Breakthrough: Scientists in India make progress towards a viable Malaria vaccine

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Anopheles mosquito. Pic credit: http://www.cdc.gov/malaria/about/biology/mosquitoes/
Anopheles mosquito
Pic credit: http://www.cdc.gov/malaria/about/biology/mosquitoes/

Scientists from Jawaharlal Nehru University (JNU) and International Centre for Genetic engineering and biotechnology in New Delhi, India have discovered a novel molecule that could be a viable target for vaccines against malaria.

The quest for a malaria vaccine has been going on for decades now, with over 200 million people being affected annually, and  over 3.2 billion people at the risk of  malaria (WHO ). Most deaths occur among children living in Africa where a child dies every minute from malaria.  In the light of these concerns, the new findings by scientists in India give hope for a malaria vaccine in the near future.

Malaria is caused by a parasite called Plasmodium which spreads to people through the bites of Anopheles mosquito which acts as the carrier. One of the crucial steps in malaria pathogenesis, is attachment of the parasite to the red blood cells of the host and its subsequent invasion.

A successful blood-stage malaria vaccine should ideally block this process and there have been several candidates such as MSP-1 and AMA-1 which have been tested in field trials, but due to their polymorphism(or multiple forms of these proteins) , they have not been able to elicit strain-transcending neutralizing antibodies. However, amongst the repertoire of proteins which were tested, the most ideal candidate was the Plasmodium falciparum reticulocyte binding-like homologous protein 5 (PfRH5) protein which binds to the erythrocytes receptor, Basigin.

PfRH5 is also a leading candidate due to their limited polymorphism and their ability to elicit potent inhibitory antibodies. It attaches to the merozoite surface in conjunction with its partner, PfRH5-interacting protein (PfRipr) through a yet unknown mechanism. Scientists from  ICGEB and JNU, have now discovered a previously unidentified protein complex formation between PfRH5-PfRipr and Cysteine-rich protective antigen (CyRPA), a conserved GPI-anchored protein which anchors this complex on the merozoite surface and together they facilitate the interaction between the parasite(PfRH5 ligand) and erythrocytes(Basigin receptor) during entry. Thus, this complex  offers a highly conserved and potent target which could be the basis for future antimalarial vaccines and strategies.

Dr Deepak Gaur, a malaria scientist, at these institutions told NDTV, “This is an Indian discovery of a novel antigen, which is very essential for the parasite to enter the red blood cells, and what we have shown is that antibodies against this novel antigen can block the parasite from entering the red blood cells and it works against multiple strains across the world. Hence, it has great relevance with respect to developing a malaria vaccine in the future.”

However, it would take atleast another decade of hard work by the team before a malaria vaccine becomes a reality.

Source:

http://www.pnas.org/content/early/2015/01/08/1415466112.abstract?sid=50f1b617-2fe0-41b7-ac00-3315d599e545

http://www.who.int/features/factfiles/malaria/en/

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