Research

Researches

17 Jun 2019

Preventing an Antigenically Disruptive Mutation in Egg-Based H3N2 Seasonal Influenza Vaccines by Mutational Incompatibility

Chris Mok, team leader at HKU-Pasteur, and Tomas Lyu, research assistant, just signed a major publication in Cell Host & Microbe with Professor Ian Wilson, Scripps Research, and Nicholas Wu, Scripps Research and 2017 HKU-Pasteur Virology Course alumnus: 
 
Chris Mok and Ian Wilson, who co-led the study, have found that a mutation called G186V could be a useful addition to the H3N2 influenza vaccine. Preparing a seasonal flu vaccine with the G186V mutation may prevent a vexing problem that commonly occurs during the vaccine manufacturing process.
 
Summary
Egg-based seasonal influenza vaccines are the major preventive countermeasure against influenza virus. However, their effectiveness can be compromised when antigenic changes arise from egg-adaptive mutations on influenza hemagglutinin (HA). The L194P mutation is commonly observed in egg-based H3N2 vaccine seed strains and significantly alters HA antigenicity. An approach to prevent L194P would therefore be beneficial. We show that emergence of L194P during egg passaging can be impeded by preexistence of a G186V mutation, revealing strong incompatibility between these mutations. X-ray structures illustrate that individual G186V and L194P mutations have opposing effects on the HA receptor-binding site (RBS), and when both G186V and L194P are present, the RBS is severely disrupted. Importantly, wild-type HA antigenicity is maintained with G186V, but not L194P. Our results demonstrate that these epistatic interactions can be used to prevent the emergence of mutations that adversely alter antigenicity during egg adaptation.
 
 
Authors: Wu NC, Lv H, Thompson AJ, Wu DC, Ng WWS, Kadam RU, Lin CW, Nycholat CM, McBride R, Liang W, Paulson JC, Mok CKP, Wilson IA (2019)
 
Cell Host Microbe pii: S1931-3128(19)30216-1. doi: 10.1016/j.chom.2019.04.013.
 
Chris Mok, team leader at HKU-Pasteur, and Tomas Lyu, research assistant

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