Recombinant Influenza A NP (A/Hong Kong/1-1/1968(H3N2))

There are four types of Influenza (flu) viruses: type A, B, C, and D.

Influenza A and B viruses are routinely spread in people and other mammals, while also known for seasonal flu epidemics each year.

Influenza A is the genus Alpha Influenzavirus of the virus family Orthomyxoviridae.

Influenza A is classified by two main protein subtypes, hemagglutinin (HA) and neuraminidase (NA), located on the surface of the virus.

Breaking down the proteins further, there are 18 hemagglutinin subtypes and 11 different neuraminidase subtypes1.

Influenza A can be even further classified into specific clades (also known as groups) and sub-clades (also known as sub-groups) based on similarity of their HA/NA gene sequences1.

The Nucleocapsid protein or nucleoprotein (NP) of the influenza virus A negative-strand RNA’s primary function is to encapsulate the virus genome for the purpose of RNA transcription, replication and packaging2.

Specifically, NP is the most abundant viral protein in infected cells2, therefore the NP can be and has been used for anti-influenza drug development3.

The NP of influenza A and B viruses share up to 38% of their amino acid sequence, indicating region functionality differences at the amino acid level4.