Impact of Mutations at Residue I223 of the Neuraminidase Protein on the Resistance Profile, Replication Level, and Virulence of the 2009 Pandemic Influenza Virus
Bibliographic record
Abstract
Amino acid substitutions at residue I223 of the neuraminidase (NA) protein have been identified in 2009 pandemic influenza (pH1N1) variants with altered susceptibilities to NA inhibitors (NAIs). We used reverse genetics and site-directed mutagenesis to generate the recombinant A/Québec/144147/09 pH1N1 wild-type virus (WT) and five (I223R, I223V, H275Y, I223V-H275Y, and I223R-H275Y) NA mutants. A fluorimetry-based assay was used to determine 50% inhibitory concentrations (IC(50)s) of oseltamivir, zanamivir, and peramivir. Replicative capacity was analyzed by viral yield assays in ST6GalI-MDCK cells. Infectivity and transmission of the WT, H275Y, and I223V-H275Y recombinant viruses were evaluated in ferrets. As expected, the H275Y mutation conferred resistance to oseltamivir (982-fold) and peramivir (661-fold) compared to the drug-susceptible recombinant WT. The single I223R mutant was associated with reduced susceptibility to oseltamivir (53-fold), zanamivir (7-fold) and peramivir (10-fold), whereas the I223V virus had reduced susceptibility to oseltamivir (6-fold) only. Interestingly, enhanced levels of resistance to oseltamivir and peramivir and reduced susceptibility to zanamivir (1,647-, 17,347-, and 16-fold increases in IC(50)s, respectively) were observed for the I223R-H275Y recombinant, while the I223V-H275Y mutant exhibited 1,733-, 2,707-, and 2-fold increases in respective IC(50)s. The I223R and I223V changes were associated with equivalent or higher viral titers in vitro compared to the recombinant WT. Infectivity and transmissibility in ferrets were comparable between the recombinant WT and the H275Y or I223V-H275Y recombinants. In conclusion, amino acid changes at residue I223 may alter the NAI susceptibilities of pH1N1 variants without compromising fitness. Consequently, I223R and I223V mutations, alone or with H275Y, need to be thoroughly monitored.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".