Antiviral resistance in influenza viruses circulating in Central and South America based on the detection of established genetic markers.
BACKGROUND
Recent influenza antiviral resistance studies reveal an alarming increase in both adamantanes and neuraminidase inhibitors (NAIs) resistant viral strains worldwide, particularly in Asia, Europe and the United States.


OBJECTIVE
In this study, we have evaluated influenza virus resistance in Central and South America.


METHODS
Influenza viruses, isolated from symptomatic patients throughout Central and South America in 2005-2008 were analyzed for inhibitor resistance. The M2 and NA genes of influenza viruses were sequenced and resistance was inferred by comparison with published sequences and known resistant mutations.


RESULTS
Our results indicate that: (i) resistance to adamantanes was seen in the majority (95.5%) of the influenza A/H3N2 isolates but only in one isolate of the influenza A/H1N1 viruses; (ii) resistance to NAIs began to be detected in A/H1N1 isolates from Central America in 2008; and (iii) none of the influenza B viruses analyzed were resistant to NAIs.


CONCLUSIONS
These findings suggest a limited effectiveness of influenza inhibitors due to the detection of resistance among A/H1 and A/H3 viruses.
García
Josefina
J
US Naval Medical Research Center Detachment, Lima, Peru. josefina.garcia@med.navy.mil
Sovero
Merly
M
Torres
Alberto L
AL
Gomez
Jorge
J
Douce
Richard
R
Barrantes
Melvin
M
Sanchez
Felix
F
Jimenez
Mirna
M
Comach
Guillermo
G
de Rivera
Ivette
I
Agudo
Roberto
R
Kochel
Tadeusz
T
D000218:Adamantane / Q000494:pharmacology / Q000627:therapeutic use; D000595:Amino Acid Sequence; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002460:Cell Line; D002489:Central America; D004285:Dogs; D024882:Drug Resistance, Viral; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D053122:Influenza A Virus, H3N2 Subtype / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000188:drug therapy / Q000821:virology*; D008297:Male; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics*; D009975:Orthomyxoviridae / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D053139:Oseltamivir / Q000494:pharmacology / Q000627:therapeutic use; D016415:Sequence Alignment; D013020:South America; D014763:Viral Matrix Proteins / Q000737:chemistry / Q000235:genetics*
D000998:Antiviral Agents; D014763:Viral Matrix Proteins; D053139:Oseltamivir; D009439:Neuraminidase; D000218:Adamantane