Gates Foundation's Grand Challenges Explorations Award for Hasegawa and team

Tuesday, June 3rd, 2014
Gates Foundation

A team comprising inStem's Kouichi Hasegawa, AstraZeneca's Vasan Sambandamurthy and Susanta Ghosh of the National Institute of Malaria Research has won the Grand Challenges Explorations grant awarded by the Bill & Melinda Gates Foundation. Hasegawa, Sambandamurthy, Ghosh and Varadharajan Sundaramurthy (NCBS) propose to develop an assay of the liver-stage (one of the several life stages) of the malaria-causing protozoan Plasmodium vivax. They will use the latest techniques in stem cell biology to develop this new assay to make it suitable for drug screening. With this venture, Hasegawa, Sambandamurthy and their team hope to throw light on the poorly-understood biology of P. vivax. The new information they generate will bring science many steps closer to controlling and ultimately eradicating P. vivax-driven malaria, a dreaded disease afflicting people in many tropical countries.

A glance at the global statistics speaks volumes about the magnitude and prevalence of malaria. Malaria affects nearly half of the world's population. An estimated 500 million people suffer from the disease annually across almost 100 countries. One to two million deaths are attributed to malaria every year, and nearly 90% of these are children in sub-Saharan Africa.

Tiny parasitic protozoans belonging to the genus Plasmodium wreak all this havoc. These protozoans complete their life cycle in two hosts: a mosquito (which is the carrier of the disease, or vector) and a vertebrate host. Infected female Anopheles mosquitoes transmit infective forms of Plasmodium to humans through bites. These infective forms invade the bloodstream and migrate into the liver, afflicting hepatocytes or liver cells. During this process, the parasites multiply, rupture the hepatocytes and foray into the bloodstream again where they infect the red blood cells (RBCs). This brings on fevers and chills, symptoms characteristic of malaria.

Atleast six Plasmodium species infect humans this way. Plasmodium falciparum is often considered the deadlier form of the parasite due to its high mortality. However, infections from Plasmodium vivax are equally debilitating and are endemic in large parts of the world, including India. Unlike P. falciparum, P. vivax has the unique ability to remain dormant in the human liver. Hypnozoites, as they are called during this stage of dormancy, can revive and resurface in the bloodstream anytime after 3 weeks or several years. Hence a single bite from a P. vivax infected mosquito can cause multiple episodes of malaria spread over months to years. Yet, very little is known about these hypnozoite forms that cause relapses, another reason why P.vivax infections have proved so difficult to eradicate.

Such characteristics coupled with the lack of an effective vaccine to eradicate malaria make diagnosis crucial for timely control and treatment. Microscopic examination of a patient's blood can reveal the presence of a malarial infection. More sophisticated molecular methods such as the polymerase chain reaction are often more effective than microscopy. But high costs and the need of specialized laboratories and technicians make it difficult for many countries to afford such diagnostic methods.

Hasegawa and the team aim to establish a cross-disciplinary platform to develop a robust, reliable and cost-effective assay that can be used to study the hypnozoites of P. vivax under in vitro conditions. "We will combine our expertise to develop a reliable malaria screening system with induced pluripotent stem (iPS) cells derived from patients to develop drugs as well as to study the molecular mechanisms of malaria infection and its development in hepatocytes," says Hasegawa. Typically, liver cell lines show very low levels of infectivity with P. vivax. This has impeded the development of a robust screening assay against P. vivax. The scientists plan to circumvent this by first deriving hepatocytes using iPS cells (stem cells generated from adult cells, which can form any kind of cell) from confirmed P.vivax patients. If these cells are permissible for P. vivax infection, it could prove to be an unlimited source of infectable hepatocytes which can help the scientists study the biology of P. vivax in detail. At present, primaquine is the only drug that can help eradicate the liver-dwelling form of P.vivax. The development of the new assay can potentially help discover novel drugs to target hypnozoites. Moreover, a variety of hepatocyte cell lines can be set up with the information generated from this work, which can serve as biological models for future studies. Screening a chemical library against hypnozoites of P. vivax grown in human hepatocytes is likely to lead to novel compounds that could eradicate vivax malaria. "A successful approach in generating iPS derived hepatocytes permissive to P. vivax infection will be a breakthrough in the field of vivax biology," says Vasan Sambandamurthy. "Such a system would be highly reproducible and cost effective in screening large compound libraries and pave way for the identification of drugs that can provide a radical cure for vivax malaria."

"I think this is a good multi-disciplinary and translational project with components of parasitology, pharmacology and stem cell biology," says Hasegawa. "This project is very exciting as it aims to synergise expertise from very different areas like stem cell biology, infection biology and field medicine in an effort to develop the much needed tools to address the elusive liver stage vivax biology," says Sundaramurthy.

The work also has particular relevance in India, where P. vivax causes a form of malaria that is endemic in many parts of the country, says Sundaramurthy. "It is both a serious and fascinating pathogen whose biology is relatively underexplored, largely due to the lack of suitable experimental systems and tools." Despite the challenges, the team of experts are looking forward to the project.

"Developing the assay as per stringent quality control metrics could go a long way in setting up a screening platform to identify suitable small molecules that impede the intracellular growth and development of the pathogen," says Sundaramurthy. He adds that this work will also help better understand the mechanism causing the disease.

"The Gates Foundation Award gives us a great opportunity to embark on this project," says Hasegawa. This is the first ever Gates Foundation grant that has been awarded to the Bangalore BioCluster. "It feels great to have our project shortlisted for funding from a total of almost 150 research proposals," says Sambandamurthy. "This highlights the global urgency and potential of this work to address an important unmet medical need to treat and eradicate vivax malaria." The Grand Challenges Explorations grants aim to "foster innovation in global health research". The Grand Challenges Explorations grants program was launched in 2008 and now more than 900 grants have been awarded to innovative, early-stage projects in more than 50 countries. While initial grants of $100,000 are awarded two times a year, successful projects can receive a follow-on grant of up to $1 million. The Bill & Melinda Gates Foundation has committed almost $100 million to develop solutions to pressing health concerns worldwide.

And with a staggering two million deaths per year, malaria is indeed one among the most pressing health concerns of modern times. The information that Hasegawa, Sundaramurthy and team will be able to generate can help build baseline data about P. vivax. Moreover, this data that could develop a potential drug to eradicate malaria would be a godsend for most developing countries of the tropics.


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