Signature peptides of influenza nucleoprotein for the typing and subtyping of the virus by high resolution mass spectrometry.

The use of high resolution mass spectrometry to record the accurate mass of signature peptides within proteolytic digests of the nucleoprotein antigen, and whole influenza virus, is shown to be able to rapidly type and subtype the virus. Conserved sequences for predicted tryptic peptides were identified through alignments of those for the nucleoprotein across all influenza types and subtypes. Peptides with unique theoretical masses from those generated in silico for all influenza antigen sequences, and from those proteins known to contaminate virus preparations in laboratory grown samples, were identified using a purpose built algorithm (FluGest). The frequency of occurrence of such conserved peptide signatures was assessed across all nucleoprotein sequences to subsequently type and subtype human strains of the virus. The application of the approach is illustrated for both type A H1N1 and H3N2, and type B strains of human influenza virus.