Rapid identification of oseltamivir-resistant influenza A(H1N1) viruses with H274Y mutation by RT-PCR/restriction fragment length polymorphism assay.

In the beginning of 2007-2008 Northern Hemisphere influenza season, the frequency of influenza A(H1N1) viruses bearing a previously defined oseltamivir resistance conferring amino acid change of Histidine to Tyrosine at position 274 (H274Y) of the neuraminidase (NA) increased dramatically. In order to rapidly detect such resistant viruses, an RT-PCR/restriction fragment length polymorphism (RT-PCR/RFLP) assay targeting amino acid 274 of the N1 NA molecule was developed to investigate the presence or absence of the H274Y mutation. The reverse primer was engineered to produce a BspHI site in the amplicon for oseltamivir-sensitive viruses with Histidine at position 274 (274H).