Immunology

Virus entry, consisting of attachment to and penetration into the host target cell, is the first step of the virus life cycle and is a critical ‘do or die’ event that governs virus emergence in host populations. Most antiviral vaccines induce neutralizing antibodies that prevent virus entry into cells. However, while the prevention of virus invasion by humoral immunity is well appreciated, considerably less is known about the immune defences present within cells (known as intrinsic immunity) that interfere with virus entry. The interferon-induced transmembrane (IFITM) proteins, known for inhibiting fusion between viral and cellular membranes, were once the only factors known to restrict virus entry. However, the progressive development of genetic and pharmacological screening platforms and the onset of the COVID-19 pandemic have galvanized interest in how viruses infiltrate cells and how cells defend against it. Several host factors with antiviral potential are now implicated in the regulation of virus entry, including cholesterol 25-hydroxylase (CH25H), lymphocyte antigen 6E (LY6E), nuclear receptor co-activator protein 7 (NCOA7), interferon-γ-inducible lysosomal thiol reductase (GILT), CD74 and ARFGAP with dual pleckstrin homology domain-containing protein 2 (ADAP2). This Review summarizes what is known and what remains to be understood about the intrinsic factors that form the first line of defence against virus infection. Besides neutralizing antibodies, viruses face a range of cell-intrinsic inhibitors that are specialized to limit virus entry into host cells. Majdoul and Compton describe the mechanisms of action of the cellular factors providing this important first line of defence against virus infection, including infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

The core function of the immune response is to distinguish between self and foreign.
The multiorgan human autoimmune disease, autoimmune polyendocrinopathy-candidiasis-ectodermal
dystrophy (APECED/autoimmune polyendocrine syndrome type 1) is an example of what
happens in the body when central immune tolerance goes astray. APECED revealed the
existence and function of the autoimmune regulator gene, which has a central role
in the development of tolerance. The discovery of autoimmune regulator was the start
of a new period in immunology and in understanding the role of central and peripheral
tolerance, also very relevant to many skin diseases as we highlight in this review.

Researchers at the Vanderbilt Institute for Infection, Immunology, and Inflammation, have identified a novel antibacterial mechanism which could open the door to new therapeutics to combat pathogenic bacterial infection.

CD4+ T-helper 22 (Th22) cells are a phenotypically distinct lymphocyte subset that produces high levels of interleukin (IL)-22 without co-production of IL-17A. However, the developmental origin and lineage classification of Th22 cells, their interrelationship to Th17 cells, and potential for plasticity at sites of infection and inflammation remain largely undefined. An improved understanding of the mechanisms underpinning the outgrowth of Th22 cells will provide insights into their regulation during homeostasis, infection, and disease. To address this knowledge gap we generated ‘IL-17A-fate-mapping IL-17A/IL-22 reporter transgenic mice’ and show that Th22 cells develop in the gastrointestinal tract and lung during bacterial infection without transitioning via an Il17a-expressing intermediate, although in some compartments alternative transition pathways exist. Th22-cell development was not dependent on T-bet; however, this transcription factor functioned as a promiscuous T-cell-intrinsic regulator of IL-17A and IL-22 production, in addition to regulating the outgrowth, phenotypic stability, and plasticity of Th22 cells. Thus, we demonstrate that at sites of mucosal bacterial infection Th22 cells develop as a distinct lineage independently of Th17 cells; though both lineages exhibit bidirectional phenotypic flexibility within infected tissues and their draining lymph nodes, and that T-bet plays a critical regulatory role in Th22-cell function and identity.

The viral receptor on human cells plays a critical role in disease progression

Several viruses are known to cause chronic infections, one is hepatitis C virus (HCV). Researchers studying these infections have now found that when they | Microbiology

COVID-19 can involve persistence, sequelae, and other medical complications that last weeks to months after initial recovery. This systematic review and meta-analysis aims to identify studies assessing the long-term effects of COVID-19. LitCOVID and Embase were searched to identify articles with original data published before the 1st of January 2021, with a minimum of 100 patients. For effects reported in two or more studies, meta-analyses using a random-effects model were performed using the MetaXL software to estimate the pooled prevalence with 95% CI. PRISMA guidelines were followed. A total of 18,251 publications were identified, of which 15 met the inclusion criteria. The prevalence of 55 long-term effects was estimated, 21 meta-analyses were performed, and 47,910 patients were included (age 17–87 years). The included studies defined long-COVID as ranging from 14 to 110 days post-viral infection. It was estimated that 80% of the infected patients with SARS-CoV-2 developed one or more long-term symptoms. The five most common symptoms were fatigue (58%), headache (44%), attention disorder (27%), hair loss (25%), and dyspnea (24%). Multi-disciplinary teams are crucial to developing preventive measures, rehabilitation techniques, and clinical management strategies with whole-patient perspectives designed to address long COVID-19 care.