Via Eurosurveillance: Emergence of influenza A(H1N1)pdm09 genogroup 6B and drug resistant virus, India, January to May 2015. The introduction:
An epidemic of influenza A(H1N1)pdm09, affecting over 39,000 persons and causing more than 2,500 deaths occurred in India in 2015. We show that genotype 6B strains forming two sub-lineages circulated during the outbreak.
Comparison of the sequences of six outbreak strains recovered in this work, to other published genotype 6B sequences, also reveals a unique combination of previously-reported mutations in the haemagglutinin (HA) gene. Two of the six sequences additionally display a E164G mutation in HA2, which has not been reported to date, moreover a N129D mutation in HA1 is observed for two sequences derived from patients with severe disease.
Among strains analysed from 12 fatal cases on prior oseltamivir treatment, two harbour the H275Y mutation in the neuraminidase (NA) gene, which confers resistance to this antiviral.