IFNLR1 and infection: Although initial studies in mice have shown that IFNλs are the predominant IFNs produced in response to infection (45) and that Ifnlr1−/−Ifnar1−/− animals are more susceptible to influenza virus infection compared to Ifnar1−/− animals, specific non-redundant functions of IFNλs in Ifnlr1−/− mice could not be described (20, 28, 46–48).