RT Journal Article SR Electronic(1) A1 Bartlett, Nathan W. A1 Buttigieg, Karen A1 Kotenko, Sergei V. A1 Smith, Geoffrey L.YR 2005 T1 Murine interferon lambdas (type III interferons) exhibit potent antiviral activity in vivo in a poxvirus infection model JF Journal of General Virology, VO 86 IS 6 SP 1589 OP 1596 DO https://doi.org/10.1099/vir.0.80904-0 PB Microbiology Society, SN 1465-2099, AB Human interferon lambdas (IFN-λs) (type III IFNs) exhibit antiviral activity in vitro by binding to a receptor complex distinct from that used by type I and type II IFNs, and subsequent signalling through the Janus kinase signal transducers and activators of transcription (STAT) pathway. However, evidence for a function of type III IFNs during virus infection in vivo is lacking. Here, the expression of murine IFN-λs by recombinant vaccinia virus (VACV) is described and these proteins are shown to have potent antiviral activity in vivo. VACV expressing murine IFN-λ2 (vIFN-λ2) and IFN-λ3 (vIFN-λ3) showed normal growth in tissue culture and expressed N-glycosylated IFN-λ in infected cell extracts and culture supernatants. The role that murine IFN-λs play during virus infection was assessed in two different mouse models. vIFN-λ2 and vIFN-λ3 were avirulent for mice infected intranasally and induced no signs of illness or weight loss, in contrast to control viruses. Attenuation of vIFN-λ2 was associated with increases in lymphocytes in bronchial alveolar lavages and CD4+ T cells in total-lung lymphocyte preparations. In addition, vIFN-λ2 was cleared more rapidly from infected lungs and, in contrast to control viruses, did not disseminate to the brain. Expression of IFN-λ2 also attenuated VACV in an intradermal-infection model, characterized by a delay in lesion onset and reduced lesion size. Thus, by characterizing murine IFN-λs within a mouse infection model, the potent antiviral and immunostimulatory activity of IFN-λs in response to poxvirus infection has been demonstrated., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.80904-0