Frequency of Amantadine-Resistant Influenza A Virus Isolated from 2001 - 02 to 2004 - 05 in Nara Prefecture

抄録

We investigated the frequency of amantadine-resistant influenza A viruses in Nara Prefecture during four epidemic seasons from 2001 - 02 to 2004 - 05. Point mutations within the M2 gene were identified using RT-PCR and DNA sequencing analysis. Five viruses (3.4%) with point mutation were observed from 145 strains analyzed. Three viruses (2.0%) possessed a change at position 31 (AGT→AAT, Ser to Asn), one virus (0.7%) showed a change at position 26 (CTT→TTT, Leu to Phe), one virus (0.7%) showed a change at position 27 (GTT→ATT, Val to Ile), and none showed a change at position 30. All of these changes were the transition type of mutation. These results indicated that the possible circulation of drug-resistant viruses to the community was not supported by the findings obtained during the 2004 - 05 season in Nara.