Effects of hydrogen peroxide on bovine leukemia virus expression.

Several activators of bovine leukemia virus (BLV) expression, including lipopolysaccharides, phorbol esters and calcium ionophores, are known to generate reactive oxygen species (ROS). Therefore the influence of H2O2 on BLV expression in two BLV producing cell lines was investigated. The effect of H2O2 on BLV expression is apparently dose-dependent. Incubation of FLK/BLV cells with low concentrations of H2O2 (2.5 to 10 microM) induced a marked enhancement of BLV p24 synthesis and an activation of the long terminal repeat (LTR). Higher concentrations resulted in a decrease of proliferation, induction of apoptosis and in a decrease of BLV synthesis. Furthermore, in both cell lines H2O2 treatment led to the activation of NF-kappaB. Pretreatment of cells with antioxidants abrogated the H2O2-induced BLV expression. Taken together, our findings suggest that oxidative stress stimulates BLV expression via activation of NF-kappaB, raising the possibility that biological sources of H2O2, such as stimulated phagocytes, may influence BLV expression.