CD8 T cells protect adult naive mice from JEV-induced morbidity via lytic function

Following japanese encephalitis virus (jev) infection neutralizing antibodies are shown to provide protection in a significant proportion of cases,but not all,suggesting additional components of immune system might also contribute to elicit protective immune response. here we have characterized the role of t cells in offering protection in adult mice infected with jev. mice lacking α/β–t cells (tcrβ–null) are highly susceptible and die over 10–18 day period as compared to the wild-type (wt) mice which are resistant. this is associated with high viral load,higher mrna levels of proinflammatory cytokines and breach in the blood-brain-barrier (bbb). infected wt mice do not show a breach in bbb; however,in contrast to tcrβ-null,they show the presence of t cells in the brain. using adoptive transfer of cells with specific genetic deficiencies we see that neither the presence of cd4 t cells nor cytokines such as il-4,il-10 or interferon-gamma have any significant role in offering protection from primary infection. in contrast,we show that cd8 t cell deficiency is more critical as absence of cd8 t cells alone increases mortality in mice infected with jev. further,transfer of t cells from beige mice with defects in granular lytic function into tcrβ-null mice shows poor protection implicating granule-mediated target cell lysis as an essential component for survival. in addition,for the first time we report that γ/δ-t cells also make significant contribution to confer protection from jev infection. our data show that effector cd8 t cells play a protective role during primary infection possibly by preventing the breach in bbb and neuronal damage. © 2017 jain et al.