Summary Paragraph Long-lasting, latently-infected, resting CD4 + T cells are the greatest obstacle to cure HIV infection, as they persist despite decades of treatment with ART. Estimates indicate the need for >70 years of continuous, fully suppressive, antiretroviral therapy (ART) to eliminate the HIV reservoir 1 . Alternatively, induction of HIV from its latent state could accelerate decline of the reservoir, thereby shortening time to eradication. Previous attempts to reactivate latent HIV in preclinical animal models and in clinical trials have measured HIV induction in peripheral blood with minimal focus on tissue reservoirs and had limited effect 2 - 9 . Here we show that activation of the non-canonical NF-κB signaling pathway via AZD5582 results in induction of HIV- and SIV-RNA expression in the blood and tissues of ART-suppressed bone marrow/liver/thymus (BLT) humanized mice and rhesus macaques. Analysis of resting CD4 + T cells from tissues after AZD5582 treatment revealed increased SIV-RNA in lymph nodes in macaques and robust induction of HIV in virtually all tissues analyzed in humanized mice including lymph nodes, thymus, bone marrow, liver, and lung. This promising new approach to latency reversal, in combination with appropriate tools for systemic clearance of persistent HIV infection, greatly increases opportunities for HIV eradication.

Why Multisystem Inflammatory Syndrome in Children (MIS-C) develops after SARS-CoV-2 infection in a subset of children is unknown. We hypothesized that aberrant virusspecific T-cell responses contribute to MIS-C pathogenesis. We quantified SARS-CoV-2 reactive T-cells, serologic responses against major viral proteins, and cytokine responses from plasma and peripheral blood mononuclear cells in children with convalescent COVID-19, acute MIS-C, and healthy controls. Children with MIS-C had significantly lower virus-specific CD4+ and CD8+ T-cell responses to major SARS-CoV-2 antigens compared with children convalescing from COVID-19. Further, T-cell responses in participants with MIS-C were similar to or lower than those in healthy controls. Serologic responses against spike receptor binding domain (RBD), full-length spike, and nucleocapsid were similar among convalescent COVID-19 and MIS-C, suggesting functional B cell responses. Cytokine profiling demonstrated predominant Th1 polarization of CD4+ T-cells from children with convalescent COVID-19 and MIS-C, although cytokine production was reduced in MIS-C. Our findings support a role for constrained induction of anti-SARS-CoV-2-specific T-cells in the pathogenesis of MIS-C.

Inducing latency reversal to reveal infected cells to the host immune system represents a potential strategy to cure HIV infection. In separate studies, we have previously shown that CD8+ T cells may contribute to the maintenance of viral latency and identified a novel SMAC mimetic/IAP inhibitor (AZD5582) capable of reversing HIV/SIV latency in vivo by activating the non-canonical (nc) NF-κB pathway. Here, we use AZD5582 in combination with antibody-mediated depletion of CD8α+ cells to further evaluate the role of CD8+ T cells in viral latency maintenance. Six rhesus macaques (RM) were infected with SIVmac239 and treated with ART starting at week 8 post-infection. After 84-85 weeks of ART, all animals received a single dose of the anti-CD8α depleting antibody (Ab), MT807R1 (50mg/kg, s.c.), followed by 5 weekly doses of AZD5582 (0.1 mg/kg, i.v.). Following CD8α depletion + AZD5582 combined treatment, 100% of RMs experienced on-ART viremia above 60 copies per ml of plasma. In comparator groups of ART-suppressed SIV-infected RMs treated with AZD5582 only or CD8α depletion only, on-ART viremia was experienced by 56% and 57% of the animals respectively. Furthermore, the frequency of increased viremic episodes during the treatment period was greater in the CD8α depletion + AZD5582 group as compared to other groups. Mathematical modeling of virus reactivation suggested that, in addition to viral dynamics during acute infection, CD8α depletion influenced the response to AZD5582. This work suggests that the latency reversal induced by activation of the ncNF-κB signaling pathway with AZD5582 can be enhanced by CD8α+ cell depletion.

Background The serologic and cytokine responses of children hospitalized with multisystem inflammatory syndrome (MIS-C) vs. COVID-19 are poorly understood. Methods We performed a prospective, multicenter, cross-sectional study of hospitalized children who met the CDC case definition for MIS-C (n=118), acute COVID-19 (n=88), or contemporaneous healthy controls (n=24). We measured SARS-CoV-2 spike receptor binding domain (RBD) IgG titers and cytokine concentrations in patients and performed multivariable analysis to determine cytokine signatures associated with MIS-C. We also measured nucleocapsid IgG and convalescent RBD IgG in subsets of patients. Results Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG than children with acute COVID-19 (median 2783 vs. 146, P<0.001), and titers correlated with nucleocapsid IgG. For patients with MIS-C, RBD IgG titers declined in convalescence (median 2783 vs. 1135, P=0.010) in contrast to patients with COVID-19 (146 vs. 4795, P<0.001). MIS-C was characterized by transient acute pro-inflammatory hypercytokinemia, including elevated levels of IL-6, IL-10, IL-17A, and IFN-γ. Elevation of at least 3 of these cytokines was associated with significantly increased prevalence of prolonged hospitalization ≥8 days (PR 3.29 95% CI 1.17-9.23). Conclusions MIS-C was associated with high titers of SARS-COV-2 RBD IgG antibodies and acute hypercytokinemia with IL-6, IL-10, IL-17A, and IFN-γ.