Avian influenza virus resistant to drugs

Mutation of the bird flu virus leads to resistance

05/30/2013

Chinese researchers warn against mutations of the bird flu virus H7N9. The bird flu infections that are currently rampant in China, which have already caused numerous deaths, are at least partially caused by pathogens that are resistant to common antiviral drugs, according to scientists from the Shanghai Public Health Clinical Center and Fudan University Shanghai in the renowned specialist journal „The Lancet“.

The reported poor treatment outlook for H7N9 infections in China is associated with pathogen resistance in the view of the scientists. Researchers studied 14 patients with H7N9 infection treated at the Shanghai Public Health Clinical Center as part of their study. „We analyzed the viral load in the throat, stool, serum and in urine samples that had been obtained from these patients“, the researchers write. Also, the viral RNA from the samples was sequenced to investigate possible mutations, to detect resistance to neuraminidase inhibitors, and to test their association with disease progression.

Resistance leads to complete treatment failure
The Chinese scientists report that all patients developed severe bird flu symptoms such as pneumonia, seven had to be artificially ventilated, three patients continued to worsen and two died. In eleven patients, the antiviral treatment initiated with the active substances oseltamivir (brand name Tamiflu) or peramivir had a clear „Reduction of viral load in throat swabs“ result. For the rest, the drugs did not show the desired success. The researchers then found that two of these patients, who had also received corticosteroids, had one „Arg292Lys mutation in the virus neuraminidase (NA) gene“ exhibited. The mutation is also associated with a resistance to the antiviral drugs, which ultimately resulted in the victims a complete treatment failure and death.

The resistance of the bird flu virus evolved with obvious ease and appears to be extremely questionable, the researchers report. „The development of antiviral resistance in H7N9 viruses, particularly in patients receiving corticosteroid therapy, is worrying, needs to be closely monitored, and considered in pandemic planning“, so the conclusion of the Chinese scientists. (Fp)

Picture: Gerd Altmann