al, 2018) in milk from cows with staphylococcal and streptococcal mastitis, has also been reported (Soltys and Quinn, 1999), which may explain the highest level of this lymphocyte subpopulation in truly infected quarters, mostly caused by streptococci. Therefore, it is difficult to compare the DCC of milk obtained by distinct methods because the type of material of the sample bottle The results are shown as the mean ± SEM.…”

Expression of L-selectin (CD62L) and CD44 on Bovine Lymphocytes and WC1.1+ γδ T Cells under Stimulation with Staphylococcus aureus

“…To determine the effect of stimulation on the expression of CD62L and CD44, the cells were cultured under unstimulated (basal, 10 μL of cell culture medium) and stimulated conditions with 10 μL of heat-inactivated S. aureus (10 bacteria per cell) or concanavalin-A type III (Con-A; cat. n. C2631, Sigma Aldrich, St. Louis, MO, USA), a widely used mitogen, at a final concentration of 10 μg mL -1 [19,20].…”