Menace Malaria
Mumbai: Scientists in the UK
have discovered how a promising malaria vaccine target - the protein RH5 -
helps parasites to invade human red blood cells, anadvance that could help
develop a more effective vaccine for thedisease.
Researchers at the Wellcome Trust
Sanger Institute found that a previously mysterious protein on the surface of
the parasite called P113 anchors the RH5 protein, and provides a molecular
bridge between the parasite and a red blood cell. Previous research by teams at
the Sanger Institute discovered that to invade human red blood cells,
Plasmodium parasites need RH5 to bind to a receptor called basigin on the
surface of the blood cells. However, it was not known how RH5 was attached to
the surface of the parasite.
In this
latest study, researchers discovered that when the Plasmodium RH5 protein is
released, it is immediately caught by another parasite protein called P113.
Thousands of
P113 molecules on the surface of each parasite act like a velcro chain,
capturing RH5 at the surface of the parasite.
The tethered
RH5 then binds to the basigin receptor on the human red blood cell, bridging
the gap just long enough to let the parasite invade the blood cell.
“We knew both
proteins were essential for invasion but this is the first time anyone has seen
the interaction between RH5 and P113 and showed that they work together,” said
Julian Rayner, from the Sanger Institute.
In theory, an
antibody that blocked P113 could stop RH5 binding, and prevent the parasite
from gaining entry to red blood cells. This makes the P113 protein another good
vaccine target,” said Rayner. Two more proteins - CyRPA and RIPR - were already
known to be essential to the parasite and to form a complex with RH5.
Researchers uncovered the details of
how these three proteins bound to each other and that only one small part of
the RH5 protein was needed to bind P113. This small region could become an
easy-to-produce and cost-effective part of a multicomponent malaria vaccine.
“RH5 is an
excellent vaccine target because it is essential for invasion by all strains of
Plasmodium falciparum, the species of parasite that causes the most severe
disease in humans,” Dr Francis Galway, from the Sanger Institute.
Source: DNA-13th February,2017
