Amantadine-resistant influenza A viruses isolated in South Korea from 2003 to 2009.
To investigate the frequency of amantadine resistance among influenza A viruses isolated in Korea during the 2003-2009 seasons, 369 (16.8%) 2199 A/H1N1 viruses and 780 (14.8%) of 5263 A/H3N2 viruses were randomly selected. The M2 and HA1 genes of each isolate were amplified by reverse transcription-polymerase chain reaction and followed by nucleotide sequencing. The results showed that the resistance rate to amantadine among A/H1N1 viruses increased significantly from 2004-2005 (33.3%) to 2007-2008 (97.8%) and then decreased dramatically in 2008-2009 (1.9%). The A/H1N1 isolates recently detected in 2008-2009 turned amantadine-sensitive containing two new substitutions at specific sites (S141N, G185A) in HA1. Compared with A/H1N1 viruses, the amantadine resistance among the A/H3N2 viruses increased from 2003-2004 (9.7%) to 2005-2006 (96.7%) and decreased in 2006-2007 (57.4%). During 2006-2007, both of amantadine-resistant and -sensitive A/H3N2 viruses co-circulated but clustered in different branches phylogenetically. All of A/H3N2 isolates tested during 2007-2009 appeared to cluster in the same group being resistant to amantadine.
Choi
Woo-Young
WY
Division of Influenza and Respiratory Viruses, Center for Infectious Diseases, National Institute of Health, Korea Centers for Disease Control & Prevention, Seoul, Republic of Korea. wychoi65@hanmail.net
Kim
SuJin
S
Lee
NamJoo
N
Kwon
Meehwa
M
Yang
InSeok
I
Kim
Min-Ji
MJ
Cheong
Seul-Gi
SG
Kwon
Donghyok
D
Lee
Joo-Yeon
JY
Oh
Hee-Bok
HB
Kang
Chun
C
D000547:Amantadine / Q000494:pharmacology*; D019943:Amino Acid Substitution; D000998:Antiviral Agents / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology / Q000821:virology; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D017422:Sequence Analysis, DNA; D014763:Viral Matrix Proteins / Q000235:genetics
D000998:Antiviral Agents; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D014763:Viral Matrix Proteins; D000547:Amantadine