Subtyping of influenza neuraminidase using mass spectrometry

A proteotyping approach which employs high resolution mass spectrometry is shown to be able to differentiate all nine neuraminidase subtypes of type A influenza viruses that infect both humans and animals. Conserved sequences among tryptic peptides were identified through alignments of influenza neuraminidase sequences across all subtypes N1–N9 among human and animal hosts. Those that were unique in mass represent signature peptides which, when detected in the mass spectra of an influenza neuraminidase or whole virus digest, enable strains to be subtyped with confidence. The ability to distinguish N1 neuraminidase derived from human H5N1 and H1N1 strains is also demonstrated. The approach provides a more rapid and direct approach with which to subtype the virus than conventional molecular based PCR methods with comparable sensitivity. This should help facilitate a more rapid response in the event of a local epidemic or global pandemic.