Abstract: Majority of the samples had some mutations in the NA gene notably: I117M, N248D, and N369K while the amantadine-resistant M mutant, S31N, was found to be absent only in the two sequences collected in 2014.
Result: The amino acid substitution S31N is the predominant amantadine-resistant M2 mutant and was found to be present in almost all of the circulating influenza A(H1N1)pdm09 strains except the two strains collected in 2014.
Discussion: Meanwhile, the amino acid substitution S31N in the M2 protein was found to be present in all but the 2014 strains.
Genetic diversity of influenza A(H3N2) viruses in Northern Cameroon during the 2014-2016 influenza seasons.
Abstract: Analysis of the coding regions of the NA and M genes showed that none had genetic markers of resistance to neuraminidase inhibitors but all strains possessed the S31N substitution of resistance to amantadine.
Evolved avian influenza virus (H7N9) isolated from human cases in a middle Yangtze River city in China, from February to April 2017.
Abstract: In this study, serial viral passages were applied to select resistance against a newly developed isoxazole-conjugated adamantane inhibitor that targets the AM2 S31N channel.
Abstract: It was found that the L46P mutation caused a conformational change in the N terminus of transmembrane residues 22-31 that ultimately broadened the drug-binding site of AM2 S31N inhibitor 4, which spans residues 26-34, but not of AM2 WT inhibitor amantadine, which spans residues 31-34.
Abstract: Molecular dynamics simulations showed that L46P causes a dilation of drug-binding site between residues 22 and 31, which affects the binding of AM2 S31N channel blockers, but not the AM2 WT inhibitor amantadine.
Abstract: Overall, these results demonstrate a unique allosteric resistance mechanism toward AM2
Amantadine resistance markers among low pathogenic avian influenza H9N2 viruses isolated from poultry in India, during 2009-2017.
Abstract: Matrix genes of 48H9N2 viruses isolated from India during 2009-2017 were sequenced and M2 trans-membrane region sequences were screened for mutations which are known to confer resistance to amantadine namely, L26F, V27A, A30 T/V, S31N and G34E.
Abstract: Four isolates showed presence of V27A + S31 N dual mutations.
Abstract: Majority of the resistant viruses exhibited S31 N mutation.
Genetic and Phylogenetic Characterization of the M Gene of Influenza A Virus Isolated from Iranian Patients.
PMID: 31223581
2019
Iranian journal of public health
Abstract: Amino acid sequence analysis showed S31N substitution in all isolates rendering the virus resistant to adamantanes.
Result: All Iranian H1N1 and H3N2 studied isolates possessed the most frequently adamantane-drug resistance mutation resulted in the amino acid substitution S31N in the M2 protein.
Discussion: However, some limited studies carried on Iranian isolates got from 2005 to 2008 have demonstrated the prevalence of amantadine-resistance A (H3N2) mutants, all resulted in the amino acid substitution S31N in the M2 protein.
Discussion: The present study showed that all strains of H1N1 and H3N2 subtypes contained the amino acid substitutions S31N, as expected.
Discussion: The single point mutation at position 31 (S31N
Complete genome sequencing of H1N1pdm09 swine influenza isolates from Nigeria reveals likely reverse zoonotic transmission at the human-animal interface in intensive piggery.
Abstract: A Q240R and S31N substitution among others were detected in the haemagglutinin and matrix genes, respectively, indicating potentials for mutations during interspecies co-mingling and transmission.
Result: There were no observed substitutions in the matrix gene except S31N that has been described for most influenza A/H1N1pdm09 isolates as the predominant amantadine-resistant mutation in M2.
Influenza A virus hemagglutinin mutations associated with use of neuraminidase inhibitors correlate with decreased inhibition by anti-influenza antibodies.
Result: Examples include NA H275Y in the pre-2009-pandemic H1N1 lineage and M2 S31 N in the majority of currently circulating seasonal influenza viruses as well as other viruses.
Mechanism and Kinetics of Copper Complexes Binding to the Influenza A M2 S31N and S31N/G34E Channels.
Abstract: Here, we investigate these concepts to explain binding and proton blockage of rimantadine variants bearing progressively larger alkyl groups to influenza A virus M2 wild type (WT) and M2 S31N protein proton channel.
Abstract: This is due to the fact that, in M2 S31N, the loss of the V27 pocket for the adamantyl cage resulted in low residence time inside the M2 pore.
Abstract: We showed that resistance of M2 S31N to rimantadine analogues compared to M2 WT resulted from their higher koff rates compared to the kon rates according to electrophysiology (EP) measurements.
Mechanism and Kinetics of Copper Complexes Binding to the Influenza A M2 S31N and S31N/G34E Channels.
Result: AM2-S31N inhibitors 1 and 2 have potent channel blockage and antiviral activity.
Result: After drug withdrawal at 1P10 for three additional passages, the 1P13 viral population retained the AM2-S31N/V27I mutation.
Result: After the second passage, the population of AM2-S31N viruses eclipsed the AM2-S31N/L26I/A30T triple mutant.
Result: a mutation of the channel facing residue alanine 30 to threonine not only changes the channel pore size, but also the polarity of the channel, which may explain the complete resistance of the AM2-S31N/L26I/A30T to compounds 1 and 2.
IV mutation literature information.
PMID: 
2019
PloS one
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