An old osteoporosis drug may be effective in killing a range of influenza viruses, including ones that are very dangerous to people like the H5N1 bird flu virus, scientists in Hong Kong reported on Wednesday.
Unlike antiviral drugs that target and mute flu viruses, the drug pamidronate boosts a certain class of human immune cells and sets them off on a killing spree to exterminate host cells that are infected with flu viruses.
The experts, who published their findings in the Journal of Experimental Medicine, described the immune cells — called gamma-delta T-cells — as being able to recognize host cells that are infected with flu viruses. They punch holes through the membrane of the infected cells, then secrete and inject an enzyme into the cells, killing them.
“The drug activates and expands this group of T-cells, their numbers dramatically increase and they kill these virus-infected cells by secreting and injecting an enzyme,” said Professor Malik Peiris, a member of the research team and leading microbiologist at the University of Hong Kong.
Unlike antiviral drugs, which constantly face the prospect of becoming useless because viruses mutate and become resistant, this drug does not deal directly with flu viruses.
“This drug boosts our own immune system, so the likelihood of it triggering a mutation (that results in viruses becoming resistant) is lower,” said Professor Lau Yu-lung, head of pediatrics and adolescent medicine at the same university.