Abstract: The resistant H275Y mutant was derived from a patient on oseltamivir prophylaxis and was the first oseltamivir-resistant isolate of the pandemic virus.
Discussion: Although the transmissibility of the oseltamivir-resistant H1N1/2009 virus was reduced by the H275Y NA mutation, the severity and course of disease was similar to that caused by oseltamivir-sensitive H1N1/2009 virus in both inoculated and direct-contact ferrets, with no apparent attenuation of clinical signs.
Discussion: As this study was undertaken, additional H275Y mutants of H1N1/2009 viruses have emerged in the absence of oseltamivir use.
Discussion: Further studies of these newly isolated H275Y mutants of H1N1/2009 viruses are warranted to determine whether they have acquired additional changes.
Discussion: In t
Clinical importance and impact on the households of oseltamivir-resistant seasonal A/H1N1 influenza virus in healthy children in Italy.
Result: A resistance of A/H1N1 influenza viruses to oseltamivir (mainly due to the H275Y mutation) has recently emerged in a number of countries.
Result: Among the A/H1N1 subtypes, the H275Y mutation was found in 2/126 samples (1.6%) in 2007-2008 and in all 17 samples (100%; p < 0.0001) in 2008-2009.
Result: However, the presence of the H275Y mutation did not seem to modify the pathogenicity of A/H1N1 influenza virus in our otherwise healthy children because all the variables evaluated for the clinical importance and impact on the households of the infections due to mutated or wild-type viruses were comparable.
Result: In conclusion, despite its frequency, A/H1N1 influenza virus with a single H275Y mutation is of marginal clinical importance and impact on the households in otherwise healthy children, but further studies are needed to cl
Oseltamivir-resistant variants of the 2009 pandemic H1N1 influenza A virus are not attenuated in the guinea pig and ferret transmission models.
Abstract: In vitro, the virus readily acquired a single histidine-to-tyrosine mutation at position 275 (H275Y) in viral neuraminidase when serially passaged in cell culture with increasing concentrations of oseltamivir.
Abstract: Unexpectedly, in guinea pigs and ferrets, the fitness of viruses with the H275Y point mutation was not detectably impaired, and both wild-type and mutant viruses were transmitted equally well from animals that were initially inoculated with 1:1 virus mixtures to naive contacts.
Oseltamivir-resistant influenza A 2009 H1N1 virus in immunocompromised patients.
PMID: 20836794
2010
Influenza and other respiratory viruses
Abstract: Four patient specimens (2.1%) were found to carry the H275Y mutation.
Abstract: PyroMark Q24 AQ software (Qiagen, Valencia, CA, USA) was used to allow for quantitative H275Y mutation analysis.
Abstract: RT-PCR and pyrosequencing were used to test for the H275Y mutation (CDC protocol).
Abstract: Resistance conferred by the H275Y neuraminidase gene mutation is concerning and likely to increase.
Table: H275Y
Discussion: Our finding of patients with 2009 H1N1 influenza virus harboring the H275Y mutation with apparently low suspicion for developing resistance is concerning.
Discussion: We focused on the H275Y neuraminidase
Treatment options for H5N1: lessons learned from the H1N1 pandemic.
Abstract: Compassionate use of intravenous zanamivir for the treatment of seriously ill patients, including those with H275Y H1N1 infections, has also shown promising results.
Abstract: Zanamivir is a potent inhibitor of H5N1, attains high lung concentrations immediately on administration, distributes into plasma at antiviral concentrations, has a low propensity for generating resistant virus, and retains activity against H275Y oseltamivir-resistant virus.
[Analyses of serological and genetic characteristics on novel H1N1 influenza A virus from the infected patient in Shenzhen].
Discussion: Furthermore, other previously analyzed influenza viruses A (H1N1) with the H275Y mutation showed impaired replicative ability in cell culture and reduced infectivity and substantially compromised pathogenicity in animal models, compared with the corresponding wild-type virus.
Discussion: Sporadically occurring A/New Caledonia/20/99-like ORVs with H275Y were detected during the 2006-07 season in the United Kingdom and United States but did not become epidemiologically important.
Discussion: The coincidental emergence of H275Y with the circulation of the A/Brisbane/59/2007 drift variant may have favored the emergence of fit transmissible ORVs.
Discussion: The finding of a high prevalence of ORVs in the community and the overall temporal increase in resistance demonstrates that the previously documented reduced fitness of viruses bearing the
Identification of a Permissive Secondary Mutation That Restores the Enzymatic Activity of Oseltamivir Resistance Mutation H275Y.
Abstract: H275Y isolates were more likely than H275 isolates to have the mutations A209T and R224G in NS1 (chi(2)=284.9, df=2, p<0.0001).
Abstract: BACKGROUND: The H275Y mutation (H274Y in N2 numbering) in the neuraminidase (NA) gene (segment 6) of the influenza virus A (H1N1) genome is linked to oseltamivir resistance.
Abstract: CONCLUSIONS: During the 2007-2008 influenza season in Toronto, Ontario, Canada, 17% of influenza virus A (H1N1) isolates carried the H275Y mutation associated with oseltamivir resistance.
Abstract: OBJECTIVES: To determine the percentage of influenza virus A (H1N1) isolates that carry the H275Y mut
Surveillance and oseltamivir resistance of human influenza a virus in Turkey during the 2007-2008 season.
Abstract: H275Y (H274Y according to N2 numbering) mutation, which is known to confer resistance to oseltamivir, was detected in 6 out of 30 (20%) H1N1 isolates from four cities (Istanbul, Bursa, Ankara, and Izmir).
IV mutation literature information.
PMID: 
2010
PLoS pathogens
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