Scientists from The Queensland Institute of Medical Research (QIMR) have found that a group of HIV drugs known as protease inhibitors may also be effective for treating or preventing malaria.
The study, published in the December 1 issue of The Journal of Infectious Diseases, found that anti-HIV drugs inhibited the growth of Plasmodium falciparum, the malaria parasite. These findings may also expose a previously unexplored vulnerability in the parasite that could lead to a new class of anti-malarial drug.
The QIMR team, led by Dr Kathy Andrews and Dr Tina Skinner Adams, tested the effects of the protease inhibitors saquinavir, ritonavir, nelfinavir, amprenavir, and indinavir on a drug-resistant line of P. falciparum. Saquinavir, ritonavir, and indinavir all inhibited parasite growth in vitro at levels routinely achieved in human patients. Saquinavir was most effective in the study and was equally effective on drug-sensitive and -resistant parasite lines, while nelfinavir and amprenavir did not demonstrate anti-malarial activity. While the effects of these drugs on co-infection need to be investigated, the study's findings may be especially significant in sub-Saharan Africa and other areas of the developing world where there are high rates of HIV and malaria co-infection.
"We believe that antiretroviral protease inhibitors attack the malaria parasite in ways that current antimalarial treatments do not. We are currently exploring the possibility that these drugs affect the parasite by interfering with proteases that are used to digest haemoglobin, a process necessary for normal parasite growth and development.", said Dr Andrews from QIMR's Clinical Tropical Medicine Laboratory. "Further research will improve our knowledge of how to treat co-infected patients with protease inhibitors, and may also lead to a new type of malaria drug that would target the parasite in novel ways." added Dr Skinner-Adams from the Malaria Biology Laboratory at QIMR.
The World Health Organization's "3 by 5" program intends to treat three million HIV-infected people, primarily in the developing world, with anti-retrovirals by the year 2005. QIMR researchers suggest that individuals treated under programs such as this may also gain an anti-parasitic benefit. While clinical application of these novel findings is still some time away, QIMR scientists are currently actively researching interactions of protease inhibitors and current antimalarial agents in order to optimize the drugs' beneficial effects on malaria infections.
HIV Aids kills around three million people each year while malaria causes more than 300 million acute illnesses and at least one million deaths annually. Approximately 40% of the world's population, mostly those living in the world's poorest countries, is at risk of malaria.