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Atuh NI, Anong DN, Jerome FC, Oriero E, Mohammed NI, D’Alessandro U, Amambua-Ngwa A. High genetic complexity but low relatedness in Plasmodium falciparum infections from Western Savannah Highlands and coastal equatorial Lowlands of Cameroon. Pathog Glob Health 2022; 116:428-437. [PMID: 34308788 PMCID: PMC9518281 DOI: 10.1080/20477724.2021.1953686] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To determine the diversity and connectivity of infections in Northwestern and Southwestern Cameroon, 232 Plasmodium falciparum infections, collected in 2018 from the Ndop Health District (NHD) in the western savannah highlands in the Northwest and the Limbe Health District (LHD) in the coastal lowland forests in the Southwest of Cameroon were genotyped for nine neutral microsatellite markers. Overall infection complexity and genetic diversity was significantly (p < 0.05) lower in NHD than LHD, (Mean MOI = 2.45 vs. 2.97; Fws = 0.42 vs. 0.47; Mean He = 0.84 vs. 0.89, respectively). Multi-locus linkage disequilibrium was generally low but significantly higher in the NHD than LHD population (mean ISA= 0.376 vs 0.093). Consequently, highly related pairs of isolates were observed in NHD (mean IBS = 0.086) compared to those from the LHD (mean IBS = 0.059). Infections from the two regions were mostly unrelated (mean IBS = 0.059), though the overall genetic differentiation across the geographical range was low. Indices of differentiation between the populations were however significant (overall pairwise Fst = 0.048, Jost's D = 0.133, p < 0.01). Despite the high human migration across the 270km separating the study sites, these results suggest significant restrictions to gene flow against contiguous geospatial transmission of malaria in west Cameroon. Clonal infections in the highland sites could be driven by lower levels of malaria prevalence and seasonal transmission. How these differences in genetic diversity and complexity affect responses to interventions such as drugs will require further investigations from broader community sampling.
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Affiliation(s)
- Ngoh Ines Atuh
- Department of Biomedical Science, Faculty of Health Science, University of Buea, Buea, Cameroon
- Disease Control and Elimination, Medical Research Council Unit the Gambia at LSHTM. Banjul, The Gambia
| | - Damian Nota Anong
- Department of Microbiology & Parasitology, Faculty of Science, University of Buea, Molyko Buea, Cameroon
| | - Fru-Cho Jerome
- Department of Biomedical Science, Faculty of Health Science, University of Buea, Buea, Cameroon
| | - Eniyou Oriero
- Disease Control and Elimination, Medical Research Council Unit the Gambia at LSHTM. Banjul, The Gambia
| | - Nuredin Ibrahim Mohammed
- Disease Control and Elimination, Medical Research Council Unit the Gambia at LSHTM. Banjul, The Gambia
| | - Umberto D’Alessandro
- Department of Microbiology & Parasitology, Faculty of Science, University of Buea, Molyko Buea, Cameroon
| | - Alfred Amambua-Ngwa
- Disease Control and Elimination, Medical Research Council Unit the Gambia at LSHTM. Banjul, The Gambia
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Tibayrenc M, Ayala FJ. Is Predominant Clonal Evolution a Common Evolutionary Adaptation to Parasitism in Pathogenic Parasitic Protozoa, Fungi, Bacteria, and Viruses? ADVANCES IN PARASITOLOGY 2016; 97:243-325. [PMID: 28325372 DOI: 10.1016/bs.apar.2016.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We propose that predominant clonal evolution (PCE) in microbial pathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure. The main features of PCE are (1) strong linkage disequilibrium, (2) the widespread occurrence of stable genetic clusters blurred by occasional bouts of genetic exchange ('near-clades'), (3) the existence of a "clonality threshold", beyond which recombination is efficiently countered by PCE, and near-clades irreversibly diverge. We hypothesize that the PCE features are not mainly due to natural selection but also chiefly originate from in-built genetic properties of pathogens. We show that the PCE model obtains even in microbes that have been considered as 'highly recombining', such as Neisseria meningitidis, and that some clonality features are observed even in Plasmodium, which has been long described as panmictic. Lastly, we provide evidence that PCE features are also observed in viruses, taking into account their extremely fast genetic turnover. The PCE model provides a convenient population genetic framework for any kind of micropathogen. It makes it possible to describe convenient units of analysis (clones and near-clades) for all applied studies. Due to PCE features, these units of analysis are stable in space and time, and clearly delimited. The PCE model opens up the possibility of revisiting the problem of species definition in these organisms. We hypothesize that PCE constitutes a major evolutionary strategy for protozoa, fungi, bacteria, and viruses to adapt to parasitism.
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Affiliation(s)
- M Tibayrenc
- Institut de Recherche pour le Développement, Montpellier, France
| | - F J Ayala
- University of California at Irvine, United States
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Tibayrenc M, Ayala FJ. New insights into clonality and panmixia in Plasmodium and toxoplasma. ADVANCES IN PARASITOLOGY 2014; 84:253-68. [PMID: 24480316 DOI: 10.1016/b978-0-12-800099-1.00005-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Until the 1990s, Plasmodium and Toxoplasma were widely considered to be potentially panmictic species, because they both undergo a meiotic sexual cycle in their definitive hosts. We have proposed that both parasites are able of clonal (nonrecombining) propagation, at least in some cycles. Toxoplasma was soon shown to be a paradigmatic case of clonal population structure in North American and in European cycles. But the proposal provoked an outcry in the case of Plasmodium and still appears as doubtful to many scientists. However, the existence of Plasmodium nonrecombining lines has been fully confirmed, although the origin of these lines is debatable. We discuss the current state of knowledge concerning the population structure of both parasites in the light of the recent developments of pathogen clonal evolution proposed by us and of new hypotheses presented here.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), IRD Center, Montpellier, France.
| | - Francisco J Ayala
- Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA
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Annan Z, Durand P, Ayala FJ, Arnathau C, Awono-Ambene P, Simard F, Razakandrainibe FG, Koella JC, Fontenille D, Renaud F. Population genetic structure of Plasmodium falciparum in the two main African vectors, Anopheles gambiae and Anopheles funestus. Proc Natl Acad Sci U S A 2007; 104:7987-92. [PMID: 17470800 PMCID: PMC1876559 DOI: 10.1073/pnas.0702715104] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated patterns of genetic diversity of Plasmodium falciparum associated with its two main African vectors: Anopheles gambiae and Anopheles funestus. We dissected 10,296 wild-caught mosquitoes from three tropical sites, two in Cameroon (Simbock and Tibati, separated by 320 km) and one in Kenya (Rota, >2,000 km from the other two sites). We assayed seven microsatellite loci in 746 oocysts from 183 infected mosquito guts. Genetic polymorphism was very high in parasites isolated from both vector species. The expected heterozygosity (H(E)) was 0.79 in both species; the observed heterozygosities (H(O)) were 0.32 in A. funestus and 0.42 in A. gambiae, indicating considerable inbreeding within both vector species. Mean selfing (s) between genetically identical gametes was s = 0.33. Differences in the rate of inbreeding were statistically insignificant among sites and between the two vector species. As expected, because of the high rate of inbreeding, linkage disequilibrium was very high; it was significant for all 21 loci pairs in A. gambiae and for 15 of 21 pairs in A. funestus, although only two pairwise comparisons were between loci on the same chromosome. Overall, the genetic population structure of P. falciparum, as evaluated by F statistics, was predominantly clonal rather than panmictic, a population structure that facilitates the spread of antimalarial drug and vaccine resistance and thus may impair the effectiveness of malaria control efforts.
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Affiliation(s)
- Zeinab Annan
- *Génétique et Evolution des Maladies Infectieuses, Unité Mixte de Recherche-Institut de Recherche pour le Développement/Centre National de la Recherche Scientifique 2724, B.P. 64501, 34394 Montpellier Cedex 5, France
- Laboratoire de Lutte Contre les Insectes Nuisibles, Unité de Recherche 016-Institut de Recherche pour le Développement, B.P. 64501, 34394 Montpellier Cedex 5, France
| | - Patrick Durand
- *Génétique et Evolution des Maladies Infectieuses, Unité Mixte de Recherche-Institut de Recherche pour le Développement/Centre National de la Recherche Scientifique 2724, B.P. 64501, 34394 Montpellier Cedex 5, France
| | - Francisco J. Ayala
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
- To whom correspondence should be addressed at:
Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, CA 92697-2525. E-mail:
| | - Céline Arnathau
- *Génétique et Evolution des Maladies Infectieuses, Unité Mixte de Recherche-Institut de Recherche pour le Développement/Centre National de la Recherche Scientifique 2724, B.P. 64501, 34394 Montpellier Cedex 5, France
| | - Parfait Awono-Ambene
- Laboratoire de Recherche sur le Paludisme-Institut de Recherche pour le Développement, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale, B.P. 288, Yaoundé, Cameroon
| | - Frédéric Simard
- Laboratoire de Recherche sur le Paludisme-Institut de Recherche pour le Développement, Organisation de Coordination pour la Lutte Contre les Endémies en Afrique Centrale, B.P. 288, Yaoundé, Cameroon
| | - Fabien G. Razakandrainibe
- Laboratoire de Parasitologie Evolutive, Unité Mixte de Recherche-Centre National de la Recherche Scientifique 7103, Université Pierre et Marie Curie, 75252 Paris, France; and
| | - Jacob C. Koella
- **Division of Biology, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, United Kingdom
| | - Didier Fontenille
- Laboratoire de Lutte Contre les Insectes Nuisibles, Unité de Recherche 016-Institut de Recherche pour le Développement, B.P. 64501, 34394 Montpellier Cedex 5, France
| | - François Renaud
- *Génétique et Evolution des Maladies Infectieuses, Unité Mixte de Recherche-Institut de Recherche pour le Développement/Centre National de la Recherche Scientifique 2724, B.P. 64501, 34394 Montpellier Cedex 5, France
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Razakandrainibe FG, Durand P, Koella JC, De Meeüs T, Rousset F, Ayala FJ, Renaud F. "Clonal" population structure of the malaria agent Plasmodium falciparum in high-infection regions. Proc Natl Acad Sci U S A 2005; 102:17388-93. [PMID: 16301534 PMCID: PMC1297693 DOI: 10.1073/pnas.0508871102] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The population genetic structure of Plasmodium falciparum, the agent of malignant malaria, has been shown to be predominantly "clonal" (i.e., highly inbred) in regions of low infectivity; in high-infectivity regions, it is often thought to be panmictic, or nearly so, although there is little supporting evidence for this. The matter can be settled by investigating the parasite's genetic makeup in the midgut oocysts of the mosquito vector, where the products of meiosis can directly be observed. The developmental stages of P. falciparum are haploid, except in the oocysts of infected mosquito vectors, where two gametes fuse, diploidy occurs, and meiosis ensues. We have investigated genetic polymorphisms at seven microsatellite loci located on five chromosomes by assaying 613 oocysts in 145 mosquitoes sampled from 11 localities of Kenya, where malignant malaria is perennial and intense. There is considerable allelic variation, 16.3 +/- 2.1 alleles per locus, and considerable inbreeding, approximately 50% on the average. The inbreeding is caused by selfing (approximately 25%) and nonrandom genotype distribution of oocysts among mosquito guts (35%). The observed frequency of heterozygotes is 0.43 +/- 0.03; the expected frequency, assuming random mating, is 0.80 +/- 0.05. Linkage disequilibrium is statistically significant for all 21 pairwise comparisons between loci, even though 19 comparisons are between loci in different chromosomes, which is consistent with strong deviation from panmixia and the consequent reproduction of genomes as clones, without recombination between gene loci. This is of considerable evolutionary significance and of epidemiological consequence, concerning the spread of multilocus drug and vaccine resistance.
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Affiliation(s)
- F G Razakandrainibe
- Génétique et Evolution des Maladies Infectieuses, Unité Mixte de Recherche-Institut de Recherche pour le Développement/Centre National de la Recherche Scientifique 2724, Montpellier, France
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Abstract
The population structure of Plasmodial parasites, especially Plasmodium falciparum, has received much attention in the recent years. Like many other micropathogens, the debate has focused on the clonality/sexuality question. Considered a panmictic species for very long, P. falciparum actually exhibits strong departures from panmictic expectations in many of its populations, which corroborates the proposal that it is able to undergo uniparental propagation.(1) The currently accepted idea to account for this surprising result is kind of "mechanical" self-fertilization due to the lack of availability of gametes with different genetic make-ups in low transmission areas. However, it could be misleading to make this simple working hypothesis a dogma, for many other explanations are possible (unknown cycles, sibling species, mating types) that deserve to be explored as well. The consequences of this combination of uniparental(1) and sexual propagation on the circulation of genes of interest (drug resistance, antigenic variability, pathogenicity) are discussed, together with the need to use more sophisticated technologies, analysing much broader samples and considering better the host and vector factors in P. falciparum population dynamics.
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Affiliation(s)
- C Gauthier
- Unit of Research 165 "Genetics and Evolution of Infectious Diseases", UMR CNRS/IRD 2724, IRD, BP 64501, 34394 Montpellier Cedex 5, France
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Leclerc MC, Durand P, de Meeûs T, Robert V, Renaud F. Genetic diversity and population structure of Plasmodium falciparum isolates from Dakar, Senegal, investigated from microsatellite and antigen determinant loci. Microbes Infect 2002; 4:685-92. [PMID: 12067827 DOI: 10.1016/s1286-4579(02)01587-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We investigated the genetic diversity and the population structure of 32 Plasmodium falciparum blood sample isolates (25 from Dakar city and suburbs and seven from other localities in Senegal) with two different types of molecular markers, 19 microsatellite and four antigenic determinant loci. Under the same technical procedure, microsatellite loci showed a mean number of alleles greater than that of antigenic loci. Both markers revealed that 15.6% of blood samples were multi-infected. Mean expected heterozygosity calculated from microsatellites and antigens was similar, 0.74 and 0.70, respectively. Significant linkage disequilibrium was observed from microsatellite loci and antigenic determinant loci. This suggests a non-panmictic structure for this sample that could be explained by two non-exclusive hypotheses: (i) a particular mating system (i.e. clonality), and/or (ii) a population structure in P. falciparum (i.e. Wahlund effect). Urban samples could have been drawn from a heterogeneous set of foci with different level of parasitic transmission. Moreover, no relationship was found between multilocus genotypes and different parameters (i.e. age, sex and blood group of parasitized patients; number of trophozoites per microliter of blood). The results are discussed taking into account recently published studies on malaria population biology.
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Affiliation(s)
- Marie Claude Leclerc
- Centre d'Etudes sur le Polymorphisme des Microorganismes (CEPM), UMR CNRS/IRD 9926, IRD, Equipe Evolution des Systèmes Symbiotiques, 911 Avenue Agropolis, BP 5045, 34032 Montpellier cedex 1, France.
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Chen F, Goodwin PH, Khan A, Hsiang T. Population structure and mating-type genes of Colletotrichum graminicola from Agrostis palustris. Can J Microbiol 2002; 48:427-36. [PMID: 12109882 DOI: 10.1139/w02-034] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Eighty-seven isolates of Colletotrichum graminicola, mostly from Agrostis palustris, were collected in grass fields, most of which were in Ontario, Canada. Specific primers were designed to amplify the mating-type (MAT) genes and, among 35 isolates tested, all yielded a band of the expected size for MAT2. For six isolates, the MAT2 PCR products were sequenced and found to be similar to that reported for MAT2 of C. graminicola from maize. Based on 119 polymorphic bands from 10 random amplified polymorphic DNA primers, analyses of genetic distances were found to generally cluster isolates by host and geographic origin. Among 42 isolates from a grass field in Ontario, significant spatial autocorrelation was found to occur within a 20-m distance, implying that this is the effective propagule dispersal distance. Although clonal propagation was observed in the 87 isolates with 67 unique genotypes, the extent of genetic variation in local populations implies some occurrence of sexual or asexual recombination.
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Affiliation(s)
- Fajun Chen
- Department of Environmental Biology, University of Guelph, ON, Canada
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Urdaneta L, Lal A, Barnabe C, Oury B, Goldman I, Ayala FJ, Tibayrenc M. Evidence for clonal propagation in natural isolates of Plasmodium falciparum from Venezuela. Proc Natl Acad Sci U S A 2001; 98:6725-9. [PMID: 11371616 PMCID: PMC34420 DOI: 10.1073/pnas.111144998] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2001] [Indexed: 11/18/2022] Open
Abstract
We have analyzed 75 isolates of Plasmodium falciparum, collected in Venezuela during both the dry (November) and rainy (May-July) seasons, with a range of genetic markers including antigen genes and 14 random amplified polymorphic DNA (RAPD) primers. Thirteen P. falciparum stocks from Kenya and four other Plasmodium species are included in the analysis for comparison. Cross-hybridization shows that the 14 RAPD primers reveal 14 separate regions of the parasite's genome. The P. falciparum isolates are a monophyletic clade, significantly different from the other Plasmodium species. We identify three RAPD characters that could be useful as "tags" for rapid species identification. The Venezuelan genotypes fall into two discrete genetic subdivisions associated with either the dry or the rainy season; the isolates collected in the rainy season exhibit greater genetic diversity. There is significant linkage disequilibrium in each seasonal subsample and in the full sample. In contrast, no linkage disequilibrium is detected in the African sample. These results support the hypothesis that the population structure of P. falciparum in Venezuela, but not in Africa, is predominantly clonal. However, the impact of genetic recombination on Venezuelan P. falciparum seems higher than in parasitic species with long-term clonal evolution like Trypanosoma cruzi, the agent of Chagas' disease. The genetic structure of the Venezuelan samples is similar to that of Escherichia coli, a bacterium that propagates clonally, with occasional genetic recombination.
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Affiliation(s)
- L Urdaneta
- Centro de Investigaciones Biomedicas, Universidad de Carabobo, Núcleo Aragua, AP 2351, Maracay, Estado Aragua, Venezuela
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Lehmann T, Blackston CR, Parmley SF, Remington JS, Dubey JP. Strain typing of Toxoplasma gondii: comparison of antigen-coding and housekeeping genes. J Parasitol 2000; 86:960-71. [PMID: 11128519 DOI: 10.1645/0022-3395(2000)086[0960:stotgc]2.0.co;2] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Molecular characterization of Toxoplasma gondii isolates is central for understanding differences in disease transmission and manifestations. Only 3 subgroups (lineages) have been discerned with subtle within-lineage variation, permitting low-resolution classification of isolates. Because proteins, coding sequences, and especially antigen-coding genes have been used extensively in previous studies, we focused on sequence variation in introns of housekeeping genes, which may be more informative for phylogenetic analysis because they evolve under lower selection. We compared sequence variation in introns of 5 housekeeping genes with 2 antigen-coding genes. Introns of housekeeping genes were slightly more polymorphic than coding and noncoding regions of antigen-coding genes and only the former showed intralineage variation. Intragenic linkage disequilibrium was complete, but intergenic linkage, although highly significant, was incomplete, suggesting that genes are partially uncoupled. Six of 7 substitutions found within the region coding for the tachyzoite surface antigen, SAG2, were nonsynonymous, indicating that diversifying selection acts on this locus. Typing isolates on the basis of housekeeping and antigen-coding genes was consistent, but the phylogenetic relationships among the resulting groups was inconsistent. A cougar isolate typed as lineage II using a restriction fragment length polymorphism assay possessed multiple unique polymorphisms, suggesting that it represents a new lineage. We concluded that introns of housekeeping genes are preferred markers for phylogenetic study, and that multilocus genotyping is preferred for typing parasites, especially from feral or unstudied environments.
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Affiliation(s)
- T Lehmann
- Division of Parasitic Diseases, CDC, Chamblee, Georgia 30341, USA
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Anderson TJ, Haubold B, Williams JT, Estrada-Franco JG, Richardson L, Mollinedo R, Bockarie M, Mokili J, Mharakurwa S, French N, Whitworth J, Velez ID, Brockman AH, Nosten F, Ferreira MU, Day KP. Microsatellite markers reveal a spectrum of population structures in the malaria parasite Plasmodium falciparum. Mol Biol Evol 2000; 17:1467-82. [PMID: 11018154 DOI: 10.1093/oxfordjournals.molbev.a026247] [Citation(s) in RCA: 582] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Multilocus genotyping of microbial pathogens has revealed a range of population structures, with some bacteria showing extensive recombination and others showing almost complete clonality. The population structure of the protozoan parasite Plasmodium falciparum has been harder to evaluate, since most studies have used a limited number of antigen-encoding loci that are known to be under strong selection. We describe length variation at 12 microsatellite loci in 465 infections collected from 9 locations worldwide. These data reveal dramatic differences in parasite population structure in different locations. Strong linkage disequilibrium (LD) was observed in six of nine populations. Significant LD occurred in all locations with prevalence <1% and in only two of five of the populations from regions with higher transmission intensities. Where present, LD results largely from the presence of identical multilocus genotypes within populations, suggesting high levels of self-fertilization in populations with low levels of transmission. We also observed dramatic variation in diversity and geographical differentiation in different regions. Mean heterozygosities in South American countries (0.3-0.4) were less than half those observed in African locations (0. 76-0.8), with intermediate heterozygosities in the Southeast Asia/Pacific samples (0.51-0.65). Furthermore, variation was distributed among locations in South America (F:(ST) = 0.364) and within locations in Africa (F:(ST) = 0.007). The intraspecific patterns of diversity and genetic differentiation observed in P. falciparum are strikingly similar to those seen in interspecific comparisons of plants and animals with differing levels of outcrossing, suggesting that similar processes may be involved. The differences observed may also reflect the recent colonization of non-African populations from an African source, and the relative influences of epidemiology and population history are difficult to disentangle. These data reveal a range of population structures within a single pathogen species and suggest intimate links between patterns of epidemiology and genetic structure in this organism.
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Affiliation(s)
- T J Anderson
- Wellcome Trust Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, Oxford, England.
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Abstract
Due to the increase of human migrations, the appearance of emerging and reemerging endemies, growing antibiotic resistance, and climatic changes, infectious diseases most probably constitute the major challenge for medicine in the next century. The advent of molecular methods of pathogen characterization has considerably improved our knowledge of the epidemiology of these diseases. However, the use of concepts of evolutionary genetics for interpreting "molecular epidemiology" data remains limited, although the application of such methods would broaden considerably the scope of this field of research, and allow epidemiologic and taxonomic approaches to be ascertained on a much firmer basis. In turn, pathogens, hosts, and vectors provide fascinating models for basic research. The artificial character of the border between "basic" and "applied" research is especially apparent with regard to the "integrated genetic epidemiology of infectious diseases" concept. The goal of this chapter is to evaluate the respective impact, on the transmission and pathogenicity of infectious diseases, of the host's, the pathogen's, and the vector's (for vector-borne diseases) genetic diversity, and the interactions between these three parameters (coevolution phenomena).
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Affiliation(s)
- M Tibayrenc
- Centre d'Etudes sur le Polymorphisme des Microorganismes (CEPM), Centre IRD de Montpellier, France.
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