[Resistance in influenza viruses].
BACKGROUND
Influenza virus infection can be prevented and treated with antiviral drugs. The usage of such drugs in Norway has been infrequent, however, they are an important component in our pandemic preparedness planning, as it will probably be difficult to get access to the appropriate vaccine in time before the pandemic reaches the country. The first generation of influenza drugs acquired resistance to a large degree, in contrast to the modern neuraminidase inhibitors that until recently have had minor problems with resistance.


METHODS
This review is based on research found in relevant published literature, together with experience from a virology reference laboratory and participation in a national and international surveillance including susceptibility testing.


CONCLUSIONS
While resistance has been a longstanding problem with the use of the "old" influenza drugs amantadine and rimantadine, only during the winter 2007/2008 did it become clear, that a certain type of virus acquired widespread resistance against the neuraminidase inhibitor oseltamivir. Resistance surveillance is crucial for the correct choice of empiric treatment for influenza infection, and will be one of the most important tasks at the National Influenza Centre in certain phases of a pandemic. The current situation with an increasing resistance problem strengthens the need to conduct continuous monitoring of antiviral susceptibility, as well as development of new antiviral drugs and treatment regimes.
Hungnes
Olav
O
Avdeling for virologi, Nasjonalt folkehelseinstitutt, Postboks 4404 Nydalen, 0403 Oslo. olav.hungnes@fhi.no
Dudman
Susanne Gjeruldsen
SG
D000818:Animals; D000998:Antiviral Agents / Q000009:adverse effects / Q000627:therapeutic use; D001717:Birds; D003140:Communicable Disease Control; D004196:Disease Outbreaks / Q000517:prevention & control; D024882:Drug Resistance, Viral / Q000235:genetics; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects / Q000235:genetics; D009981:Influenza B virus / Q000187:drug effects / Q000235:genetics; D005585:Influenza in Birds / Q000635:transmission / Q000821:virology; D007251:Influenza, Human / Q000188:drug therapy*; D009982:Gammainfluenzavirus / Q000187:drug effects / Q000235:genetics; D007391:International Cooperation; D009439:Neuraminidase / Q000037:antagonists & inhibitors; D009975:Orthomyxoviridae / Q000187:drug effects / Q000235:genetics; D014763:Viral Matrix Proteins / Q000187:drug effects; D015047:Zoonoses / Q000821:virology; D000086082:Viroporin Proteins
D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D009439:Neuraminidase; D014763:Viral Matrix Proteins; C488937:M2 protein, Influenza A virus; D000086082:Viroporin Proteins