Tingting Ning1,2, Jianhui Nie1, Weijin Huang1, Changgui Li3, Xuguang Li4, Qiang Liu1, Hui Zhao3, Youchun Wang1,2. 1. Division of HIV/AIDS and Sexually Transmitted Virus Vaccines, Beijing, China. 2. Graduate School of Peking Union Medical College, Beijing, China. 3. Division of Respiratory Virus Vaccines, National Institutes for Food and Drug Control, Beijing, China. 4. Centre for Biologics Evaluation, Biologics and Genetic Therapies Directorate, Health Canada, Ottawa, Canada.
Abstract
Background: Since the emergence of influenza A(H7N9) virus in 2013, there have been 5 waves of influenza A(H7N9) epidemics in China. However, evolution of the hemagglutinin (HA) protein antigenicity has not been systematically investigated. Methods: To better understand how antigenic drift in HA proteins of influenza (A)H7N9 virus occurs, 902 influenza A(H7N9) virus HA protein sequences from a public database were retrieved and analyzed. Fifty-three mutants with single amino acid substitutions in HA protein were introduced into pseudoviruses, and their antigenic characteristics were analyzed using pseudovirus-based assays. Results: The frequencies of 9 mutations incrementally increased over the past 5 years, with mutations identified at multiple sites. While mean neutralization titers of most variants remained unchanged, 3 mutations, A143V, A143T, and R148K, displayed a median 4-fold lower susceptibility to neutralization by antisera against influenza A/Anhui/1/2013(H7N9) virus. Notably, A143V and A143T were located outside the previously reported antigenic sites. The most dominant variant (A143V/R148K) in the most recent season constituted 74.11% of all mutations and demonstrated a 10-fold reduction in its reactivity to influenza A/Anhui/1/2013(H7N9) virus antisera. Importantly, compared with the DNA construct without the corresponding HA protein mutation, DNA vaccine encoding the A143V/R148K mutant induced a 5-fold increase in the neutralizing activity against this circulating virus. Conclusions: An appropriate vaccine strain should be considered in response to increasing antigenic drift in influenza A(H7N9) virus HA protein.
Background: Since the emergence of influenza A(H7N9) virus in 2013, there have been 5 waves of influenza A(H7N9) epidemics in China. However, evolution of the hemagglutinin (HA) protein antigenicity has not been systematically investigated. Methods: To better understand how antigenic drift in HA proteins of influenza (A)H7N9 virus occurs, 902 influenza A(H7N9) virus HA protein sequences from a public database were retrieved and analyzed. Fifty-three mutants with single amino acid substitutions in HA protein were introduced into pseudoviruses, and their antigenic characteristics were analyzed using pseudovirus-based assays. Results: The frequencies of 9 mutations incrementally increased over the past 5 years, with mutations identified at multiple sites. While mean neutralization titers of most variants remained unchanged, 3 mutations, A143V, A143T, and R148K, displayed a median 4-fold lower susceptibility to neutralization by antisera against influenza A/Anhui/1/2013(H7N9) virus. Notably, A143V and A143T were located outside the previously reported antigenic sites. The most dominant variant (A143V/R148K) in the most recent season constituted 74.11% of all mutations and demonstrated a 10-fold reduction in its reactivity to influenza A/Anhui/1/2013(H7N9) virus antisera. Importantly, compared with the DNA construct without the corresponding HA protein mutation, DNA vaccine encoding the A143V/R148K mutant induced a 5-fold increase in the neutralizing activity against this circulating virus. Conclusions: An appropriate vaccine strain should be considered in response to increasing antigenic drift in influenza A(H7N9) virus HA protein.
Authors: Mohammad Reza Sepand; Banafsheh Bigdelou; Jim Q Ho; Mohammad Sharaf; Alexis J Lannigan; Ian M Sullivan; Alecsander P da Silva; Leland O Barrett; Scott McGoldrick; Yuvraj Lnu; Shannon E Lynch; Jared M Boisclair; Dakarai D Barnard-Pratt; Steven Zanganeh Journal: Antibodies (Basel) Date: 2022-05-12