{"id":14606,"date":"2021-03-31T00:00:00","date_gmt":"2021-03-31T00:00:00","guid":{"rendered":"https:\/\/www.nextias.com\/current_affairs\/uncategorized\/31-03-2021\/cd8-t-cell-and-covid-19-variants\/"},"modified":"2021-03-31T00:00:00","modified_gmt":"2021-03-31T00:00:00","slug":"cd8-t-cell-and-covid-19-variants","status":"publish","type":"post","link":"https:\/\/www.nextias.com\/ca\/current-affairs\/31-03-2021\/cd8-t-cell-and-covid-19-variants","title":{"rendered":"CD8+ T Cell and Covid-19 Variants"},"content":{"rendered":"<p><strong>In News<\/strong><\/p>\n<p>Recently, the <strong>US National Institute of Allergy and Infectious Diseases<\/strong> (NIAID) has found that the <strong>CD8+ T cell<\/strong> of the human immune response has <strong>remained active against the new variants of Covid-19<\/strong>.<\/p>\n<p><strong>About the CD8+ T Cell<\/strong><\/p>\n<ul>\n<li>These are also called <strong>cytotoxic T lymphocytes<\/strong>, or <strong>CTLs<\/strong> and like CD4+ Helper T cells, are <strong>generated in the thymus<\/strong> and express the T-cell receptor.\n<ul>\n<li>The thymus is a <strong>lymphoid gland<\/strong> composed of <strong>two identically sized lobes<\/strong>, located<strong> behind the sternum<\/strong> (breastbone) but in front of the heart.<\/li>\n<li>It filters and monitors blood content and produces the<strong> white blood cells<\/strong> called <strong>T-lymphocytes<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<li>These are very important for <strong>immune defence against intracellular pathogens<\/strong>, including viruses and bacteria, and for tumour surveillance.<\/li>\n<li>When a CD8+ T cell recognises its antigen and becomes activated, it has<strong> three major mechanisms <\/strong>to kill infected or malignant cells.\n<ul>\n<li>The first is <strong>secretion of cytokines<\/strong>, primarily TNF-\u03b1 and IFN-\u03b3, which have antitumor and anti-viral microbial effects.<\/li>\n<li>The second major function is th<strong>e production and release of cytotoxic granules<\/strong>, which contain two families of proteins namely perforin and granzymes.\n<ul>\n<li><strong>Perforin <\/strong>forms a pore in the membrane of the target cell which allows the granzymes to enter the infected or malignant cell.<\/li>\n<li><strong>Granzymes <\/strong>sever the proteins inside the cell, shutting down the production of viral proteins and ultimately resulting in apoptosis (programmed cell death) of the target cell.<\/li>\n<li>CD8+ T cells are able to release their granules, kill an infected cell, then move to a new target and kill again, often referred to as <strong>serial killing<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<li>The third major function of CD8+ T <strong>cell destruction of infected cells is via Fas\/FasL interactions<\/strong>.\n<ul>\n<li>Activated CD8+ T cells express<strong> Fas ligand <\/strong>(FasL, a type II membrane protein which can induce apoptotic cell death) on the cell surface, which binds to its receptor, Fas, on the surface of the target cell.<\/li>\n<li>This binding results in the activation of the <strong>caspase cascade<\/strong>, which results in apoptosis of the target cell.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><strong>About the Research<\/strong><\/p>\n<ul>\n<li>The scientists <strong>investigated whether CD8+ T cells<\/strong> in the blood of recovered Covid-19 patients, infected with the initial virus, could<strong> still recognise the <\/strong><a href=\"https:\/\/www.nextias.com\/current-affairs\/25-03-2021\/432\"><strong>Covid-19 variants<\/strong><\/a>, namely\n<ul>\n<li>United Kingdom Variant (B.1.1.7)<\/li>\n<li>South African Variant (B.1.351)<\/li>\n<li>Brazil Variant (B.1.1.248)<\/li>\n<\/ul>\n<\/li>\n<li>Each of these variants has <strong>mutations throughout the virus<\/strong>, and <strong>mainly <\/strong>in the region of <strong>spike protein<\/strong> that the virus<strong> uses to attach to and enter human cells<\/strong>.<\/li>\n<li>Scientists thought that <strong>mutations <\/strong>in this spike protein region <strong>could make it less recognisable to T cells<\/strong> and <strong>neutralising antibodies<\/strong>, which are made by the immune system\u2019s B cells following infection or vaccination.<\/li>\n<\/ul>\n<p><strong>Key Findings<\/strong><\/p>\n<ul>\n<li>In their study of recovered Covid-19 patients, the researchers determined that <strong>Covid-19 specific CD8+ T cell responses remained largely intact<\/strong> and <strong>could recognise virtually all mutations in the variants<\/strong> studied.<\/li>\n<li>Although more studies and research is needed, the researchers note that the <strong>T cell response in convalescent individuals<\/strong>, and most likely in <strong>vaccine recipients<\/strong>, are largely <strong>not affected by the mutations<\/strong> found in these three variants, and <strong>should offer protection against emerging variants<\/strong>.<\/li>\n<li>Optimal immunity to Covid-19 likely requires<strong> strong multivalent T-cell responses<\/strong> in <strong>addition to neutralising antibodies<\/strong> and <strong>other responses to protect against current and emerging strains<\/strong>.<\/li>\n<li>They have also emphasised on the importance of <strong>monitoring the breadth, magnitude and durability of the anti-Covid-19 T-cell responses<\/strong> in recovered and vaccinated individuals as<strong> part of any assessment<\/strong> to determine if booster vaccinations are needed.<\/li>\n<\/ul>\n<p>Source: <a href=\"https:\/\/indianexpress.com\/article\/explained\/t-cells-of-earlier-covid-patients-recognise-all-3-major-new-variants-7251962\/\" target=\"_blank\" rel=\"noopener\">IE<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>In News Recently, the US National Institute of Allergy and Infectious Diseases (NIAID) has found that the CD8+ T cell of the human immune response has remained active against the new variants of Covid-19. About the CD8+ T Cell These are also called cytotoxic T lymphocytes, or CTLs and like CD4+ Helper T cells, are [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":14607,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[21],"tags":[101,100,26,33],"class_list":["post-14606","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-current-affairs","tag-applications-effects-on-everyday-life","tag-developments","tag-gs-3","tag-science-technology"],"acf":[],"jetpack_featured_media_url":"https:\/\/wp-images.nextias.com\/cdn-cgi\/image\/format=auto\/ca\/uploads\/2023\/07\/49707526268277current-affairs.jpg","_links":{"self":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts\/14606","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/comments?post=14606"}],"version-history":[{"count":0,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/posts\/14606\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/media\/14607"}],"wp:attachment":[{"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/media?parent=14606"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/categories?post=14606"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.nextias.com\/ca\/wp-json\/wp\/v2\/tags?post=14606"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}