Malaria drug takes on two deadly emerging viruses

March 6th, 2009 - 1:46 pm ICT by IANS  

Washington, March 6 (IANS) Two lethal viruses that have emerged in recent outbreaks met their nemesis in chloroquine, an established drug to prevent and treat malaria, according to a new study.
The two henipaviruses that are the subject of the study - Hendra Virus (HeV) and Nipah Virus (NiV) - emerged during the 1990s in Australia and Southeast Asia. Harboured by fruit bats, they cause potentially fatal encephalitis and respiratory disease in humans, with a devastating 75 percent fatality rate.

More recently, NiV outbreaks in Bangladesh involving human-to-human transmission have focussed attention on it as a global health concern.

The researchers, based in Weill Cornell Medical College’s (WCMC) paediatrics department, were surprised by their discovery that chloroquine, a safe, low-cost medicine that has been used to combat malaria for more than 50 years, is a highly active inhibitor of infection by Hendra and Nipah.

“The fact that chloroquine is safe and widely used in humans means that it may bypass the usual barriers associated with drug development and move quickly into clinical trials,” said Anne Moscona, professor of paediatrics and microbiology & immunology at WCMC and study co-author.

“Chloroquine stands a good chance of making it through the development process in time to prevent further outbreaks of these deadly infections,” added Moscona.

Like the avian flu, SARS, and Ebola viruses, Hendra and Nipah are zoonotic pathogens. That means they originate in certain animals but can jump between animal species and between animals and humans.

There are currently no vaccines or treatments against the two henipaviruses, which are listed by the US government as possible bio-terror agents.

Chloroquine does not prevent Hendra or Nipah virus from entering the cell. Instead, the chloroquine molecule appears to block the action of a key enzyme, called cathepsin L, which is essential to the virus’s growth and maturation, said a WCMC release.

Without this enzyme, newly formed Hendra or Nipah viruses cannot process the protein that permits the viruses to fuse with the host cell. Newly formed viruses then cannot spread the infection; in other words, they can invade, but cannot cause disease.

These findings were published in the Journal of Virology.

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