Kinetics of Type I Interferon responses determine either establishment of antiviral memory or no induction of adaptive immunity (#77)
Many
pathogens trigger type I interferon (IFN-I) responses early after infection
that confer protection until adaptive immunity is induced. Upon infection with
vesicular stomatitis virus (VSV) Toll-like receptor (TLR) and RIG-I-like
helicase (RLH) signaling platforms are indispensable for the induction of protective
IFN-I. Hence, TLR- and RLH-ablated MyTrCa‑/‑ mice challenged with
VSV do not mount IFN-I responses and are inevitably susceptible to lethal VSV
infection. To study the impact of the kinetics of IFN-I responses on the
induction of adaptive immunity, we infected MyTrCa‑/‑ mice with VSV and
treated them 4, 8, 16, and 24 h after infection with recombinant IFN-α (rIFN-α). Interestingly, under such conditions MyTrCa-/-
mice mounted normal adaptive immune responses and approximately 76% of the mice
survived. On the contrary, initiation of the rIFN-α treatment scheme 4 h before VSV infection
significantly prolonged survival, whereas reduced VSV-specific cytotoxic
T-lymphocytes and basically no VSV neutralizing antibody responses were induced
and 100% of the mice finally died. Long-term rIFN-α treatment for 9 days initiated 4 h after VSV
infection promoted 100% survival of MyTrCa-/- mice and protective
immunity was induced normally as verified by 100% of the animals surviving even
a VSV re-challenge 3 weeks after discontinuation of the rIFN-α treatment. Initiation of the 9 days rIFN-α regimen 4 h prior to infection also rescued
100% of the mice, however, no adaptive immunity developed and 100% of the
animals succumbed to re-challenge. In conclusion, long-term rIFN-α treatment initiated before virus infection
prevented induction of protective adaptive immunity, whereas initiation of rIFN-α treatment hours after infection supported
development of normal adaptive immunity and protective memory response. These observations have implications for
immunotherapies and vaccination strategies, in particular for patients under
long-term IFN-I therapy who are treated with live attenuated vaccines.