Article · Virology & COVID-19 · March 2020 · Episode 1/3
24 March 2020 · ~6 pages · English
Historical note. This article was written on 24 March 2020, during the first week of lockdown in France. Some initial hypotheses have been refined by subsequent research — notably, SARS-COV2 is a positive-sense single-stranded RNA virus using an RNA-dependent RNA polymerase (RdRp), not a retrovirus. The article is published here as a period document reflecting real-time scientific reasoning under crisis conditions.
1 · What is a virus?
Fundamental virology: the virus as an obligate intracellular parasite. Structure (capsid, envelope, spike proteins), classification (DNA vs RNA, single-stranded vs double-stranded), and the key distinction between virus and cell — a virus cannot replicate without hijacking cellular machinery.
2 · How does infection work?
Step-by-step infection cycle: attachment (spike protein → receptor), membrane fusion, RNA release, ribosome hijacking, protein synthesis, genome replication, assembly, and budding. Why SARS-COV2's spike protein affinity for ACE2 receptors makes it particularly efficient.
3 · Mutation and recombination
RNA virus mutation rates (10⁻³ to 10⁻⁵ per nucleotide per replication), genetic drift, and recombination events. The RaTG13 bat coronavirus as the closest known relative of SARS-COV2 (96.2% genome identity). Zoonotic transmission hypothesis and the role of intermediate hosts.
Written during the first days of the French lockdown, this article was part of a pedagogical effort to explain the science behind the pandemic to a non-specialist audience. The author's background in biotechnology (PhD ENS Ulm / AgroParisTech) informed a level of technical detail unusual for LinkedIn publications, yet the explanations remain accessible.
The series demonstrates the same analytical discipline — starting from first principles, building structural understanding before addressing policy — that characterises the author's later work on predictive medicine (PREDICARE) and digital twins (TweenMe).