This Week in Virology TWiV 1299: Moth balls and blood clots
Feb 22, 2026
They dig into how rare clotting after adenovirus vaccines can arise from antibody cross-reactivity and somatic hypermutation. A detective-style rundown traces the viral P7 peptide that mimics platelet factor 4 and the lab tests that prove pathogenic antibodies cause thrombosis in mice. They also explore how a wasp-associated virus uses a protein tyrosine phosphatase to castrate insect hosts and what that reveals about host vulnerability.
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Mechanism Linking Adenovirus To VITT
- VITT arises from cross-reactive antibodies that bind platelet factor 4 after adenovirus exposure.
- A conserved adenoviral core protein P7 shares a structural epitope with PF4, explaining memory B cell boosting within days of vaccination or infection.
Mutation Reversion Confirms Epitope Mimicry
- Reverting K31E restores adenoviral P7 binding and reduces PF4 binding, proving the mutation shifts specificity.
- The core P7 linear 15-mer epitope structurally mimics PF4 and is conserved across chimp and human adenoviruses.
Engineer Adenovirus Vectors To Remove Offending Epitope
- To reduce VITT risk, vaccine developers can modify adenovirus vectors to remove or alter the P7 PF4-mimicking epitope.
- The authors suggest engineering safer vectors while retaining adenovirus utility for low-resource vaccine deployment.
