Scientists Decode Genome of Parasite
that Causes Relapsing Malaria
Advance May Speed Development of Malaria Drugs and Vaccines
Scientists have deciphered the complete genetic sequence of the
parasite Plasmodium vivax, the leading cause of relapsing
malaria, and compared it with the genomes of other species of malaria
parasites. The findings shed light on distinctive genetic features
of P. vivax, and may lead to new tools to prevent and
treat P. vivax malaria. Results of the study, funded by
the National Institute of Allergy and Infectious Diseases (NIAID),
part of the National Institutes of Health (NIH), appear in the
Oct. 9 issue of Nature.
More than 2.6 billion people are at risk of developing vivax malaria,
with a heavy concentration of cases in Asia and Latin America.
Although infection is rarely fatal, it causes severe clinical symptoms
that include repeated episodes of high fever followed by headache,
chills and profuse sweating, often accompanied by vomiting, diarrhea
and enlargement of the spleen. Patients treated for the primary
blood stage infection but not specifically for dormant disease
in the liver are at substantial risk of relapse.
According to coauthors at The Institute for Genomic Research/J.
Craig Venter Institute in Rockville, Md., and their colleagues,
the P. vivax gene sequence will drive research in three
key areas: study of the genetic diversity of P. vivax,
the problem of drug resistance and the phenomenon of P. vivax relapse.
"Plasmodium vivax relapse presents serious challenges
to scientists and doctors alike," says NIAID Director Anthony
S. Fauci, M.D. "Completion of the P. vivax genome
promises to provide new insights into the biology of vivax malaria
and new leads for therapies and vaccines."
One obstacle for researchers has been that P. vivax cannot
be grown in the laboratory, making it a relatively neglected area
of study. "With the publication of the first genome sequence,
we hope to reverse this trend and provide a resource for scientists
to pursue studies on this important parasite," says lead investigator
Jane M. Carlton, Ph.D., of the NYU Langone Medical Center.
Four species of Plasmodium parasite commonly cause malaria
in humans: P. falciparum, P. malariae, P.
ovale and P. vivax. Although P. vivax resembles
the other three species of human malaria parasites, it has novel
gene families that encode for potential alternative pathways into
red blood cells not recognized previously, according to study authors.
Importantly, Dr. Carlton’s team identified some P. vivax genes
with similarities to genes in other organisms, such as yeast, that
are responsible for dormancy. These genes may allow scientists
to study the mechanisms of the dormant liver stage P. vivax — and
perhaps find ways to disrupt it.
Research resources generated by this work are available for use
by the malaria research community and are deposited in the NIAID
funded Malaria Research and Reference Reagent Resource Center (MR4) http://www.mr4.org and
the Pathogen Functional Genomics Resource Center (PFGRC) http://pfgrc.jcvi.org/index.php/microarray/array_description/plasmodium_vivax/version1.html.
The NIH National Institute of General Medical Sciences also provided
funding for this study.
NIAID conducts and supports research — at NIH, throughout
the United States, and worldwide — to study the causes of
infectious and immune-mediated diseases, and to develop better
means of preventing, diagnosing and treating these illnesses. News
releases, fact sheets and other NIAID-related materials are available
on the NIAID Web site at http://www.niaid.nih.gov.
News releases, fact sheets and other NIAID-related materials
are available on the NIAID Web site at http://www.niaid.nih.gov.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.
JM Carlton et al. Comparative genomics of the neglected
human malaria parasite Plasmodium vivax. Nature DOI:10.1038/nature