Friday, October 28, 2011

H1N1: Novel human influenza virus changes its genetic make-up, develops resistance to oseltamivir

Syed Akbar
Hyderabad: Causing concern to doctors, the novel human
influenza virus has changed its genetic make-up, developing resistance
to the commonly used drug, oseltamivir, for treatment of human flu.

The flu virus is made up of two antigens, hemagglutinin and
neuraminidase, which gives it the nomenclature HN. There are 16
different types of hemagglutinin and nine variants of neuraminidase.
Depending on the type, the flu virus is named, for instance H1N1 in
the case of the novel human influenza.

The virus has now developed changes or mutations in the neuraminidase
active site. And this has reduced the susceptibility of the virus to
oseltamivir. Incidentally, the novel human influenza virus has been
responding to only two drugs, one of which is oseltamivir.

"Resistance to oseltamivir is a major concern. But the mutation was
found in only a small isolates of flu virus. If this spreads to a
large geographical area, the problem may be difficult to tackle. At
present the mutation has been found in a small pocket in the USA. In
view of global movement of people, it's only a matter of time before
it spreads if preventive measures are not taken," senior geneticist Dr
MN Khaja pointed out.

The current monsoon season and the ensuing winter is conducive for the
spread of influenza virus. Hyderabad and other places in the State
have recorded hundreds of cases of human influenza cases in the last
three years. There were several deaths too.

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