RESEARCH & DEVELOPMENT
LIPOSOMES IN THE CREATION OF A COVID-19 VACCINE Messenger RNA (mRNA) is the basis of a vaccine against the Covid-19 virus and viral proteins are potential vaccine candidates. The novel Corona virus spike protein, chosen as a target antigen, is incorporated in the form of mRNA in liposomes which on injection are endocytosed by cells. Within the cytoplasm, the endocytic vacuoles open to release the mRNA which is then expressed as the spike protein promoting an immune response that kills the invading virus. Gregory Gregoriadis, University College London
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essenger RNA (mRNA) is a versatile and safe platform for the expression of proteins. Unlike DNA, mRNA is not integrated into the host genome and its translation machinery resides in the cytosol. Recently, mRNA has become the basis of vaccines against Covid-19 and viral proteins were identified as potential vaccine candidates, in particular the mRNA coding for the spike protein of the Corona virus. Within a relatively short period, Pfizer/ BioNTech and Moderna developed and marketed anti-Covid-19 vaccines based on the so-called lipid nanoparticles which served a two-fold function: to protect the mRNA from the biological environ-
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ISSUE 44 45 - 2021
ment and to facilitate its entry into the cytosol, the very place where mRNA would eventually be expressed into the spike protein which would generate an immune response and the inactivation of the invading Corona virus. The vaccines have now been administered to millions of people worldwide and countless lives have already been saved. There is, however, a long past to the story spanning over half-a-century of work. The Long Past of the Coronavirus Vaccines
Long before the appearance of the Corona virus, scientists were interested in the targeting of therapeutics in the body.
Targeting of drugs and vaccines would potentially reduce their side-effects and also facilitate or augment their pharmacological action. Fifty one years ago, in 1970, the idea of using liposomes for drug and vaccine delivery was born at the Royal Free Hospital School of Medicine in London when the author and the late Brenda Ryman thought of using liposomes as a drug delivery system. Liposomes, discovered a few years earlier by the late Alec Bangham and colleagues at the Babraham Institute in Cambridge, were used as a model for the study of membrane biophysics. Liposomes were originally named ‘Bangasomes’ (to honour their discoverer), ‘Phospholipid Vesicles’,
