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Objectives To report methods and findings of 2 autopsies with molecular evaluation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive individuals. Methods Postmortem examination was completed following Centers for Disease Control and Prevention public guidelines. Numerous formalin-fixed paraffin-embedded (FFPE) tissue types from each case were surveyed for SARS-CoV-2 RNA by quantitative reverse transcription polymerase chain reaction (qRT-PCR). SARS-CoV-2 viral genome was sequenced by next-generation sequencing (NGS) from FFPE lung tissue blocks. Results Postmortem examinations revealed diffuse alveolar damage, while no viral-associated hepatic, cardiac, or renal damage was observed. Viral RNA was detected in lungs, bronchi, lymph nodes, and spleen in both cases using qRT-PCR method. RNA sequencing using NGS in case 1 revealed mutations most consistent with Western European Clade A2a with ORF1a L3606F mutation. Conclusions SARS-CoV-2 testing and viral sequencing can be performed from FFPE tissue. Detection and sequencing of SARS-CoV-2 in combination with morphological findings from postmortem tissue examination can aid in gaining a better understanding of the virus’s pathophysiologic effects on human health.

Persistent type I IFN production occurs during chronic viral infections, such as HIV disease. As type I IFNs have antiproliferative activity, it is possible that chronic exposure to these cytokines could adversely affect T cell homeostasis. We investigated the capacity of IFN-α to impair T cell proliferation induced by the homeostatic cytokine, IL-7, or another common γ-chain cytokine, IL-2, in cells from healthy human donors. We found that IL-7- or IL-2-induced proliferation of CD4+ T cells was partially inhibited in the presence of IFN-α. The CD4+ T cells that were exposed to IFN-α also displayed attenuated induction of IL-2 and CD40L following TCR stimulation. Analyses of signaling pathways indicated that IL-7 and IL-2 induced a delayed and sustained P-Akt signal that lasted for several days and was partially inhibited by IFN-α. In contrast, IL-7-induced P-STAT5 was not affected by IFN-α. Furthermore, IFN-α had no detectable effect on P-Akt that was induced by the chemokine SDF-1. Both inhibitors of P-Akt and P-STAT5 blocked IL-7-induced T cell proliferation, confirming that both signaling pathways are important for IL-7-induced T cell proliferation. These results demonstrate that IFN-α can selectively inhibit cytokine-induced P-Akt as a potential mechanism to disrupt homeostasis of T lymphocytes.

Acute hepatitis C virus (HCV) infection becomes persistent in a majority of cases [1], and the long-term risk of cirrhosis, liver failure, cancer, and mortality among those with chronic infection highlight the importance of effective therapy [1, 2]. HCV magnitude decrease at 4 and 12 weeks of pegylated interferon (IFN)–α plus ribavirin therapy is predictive of sustained virologic response [3]. Although mechanisms underlying IFN-α responsiveness remain unclear, factors associated with response to IFN-α therapy include HCV genotype, age, race, human immunodeficiency virus (HIV) coinfection, baseline HCV level, and polymorphism near the interleukin 28B (IL-28B) (IFN-λ3) gene locus [3–9]. Despite introduction of protease inhibitors, the need to combine these agents with IFN means that response to newer regimens continues to depend on factors regulating IFN-α responsiveness. Natural killer (NK) cells provide essential host defense during mouse hepatic viral [10, 11] and human herpesvirus infection [12–15]. They are innate lymphocytes with cytokine-producing, chemokine-producing, and cytotoxic activities regulated by activating and inhibitory receptors [16, 17]. Evidence for NK cells contributing to control of HCV derives from observations that genetically determined NK-KIR (Killer Immunoglobulin like Receptor)/ligand pairing correlates with the course of acute HCV infection [18] and that, during chronic infection, NK KIR2DL3, NKG2C, and NKp30 expression are associated with response to IFN-α–based therapy [19–21]. In addition, TRAIL expression is upregulated on NK cells during IFN-α–based therapy, and this correlates with in vitro cytolysis of HCV JFH-1–infected Huh 7.5 cells [22]. We observed NK IFN-αR and NKp30 expression to associate with IFN-α–dependent killer activity during HIV infection [23]. NK cells of individuals with preserved activity appeared to have enhanced IFN-αR expression. We hypothesized that IFN-αR expression is upregulated during chronic viral infection, in turn determining IFN-α–dependent function. Here, we evaluated NK cell subset IFN-αR and NKp30 expression in HCV genotype 1–infected patients at baseline, longitudinally over the course of IFN-α–based therapy, and in relation to IFN-α signaling capacity and viral decrease.

Mtb regulates many aspects of the host immune response, including CD4+ T lymphocyte responses that are essential for protective immunity to Mtb, and Mtb effects on the immune system are paradoxical, having the capacity to inhibit (immune evasion) and to activate (adjuvant effect) immune cells. Mtb regulates CD4+ T cells indirectly (e.g., by manipulation of APC function) and directly, via integrins and TLRs expressed on T cells. We now report that previously uncharacterized Mtb protein Rv2468c/MT2543 can directly regulate human CD4+ T cell activation by delivering costimulatory signals. When combined with TCR stimulation (e.g., anti-CD3), Rv2468c functioned as a direct costimulator for CD4+ T cells, inducing IFN-γ secretion and T cell proliferation. Studies with blocking antibodies and soluble RGD motifs demonstrated that Rv2468c engaged integrin VLA-5 (α5β1) on CD4+ T cells through its FN-like RGD motif. Costimulation by Rv2468c induced phosphorylation of FAKs and Pyk2. These results reveal that by expressing molecules that mimic host protein motifs, Mtb can directly engage receptors on CD4+ T cells and regulate their function. Rv2468c-induced costimulation of CD4+ T cells could have implications for TB immune pathogenesis and Mtb adjuvant effect.

Both clinical experience and a growing medical literature indicate that there are persons who have been exposed to HIV infection who have remained uninfected. While in some instances this may represent good fortune, cohorts of uninfected persons have been reported where risks for infection are thought to be high. In these cohorts a variety of characteristics have been proposed as mediating protection but to date only the 32 base pair deletion in the CCR5 gene that results in complete failure of cell surface expression of this co-receptor has been associated with high level protection from HIV infection. With this in mind, there are likely numerous other factors that may individually or in combination provide some level of protection from acquisition of HIV infection. As some of these factors are likely incompletely protective or inconsistently active, identifying them with confidence will be difficult. Nonetheless, clarifying the determinants of protection against HIV infection is a high priority that will require careful selection of high risk uninfected cohorts to which targeted studies of plausible mediators and broad screening for unexpected determinants of protection should be applied.