Photo courtesy of CDC
Past research has shown that malaria-carrying mosquitoes prefer to feed on humans who are already infected with malaria.
Now, researchers believe they have discovered why.
The
team identified a naturally occurring compound, known as HMBPP, that is derived from the malaria parasite Plasmodium falciparum and
triggers the release of mosquito-attracting chemicals, making a human
host more enticing to the insects.
“The malaria parasite produces a molecule, HMBPP, which stimulates the human red blood cells to release more carbon dioxide and volatile compounds with an irresistible smell to malaria mosquitoes,” explained study author Ingrid Faye, of Stockholm University in Sweden.
She and her colleagues described this discovery in Science.
To determine if HMBPP could influence mosquitoes’ blood-meal-seeking and feeding behaviors, the researchers devised a “dual choice attraction” test for Anopheles gambiae mosquitoes.
Specifically, the team evaluated the mosquitoes’ preference to land on and feed off of an artificial membrane containing HMBPP-supplemented red blood cells (hmbRBCs) or normal red blood cells (RBCs).
More than 95% of the mosquitoes tested chose hmbRBCs over RBCs, and the mosquitoes consumed hmbRBCs more intensively and for longer periods of time than they did RBCs.
The researchers also found that blood spiked with HMBPP activated the expression of Plasmodium-specific genes involved in protecting the mosquitoes’ vital functions while also improving receptivity to infection and amplifying the likelihood of parasite transmission.
“This seems to be a well-functioning system, developed over millions of years, which means that the malaria parasite can survive and spread to more people without killing the host,” Faye said.
She and her colleagues believe the discovery of HMBPP as a driver of mosquito attraction exposes a weakness in Plasmodium that could be exploited to better pinpoint disease-carrying Anopheles gambiae mosquitoes and possibly prevent the spread of malaria.
