The sequencing of new genomes of Plasmodium parasites, responsible for malaria in humans and monkeys, is reported in two related studies published online this week in Nature Genetics.
Plamodium vivax infects about 100 million people each year, and is responsible for over half of the malaria cases outside of Africa. P. vivax has been called the neglected Plasmodium, due to its more limited study as compared to the P. falciparum parasite. Another Plasmodium, P. cynomolgi, is a closely related species to P. vivax and a cause of malaria in Asian Old World monkeys, providing an important model system for characterizing P. vivax and human malaria.
Jane Carlton and colleagues report the sequencing, assembly and annotation of four P. vivax strains from diverse geographic locations. Though the species has been sequenced in the past, the authors triple the number of sequences, bringing the total to six, and provide a global sampling, which has been challenging due to the difficulties in culturing this species. They also provide the first genome-wide estimates of genetic variation in this species - They find twice as much genetic variation as in a comparable collection of P. falciparum, providing insight into the pathogens evolution. Their findings also have implications for design of therapies, and warn that eradication strategies could face challenges.
In a second study, Kazuyuki Tanabe, Jane Carlton and colleagues report the first reference genome sequence for P. cynomolgi, sequencing the whole genomes of three diverse strains. The authors provide a map of genetic variation in this species, providing a resource for mapping traits and functional studies. Their comparative genomic analysis with P. vivax and P. knowlesi provides insights into the monkey malaria clade, and suggesting genes involved in host specificity.