H275Y Mutation In Neuraminidase Research Articles

Influenza pH1N1 Virus Accumulated H275Y Mutation in Neuraminidase during Propagation in MDCK Cells.

Here, we sequenced the genome of the influenza A/Finland/741 M/2014(H1N1) virus and found that the virus accumulated oseltamivir resistance mutation H275Y in its neuraminidase during propagation in cell culture. This indicates that propagation in cell culture modifies virus genomes. The instability of influenza genomes should be taken into consideration during drug-sensitivity studies.

Pharmacokinetic Properties ofAnti‐Influenza Neuraminidase Inhibitors

Neuraminidase inhibitors are the mainstay of anti-influenza treatment. Oseltamivir is the most widely used drug but is currently available only as an oral formulation. Resistance spreads rapidly in seasonal H1N1 influenza A viruses, which were universally resistant in 2008, because of the H275Y mutation in the neuraminidase (NA) gene. Oseltamivir is a prodrug for the active carboxylate metabolite. Ex vivo conversion in blood samples may have confounded early pharmacokinetic studies. Oseltamivir shows dose linear kinetics, and oseltamivir carboxylate has an elimination half-life (t(1/2) β) after oral administration in healthy individuals of approximately 7.7 hours. Oseltamivir carboxylate is eliminated primarily by tubular secretion, and both clearance and tissue distribution are reduced by probenecid. The H275Y mutation in NA confers high-level oseltamivir resistance and intermediate peramivir resistance but does not alter zanamivir susceptibility. Zanamivir is available as a powder for inhalation, and a parenteral form is under development. Zanamivir distributes in an apparent volume of distribution approximating that of extracellular water and is rapidly eliminated (t(1/2) β of approximately 3.0 hours). Peramivir is slowly eliminated (t(1/2) β of 7.7-20.8 hours) and is prescribed as either a once-daily injection or as a single infusion. Laninamivir is a recently developed slowly eliminated compound for administration by inhalation.

Rapid detection of the S247N neuraminidase mutation in influenza A(H1N1)pdm09 virus by one-step duplex RT-PCR assay

Neuraminidase inhibitors, especially oseltamivir, have been used worldwide for the prophylaxis or treatment of pandemic influenza H1N1 2009 (A(H1N1)pdm09) viruses. The most commonly detected oseltamivir-resistant A(H1N1)pdm09 viruses possess the H275Y mutation in neuraminidase (NA). Recently, a novel A(H1N1)pdm09 variant containing the S247N mutation in NA was found mainly in the Asia-Pacific area. This mutation reduces sensitivity to oseltamivir and confers extremely high resistance to oseltamivir in association with the H275Y mutation compared with the resistance caused by the H275Y mutation alone. In this study, a rapid and simple one-step duplex RT-PCR assay for identifying A(H1N1)pdm09 viruses possessing the S247N mutation was developed. This assay is based on an endpoint genotyping analysis method and can use isolates from cell culture supernatants without RNA extraction, similar to the H275Y RT-PCR assay reported previously. The combination of the S247N and H275Y RT-PCR assays is a powerful surveillance method for determining whether A(H1N1)pdm09 viruses with the S247N mutation acquire the H275Y mutation.

Intrahost emergent dynamics of oseltamivir-resistant virus of pandemic influenza A (H1N1) 2009 in a fatally immunocompromised patient

The oseltamivir-resistant pandemic influenza virus A (2009 H1N1) with H275Y mutation in neuraminidase (NA) has been sporadically reported, and its wide spread remains a potential threat. Here we detected the uneven distribution of H275Y mutant virus in a patient who received a 21-day long-term administration of oseltamivir. Intrahost variation of the virus showed that the H275Y mutant virus was the predominant population in both nasopharynx and right lung, whereas the oseltamivir-sensitive virus comprised half the population in the left lung. By constructing minimum spanning trees, it is proposed that the H275Y mutant might be generated primarily in the nasopharynx, then spread to the right and left lungs.

Oseltamivir-resistant pandemic influenza a (H1N1) 2009 viruses in Spain

BackgroundPandemic influenza A (H1N1) 2009 virus appeared in Spain on April 25, 2009 for the first time. This new virus was adamantane-resistant but it was sensitive to neuraminidase (NA) inhibitors oseltamivir and zanamivir. ObjectivesTo detect oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses by the Spanish Influenza Surveillance System (SISS) and a possible spread of oseltamivir-resistant viruses in Spain since starting of the pandemic situation. Study designA total of 1229 respiratory samples taken from 413 severe and 766 non-severe patients with confirmed viral detection of pandemic influenza A (H1N1) 2009 viruses from different Spanish regions were analyzed for the specific detection of the H275Y mutation in NA between April 2009 and May 2010. ResultsH275Y NA substitution was found in 8 patients infected with pandemic influenza A (H1N1) 2009 viruses collected in November and December 2009 and in January 2010. All oseltamivir-resistant viruses were detected in severe patients (8/413, 1.93%) who previously received treatment with oseltamivir. Six of these patients were immunocompromised. ConclusionIn Spain, the number of oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses is until now very low. No evidence for any spread of oseltamivir-resistant H1N1 viruses is achieved in our Country.

Reduced Effectiveness of Oseltamivir in Children Infected With Oseltamivir-resistant Influenza A (H1N1) Viruses With His275Tyr Mutation

Little is known about whether neuraminidase inhibitors are effective for children infected with oseltamivir-resistant influenza A(H1N1) viruses. Children aged 15 years and younger having influenza-like illness and who visited outpatient clinics within 48 hours of fever onset were enrolled from 2006-2007 to 2008-2009 influenza seasons in Japan. Patients received oseltamivir, zanamivir, or no treatment after screening by a rapid antigen test. Nasopharyngeal swabs were collected before antiviral therapy and were used for virus isolation. Oseltamivir resistance was determined by detection of the H275Y mutation in neuraminidase, and susceptibility test using neuraminidase inhibition assay. Daily body temperature was evaluated according to drug type and susceptibility by univariate and multivariate analyses. Of 1647 patients screened, 238 oseltamivir-resistant H1N1 cases (87 oseltamivir-treated, 64 zanamivir-treated, and 87 nontreated) and 110 oseltamivir-susceptible cases (60 oseltamivir-treated and 50 nontreated) were evaluated. In oseltamivir-resistant cases, fever on days 4 to 5 after the start of treatment was significantly higher in oseltamivir-treated and nontreated than in zanamivir-treated patients (P < 0.05). In oseltamivir-susceptible cases, fever was significantly lower in oseltamivir-treated than nontreated on days 3 to 6 (P < 0.01). Similar findings were obtained for duration of the fever and proportion of recurrent fever. Reduced effectiveness of oseltamivir was more prominent in children 0 to 6 years old than in those 7 to 15 years old. Multiple logistic regression analysis showed that lower age, nontreatment, and oseltamivir treatment of oseltamivir-resistant patients were factors associated with the duration of the longer fever. Infection with oseltamivir-resistant viruses significantly reduced the effectiveness of oseltamivir, and this tendency was more apparent in younger children.

Psychophysiology in visual recognition memory

Neuraminidase inhibitors, especially oseltamivir, have been used worldwide for the prophylaxis or treatment of pandemic influenza H1N1 2009 (A(H1N1)pdm09) viruses. The most commonly detected oseltamivir-resistant A(H1N1)pdm09 viruses possess the H275Y mutation in neuraminidase (NA). Recently, a novel A(H1N1)pdm09 variant containing the S247N mutation in NA was found mainly in the Asia-Pacific area. This mutation reduces sensitivity to oseltamivir and confers extremely high resistance to oseltamivir in association with the H275Y mutation compared with the resistance caused by the H275Y mutation alone. In this study, a rapid and simple one-step duplex RT-PCR assay for identifying A(H1N1)pdm09 viruses possessing the S247N mutation was developed. This assay is based on an endpoint genotyping analysis method and can use isolates from cell culture supernatants without RNA extraction, similar to the H275Y RT-PCR assay reported previously. The combination of the S247N and H275Y RT-PCR assays is a powerful surveillance method for determining whether A(H1N1)pdm09 viruses with the S247N mutation acquire the H275Y mutation.