COVID-19 Immunology
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Differential Effects of SARS-CoV-2 Infection on Monocyte-Derived Dendritic Cells and Monocyte-Derived Macrophages
As some of the primary surveillance cells of the immune system, dendritic cells and macrophages are often the first immune cells to encounter pathogens in the body. Their role as antigen presenting cells means that they sit at a crucial hub in the initiation of the immune response; as a result, infecting agents have evolved…
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Inhibition of Type I Interferon Production by SARS-CoV-2 Orf9b
Ultimate understanding of our options for treatment and prevention of COVID-19 will come only as a result of our ability to ascertain the functions of the various SARS-CoV-2 genes and how they interact with the host organism. I’ve written previously about some of these interactions (see updates from 6/2 and 6/15), which are involved largely…
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SARS-CoV-2 Induces Activation and Differentiation of Plasmacytoid Dendritic Cells In Vitro
As part of the innate immune system, interferons act to initiate the antiviral response in host organisms. While several immune cell types produce and secrete interferons (IFNs) – including natural killer cells, T cells, and macrophages – a subset of dendritic cells known as plasmacytoid dendritic cells (pDCs) are the body’s major producer of type…
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CD209 and CD209L Mediate SARS-CoV-2 Entry
Though ACE2 has been identified as the primary mediator of SARS-CoV-2 attachment and entry into host cells, various other molecules have also been implicated in SARS-CoV-2 infection, including the neuropilin-I receptor and CD147 (Zhang et al., 2020; Cantuti-Castelvetri et al., 2020; Wang et al., 2020). Additionally, the molecules CD209 and CD209L (DC-SIGN and L-SIGN, respectively)…
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HLA Susceptibility Map for SARS-CoV-2 Infection
The Human Leukocyte Antigen (HLA) family – the name given to the Major Histocompatibility Complex in humans – is a highly polymorphic gene cluster involved in presentation of foreign antigens to the immune system and, importantly, in graft rejection (Choo, 2007). HLA molecules come in three main types (called, types I, II, and III); type…
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SARS-CoV-2 Spike Protein Suppresses NK Cell Function
Much of the research thus far on the host immune response to SARS-CoV-2 infection has been geared toward the development of novel vaccines, and for this reason has focused largely on the roles of T and B cells in fighting infection. However, another class of immune cells, the so-called “natural killer” cells, are central to…
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SARS-CoV-2 ORF8 Downregulates Expression of MHC I
Though much progress has been made in determining the specific interactions between SARS-CoV-2 infectious particles and host cells (Liang et al., 2020; see updates for week of 6/2/2020), we are only beginning to understand the exact mechanisms of pathogenicity in detail. As part of this ongoing inquiry, Zhang et al. surveyed the four structural proteins…
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Immune Thrombocytopenic Purpura as a Sequela of COVID-19
In the process of lymphocyte development, progenitor T and B cells undergo several rounds of signaling and selection before being released to the periphery to fight infections. As part of the normal developmental routine, immature lymphocytes undergo “negative selection” in which cells bearing autoreactive (self-reactive) antigen receptors are removed from the population, thereby preventing potential…
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Lymphocyte Antigen 6 Complex, Locus E Inhibits SARS-CoV-2 Infection; SARS-CoV-2 Non-structural Protein Interactions with Host Immune Signaling
The role of interferons in fending against viruses has been known and investigated for decades, and in light of this, interferon therapy is well-established for treating viral infections and even some cancers (Sen, 2001; Samuel, 2001; Korenman et al., 1991; Tanner et al., 1990). Interferon therapy has recently been suggested as an option for use…