ABSTRACT
Inicialmente el virus de influenza A(H1N1)pdm09 fue susceptible a los inhibidores de neuraminidasa oseltamivir y zanamivir. Las cepas virales resistentes presentan una sustitución que produce un cambio del aminoácido histidina (H) por una tirosina (Y) en el codón 274 del gen de la neuroaminidasa. El objetivo del trabajo fue realizar un análisis retrospectivo de los resultados obtenidos en muestras estudiadas para influenza A durante el periodo junio - agosto de 2013 y en las muestras positivas determinar la presencia de la mutación H274Y. Se estudiaron 1783 muestras de pacientes con diagnóstico presuntivo de influenza A(H1N1)pdm09, 171 (9.6%) resultaron positivas, a estas se les estudió la presencia de la mutación H274Y. Únicamente dos muestras presentaron la mutación de resistencia. Los métodos para detectar cepas de infuenza A(H1N1)pdm09 resistentes son necesarios para ayudar a los médicos en la selección de la terapia antiviral apropiada de la influenza.
Initially the circulating influenza virus A(H1N1)pdm09 was susceptible to neuraminidase inhibitors oseltamivir and zanamivir. Virtually all resistant viruses possess a substitution at codon 274 of the neuraminidase gene which produces a change of the amino acid histidine (H) to a tyrosine (Y). The aims of the study were to perform a retrospective analysis of samples studied in the Laboratory of Genomic Medicine - MANLAB for influenza A during the period June to August 2013 in Buenos Aires, and to determine the presence of the H274Y mutation. 1783 samples from patients with a presumptive diagnosis of influenza A(H1N1) pdm09 were studied, the virus was detected in 171 samples (9.6%). Then, we studied the presence of the mutation H274Y. Only two samples showed the characteristic resistance mutation. Methods for detecting oseltamivir-resistant A(H1N1)pdm09 influenza strains are needed to assist physicians in the selection of appropriate antiviral therapy for influenza treatment.
Subject(s)
Influenza A virus , Influenza A Virus, H1N1 Subtype , OseltamivirABSTRACT
After the World Health Organization officially declared the end of the first pandemic of the XXI century in August 2010, the influenza A(H1N1)pdm09 virus has been disseminated in the human population. In spite of its sustained circulation, very little on phylogenetic data or oseltamivir (OST) resistance is available for the virus in equatorial regions of South America. In order to shed more light on this topic, we analysed the haemagglutinin (HA) and neuraminidase (NA) genes of influenza A(H1N1)pdm09 positive samples collected during the pandemic period in the Pernambuco (PE), a northeastern Brazilian state. Complete HA sequences were compared and amino acid changes were related to clinical outcome. In addition, the H275Y substitution in NA, associated with OST resistance, was investigated by pyrosequencing. Samples from PE were grouped in phylogenetic clades 6 and 7, being clustered together with sequences from South and Southeast Brazil. The D222N/G HA gene mutation, associated with severity, was found in one deceased patient that was pregnant. Additionally, the HA mutation K308E, which appeared in Brazil in 2010 and was only detected worldwide the following year, was identified in samples from hospitalised cases. The resistance marker H275Y was not identified in samples tested. However, broader studies are needed to establish the real frequency of resistance in this Brazilian region.
Subject(s)
Female , Humans , Pregnancy , Hemagglutinins/genetics , Influenza A Virus, H1N1 Subtype/genetics , Influenza, Human/epidemiology , Neuraminidase/genetics , Pandemics , Antiviral Agents/therapeutic use , Biomarkers/analysis , Brazil/epidemiology , Drug Resistance, Viral/physiology , Gene Frequency/genetics , Influenza A Virus, H1N1 Subtype/classification , Influenza A Virus, H1N1 Subtype/pathogenicity , Influenza, Human/virology , Mutation/genetics , Oseltamivir/therapeutic use , Phylogeny , RNA, Viral/analysis , Sequence Analysis, DNA/methods , Virulence , Virulence Factors/geneticsABSTRACT
Background: Recent studies on antiviral susceptibiliy from South-East Asia, Europe and the United States have shown sporadic neuraminidase inhibitor (NAI) resistance in A(H1N1)pdm09 viruses. We undertook a study to evaluate NAI resistance in these viruses isolated in India. Methods: Pandemic influenza viruses, isolated from 2009 to 2013, along with clincal samples were genetically analysed for known resistance markers in the neuraminidase (NA) gene. Clinical samples (n=1524) were tested for H275Y (N1 numbering; H274Y in N2 numbering) mutation by real time reverse transcriptase PCR (rRT-PCR). One hundred and ten randomly selected resistant and sensitive viruses were analysed by phenotypic assay. Results: All but one of the 2013 A(H1N1)pdm09 isolates were sensitive to oseltamivir. Genetic analysis of this isolate as well as the original clinical material showed that the presence of H275Y mutation was responsible for reduced susceptibility to oseltamivir in the patient. This was confirmed by phenotypic assay. Conclusion: The emergence of a pandemic influenza strain resistant to oseltamivir emphasizes the need for monitoring antiviral resistance as part of the National Influenza Programme in India.