Diversity Of Plasmodium Falciparum Isolates Research Articles

The diversity of Plasmodium falciparum isolates from asymptomatic and symptomatic school-age children in Kinshasa Province, Democratic Republic of Congo

BackgroundUnderstanding Plasmodium falciparum population diversity and transmission dynamics provides information on the intensity of malaria transmission, which is needed for assessing malaria control interventions. This study aimed to determine P. falciparum allelic diversity and multiplicity of infection (MOI) among asymptomatic and symptomatic school-age children in Kinshasa Province, Democratic Republic of Congo (DRC).MethodsA total of 438 DNA samples (248 asymptomatic and 190 symptomatic) were characterized by nested PCR and genotyping the polymorphic regions of pfmsp1 block 2 and pfmsp2 block 3.ResultsNine allele types were observed in pfmsp1 block2. The K1-type allele was predominant with 78% (229/293) prevalence, followed by the MAD20-type allele (52%, 152/293) and RO33-type allele (44%, 129/293). Twelve alleles were detected in pfmsp2, and the 3D7-type allele was the most frequent with 84% (256/304) prevalence, followed by the FC27-type allele (66%, 201/304). Polyclonal infections were detected in 63% (95% CI 56, 69) of the samples, and the MOI (SD) was 1.99 (0.97) in P. falciparum single-species infections. MOIs significantly increased in P. falciparum isolates from symptomatic parasite carriers compared with asymptomatic carriers (2.24 versus 1.69, adjusted b: 0.36, (95% CI 0.01, 0.72), p = 0.046) and parasitaemia > 10,000 parasites/µL compared to parasitaemia < 5000 parasites/µL (2.68 versus 1.63, adjusted b: 0.89, (95% CI 0.46, 1.25), p < 0.001).ConclusionThis survey showed low allelic diversity and MOI of P. falciparum, which reflects a moderate intensity of malaria transmission in the study areas. MOIs were more likely to be common in symptomatic infections and increased with the parasitaemia level. Further studies in different transmission zones are needed to understand the epidemiology and parasite complexity in the DRC.

Genetic diversity of plasmodium falciparum isolates in Minna, North Central Nigeria inferred by PCR genotyping of Merozoite surface protein 1 and 2.

North Central Nigeria is one region in Nigeria with a significant incidence of malaria caused majorly by Plasmodium falciparum. This study utilizes the msp1 and msp2 genes of P. falciparum to examine its diversity and multiplicity of infection (MOI). Blood samples were collected from 247 children across selected healthcare facilities in Minna, from infants and children aged 6months to 17years. Of the total collection, 143 (58%) of the children were infected with P. falciparum with parasite density≥1000μl, and from which fifty (50) samples was randomly selected and presented for PCR for the characterization of msp1 and msp2 gene using nested-PCR method. Overall, 57 msp1 genotypes, including K1, MAD20 and RO33 were identified, ranging from (250-1000bp), (100-500bp) and (400-500bp), respectively. In addition, 54 different msp2 genotypes of FC27 and 3D7 alleles ranging from (100-900bp) and (100-800bp), respectively were selected. A monoclonal infection of 39% and a polyclonal infection of 61% was recorded, however, a particularity about this study is the polyclonal nature of RO33. Determination of gene diversity revealed MAD20 as the predominant allele for msp1 with a mean MOI of 1.35 and FC27 for msp2 with 1.72 MOI. The overall MOI recorded for the study was 1.60. There was, however, no statistical significance difference between MOI and age of the child (P>0.05). Meanwhile, findings from this study revealed P. falciparum populations were not genetically diverse with Heterozygosity (He) index of 0.0636. However, a significant level gene diversity within the antigenic markers of msp1 and msp2 was observed with He index of 0.714 and 0.830, respectively. This study has demonstrated the potential of gene diversity and MOI of P. falciparum, as important markers for assessing differences in malaria transmission intensity. Continuous malaria genetic surveillance is therefore recommended as a fundamental tool for monitoring changes in gene types and for intervention programs' effectiveness.

Genetic polymorphisms of Plasmodium falciparum isolates from Melka-Werer, North East Ethiopia based on the merozoite surface protein-2 (msp-2) gene as a molecular marker

BackgroundThe characterization of parasite populations circulating in malaria endemic areas is necessary to evaluate the success of ongoing interventions and malaria control strategies. This study was designed to investigate the genetic diversity of Plasmodium falciparum isolates from the semi-arid area in North East Ethiopia, using the highly polymorphic merozoite surface protein-2 (msp2) gene as a molecular marker.MethodsDried blood spot isolates were collected from patients with P. falciparum infection between September 2014 and January 2015 from Melka-Werer, North East Ethiopia. Parasite DNA was extracted and genotyped using allele-specific nested polymerase chain reactions for msp2.Results52 isolates were collected with msp2 identified in 41 (78.8%) isolates. Allele typing of the msp2 gene detected the 3D7/IC allelic family in 54% and FC27 allelic family in 46%. A total of 14 different msp2 genotypes were detected including 6 belonging to the 3D7/IC family and 8 to the FC27 family. Forty percent of isolates had multiple genotypes and the overall mean multiplicity of infections (MOI) was 1.2 (95%CI 0.96–1.42). The heterozygosity index was 0.50 for the msp2 locus. There was no difference in MOI between age groups. A negative correlation between parasite density and multiplicity of infection was found (p = 0.02).ConclusionPlasmodium falciparum isolates from the semi-arid area of North East Ethiopia are mainly monoclonal with low MOI and limited genetic diversity in the study population.

Genetic diversity of Plasmodium falciparum isolates from patients with uncomplicated and severe malaria based on msp-1 and msp-2 genes in Gublak, North West Ethiopia

BackgroundMalaria infection can present with a wide variety of symptoms, ranging from mild to severe. Plasmodium falciparum isolates in uncomplicated and severe malaria infections may have different parasite genetic profiles. This study was conducted to assess differences in genetic diversity and allelic frequencies in P. falciparum isolates according to malaria severity and age of patients in the Gublack area, northwest Ethiopia.MethodsCross-sectional health facility-based study conducted in Gublak, Ethiopia between July, 2017 and October, 2017. Symptomatic P. falciparum malaria patients with microscopically-confirmed infection were enrolled. Parasite DNA was extracted from filter paper blood spots and the polymorphic regions of the msp-1 and msp-2 genes were genotyped using allele-specific nested-PCR with fragment analysis by gel electrophoresis.ResultsA total of 118 patients were enrolled including 95 (80.5%) with uncomplicated infection and 23 (19.5%) with severe disease. In msp-1, the K1 allelic family was similarly prevalent in uncomplicated 42 (44.2%) and severe disease 12 (52.2%). In msp-2, FC27 was detected in 55 (57.9%) of uncomplicated infections and IC/3D7 in 14 (60.9%) of severe infections. 76 (64.4%) of the 118 isolates contained multiple genotypes; 56 (58.9%) in uncomplicated infections and 19 (82.6%) in severe infections. The overall of multiplicity of infection was 2.2 (95% CI 1.98–2.42) with 1.4 (95% CI 1.23–1.55) and 1.7 (95% CI 1.49–1.86) for msp-1 and msp-2, respectively. Multiplicity of infection was significantly higher in severe than uncomplicated infections (3.0 (95% CI 2.61–3.47) versus 2.0 (95% CI 1.83–2.23), respectively, p = 0.001). There was no difference in multiplicity of infection across age groups (p = 0.104).ConclusionPatients with severe malaria were more likely to have multiclonal infections. Further studies are needed to describe the association between P. falciparum genotypes and malaria severity in different malaria transmission areas.

Low levels of Plasmodium falciparum genetic diversity in two Nigerian communities bordering the Niger River

Introduction: Extensive genetic diversity of malaria parasites is a major draw back to ongoing control efforts. Population-specific investigation of genetic structure of the parasite is important for effective malaria intervention in endemic populations such as Nigeria where about one-third of the global burden of the disease is borne. This study describes the genetic diversity of Plasmodium falciparum isolates in the Niger River basins, North-Central Nigeria. Methodology: Parasite DNA w as extracted fr om finger -prick blood samples collected from eighty P. falciparum positive individuals. Polymerase Chain Reaction (PCR) genotyping was carried out to target K1, MAD20 and R033 allelic families of Merozoite Surface Protein (MSP) -1 gene and FC27 and 3D7 allelic families of MSP-2 gene. Results: Proportion of isolates with K1 family w as 28(70%) with two alleles in Idah and 16(40%) with two alleles in Ibaji. Proportion of isolates with MAD20 family was 8 (20%) and a total of two alleles were observed in Idah and 4(10%) with two alleles in Ibaji. RO33 proportion was 16 (40%) in Idah one allele and 8(20%) in Ibaji where the allelic family was also observed to be monomorphic. K1 was the most predominant MSP1 allele in the two parasite populations and the frequency of FC27 genotype was higher than 3D7 in both populations. Multiplicity of infection (Mol) with MSP-1 loci was higher in Ibaji (1.30) than Idah (1.05) while MoI with MSP-2 loci was lower in Ibaji (2.00) than Idah (2.13). However, there is no significant difference in the mean Mol between Idah and Ibaji (P &gt; 0.05). The expected heterozygosity (HE) value was 0.56 for MSP-1 and 0.84 for MSP-2. Conclusion: Our findings revealed high levels of monoclonal infections with P. falciparum, suggesting low parasite diversity. This may be a pointer to a reduction in malaria transmission in the river basins.

Genetic diversity of Plasmodium falciparum isolates from uncomplicated malaria cases in Ghana over a decade.

BackgroundGenotyping malaria parasites to assess their diversity in different geographic settings have become necessary for the selection of antigenic epitopes for vaccine development and for antimalarial drug efficacy or resistance investigations. This study describes the genetic diversity of Plasmodium falciparum isolates from uncomplicated malaria cases over a ten year period (2003–2013) in Ghana using the polymorphic antigenic marker, merozoite surface protein 2 (msp2).MethodsArchived filter paper blood blots from children aged nine years and below with uncomplicated malaria collected from nine sites in Ghana were typed for the presence of the markers. A total of 880 samples were genotyped for msp2 for the two major allelic families, FC27 and 3D7, using nested polymerase chain reaction (PCR). The allele frequencies and the multiplicity of infection were determined for the nine sites for five time points over a period of ten years, 2003–2004, 2005–2006, 2007–2008, 2010 and 2012–2013 malaria transmission seasons.ResultsThe number of different alleles detected for the msp2 gene by resolving PCR products on agarose gels was 14. Both of the major allelic families, 3D7 and FC27 were common in all population samples. The highest multiplicity of infection (MOI) was observed in isolates from Begoro (forest zone, rural site): 3.31 for the time point 2007–2008. A significant variation was observed among the sites in the MOIs detected per infection (Fisher's exact test, P < 0.001) for the 2007 isolates and also at each of the three sites with data for three different years, Hohoe, P = 0.03; Navrongo, P < 0.001; Cape Coast, P < 0.001. Overall, there was no significant difference between the MOIs of the three ecological zones over the years (P = 0.37) and between the time points when data from all sites were pooled (P = 0.40).ConclusionsThe diversity and variation between isolates detected using the msp2 gene in Ghanaian isolates were observed to be profound; however, there was homogeneity throughout the three ecological zones studied. This is indicative of gene flow between the parasite populations across the country probably due to human population movements (HPM).Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1692-1) contains supplementary material, which is available to authorized users.

Multiplicity of infection and genetic diversity of Plasmodium falciparum isolates from patients with uncomplicated and severe malaria in Gezira State, Sudan.

BackgroundMultiplicity and genetic diversity of Plasmodium falciparum infection might play a role in determining the clinical outcome of malaria infection and could be a fair reflection of the disease transmission rate. This study investigated the genetic diversity of P. falciparum and multiplicity of infection in relation to the severity of malaria and age of patients in Gezira State, Sudan.MethodsA cross-sectional health facilities-based survey was conducted in Gezira State, Sudan in January 2012. A total of 140 P. falciparum malaria patients diagnosed with microscopy and confirmed using nested PCR were recruited and classified into uncomplicated malaria and severe malaria states according to the standard WHO criteria. DNA was extracted and MSP1 and MSP2 allelic families were determined using nested PCR.ResultsThe overall multiplicity of infection (MOI) was 2.25 and 2.30 and 2.15 for uncomplicated and severe malaria respectively. There were no statistically significant differences between uncomplicated and severe malaria (SM) patient groups in MOI with regard to MSP1, MSP2 and overall MOI (Mann-Whitney U-test; all P < 0.05). The predominant MSP1 allelic families were MAD20 for uncomplicated malaria and RO33 for severe malaria. The distribution of both FC27 and IC1/3D7 MSP2 allelic families were approximately the same across disease severity. One hundred and eleven P. falciparum isolates (81 %) consisted of multiple genotypes; 71/90 (78.9 %) in uncomplicated malaria and 40/50 (85.1 %) in severe malaria patient groups. Neither MSP1 nor MSP2 allelic families showed association with malaria severity. No statistically significant differences in multiplicity of infection were observed between different age groups.ConclusionIn this study the majority of P. falciparum isolates from uncomplicated and severe malaria patients consisted of multiple genotypes. Further molecular epidemiological studies delineate the link between P. falciparum genotype with the malaria phenotype in different regions are encouraged.

Genetic diversity of Plasmodium falciparum isolates from concurrent malaria and arbovirus co-infections in Kedougou, southeastern Senegal.

BackgroundConcurrent malaria and arbovirus infections are common and represent an important public health concern in regions where both diseases are endemic. The present study investigates the genetic diversity and complexity of Plasmodium falciparum infection in concurrent malaria-arbovirus infections in Kedougou region, southeastern Senegal.MethodsParasite DNA was extracted from 60 to 27 sera samples collected from P. falciparum isolates of malaria and concurrent malaria-arbovirus infected patients, respectively, and followed by PCR-genotyping targeting the msp-1 (block2) and msp-2 (block3) allelic families.ResultsThe mean number of genotype per allelic family was comparable between the two groups. K1 was the predominant msp-1 allelic type both in malaria (94.91 %) and arbovirus-malaria (92.59 %) groups, whereas IC/3D7 was the most prevalent msp-2 allelic type in malaria (94.91 %) and arbovirus-malaria (96.29 %) groups. Frequencies of msp-1 and msp-2 allelic types were statistically comparable between the two groups (Fisher exact test, P > 0.05) and were not associated with age. FC27 was strikingly the least prevalent in both groups and was absent in children under 5 years of age. The proportions of P. falciparum isolates from malaria-infected patients carrying the three msp-1 allelic types (67.44 %) or the two msp-2 allelic types (76.47 %) were significantly higher than those from arbovirus-malaria co-infected patients (Exact binomial test, P < 0.05). The multiplicities of infection (MOI) were low and comparable for msp-1 (1.19 vs 1.22) and msp-2 (1.11 vs 1.10), respectively between malaria and arbovirus-malaria groups.ConclusionThe study showed no difference in the genetic diversity between P. falciparum isolates from malaria and concurrent malaria-arbovirus infected patients in Kedougou. The MOI was low despite intense malaria transmission in Kedougou. The overall results suggest a limited or no influence of arbovirus infections on P. falciparum diversity and complexity of malaria infection.

Genetic diversity of Plasmodium falciparum isolates from Baka Pygmies and their Bantu neighbours in the north of Gabon.

BackgroundThere have been many reports on the population genetic structure of Plasmodium falciparum from different endemic regions especially sub-Saharan Africa. However, few studies have been performed on neglected populations, such as the Pygmy populations. In this study, the population genetic structure of P. falciparum was investigated in the Baka Pygmies of Gabon and compared to that observed in neighboring villages composed mostly of Bantu farmers.MethodsA total of 342 blood samples were collected from 170 Baka Pygmies and 172 Bantus in the north of Gabon (Woleu Ntem Province). Plasmodium infections were characterized by sequencing a portion of the parasite cytochrome b gene. Population genetic structure of P. falciparum in the different villages was analysed using microsatellite markers and genes coding for antigenic proteins (MSP1, MSP2, GLURP, and EBA-175).ResultsOverall, prevalence of P. falciparum was around 57 % and no significant difference of prevalence was observed between Pygmies and Bantus. No significant differences of population genetic structure of P. falciparum was found between Pygmy and Bantu people except for one antigen-coding gene, glurp, for which genetic data suggested the existence of a potentially disruptive selection acting on this gene in the two types of populations. The genetic structure of P. falciparum followed a pattern of isolation by distance at the scale of the study.ConclusionThe prevalence and genetic diversity of P. falciparum observed in Baka demonstrates a significant transmission of the parasite in this population, and some exchanges of parasites with Bantu neighbours. Despite that, some antigen-coding genes seem to have had a particular evolutionary trajectory in certain Pygmy populations due to specific local human and/or mosquito characteristics.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0862-5) contains supplementary material, which is available to authorized users.

Genetic Diversity Block 2 of Surface Protein-1 in Plasmodium Falciparum Merozoite by Nested-PCR Method in Southeastern Iran

Background and Objectives: Plasmodium falciparum merozoite surface protein-1 (PfMSP-1) is a promising vaccine against malaria during its blood stages which play an important role in immunity to this disease. Polymorphic nature of this gene is a major obstacle in making an effective vaccine against malaria. In this study, the genetic diversity of Plasmodium falciparum isolates was investigated in Sistan-Baluchestan Province using allelic families of the MSP-1. Methods: From March/April 2011 to August/September 2012, 94 blood samples were collected from patients with falciparum malaria who were living in four districts of Sistan-Baluchestan Province. The extracted genomic DNA and genetic diversity of MSP-1 block 2 were evaluated by nested polymerase chain reaction. Results: From a total of 94 patients, 89 patients (94.7%) had positive PCR results and the remaining five patients were excluded. Seven different alleles of MSP-1 were identified through size difference on agarose gel. Comprising 46.1% of the samples, MAD20 was identified as the predominant MSP-1 allelic family, while the RO33 family had the lowest frequency (with 7.9%). In 10% of samples infection with two alleles was observed. Conclusion: The results of this study suggest that genetic diversity of PfMSP-1 in Southeastern Iran is relatively low and most infections originate from a clone that is consistent with an area of low malaria transmission. This information is useful for the prevention and control of malaria in Iran.

Genetic diversity of Plasmodium falciparum isolates based on MSP-1 and MSP-2 genes from Kolla-Shele area, Arbaminch Zuria District, southwest Ethiopia.

BackgroundThe genetic diversity of Plasmodium falciparum has been extensively studied in various countries. However, limited data are available from Ethiopia. This study was conducted to evaluate the extent of genetic diversity of P. falciparum in Kolla-Shele, in the southwest of Ethiopia.MethodsA total of 88 isolates from patients with uncomplicated P. falciparum attending Kolla-Shele Health Centre was collected from September to December, 2008. After extraction of DNA by Chelex® method, the samples were genotyped by using nested-PCR of msp1 (block 2) and msp2 (block 3) including their allelic families: K1, MAD20, RO33 and FC27, 3D7/IC1, respectively.ResultsAllelic variation in both msp1 and msp2 were identified in the 88 blood samples. For msp1 67% (59/88) and msp2 44% (39/88) were observed. K1 was the predominant msp1 allelic family observed in 33.9% (20/59) of the samples followed by RO33 and MAD20. Of the msp2 allelic family 3D7/IC1 showed higher frequency (21.5%) compared to FC27 (10.3%). A total of twenty-three alleles were detected; of which, eleven were from msp2 and twelve from msp2 genes. Fifty-nine percent of isolates had multiple genotypes and the overall mean multiplicity of infection was 1.8 (95% CI: 1.48-2.04). The heterozygosity index was 0.79 and 0.54for msp1 and msp2, respectively. There was no statically significant difference in the multiplicity of infection by either age or parasite density (P > 0.05).ConclusionThis genetic diversity study showed the presence of five allelic types in the study area, with dominance K1 in the msp1 family and 3D7/IC1 in the msp2 family. Multiple infections were observed in nearly 60% of the samples.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-015-0604-8) contains supplementary material, which is available to authorized users.

Genetic diversity of Plasmodium falciparum isolates from naturally infected children in north-central Nigeria using the merozoite surface protein-2 as molecular marker

ObjectiveTo characterize the genetic diversity of Plasmodium falciparum (P. falciparum) field isolates in children from Lafia, North-central Nigeria, using the highly polymorphic P. falciparum merozoite surface protein 2 (MSP-2) gene as molecular marker. MethodsThree hundred and twenty children were enrolled into the study between 2005 and 2006. These included 140 children who presented with uncomplicated malaria at the Dalhatu Araf Specialist Hospital, Lafia and another 180 children from the study area with asymptomatic infection. DNA was extracted from blood spot on filter paper and MSP-2 genes were genotyped using allele-specific nested PCR in order to analyze the genetic diversity of parasite isolates. ResultsA total of 31 and 34 distinct MSP-2 alleles were identified in the asymptomatic and uncomplicated malaria groups respectively. No difference was found between the multiplicity of infection in the asymptomatic group and that of the uncomplicated malaria group (P>0.05). However, isolates of the FC27 allele type were dominant in the asymptomatic group whereas isolates of the 3D7 allele type were dominant in the uncomplicated malaria group. ConclusionsThis study showed a high genetic diversity of P. falciparum isolates in North-central Nigeria and is comparable to reports from similar areas with high malaria transmission intensity.

Genetic diversity of Plasmodium falciparum isolates from Pahang, Malaysia based on MSP-1 and MSP-2 genes

BackgroundMalaria is still a public health problem in Malaysia especially in the interior parts of Peninsular Malaysia and the states of Sabah and Sarawak (East Malaysia). This is the first study on the genetic diversity and genotype multiplicity of Plasmodium falciparum in Malaysia.MethodsSeventy-five P. falciparum isolates were genotyped by using nested-PCR of MSP-1 (block 2) and MSP-2 (block 3).ResultsMSP-1 and MSP-2 allelic families were identified in 65 blood samples. RO33 was the predominant MSP-1 allelic family identified in 80.0% (52/65) of the samples while K1 family had the least frequency. Of the MSP-2 allelic families, 3D7 showed higher frequency (76.0%) compared to FC27 (20.0%). The multiplicity of P. falciparum infection (MOI) was 1.37 and 1.20 for MSP-1 and MSP-2, respectively. A total of seven alleles were detected; of which three MSP-1 allelic families (RO33, MAD20 and K1) were monomorphic in terms of size while MSP-2 alleles were polymorphic (two 3D7 and two FC27). Heterozygosity (HE) was 0.57 and 0.55 for MSP-1 and MSP-2, respectively.ConclusionsThe study showed that the MOI of P. falciparum is low, reflected the low intensity of malaria transmission in Pahang, Malaysia; RO33 and 3D7 were the most predominant circulating allelic families. The findings showed that P. falciparum has low allelic diversity with a high frequency of alleles. As a result, antimalarial drug efficacy trials based on MSP genotyping should be carefully interpreted.

13 Genetic diversity of Plasmodium falciparum isolates from wild African malaria mosquitoes(一般講演,第55回日本衛生動物学会南日本支部大会講演要旨)

13 Genetic diversity of Plasmodium falciparum isolates from wild African malaria mosquitoes(一般講演,第55回日本衛生動物学会南日本支部大会講演要旨)

Extensive genetic diversity of Plasmodium falciparum isolates collected from patients with severe malaria in Dakar, Senegal

While some genetic host factors are known to protect against severe Plasmodium falciparum malaria, little is known about parasite virulence factors. We have compared the genetic characteristics of P. falciparum isolates collected from 56 severe malaria patients and from 30 mild malaria patients recruited in Hôpital Principal, Dakar, Senegal. All isolates were typed using polymerase chain reaction amplification of polymorphic genetic loci ( MSP-1, MSP-2, HRP1, glurp, CSP, resa, and the multigene family Pf60). The complexity of infections was lower in severe than in mild malaria and the parasite genetic diversity in both groups was very large. No specific genetic make-up was associated with severity; there were, however, marked differences in allele frequencies in both groups, with a prevalence up to 60% of MSP-2 alleles specifically observed in the severe malaria isolates. In addition, the presence of MSP-1/RO33 alleles was significantly associated with a higher plasma level of tumour necrosis factor a receptor 1 ( P < 0.05), a reported indicator of severity in human malaria. These results point to potential differences in the genetic characteristics of parasites inducing severe versus mild pathology.