TWiV 1341: Phage breaks and COVID origins

Mycobacteriophage D29 utilizes a lysin protein, LysB, to modulate infection dynamics beyond simple cell lysis. By accumulating outside infected cells, LysB reduces phage adsorption to bystander mycobacteria, preventing host extinction and suggesting a mechanism for self-limiting viral spread. Meanwhile, genomic analysis of over 16 million SARS-CoV-2 sequences refutes claims that the virus's furin cleavage site originated from a mouse-adapted MERS coronavirus. The data demonstrate that the RRAR sequence is highly conserved, while the proposed ancestral RRVR sequence lacks fitness and fails to persist in human populations. These findings underscore the importance of rigorous phylogenetic and experimental evidence in evaluating viral origins. The discussion also addresses the broader challenges of communicating scientific consensus regarding vaccine safety and viral evolution to a public increasingly influenced by misinformation.