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      Genomic analysis of local variation and recent evolution in Plasmodium vivax

      Nature genetics

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          Abstract

          The widespread distribution and relapsing nature of Plasmodium vivax infection present major challenges for malaria elimination. To characterise the genetic diversity of this parasite within individual infections and across the population, we performed deep genome sequencing of >200 clinical samples collected across the Asia-Pacific region, and analysed data on >300,000 SNPs and 9 regions of the genome with large copy number variations. Individual infections showed complex patterns of genetic structure, with variation not only in the number of dominant clones but also in their level of relatedness and inbreeding. At the population level, we observed strong signals of recent evolutionary selection both in known drug resistance genes and at novel loci, and these varied markedly between geographical locations. These findings reveal a dynamic landscape of local evolutionary adaptation in P. vivax populations, and provide a foundation for genomic surveillance to guide effective strategies for control and elimination.

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          Most cited references41

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          Is Open Access

          Comparative genomics of the neglected human malaria parasite Plasmodium vivax.

          The human malaria parasite Plasmodium vivax is responsible for 25-40% of the approximately 515 million annual cases of malaria worldwide. Although seldom fatal, the parasite elicits severe and incapacitating clinical symptoms and often causes relapses months after a primary infection has cleared. Despite its importance as a major human pathogen, P. vivax is little studied because it cannot be propagated continuously in the laboratory except in non-human primates. We sequenced the genome of P. vivax to shed light on its distinctive biological features, and as a means to drive development of new drugs and vaccines. Here we describe the synteny and isochore structure of P. vivax chromosomes, and show that the parasite resembles other malaria parasites in gene content and metabolic potential, but possesses novel gene families and potential alternative invasion pathways not recognized previously. Completion of the P. vivax genome provides the scientific community with a valuable resource that can be used to advance investigation into this neglected species.
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            Vivax malaria: neglected and not benign.

            Plasmodium vivax threatens almost 40% of the world's population, resulting in 132-391 million clinical infections each year. Most of these cases originate from Southeast Asia and the Western Pacific, although a significant number also occurs in Africa and South America. Although often regarded as causing a benign and self-limiting infection, there is increasing evidence that the overall burden, economic impact, and severity of disease from P. vivax have been underestimated. Malaria control strategies have had limited success and are confounded by the lack of access to reliable diagnosis, emergence of multidrug resistant isolates, the parasite's ability to transmit early in the course of disease and relapse from dormant liver stages at varying time intervals after the initial infection. Progress in reducing the burden of disease will require improved access to reliable diagnosis and effective treatment of both blood-stage and latent parasites, and more detailed characterization of the epidemiology, morbidity, and economic impact of vivax malaria. Without these, vivax malaria will continue to be neglected by ministries of health, policy makers, researchers, and funding bodies.
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              Determinants of relapse periodicity in Plasmodium vivax malaria

              Plasmodium vivax is a major cause of febrile illness in endemic areas of Asia, Central and South America, and the horn of Africa. Plasmodium vivax infections are characterized by relapses of malaria arising from persistent liver stages of the parasite (hypnozoites) which can be prevented only by 8-aminoquinoline anti-malarials. Tropical P. vivax relapses at three week intervals if rapidly eliminated anti-malarials are given for treatment, whereas in temperate regions and parts of the sub-tropics P. vivax infections are characterized either by a long incubation or a long-latency period between illness and relapse - in both cases approximating 8-10 months. The epidemiology of the different relapse phenotypes has not been defined adequately despite obvious relevance to malaria control and elimination. The number of sporozoites inoculated by the anopheline mosquito is an important determinant of both the timing and the number of relapses. The intervals between relapses display a remarkable periodicity which has not been explained. Evidence is presented that the proportion of patients who have successive relapses is relatively constant and that the factor which activates hypnozoites and leads to regular interval relapse in vivax malaria is the systemic febrile illness itself. It is proposed that in endemic areas a large proportion of the population harbours latent hypnozoites which can be activated by a systemic illness such as vivax or falciparum malaria. This explains the high rates of vivax following falciparum malaria, the high proportion of heterologous genotypes in relapses, the higher rates of relapse in people living in endemic areas compared with artificial infection studies, and, by facilitating recombination between different genotypes, contributes to P. vivax genetic diversity particularly in low transmission settings. Long-latency P. vivax phenotypes may be more widespread and more prevalent than currently thought. These observations have important implications for the assessment of radical treatment efficacy and for malaria control and elimination.
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                Author and article information

                Journal
                9216904
                2419
                Nat Genet
                Nat. Genet.
                Nature genetics
                1061-4036
                1546-1718
                13 June 2016
                27 June 2016
                August 2016
                27 December 2016
                : 48
                : 8
                : 959-964
                Affiliations
                [1 ]Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
                [2 ]MRC Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN, UK
                [3 ]Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territories 0811, Australia
                [4 ]Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
                [5 ]National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA
                [6 ]National Centre for Parasitology, Entomology, and Malaria Control, Phnom Penh, Cambodia
                [7 ]Sampov Meas Referral Hospital, Pursat, Cambodia
                [8 ]Eijkman Institute for Molecular Biology, Jakarta 10430, Indonesia
                [9 ]Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit and Queen Elizabeth Hospital Clinical Research Centre, Kota Kinabalu, Sabah, Malaysia
                [10 ]Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
                [11 ]Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
                [12 ]Faculty of Medicine and Health Sciences, Divine Word University, Madang, Papua New Guinea
                [13 ]Division of Population Health and Immunity, The Walter and Eliza Hall Institute for Medical Research, Parkville, Victoria, Australia
                [14 ]Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
                [15 ]Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
                [16 ]Department of Parasitology, Faculty of Medicine, University of Colombo, Sri Lanka
                [17 ]Institut Pasteur de Madagascar, Antananarivo, Madagascar
                [18 ]Jiangsu Institute of Parasitic Diseases, Key Laboratory of Parasitic Disease Control and Prevention (Ministry of Health), Jiangsu Provincial Key Laboratory of Parasite Molecular Biology, Wuxi, Jiangsu, People’s Republic of China
                [19 ]Shoklo Malaria Research Unit, Mae Sot, Tak 63110, Thailand
                [20 ]Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, OX3 7LJ, UK
                Author notes
                Correspondence should be addressed to D.P.K. ( dominic@ 123456sanger.ac.uk ).
                Article
                EMS68623
                10.1038/ng.3599
                4966634
                27348299
                b4cfdf2c-ab9b-4bc1-9bc1-5e75345a5317

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