Antibody neutralization of an influenza virus that uses neuraminidase for receptor binding

Abstract

Influenza virus infection elicits antibodies against the receptor-binding protein hemagglutinin (HA) and the receptor-cleaving protein neuraminidase (NA). Because HA is essential for viral entry, antibodies targeting HA often potently neutralize the virus in single-cycle infection assays. But antibodies against NA are not potently neutralizing in such assays, since NA is dispensable for single-cycle infection. Here we show that a modified influenza virus that depends on NA for receptor binding is much more sensitive than a virus with receptor-binding HA to neutralization by some anti-NA antibodies. Specifically, virus with a receptor-binding G147R N1 NA and a binding-deficient HA is completely neutralized in single-cycle infections by an antibody that binds near the NA active site. Infection is also substantially inhibited by antibodies that bind NA epitopes distant from the active site. Finally, we demonstrate that this modified virus can be used to efficiently select mutations in NA that escape antibody binding, a task that can be laborious with typical influenza viruses that are not well-neutralized by anti-NA antibodies. Thus, viruses dependent on NA for receptor binding allow for sensitive in vitro detection of antibodies binding near the catalytic site of NA and enable selection of viral escape mutants.

Kinetics and persistence of anti‐SARS‐CoV‐2 neutralisation and antibodies after BNT162b2 vaccination in a Swiss cohort

“…Indeed, antibodies may have various functions, 16 and although neutralisation is a correlate of protection for many viral diseases, 17 not all antibodies that bind a virus will neutralise it. For a given antigen, antibodies may neutralise (e.g., influenza hemagglutinin), bind the antigen on the virus surface and thereby perhaps slow the spread of infection without being neutralising (e.g., influenza neuraminidase), 18 or in some instances even enhance the infection (e.g., dengue virus). 19 Noval et al 20 recently showed that the antibody isotype diversity against SARS-CoV-2 was associated with differential serum neutralisation capacities in 101 convalescent patients.…”

Attenuated Influenza Virions Expressing the SARS-CoV-2 Receptor-Binding Domain Induce Neutralizing Antibodies in Mice

“…Neutralization was measured against the virus containing H3 from the A/Aichi/2/1968 virus with two mutations, Y98F and G379W, carrying GFP in the PB1 segment, and all other internal genes from A/WSN/33. The neutralization assays were performed in MDCK-SIAT1-CMV-PB1 cells using this GFP-expressing virus as described previously [ 36 , 37 , 38 , 39 ]. As with spike pseudotyped lentivirus neutralization assays, the curves were plotted and IC50s were calculated using the neutcurve Python package.…”

Attenuated influenza virions expressing the SARS-CoV-2 receptor-binding domain induce neutralizing antibodies in mice

“…Neutralization was measured against virus containing H3 from A/Aichi/2/1968 virus with two mutations Y98F and G379W, carrying GFP in the PB1 segment, and all other internal genes from A/WSN/33. The neutralization assays were performed in MDCK-SIAT1-CMV-PB1 cells using this GFP-expressing virus as described previously [ 36 – 39 ]. As with Spike pseudotyped lentivirus neutralization assays, curves were plotted and IC50s were calculated using the neutcurve Python package.…”