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of poultry farms in the past few years may backfire because the mutation was partly suspected to have been caused by an outdated vaccine.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still being used by most vaccine producers here as the vaccine seed and the recent mutations may mean the seed virus is outdated.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.
The most recent viral outbreak in poultry populations was reported on Monday from Pekanbaru where thousands of chickens died in several villages. In one of the villages in Indragiri Hulu, two toddlers — aged three years and six months old — are suspected of having been infected.
A Web site jointly developed by Surabaya’s Airlangga University and Kobe University in Japan, www.birdflucorner.wordpress.com, reported that the two neighboring toddlers had had a history of contact with dead chickens.
Indonesia has been the hardest hit by the spread of avian flu, both in humans and poultry. The first outbreaks in bird populations were reported in 2003 with the virus spreading to humans two years later. At least 125 people have died of this bird flu.
So far, human infections can only result from direct contact with dead fowls and there is no scientific evidence that the virus is able to transmit from human to human although suspicions were raised after a few cluster cases were found in which a number of members from the same family had became infected. Simple hygienic practices such as hand washing help prevent infections.
Microbiology clinic professor with the University of Indonesia, Amin Soebandrio, concurred with Mahardhika’s findings, saying he had suspected that such changes would come.
Source: http://www.thejakartaglobe.com/home/mutated-bird-flu-virus-raises-doubts-about-the-effectiveness-of-flu-vaccines/356376 
