Malaria's severity reset by mosquito

May 30, 2013
Mosquito transmission of P.c. chabaudi modifies parasite gene expression in the blood stage of the cycle.

(Medical Xpress)—For the first time, researchers have proven that the way in which malaria is transmitted to the host affects how severe the resulting infection will be.

The route of infection modifies the 's gene activity levels and regulates the parasite's spread in the blood by controlling the mouse's . This study begins to understand how to malaria occurs, an important step for the development of effective vaccines.

Researchers have known that the severity of symptoms of malaria increases when the malaria parasite is transferred repeatedly through in mice rather than by a mosquito, but up until now they have not known why.

"Understanding how malaria becomes more or less virulent is central to understanding how to manage and treat the disease," says Dr Matt Berriman, a senior author from the Wellcome Trust Sanger Institute. "We studied a rodent malaria species, that exhibits many of the same responses as seen in a human . Our understanding of how the parasite interacts with the immune system is fundamentally changed by this study."

To explore the effect that the route of transmission had, the team examined the levels of in the malaria parasite during its life cycle in mice.

They found that P.c. chabaudi 'resets' its when it is transmitted between the mosquito and mouse, making it less virulent. However, transferring the parasite through multiple blood transfers between mice in the laboratory loses this resetting. Because there is no reset the malaria parasite multiples much more quickly in mice after blood transfers, and causes an increase in .

The team uncovered a direct association between a specific gene family in the malaria parasite, known as cir genes, and the control of severity of the disease symptoms in mice. It appears that malaria parasite genes control the immune response of mice to the disease.

"Our research is helping to better understand vaccine targets," says Dr Adam Reid, author from the Wellcome Trust Sanger Institute. "RNA sequencing allowed us to identify a set of Plasmodium genes that control the immune response and the degree of severity of the disease in mice. We anticipate that we will be able to transfer the findings from our study in mice to human malaria studies, the next phase of our research."

The team expect that the cir gene family plays a role in activating the immune system and controls the level of parasite in the blood to keep malaria from harming the host. This is the largest in malaria parasites, including the deadly human parasite, P. falciparum.

The study was led by Dr Jean Langhorne based at the Medical Research Council National Institute for Medical Research: "These results place the mosquito at the centre of our efforts to pick apart the processes behind protective immunity to malaria. Malaria is both preventable and curable but still has a huge burden on those who are vulnerable to severe forms of the infection, mostly young children. Understanding protective immunity in the body would be an important first step towards developing an effective vaccine."

Explore further: Improving human immunity to malaria

More information: Spence, P. et al. Vector transmission regulates immune control of Plasmodium virulence, Nature 2013. DOI: 10.1038/nature12231

Related Stories

Improving human immunity to malaria

August 1, 2012

The deadliest form of malaria is caused the protozoan Plasmodium falciparum. During its life-cycle in human blood, the parasite P. falciparum expresses unique proteins on the surface on infected blood cells.

Recommended for you

We've all got a blind spot, but it can be shrunk

August 31, 2015

You've probably never noticed, but the human eye includes an unavoidable blind spot. That's because the optic nerve that sends visual signals to the brain must pass through the retina, which creates a hole in that light-sensitive ...

Biologists identify mechanisms of embryonic wound repair

August 31, 2015

It's like something out of a science-fiction movie - time-lapse photography showing how wounds in embryos of fruit flies heal themselves. The images are not only real; they shed light on ways to improve wound recovery in ...

New 'Tissue Velcro' could help repair damaged hearts

August 28, 2015

Engineers at the University of Toronto just made assembling functional heart tissue as easy as fastening your shoes. The team has created a biocompatible scaffold that allows sheets of beating heart cells to snap together ...

Research identifies protein that regulates body clock

August 26, 2015

New research into circadian rhythms by researchers at the University of Toronto Mississauga shows that the GRK2 protein plays a major role in regulating the body's internal clock and points the way to remedies for jet lag ...

Fertilization discovery: Do sperm wield tiny harpoons?

August 26, 2015

Could the sperm harpoon the egg to facilitate fertilization? That's the intriguing possibility raised by the University of Virginia School of Medicine's discovery that a protein within the head of the sperm forms spiky filaments, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.