#Hemagglutinin #stalk-reactive #antibodies interfere with #influenza virus #neuraminidase activity by steric hindrance (J Virol., abstract)

[Source: Journal of Virology, full page: (LINK). Abstract, edited.]

Hemagglutinin stalk-reactive antibodies interfere with influenza virus neuraminidase activity by steric hindrance

Yao-Qing Chen, Linda Yu-Ling Lan, Min Huang, Carole Henry, Patrick C. Wilson

DOI: 10.1128/JVI.01526-18



Hemagglutinin (HA) stalk-reactive antibodies are the basis of several current “one-shot” universal influenza vaccine efforts because they protect against a wide spectrum of influenza virus strains. The appreciated mechanism of protection by HA-stalk antibodies is to inhibit HA stalk reconfiguration, blocking viral fusion and entry. This study shows that HA stalk-reactive antibodies also inhibit neuraminidase (NA) enzymatic activity, prohibiting viral egress. NA inhibition (NI) is evident for an attached substrate but not for unattached small molecule cleavage of sialic acid. This suggests that the antibodies inhibit NA enzymatic activity through steric hindrance, thus limiting NA access to sialic acids when adjacent to HA on whole virions. Consistently, F(ab’)2 fragments that occupy reduced area without loss of avidity or disrupted HA/NA interactions show significantly reduced NI activity. Notably, HA stalk binding antibodies lacking NI activity were unable to neutralize viral infection via microneutralization assays. This work suggests that NI activity is an important component of HA-stalk antibody mediated protection.



This study reports a new mechanism of protection that is mediated by influenza hemagglutinin-stalk reactive antibodies: inhibition of neuraminidase activity by steric hindrance, blocking access of neuraminidase to sialic acids when it is abutted next to hemagglutinin on whole virions.

Copyright © 2018 American Society for Microbiology. All Rights Reserved.

Keywords: Influenza A; Vaccines.


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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum (FluTrackers.com) in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.