Cytokine secretion may play a role in the induction of lymphocyte apoptosis, since MARV-infected cells secrete cytokines known to induce apoptosis, including TNFα [194, 198, 200, 209] . Increased levels of TNFα have been observed in infected rhesus macaques [210] and mice [130] , although no increase was observed in infected cynomolgus macaques [14] . Elevated TNFα levels may also play a role in the formation of endothelial gaps in the context of MARV infection [198, 199] . In addition, increased survival of MARV-infected guinea pigs treated with anti-TNFα antibodies suggests that TNFα indeed plays an important role in MVD pathogenesis [209] .