Oseltamivir-resistant pandemic (H1N1) 2009 virus, Mexico

Abstract

During May 2009-April 2010, we analyzed 692 samples of pandemic (H1N1) 2009 virus from patients in Mexico. We detected the H275Y substitution of the neuraminidase gene in a specimen from an infant with pandemic (H1N1) 2009 who was treated with oseltamivir. This virus was susceptible to zanamivir and resistant to adamantanes and oseltamivir.

Figure 1

Reverse transcription–PCR (RT-PCR)/sequencing primers scheme for the neuraminidase (NA) gene. A) Primer position for screening RT-PCR protocol. B) Primer position and the 2 overlapping RT-PCR products for the complete NA sequence. UTR, untranslated region.

Figure 2

DNA sequence electropherograms for neuraminidase (NA) gene sequences. A) Analysis of molecular markers (V116, I117, E119, Q136, K150, D151, D198, I223, H275, and N295) for oseltamivir and/or zanamivir resistance among the pandemic (H1N1) 2009 virus isolates. The oseltamivir resistance–conferring mutation CAC (histidine) to TAC (tyrosine) at position 275 was detected in the InDRE797 sample. B) Detection of the H275Y mutation in the NA of the viruses by single-nucleotide polymorphism analysis at NA275 position (yellow area).