Vivax doubly diverse than falciparum
doi:10.1038/nindia.2012.117 Published online 10 August 2012
Researchers sequencing the genomes of four strains of the malaria-causing parasite Plasmodium vivax — including one strain from India — have found it to be almost twice as genetically diverse as its more lethal cousin Plasmodium falciparum. The finding suggests a capacity for 'greater functional variation' in the global population of P. vivax.
Half the world's population is estimated to be at risk for malaria caused by P. vivax while P. falciparum is responsible for majority of the contemporary malaria-related mortality. However, studies say P. vivax was more virulent before the advent of modern medicine. More recently, research has shown that P. vivax is capable of causing the severe malaria syndromes that have long been attributed only to P. falciparum.
The international research team sequenced and annotated the genomes of four P. vivax strains collected from various geographic locations thus tripling the number of genome sequences available for this understudied parasite. The study provides the first genome-wide perspective of global variability in this species. The four newly sequenced P. vivax strains (North Korean, India VII, Mauritania I and Brazil I) were from genomic DNA derived from leukocyte-depleted monkey blood. The P. falciparum isolates (from Honduras, India, Indochina and Senegal) were sequenced using template derived from in vitro cultures.
The team observed approximately twice as much Single Nucleotide Polymorphism (SNP) diversity among these isolates as among a comparable collection of isolates of P. falciparum. They say this indicates a distinct history of global colonization and/or a more stable demographic history for P. vivax relative to P. falciparum.
"The SNP diversity, as well as additional microsatellite and gene family variability, suggests a capacity for greater functional variation in the global population of P. vivax," they report adding that there's need for a deeper survey of variation in P. vivax. This will aid diagnosis and treatment of malaria caused by this neglected but major pathogen.
The authors of this work are from: Broad Institute, Cambridge, Massachusetts, USA; National Institute of Malaria Research, Indian Council of Medical Research, New Delhi, India; Department of Biology, Center for Genomics and Systems Biology, New York University, USA; Center for Evolutionary Medicine & Informatics, The Biodesign Institute, School of Life Sciences, Arizona State University, Tempe, Arizona, USA & Center for Global Health, Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Atlanta, Georgia, USA.
- Neafsey, D. E. et al. The malaria parasite Plasmodium vivax exhibits greater genetic diversity than Plasmodium falciparum. Nat. Genet. doi: 10.1038/ng.2373 (2012)