Structure of the sialic acid binding site in influenza a virus: hemagglutinin

Influenza A viruses have several key features accounted for public health concerns and for a number of historic pandemics. The genome of the virus is segmented RNA with negative polarity which attributed significantly to the stability of the virus during replication. Furthermore, the virus has two major variable surface glycoproteins Hemagglutinin (HA) and Neuraminidase (NA), which affected by antigenic changes (drift and shift) and recombination leading to recurrent outbreaks of influenza viruses. HA cleavage, intracellularly by host proteases into HA! and HA2 subunits is one of the determinants of tropism and pathogenicity, is characteristics for binding of the virus to cellular sialic acid-containing receptors. Because of the importance of HA in viral infection and as inducer of neutralizing antibodies, this review will focus on the molecular basis of HA-binding site. Molecular and biologically approaches elucidating HA-binding site will advance methods ranging from vaccine development to the designing effective inhibitors