Common medicine found able to overcome drug-resistant viruses

University of Hong Kong (HKU) researchers have discovered a new flu treatment that may resolve the growing problem of influenza viruses becoming resistant to medications.

The methodology requires boosting the body's natural immune system to kill flu virus-infected cells.

Scientists of HKU found that a drug for treating bone disease, Pamidornate, rapidly and significantly increases a white blood cell subset called gamma-delta T cells.

These particular cells can recognize infected cells, punch holes in them, inject an enzyme and kill the cells.

Tests on mice have proven the treatment can effectively inhibit virus replication and prevent inflammation of infected lungs.

The virus decreased by 100 fold in mice given Pamidornate treatment.

The treatment is capable of controlling all strains of influenza caused by seasonal, pandemic and avian H5N1 influenza viruses.

The research was led by five scholars at the Li Ka Shing Faculty of Medicine at the university.

The study has been published in the Journal of Experimental Medicine.

The next stage of the scientific research will move into human clinical trials to observe the effectiveness of treatment and to develop a reasonable dosage range.

Lau Yu-lung, a professor of the HKU medical school, said flu viruses are "unlikely" to acquire resistance to the action of the gamma-delta T cells, as the cells are part of the natural immune system of the human body.

Conventional drugs, however, target special viral proteins in order to block the virus's entry into cells.

Increasingly more flu strains has been found resistant to anti-viral drugs in recent years, including the H1N1 swine flu medication, Tamiflu.

Lau noted that there is "an acute need" to develop alternative strategies for flu therapy.

The researchers believe the bone-disease medication can be "a ready and cost-effective solution".

The advantage of the "new application of an old drug" is that the safety of the drug is already proven.

The drug has been used to treat osteoporosis and Paget's disease for two decades. The side effects are limited.

It is also affordable. Associate Professor Tu Wenwei said the price for the drug is similar to that of Tamiflu, about $8-10, or HK$62-78, a dose.

Animal testing proved a major challenge of the research.

The test may not be done on normal laboratory rats which lack human immune cells.

Tu developed a strain of mice with immune systems similar to humans in 2008.

HKU owns one of the few laboratories worldwide to possess the mice.

Tu revealed that the researchers also are studying whether the therapy can be applied to the treatment of other diseases such as cancer, since the action of gamma-delta T cells doesn't target on the flu virus in particular but on malfunctioning cells.

"It works theoretically, but there's no proof yet," he said.

guojiaxue@chinadailyhk.com

China Daily

(HK Edition 06/30/2011 page1)