Ordinarily when we consider anti-pathogen response we think about adaptive immune response with antibodies or T cells. However, the more we study innate immune system the more we uncover about its hidden potential.
This new study in journal Science from Herbert Virgin's lab at the Washington University School of Medicine, showed new function for interferon molecule called IFN-λ. IFN-λ is a member of family called type III IFNs.
The authors has analysed immune response to murine norovirus, an chronic gut viral infection that mimics human norovirus infection.
First, the authors observed that mice deficient for IFN-lambda receptor 1 expression (IFN-λR1) (but not IFNγR or IFNαR1) showed high viral burden in the gut.
Indeed, exogenous application of IFN-lambda could clear chronic murine norovirus infection from the gut in control wild-type and IFNalphaR1-KO mice but not from IFN-lambdaR1-KO mice.
Surprisingly, IFN-lambda was active against chronic murine norovirus infection even in RAG-KO mice lacking adaptive immune system.
Interestingly, IFN-lambda treated mice that clear first norovirus infection remained susceptible to second norovirus infection, implying the absence of immune memory.
In summary, the authors showed that for certain viral infection innate system can provide "sterile" immunity, though it lacked memory component.
Chronic viral infection exist because they are able to find ways to co-exist with both innate and adaptive immune system. Here, for example, the authors showed that norovirus (CR6 strain) was able to establish chronic gut infection in wild-type, IFN-lambda sufficient environment, because it did not activate IFN-lambda system. This knowledge may help to design optimal natural anti-viral treatments for human noroviral infections.