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Awasthi G, Das A. Genetics of chloroquine-resistant malaria: a haplotypic view. Mem Inst Oswaldo Cruz 2015; 108:947-61. [PMID: 24402147 PMCID: PMC4005552 DOI: 10.1590/0074-0276130274] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 09/26/2013] [Indexed: 02/05/2023] Open
Abstract
The development and rapid spread of chloroquine resistance (CQR) in
Plasmodium falciparum have triggered the identification of
several genetic target(s) in the P. falciparum genome. In
particular, mutations in the Pfcrt gene, specifically, K76T and
mutations in three other amino acids in the region adjoining K76 (residues 72, 74, 75
and 76), are considered to be highly related to CQR. These various mutations form
several different haplotypes and Pfcrt gene polymorphisms and the
global distribution of the different CQR- Pfcrt haplotypes in
endemic and non-endemic regions of P. falciparum malaria have been
the subject of extensive study. Despite the fact that the Pfcrt gene
is considered to be the primary CQR gene in P. falciparum , several
studies have suggested that this may not be the case. Furthermore, there is a poor
correlation between the evolutionary implications of the Pfcrt
haplotypes and the inferred migration of CQR P. falciparum based on
CQR epidemiological surveillance data. The present paper aims to clarify the existing
knowledge on the genetic basis of the different CQR- Pfcrt
haplotypes that are prevalent in worldwide populations based on the published
literature and to analyse the data to generate hypotheses on the genetics and
evolution of CQR malaria.
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Abdul-Ghani R, Farag HF, Allam AF, Azazy AA. Measuring resistant-genotype transmission of malaria parasites: challenges and prospects. Parasitol Res 2014; 113:1481-7. [PMID: 24562760 DOI: 10.1007/s00436-014-3789-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 01/28/2014] [Indexed: 01/09/2023]
Abstract
Increased gametocytemia in infections with resistant strains of Plasmodium species and their enhanced transmissibility are a matter of concern in planning and evaluating the impact of malaria control strategies. Various studies have determined weekly gametocyte carriage in response to antimalarial drugs in clinical trials. The advent of molecular biology techniques makes it easy to detect and quantify gametocytes, the stages responsible for transmission, and to detect resistant genotypes of the parasite. With the validation of molecular markers of resistance to certain antimalarial drugs, there is a need to devise a simpler formula that could be used with these epidemiological antimalarial resistance tools. Theoretical models for transmission of resistant malaria parasites are difficult to deploy in epidemiological studies. Therefore, devising a simple formula that determines the potential resistant-genotype transmission of malaria parasites should provide further insights into understanding the spread of drug resistance. The present perspective discusses gametocytogenesis in the context of antimalarial treatment and drug resistance. It also highlights the difficulties in applying the available theoretical models of drug resistance transmission and suggests Rashad's devised formula that could perhaps be used in determining potentially transmissible resistant genotypes as well as in mapping areas with high potential risk for the transmission of drug-resistant malaria. The suggested formula makes use of the data on gametocytes and resistant genotypes of malaria parasites, detected by molecular techniques in a certain geographical area within a particular point in time, to calculate the potential risk of resistant genotype transmission.
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Affiliation(s)
- Rashad Abdul-Ghani
- Department of Parasitology, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Yemen,
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Chauhan K, Pande V, Das A. Analyses of genetic variations at microsatellite loci present in-and-around the Pfcrt gene in Indian Plasmodium falciparum. INFECTION GENETICS AND EVOLUTION 2013; 20:476-87. [PMID: 24157593 DOI: 10.1016/j.meegid.2013.10.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/10/2013] [Accepted: 10/10/2013] [Indexed: 10/26/2022]
Abstract
Evolution and spread of chloroquine resistant (CQR) malaria parasite Plasmodium falciparum have posed great threat in malaria intervention across the globe. The occurrence of K76T mutation in the P. falciparum chloroquine resistance transporter (pfcrt) gene has been widely attributed to CQR with four neighboring mutations providing compensatory fitness benefit to the parasite survival. Understanding evolutionary patterns of the pfcrt gene is of great relevance not only for devising new malaria control measures but also could serve as a model to understand evolution and spread of other human drug-resistant pathogens. Several studies, mainly based on differential patterns of diversities of the microsatellite loci placed in-and-around the pfcrt gene have indicated the role of positive natural selection under the 'hitchhiking' model of molecular evolution. However, the studies were restricted to limited number of microsatellite loci present inside the pfcrt gene. Moreover, comparatively higher level of diversities in microsatellite loci present inside the pfcrt gene than the loci flanking the pfcrt gene are hallmarks of Indian P. falciparum, presenting contrasting evolutionary models to global isolates. With a view to infer evolutionary patterns of the pfcrt gene in Indian P. falciparum, we have adopted a unique sampling scheme of two types of populations (cultured and field collected) and utilized 20 polymorphic microsatellite loci (16 located inside the pfcrt gene and four in the two flanking regions) to disentangle between genetic drift (inbred cultured isolates) and natural selection (field isolates). Data analyses employing different population genetic tests could not straightforwardly explain either the model invoking 'genetic hitchhiking' or 'genetic drift'. However, complex evolutionary models influenced by both demography and natural selection or an alternative model of natural selection (e.g. diversifying/balancing selection) might better explain the observed microsatellite variation in-and-around the pfcrt gene in Indian P. falciparum.
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Affiliation(s)
- Kshipra Chauhan
- Evolutionary Genomics and Bioinformatics Laboratory, Division of Genomics and Bioinformatics, National Institute of Malaria Research, Sector 8, Dwarka, New Delhi 110077, India
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Awasthi G, Satya Prasad GBK, Satya GBK, Das A. Pfcrt haplotypes and the evolutionary history of chloroquine-resistant Plasmodium falciparum. Mem Inst Oswaldo Cruz 2012; 107:129-34. [PMID: 22310546 DOI: 10.1590/s0074-02762012000100018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 10/20/2011] [Indexed: 11/22/2022] Open
Abstract
Mutations in the Pfcrt gene that change the resulting amino acids and form different haplotypes are common and correlate with the prevalence of chloroquine resistant (CQR) field isolates of the malaria parasite, Plasmodium falciparum. This correlation provides opportunities to infer the global evolutionary history of CQ resistance by analysing CQR Pfcrt haplotype data. We collated data on the Pfcrt haplotypes from different global studies and performed evolutionary genetic analysis to present comprehensive and comparative information on the global distribution of five major CQR-Pfcrt haplotypes and evolutionary inter-relationships among 38 different countries. Using the haplotype diversity data, inter-continental genetic differentiation was also ascertained.
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Affiliation(s)
- Gauri Awasthi
- Evolutionary Genomics and Bioinformatics Laboratory, Division of Genomics and Bioinformatics, National Institute of Malaria Research, New Delhi, India
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Narayanasamy K, Chery L, Basu A, Duraisingh MT, Escalante A, Fowble J, Guler JL, Herricks T, Kumar A, Majumder P, Maki J, Mascarenhas A, Rodrigues J, Roy B, Sen S, Shastri J, Smith J, Valecha N, White J, Rathod PK. Malaria evolution in South Asia: knowledge for control and elimination. Acta Trop 2012; 121:256-66. [PMID: 22266213 PMCID: PMC3894252 DOI: 10.1016/j.actatropica.2012.01.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 01/04/2012] [Accepted: 01/05/2012] [Indexed: 11/16/2022]
Abstract
The study of malaria parasites on the Indian subcontinent should help us understand unexpected disease outbreaks and unpredictable disease presentations from Plasmodium falciparum and Plasmodium vivax infections. The Malaria Evolution in South Asia (MESA) research program is one of ten International Centers of Excellence for Malaria Research (ICEMR) sponsored by the US National Institutes of Health. In this second of two reviews, we describe why population structures of Plasmodia in India will be characterized and how we will determine their consequences on disease presentation, outcome and patterns. Specific projects will determine if genetic diversity, possibly driven by parasites with higher genetic plasticity, plays a role in changing epidemiology, pathogenesis, vector competence of parasite populations and whether innate human genetic traits protect Indians from malaria today. Deep local clinical knowledge of malaria in India will be supplemented by basic scientists who bring new research tools. Such tools will include whole genome sequencing and analysis methods; in vitro assays to measure genome plasticity, RBC cytoadhesion, invasion, and deformability; mosquito infectivity assays to evaluate changing parasite-vector compatibilities; and host genetics to understand protective traits in Indian populations. The MESA-ICEMR study sites span diagonally across India and include a mixture of very urban and rural hospitals, each with very different disease patterns and patient populations. Research partnerships include government-associated research institutes, private medical schools, city and state government hospitals, and hospitals with industry ties. Between 2012 and 2017, in addition to developing clinical research and basic science infrastructure at new clinical sites, our training workshops will engage new scientists and clinicians throughout South Asia in the malaria research field.
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Affiliation(s)
| | - Laura Chery
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Analabha Basu
- National Institute of Biomedical Genomics, Kalyani, West Bengal, India
| | | | | | - Joseph Fowble
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | | | | | - Ashwani Kumar
- National Institute of Malaria Research (ICMR), Panaji, Goa, India
| | - Partha Majumder
- National Institute of Biomedical Genomics, Kalyani, West Bengal, India
| | - Jennifer Maki
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | | | | | - Bikram Roy
- National Institute of Biomedical Genomics, Kalyani, West Bengal, India
| | - Somdutta Sen
- SphaeraPharma Research and Development, Manesar, Haryana, India
| | - Jayanthi Shastri
- Kasturba Hospital for Infectious Diseases, Mumbai, Maharashtra, India
- Topiwala Medical College & BYL Nair Hospital, Mumbai, Maharashtra, India
| | - Joseph Smith
- Seattle Biomedical Research Institute, Seattle, WA, USA
| | - Neena Valecha
- National Institute of Malaria Research (ICMR), New Delhi, India
| | - John White
- Department of Chemistry, University of Washington, Seattle, WA, USA
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