Plos iconPlosSep 28, 2026 ~1 min source read

Epistasis and pleiotropy constrain the evolution of cross-reactive breadth in a broadly neutralizing influenza antibody

Dailey, Yiquan Wang, Qi Wen Teo, Chaoyang Wang, Huibin Lv, Ruipeng Lei, Meixuan Tong, Lucia A. Wu The highly conserved influenza virus hemagglutinin (HA) stem domain is a major target for broadly neutralizing antibodies (bnAbs).

Epistasis and pleiotropy constrain the evolution of cross-reactive breadth in a broadly neutralizing influenza antibody

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Dailey, Yiquan Wang, Qi Wen Teo, Chaoyang Wang, Huibin Lv, Ruipeng Lei, Meixuan Tong, Lucia A.

Wu The highly conserved influenza virus hemagglutinin (HA) stem domain is a major target for broadly neutralizing antibodies (bnAbs).

However, despite being discovered more than a decade ago, the IGHV1-69-encoded CR9114 remains the only HA stem bnAb that cross-reacts with both influenza A and B viruses.

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The useful part

Dailey, Yiquan Wang, Qi Wen Teo, Chaoyang Wang, Huibin Lv, Ruipeng Lei, Meixuan Tong, Lucia A. Wu The highly conserved influenza virus hemagglutinin (HA) stem domain is a major target for broadly neutralizing antibodies (bnAbs). However, despite being discovered more than a decade ago, the IGHV1-69-encoded CR9114 remains the only HA stem bnAb that cross-reacts with both influenza A and B viruses.

How it works

  • Many mutations that minimally affect or even improve the H1 HA binding are detrimental for binding to H3 HA and influenza B virus HA.

Details worth keeping

To investigate the constraints on the breadth evolution of CR9114, this study performs four deep mutational scanning experiments to compare the binding affinity landscapes of the germline and somatic CR9114 against H1 HA, H3 HA, and influenza B virus HA. We further reveal the prevalence of epistasis in IGHV1-69 HA stem bnAbs. Overall, our findings provide a mechanistic explanation for the scarcity of HA stem bnAbs with cross-reactivity against both influenza A and B viruses, and have important implications for developing broadly protective influenza vaccines.

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