Result: To evaluate the role of swine as the host for influenza A viruses harboring the I27T-M2, we analyzed sequences with this substitution that were available in the IRD: 96.7% (589/609) genes were of swine origin, and 97.3% (573/609) were reported from the U.S., suggesting that viruses with the I27T-M2 were predominantly circulating in swine populations (data not shown).

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Discussion: Together, these data suggest that the possible spread of variant viruses carrying an M gene of classic swine origin, of which 43% possess the I27T- Discussion: We identified the I27T-M2 as the amino acid substitution that confers an intermediate level of resistance to amantadine in IAV-S of classic swine M lineage.

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