February 2, 2010
A genetically mutated avian flu virus is believed to be behind a string of deadly outbreaks in bird populations over the past two years, a scientist said on Tuesday, warning that the new virus had the potential to be more lethal than its ancestor should it infect humans.
Virologist I Gusti Ngurah Mahardhika said the government’s vaccination program with a large number of poultry farms in the past few years may backfire because the mutation was partly suspected to have been caused by an outdated vaccine.
“I have strong evidence that the old vaccine seed [already developed by the country’s vaccine makers] cannot stop the new virus,” said Mahardhika, who is also head of the Biomedical and Molecular Biology Laboratory at the Udayana University’s Veterinary Medicine School.
He said isolated virus samples taken from already vaccinated farms in Java, Sumatra, Bali and Sulawesi from 2008 to 2009 were compared with samples from their ancestor H5N1 virus taken from Legok, Banten, in 2003.
“From the study, we found genetic differences of up to 8.7 percent from the ancestor virus,” he said.
The Legok virus is still being used by most vaccine producers here as the vaccine seed and the recent mutations may mean the seed virus is outdated. The genetic differences in the virus samples are mostly represented by changes in the acid composition, or RNA [ribonucleic acid], which “have never been found before [in the 2003 virus samples].” Genetic mutations, according to Mahardhika, could be triggered by either natural causes or vaccine resistance. In the case of samples he studied, Mahardhika said the changes pointed more to the possibility of vaccine resistance rather than natural causes.
“Flu viruses are highly mutagenic and their RNA structure can quite easily undergo changes, or a deletion. The vaccine also has a masking effect whereby it only provokes immunity in the birds’ respiratory systems although the virus can still be found in the bird’s saliva. So now we can see a seemingly healthy chicken but its droppings and saliva are full of this virus,” he said.
Microbiology clinic professor with the University of Indonesia, Amin Soebandrio, concurred with Mahardhika’s findings, saying he had suspected that such changes would come.
“Research has also been carried out by my students on a similar issue using only 2004 virus samples. And genetic changes are apparent.”
Amin said further study must be done to check whether the changes directly affect the resistance of the virus to the vaccine being used by the government.
“We need to see whether the changes increase the capacity of the virus to infect the human respiratory system,” he said. “If that’s the case, it’s more than likely the virus will also be resistant to the antiviral we are now using to treat patients with avian influenza.”
Tjandra Yoga Aditama, the director general of disease monitoring at the Ministry of Health said the public should not worry too much about these findings because it did not mean a new virus had been created.
“Viruses always have the potential to mutate, that’s common in nature, but these studies don’t meant we’ve found a new strain of virus,” he said.
Memed Zoelkarnain, spokesman for the National Commission for Avian Influenza and Pandemic Prevention, said the findings must be studied further in a bid not to scare people and called on the media to be sensible when reporting on this issue given the findings are preliminary.
“We don’t want to frighten the public,” he said.
Memed, also a veterinary doctor, said Mahardhika should double check with “all vaccine makers” because there was more than one vaccine maker in the country but only a few of them used the 2003 vaccine seed.
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