News

Setting it Straight - Issue #34

Written by Nobel Laureate Professor Peter Doherty

Now we finally come to the point of discussing how the cellular assassins of immunity, variously known as the ‘killer’ T cells or the CD8+ cytotoxic T lymphocytes (CTLs), do their job in a virus infection like COVID-19. All viruses are ‘obligate intracellular parasites’, meaning that they have to enter our body cells and use their small genomes to take over elements of the big genome that encodes the molecular machinery of us. The only ‘evolutionary aim’ of SARS-CoV-2 is to produce new virus particles (virions) that will ultimately infect other individuals and keep the pathogen in circulation. The more cells that are infected in our respiratory tract, the greater the amount of SARS-CoV-2 that they produce to be coughed and spluttered into the air around us. The CD8+ CTLs interrupt that pathway by killing these virus ‘factories.’ Think of that like an aerial bomb-hit that destroys both a weapons-production facility and any ‘product’ (virus) that hasn’t yet shipped out!