Dominant Vγ2Vδ2 T-cell subset recognizes phosphoantigen, and exist only in humans and nonhuman primates. Despite the discovery of γδ T cells for >30 years, a proof-of-concept (POC) study has not been done to prove the principle that Vγ2Vδ2 T-cell subset is protective against M. tuberculosis (Mtb) and other infections. Here, we employed adoptive cell transfer strategy to define protective role for Vγ2Vδ2 T cells in primate TB model. Vγ2Vδ2 T cells for adoptive transfer displayed central/effector memory and mounted effector functions of producing anti-Mtb cytokines and inhibiting intracellular mycobacteria. They also expressed CXCR3/CCR5/LFA-1 trafficking/tissue-resident phenotypes and consistently trafficked to the airway and retained there detectable from 6 hours through 7 days after adoptive transfer. Interestingly, the test group of macaques receiving transfer of Vγ2Vδ2 T cells at weeks 1 and 3 after high-dose 500 CFU Mtb infection exhibited significantly lower levels of Mtb infection burdens in lung lobes and extra-pulmonary organs than the control groups receiving PBL or saline. Consistently, adoptive transfer of Vγ2Vδ2 T cells attenuated TB pathology and contained lesions mostly in the infection-site of right caudal lung lobe, with no or reduced TB dissemination to other lobes, spleens or livers/kidneys whereas the controls showed widespread TB dissemination. The POC finding supports the view that dominant Vγ2Vδ2 T-cell subset may be included for the rational design of TB vaccine or host-directed therapy.

Tuberculosis (TB) remains a leading killer among infectious diseases, and a better TB vaccine is urgently needed. The critical components and mechanisms of vaccine-induced protection againstMycobacterium tuberculosis(Mtb) remain incompletely defined. Our previous studies demonstrate that Vγ2Vδ2 T cells specific for (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) phosphoantigen are unique in primates as multifunctional effectors of immune protection against TB infection. Here, we selectively immunized Vγ2Vδ2 T cells and assessed the effect on infection in a rhesus TB model. A single respiratory vaccination of macaques with an HMBPP-producing attenuatedListeria monocytogenes(LmΔactA prfA*) caused prolonged expansion of HMBPP-specific Vγ2Vδ2 T cells in circulating and pulmonary compartments. This did not occur in animals similarly immunized with an LmΔgcpEstrain, which did not produce HMBPP. LmΔactA prfA* vaccination elicited increases in Th1-like Vγ2Vδ2 T cells in the airway, and induced containment of TB infection after pulmonary challenge. The selective immunization of Vγ2Vδ2 T cells reduced lung pathology and mycobacterial dissemination to extrapulmonary organs. Vaccine effects coincided with the fast-acting memory-like response of Th1-like Vγ2Vδ2 T cells and tissue-resident Vγ2Vδ2 effector T cells that produced both IFN-γ and perforin and inhibited intracellular Mtb growth. Furthermore, selective immunization of Vγ2Vδ2 T cells enabled CD4+and CD8+T cells to mount earlier pulmonary Th1 responses to TB challenge. Our findings show that selective immunization of Vγ2Vδ2 T cells can elicit fast-acting and durable memory-like responses that amplify responses of other T cell subsets, and provide an approach to creating more effective TB vaccines.

The linear ubiquitin chain assembly complex (LUBAC), composed of heme-oxidized IRP2 ubiquitin ligase 1 (HOIL1), HOIL1-interacting protein (HOIP), and SHANK-associated RH domain-interacting protein (SHARPIN), is a crucial regulator of multiple immune signaling pathways. In humans, HOIL1 or HOIP deficiency is associated with an immune disorder involving autoinflammation, immunodeficiency, and inflammatory bowel disease (IBD)-like symptoms. During viral infection, LUBAC is reported to inhibit the induction of interferon (IFN) by the cytosolic RNA sensor retinoic acid-inducible gene I (RIG-I). Surprisingly, we found that HOIL1 is essential for the induction of both type I and type III IFNs, as well as the phosphorylation of IFN regulatory factor 3 (IRF3), during murine norovirus (MNoV) infection in cultured dendritic cells. The RIG-I-like receptor, melanoma differentiation-associated protein 5 (MDA5), is also required for IFN induction and IRF3 phosphorylation during MNoV infection. Furthermore, HOIL1 and MDA5 were required for IFN induction after Theiler's murine encephalomyelitis virus infection and poly(I·C) transfection, but not Sendai virus or vesicular stomatitis virus infection, indicating that HOIL1 and LUBAC are required selectively for MDA5 signaling. Moreover, mice exhibited defective control of acute and persistent murine norovirus infection and defective regulation of MNoV persistence by the microbiome as also observed previously for mice deficient in interferon lambda (IFN-λ) receptor, signal transducer and activator of transcription factor 1 (STAT1), and IRF3. These data indicate that LUBAC plays a critical role in IFN induction to control RNA viruses sensed by MDA5. Human noroviruses are a leading cause of gastroenteritis throughout the world but are challenging to study and Murine norovirus (MNoV) provides a tractable genetic and small-animal model to study norovirus biology and immune responses. Interferons are critical mediators of antiviral immunity, but excessive expression can dysregulate the immune system. IFN-λ plays an important role at mucosal surfaces, including the gastrointestinal tract, and both IFN-λ and commensal enteric bacteria are important modulators of persistent MNoV infection. LUBAC, of which HOIL1 is a component, is reported to inhibit type I IFN induction after RIG-I stimulation. We show, in contrast, that HOIL1 is critical for type I and III IFN induction during infection with MNoV, a virus that preferentially activates MDA5. Moreover, HOIL1 regulates MNoV infection These data reveal distinct functions for LUBAC in these closely related signaling pathways and in modulation of IFN expression.