Evaluating vaccinia virus cytokine co‐expression in TLR GKO mice

Abstract

Using Toll-like receptor (TLR) and MyD88 gene knock-out (GKO) mice the effect of TLRs and MyD88 on virus replication, interferon (IFN)-b production, natural killer (NK) cell and CD8T cell responses were assessed following ectromelia virus (ECTV) and recombinant vaccinia virus (rVV) infection. The capacity for rVVs encoding cytokines to restore immune function in MyD88 À/À mice was clearly demonstrated. Results showed that TLR2 À/À , TLR4 À/À and TLR7 À/À mice survived ECTV infection whereas MyD88 À/À and TLR9 À/À mice, in contrast, were highly susceptible. Next, following infection with rVV, MyD88 À/À mice elicited reduced serum IFN-b, NK cell and CD8T cell responses compared with wild-type mice, whereas TLR9 À/À mice showed elevated CD8T cell responses. When MyD88 À/À mice were infected with rVV co-expressing IFN-b these mice were able to restore IFN-b levels and CD8T cell responses but not NK cell activation. Interestingly, even though rVV co-expressing interleukin (IL)-2 enhanced NK cell activation in MyD88 À/À mice, this was not associated with an antiviral effect, as observed in normal mice. Surprisingly, co-infection with rVV IL-2/rVV IL-12, but not rVV IL-2/rVV IFN-b, restored the attenuated phenotype of rVV IL-2 in MyD88 À/À mice indicating that the IL-2/IL-12 combination promotes antiviral responses. Our results clearly show that the CD8T cell defect observed in MyD88 À/À mice to vaccinia virus infection can be restored by rVV-encoding IFN-b demonstrating the critical role of this cytokine in T cell mediated immunity and illustrates that the model can provide an effective platform for the elucidation of cytokine immunobiology.

Sequential Activation of Two Pathogen-Sensing Pathways Required for Type I Interferon Expression and Resistance to an Acute DNA Virus Infection

“…The TLR adapter MyD88 is required for the inherent resistance of B6 mice to mousepox (Rubio et al, 2013; Sutherland et al, 2011), while TRIF is not necessary (data not shown). We performed experiments to identify the specific role of MyD88, as well as of MAVS- and STING-driven pathways, in resistance to mousepox and IFN-I expression in vivo during acute ECTV infection.…”

Migratory Dendritic Cells, Group 1 Innate Lymphoid Cells, and Inflammatory Monocytes Collaborate to Recruit NK Cells to the Virus-Infected Lymph Node

“…This finding differs from previous work showing impaired function of Tlr2 −/− and Myd88 −/− NK cells in mice infected intraperitoneally with the related vaccinia virus (Martinez et al, 2010). It should be noted, however, that TLR2 is not required for the control of ECTV (O’Gorman et al, 2010; Sutherland et al, 2011). The reasons for these differences remain undetermined, but the disparate results highlight the fact that the mechanisms of control can vary, even for highly related viruses.…”

Characterization of the termini of the West Nile virus genome and their interactions with the small isoform of the 2′ 5′-oligoadenylate synthetase family

“…TLR9 has been observed to mediate the antiviral response against DNA viruses including MCMV, HSV--1 and HSV--2 [73,84,86,96,97]. For DNA viruses like mouse poxvirus and ectromelia virus, the only PRR that is shown to recognize their PAMPs is TLR9 [97,98]. Antiviral immune responses against DNA viruses (MCMV, RSV and Vaccinia virus) by TLR2 have also been reported.…”