scholarly journals Genetic polymorphism of histidine rich protein 2 in Plasmodium falciparum isolates from different infection sources in Yunnan Province, China

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Ying Dong ◽  
Shuping Liu ◽  
Yan Deng ◽  
Yanchun Xu ◽  
Mengni Chen ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Falciparum Malaria ◽  
Dna Sequences ◽  
Yunnan Province ◽  
Diversity Index ◽  
Peptide Sequence ◽  
Peptide Chain ◽  
Blood Samples

Abstract Background Failed diagnoses of some falciparum malaria cases by RDTs are constantly reported in recent years. Plasmodium falciparum histidine-rich protein 2 (pfhpr2) gene deficiency has been found to be the major reason of RDTs failure in many countries. This article analysed the deletion of pfhpr2 gene of falciparum malaria cases isolated in Yunnan Province, China. Methods Blood samples from falciparum malaria cases diagnosed in Yunnan Province were collected. Plasmodium genomic DNA was extracted and the pfhrp2 gene exon2 region was amplified via nested PCR. The haplotype of the DNA sequence, the nucleic acid diversity index (PI) and expected heterozygosity (He) were analyzed. Count PfHRP2 amino acid peptide sequence repeat and its times, and predict the properties of PfHRP2 peptide chain reaction to RDTs testing. Results A total of 306 blood samples were collected, 84.9% (259/306) from which pfhrp2 PCR amplification products (gene exon2) were obtained, while the remaining 47 samples were false amplification. The length of the 250 DNA sequences ranged from 345 - 927 bp, with 151 haplotypes, with PI and He values of 0.169 and 0.983, respectively. The length of the PfHRP2 peptide chain translated from 250 DNA sequences ranged from 115 to 309 aa. All peptide chains had more than an amino acid codon deletion. All 250 PfHRP2 strands ended with a type 12 amino acid repeat, 98.0% (245/250) started with a type 1 repetition and 2.0% (5/250) with a type 2 repetition. The detection rate for type 2 duplicates was 100% (250/250). Prediction of RDT sensitivity of PfHRP2 peptide chains based on type 2 and type 7 repeats showed that 9.60% (24/250), 50.0% (125/250), 13.20% (33/250) and 27.20.5% (68/250) of the 250 peptide chains were very sensitive, sensitive, borderline and non-sensitive, respectively. Conclusion The diversified polymorphism of the pfhrp2 gene deletion from different infection sources in the Yunnan province are extremely complex. The cause of the failure of pfhrp2 exon2 amplification is still to be investigated. The results of this study appeal to Yunnan Province for a timely evaluation of the effectiveness and applicability of RDTs in the diagnosis of malaria.

scholarly journals Polymorphism analysis of propeller domain of k13 gene in Plasmodium ovale curtisi and Plasmodium ovale wallikeri isolates original infection from Myanmar and Africa in Yunnan Province, China

2020 ◽  
Author(s):  
Mengni Chen ◽  
Ying Dong ◽  
Yan Deng ◽  
Yanchun Xu ◽  
Yan Liu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Spatial Structure ◽  
Spatial Model ◽  
Yunnan Province ◽  
Cdna Sequence ◽  
Peptide Chain ◽  
Base Substitution ◽  
Plasmodium Ovale ◽  
Coding Region ◽  
Blood Samples

Abstract Background: More than 20 cases of imported ovale malaria patients have been diagnosed and reported in Yunnan Province over the past eight years. By applying morphological examination and 18ss RNA gene analysis of P. ovale , more than 90% of the cases have achieved definite diagnosis. Nevertheless, some cases with observation of typical P. ovale morphology could be identified as the other Plasmodium species based on 18ss RNA gene test, thusly posing challenges on the accurate diagnosis of malaria. To help establish a more sensitive and specific method for the detecting of P. ovale genes, the present study performs sequence analysis on k13-propeller polymorphisms in P. ovale.Methods: The blood samples of ovale malaria patients in Yunnan Province were collected from January 2013 to August 2019, and the infection sources were confirmed according to epidemiological investigation. The DNAs of P. ovale were extracted, and the coding region (from 206 th aa to 725 th aa) in k13 gene propeller domain was amplified using nested PCR. Subsequently, the amplified products were sequenced and compared with reference sequence to obtain cDNA sequence. The haplotypes and mutation loci of the cDNA sequence were analyzed, and the spatial structure of the amino acid peptide chain of k13 gene propeller domain was predicted by using SWISS-MODEL database ( www.swissmodel.expasy.org/interactive ).Results: Of the 18 collected blood samples of ovale malaria patients, the coding region from 224 th aa to 725 th aa of k13 gene from P. ovale in 83.3% of the samples (15/18) were amplified and the amplified products were around 1732 bp in length. 15 cDNA sequences were obtained. Three haplotypes were observed in these sequences, and the values of Ka / Ks, nucleic acid diversity index (π) and expected heterozygosity (He) were 3.784, 0.0095, and 0.4250, respectively. Curtisi haplotype, Wallikeri haplotype, and mutant type accounted for 73.3% (11/15), 20.0% (3/15), and 6.7% (1/15), respectively. The predominant haplotypes of P. ovale curtisi were determined in all six Myanmar isolates yielded. Of the nine African isolates, six were identified as P. ovale curtisi ; and three were P. ovale wallikeri . Base substitutions between the sequences of P. ovale curtisi and P. ovale wallikeri were determined at 38 loci, such as c.711. Moreover, the A> T base substitution at c.1426 is a nonsynonymous mutation, resulting in amino acid variation of T476S in the 476 th position. Compared with sequence of P. ovale wallikeri , the double nonsynonymous mutations of G> A and A> T at the sites of c.1186 and c.1426 leads to the variations of D396N and T476S for the 396 th and 476 th amino acids positions, respectively. For P. ovale curtisi and P. ovale wallikeri , the peptide chains in the coding region from 224 th aa to 725 th aa of k13 gene merely formed a monomeric spatial model, whereas the double-variant peptide chains of D396N and T476S formed homodimeric spatial model.Conclusion: The propeller domain of k13 gene in the Plasmodium ovale isolates imported into Yunnan Province from Myanmar and Africa showed high differentiation. The sequences of Myanmar-imported isolates belong to P. ovale curtisi , while the sequences of African isolates showed the sympatric distribution from P. ovale curtis i, P. ovale wallikeri and mutant isolates. The cDNA sequence with a double base substitution formed a dimeric spatial model to encode the peptide chain, which is completely different from the monomeric spatial structure to encode the peptide chain from P. ovale curtisi and P. ovale wallikeri .

Structural and antigenic polymorphism of the 35- to 48-kilodalton merozoite surface antigen (MSA-2) of the malaria parasite Plasmodium falciparum

1991 ◽  
Vol 11 (2) ◽  
pp. 963-971
Author(s):  
B Fenton ◽  
J T Clark ◽  
C M Khan ◽  
J V Robinson ◽  
D Walliker ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Surface Antigen ◽  
Dna Sequences ◽  
Amino Acid Sequences ◽  
Merozoite Surface Antigen ◽  
Parasite Plasmodium ◽  
Genes Encoding ◽  
Parasite Plasmodium Falciparum ◽  
Group B

Merozoite surface antigen MSA-2 of the human parasite Plasmodium falciparum is being considered for the development of a malaria vaccine. The antigen is polymorphic, and specific monoclonal antibodies differentiate five serological variants of MSA-2 among 25 parasite isolates. The variants are grouped into two major serogroups, A and B. Genes encoding two different variants from serogroup A have been sequenced, and their DNA together with deduced amino acid sequences were compared with sequences encoded by other alleles. The comparison shows that the serological classification reflects differences in DNA sequences and deduced primary structure of MSA-2 variants and serogroups. Thus, the overall homologies of DNA and amino acid sequences are over 95% among variants in the same serogroup. In contrast, similarities between the group A variants and a group B variant are only 70 and 64% for DNA and amino acid sequences, respectively. We propose that the MSA-2 protein is encoded by two highly divergent groups of alleles, with limited additional polymorphism displayed within each group.

scholarly journals Structural and antigenic polymorphism of the 35- to 48-kilodalton merozoite surface antigen (MSA-2) of the malaria parasite Plasmodium falciparum.

1991 ◽  
Vol 11 (2) ◽  
pp. 963-971 ◽  
Author(s):  
B Fenton ◽  
J T Clark ◽  
C M Khan ◽  
J V Robinson ◽  
D Walliker ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Surface Antigen ◽  
Dna Sequences ◽  
Amino Acid Sequences ◽  
Merozoite Surface Antigen ◽  
Parasite Plasmodium ◽  
Genes Encoding ◽  
Parasite Plasmodium Falciparum ◽  
Group B

Merozoite surface antigen MSA-2 of the human parasite Plasmodium falciparum is being considered for the development of a malaria vaccine. The antigen is polymorphic, and specific monoclonal antibodies differentiate five serological variants of MSA-2 among 25 parasite isolates. The variants are grouped into two major serogroups, A and B. Genes encoding two different variants from serogroup A have been sequenced, and their DNA together with deduced amino acid sequences were compared with sequences encoded by other alleles. The comparison shows that the serological classification reflects differences in DNA sequences and deduced primary structure of MSA-2 variants and serogroups. Thus, the overall homologies of DNA and amino acid sequences are over 95% among variants in the same serogroup. In contrast, similarities between the group A variants and a group B variant are only 70 and 64% for DNA and amino acid sequences, respectively. We propose that the MSA-2 protein is encoded by two highly divergent groups of alleles, with limited additional polymorphism displayed within each group.

scholarly journals Transcriptome-based analysis of blood samples reveals elevation of DNA damage response, neutrophil degranulation, cancer and neurodegenerative pathways in Plasmodium falciparum patients

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Akua A. Karikari ◽  
Wasco Wruck ◽  
James Adjaye
Keyword(s):  
Dna Damage ◽  
Plasmodium Falciparum ◽  
Falciparum Malaria ◽  
Dna Damage Response ◽  
Neurological Deficits ◽  
Down Regulation ◽  
Alcoholic Fatty Liver ◽  
Blood Samples ◽  
Damage Response ◽  
Neutrophil Degranulation

Abstract Background Malaria caused by Plasmodium falciparum results in severe complications including cerebral malaria (CM) especially in children. While the majority of falciparum malaria survivors make a full recovery, there are reports of some patients ending up with neurological sequelae or cognitive deficit. Methods An analysis of pooled transcriptome data of whole blood samples derived from two studies involving various P. falciparum infections, comprising mild malaria (MM), non-cerebral severe malaria (NCM) and CM was performed. Pathways and gene ontologies (GOs) elevated in the distinct P. falciparum infections were determined. Results In all, 2876 genes were expressed in common between the 3 forms of falciparum malaria, with CM having the least number of expressed genes. In contrast to other research findings, the analysis from this study showed MM share similar biological processes with cancer and neurodegenerative diseases, NCM is associated with drug resistance and glutathione metabolism and CM is correlated with endocannabinoid signalling and non-alcoholic fatty liver disease (NAFLD). GO revealed the terms biogenesis, DNA damage response and IL-10 production in MM, down-regulation of cytoskeletal organization and amyloid-beta clearance in NCM and aberrant signalling, neutrophil degranulation and gene repression in CM. Differential gene expression analysis between CM and NCM showed the up-regulation of neutrophil activation and response to herbicides, while regulation of axon diameter was down-regulated in CM. Conclusions Results from this study reveal that P. falciparum-mediated inflammatory and cellular stress mechanisms may impair brain function in MM, NCM and CM. However, the neurological deficits predominantly reported in CM cases could be attributed to the down-regulation of various genes involved in cellular function through transcriptional repression, axonal dysfunction, dysregulation of signalling pathways and neurodegeneration. It is anticipated that the data from this study, might form the basis for future hypothesis-driven malaria research.

scholarly journals Status of Artemisinin Resistance in Malaria Parasite Plasmodium falciparum from Molecular Analyses of the Kelch13 Gene in Southwestern Nigeria

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Mary Aigbiremo Oboh ◽  
Daouda Ndiaye ◽  
Hiasindh Ashmi Antony ◽  
Aida Sadikh Badiane ◽  
Upasana Shyamsunder Singh ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Dna Sequences ◽  
Malaria Parasite ◽  
Combined Therapy ◽  
Artemisinin Resistance ◽  
Sub Saharan Africa ◽  
Sequence Analyses ◽  
Southwestern Nigeria ◽  
Prime Concern

Evolution and spread of malaria parasite Plasmodium falciparum capable of evading antimalarials are the prime concern to malaria control. The currently effective drug, artemisinin (ART), is under threat due to detection of ART-resistant P. falciparum parasites in the Southeast Asian countries. It has been shown that amino acid (AA) mutations at the P. falciparum Kelch13 (Pfk13) gene provide resistance to ART. Nigeria, a part of the Sub-Saharan Africa, is highly endemic to malaria, contributing quite significantly to malaria, and resistance to chloroquine (CQ) and sulfadoxine-pyrimethamine (SP) combination drugs has already been reported. Since artemisinin combined therapy (ACT) is the first-line drug for treatment of uncomplicated malaria in Nigeria and five amino acid mutations have been validated in the Pfk13 gene alongside with candidate mutations for ART resistance, we performed molecular surveillance for mutations (following PCR and DNA sequence analyses) in this gene from two southwestern states of Nigeria. Statistical analyses of DNA sequences were also performed following different evolutionary models. None of the different validated and candidate AA mutations of Pfk13 gene conferring resistance to ART could be detected in P. falciparum sampled in the two southwestern states of Nigeria. In addition, DNA sequencing and sequence analyses indicated neither evolutionary selection pressure on the Pfk13 gene nor association of mutations in Pfk13 gene with mutations of other three genes conferring resistance to CQ and SP. Therefore, based on the monomorphism at the Pfk13 gene and nonassociation of mutations of this gene with mutations in three other drug-resistant genes in malaria parasite P. falciparum, it can be proposed that malaria public health is not under immediate threat in southwestern Nigeria concerning ART resistance.

scholarly journals Polymorphism analysis of propeller domain of k13 gene in Plasmodium ovale curtisi and Plasmodium ovale wallikeri isolates original infection from Myanmar and Africa in Yunnan Province, China

2020 ◽  
Author(s):  
Mengni Chen ◽  
Ying Dong ◽  
Yan Deng ◽  
Yanchun Xu ◽  
Yan Liu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Spatial Structure ◽  
Spatial Model ◽  
Yunnan Province ◽  
Peptide Chain ◽  
Base Substitution ◽  
Plasmodium Ovale ◽  
Coding Region ◽  
Mutant Type ◽  
Double Base

Abstract Background: 19 imported ovale malaria patients have been reported in Yunnan Province, China over the past eight years. All of them have been confirmed by morphological examination and 18S small subunit ribosomal RNA gene (18S rRNA) based PCR in YNRL. Nevertheless, the subtypes of P. ovale could not be identified based on 18S rRNA gene test, thus posing challenges on its accurate diagnosis. To help establish a more sensitive and specific method for the detection of P. ovale genes, the present study performs sequence analysis on k13-propeller polymorphisms in P. ovale. Methods: The dried blood spots (DBS) of ovale malaria patients in Yunnan Province were collected from January 2013 to December 2018, and the infection sources were confirmed according to epidemiological investigation. The DNAs were extracted, and the coding region (from 206th aa to 725th aa) in k13 gene propeller domain was amplified using nested PCR. Subsequently, the amplified products were sequenced and compared with reference sequence to obtain CDS. The haplotypes and mutation loci of the CDS were analyzed, and the spatial structure of the amino acid peptide chain of k13 gene propeller domain was predicted by SWISS-MODEL.Results: The coding region from 224th aa to 725th aa of k13 gene from P. ovale in 83.3% of collected samples (15/18) were amplified. Three haplotypes CDS were observed in 15 samples, and the values of Ka / Ks, nucleic acid diversity index (π) and expected heterozygosity (He) were 3.784, 0.0095, and 0.4250. Curtisi haplotype, Wallikeri haplotype, and mutant type accounted for 73.3% (11/15), 20.0% (3/15), and 6.7% (1/15). The predominant haplotypes of P. ovale curtisi were determined in all five Myanmar isolates. Of the ten African isolates, six were identified as P. ovale curtisi, three were P. ovale wallikeri and one was mutant type. Base substitutions between the sequences of P. ovale curtisi and P. ovale wallikeri were determined at 38 loci, such as c.711. Moreover, the A> T base substitution at c.1428 was a nonsynonymous mutation, resulting in amino acid variation of T476S in the 476th position. Compared with sequence of P. ovale wallikeri, the double nonsynonymous mutations of G> A and A> T at the sites of c.1186 and c.1428 leads to the variations of D396N and T476S for the 396th and 476th amino acids positions. For P. ovale curtisi and P. ovale wallikeri, the peptide chains in the coding region from 224th aa to 725th aa of k13 gene merely formed a monomeric spatial model, whereas the double-variant peptide chains of D396N and T476S formed homodimeric spatial model.Conclusion: The propeller domain of k13 gene in the P. ovale isolates imported into Yunnan Province from Myanmar and Africa showed high differentiation. The sequences of Myanmar-imported isolates belong to P. ovale curtisi, while the sequences of African isolates showed the sympatric distribution from P. ovale curtisi, P. ovale wallikeri and mutant isolates. The CDS with a double base substitution formed a dimeric spatial model to encode the peptide chain, which is completely different from the monomeric spatial structure to encode the peptide chain from P. ovale curtisi and P. ovale wallikeri.

scholarly journals Polymorphism analysis of propeller domain of k13 gene in Plasmodium ovale curtisi and Plasmodium ovale wallikeri isolates original infection from Myanmar and Africa in Yunnan Province, China

2020 ◽  
Author(s):  
Mengni Chen ◽  
Ying Dong ◽  
Yan Deng ◽  
Yanchun Xu ◽  
Yan Liu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Spatial Structure ◽  
Spatial Model ◽  
Yunnan Province ◽  
Peptide Chain ◽  
Base Substitution ◽  
Plasmodium Ovale ◽  
Coding Region ◽  
Mutant Type ◽  
Double Base

Abstract Background Eighteen imported ovale malaria cases imported from Myanmar and various African countries have been reported in Yunnan Province, China from 2013 to 2018. All of them have been confirmed by morphological examination and 18S small subunit ribosomal RNA gene (18S rRNA) based PCR in YNRL. Nevertheless, the subtypes of Plasmodium ovale could not be identified based on 18S rRNA gene test, thus posing challenges on its accurate diagnosis. To help establish a more sensitive and specific method for the detection of P. ovale genes, this study performs sequence analysis on k13-propeller polymorphisms in P. ovale. Methods Dried blood spots (DBS) from ovale malaria cases were collected from January 2013 to December 2018, and the infection sources were confirmed according to epidemiological investigation. DNA was extracted, and the coding region (from 206th aa to 725th aa) in k13 gene propeller domain was amplified using nested PCR. Subsequently, the amplified products were sequenced and compared with reference sequence to obtain CDS. The haplotypes and mutation loci of the CDS were analysed, and the spatial structure of the amino acid peptide chain of k13 gene propeller domain was predicted by SWISS-MODEL.Results The coding region from 224th aa to 725th aa of k13 gene from P. ovale in 83.3% of collected samples (15/18) were amplified. Three haplotypes were observed in 15 samples, and the values of Ka / Ks, nucleic acid diversity index (π) and expected heterozygosity (He) were 3.784, 0.0095, and 0.4250. Curtisi haplotype, Wallikeri haplotype, and mutant type accounted for 73.3% (11/15), 20.0% (3/15), and 6.7% (1/15). The predominant haplotypes of P. ovale curtisi were determined in all five Myanmar isolates. Of the ten African isolates, six were identified as P. o. curtisi, three were P. o. wallikeri and one was mutant type. Base substitutions between the sequences of P. o. curtisi and P. o. wallikeri were determined at 38 loci, such as c.711. Moreover, the A > T base substitution at c.1428 was a nonsynonymous mutation, resulting in amino acid variation of T476S in the 476th position. Compared with sequence of P. o. wallikeri, the double nonsynonymous mutations of G > A and A > T at the sites of c.1186 and c.1428 leads to the variations of D396N and T476S for the 396th and 476th amino acids positions. For P. o. curtisi and P. o. wallikeri, the peptide chains in the coding region from 224th aa to 725th aa of k13 gene merely formed a monomeric spatial model, whereas the double-variant peptide chains of D396N and T476S formed homodimeric spatial model.Conclusion The propeller domain of k13 gene in the P. ovale isolates imported into Yunnan Province from Myanmar and Africa showed high differentiation. The sequences of Myanmar-imported isolates belong to P. o. curtisi, while the sequences of African isolates showed the sympatric distribution from P. o. curtisi, P. o. wallikeri and mutant isolates. The CDS with a double base substitution formed a dimeric spatial model to encode the peptide chain, which is completely different from the monomeric spatial structure to encode the peptide chain from P. o. curtisi and P. o. wallikeri.

scholarly journals PfEMP1-DBL1  amino acid motifs in severe disease states of Plasmodium falciparum malaria

2007 ◽  
Vol 104 (40) ◽  
pp. 15835-15840 ◽  
Author(s):  
J. Normark ◽  
D. Nilsson ◽  
U. Ribacke ◽  
G. Winter ◽  
K. Moll ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Falciparum Malaria ◽  
Severe Disease ◽  
Plasmodium Falciparum Malaria ◽  
Disease States

scholarly journals Polymorphism analysis of propeller domain of k13 gene in Plasmodium ovale curtisi and Plasmodium ovale wallikeri isolates original infection from Myanmar and Africa in Yunnan Province, China

2020 ◽  
Author(s):  
Mengni Chen ◽  
Ying Dong ◽  
Yan Deng ◽  
Yanchun Xu ◽  
Yan Liu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Spatial Structure ◽  
Spatial Model ◽  
Yunnan Province ◽  
Peptide Chain ◽  
Base Substitution ◽  
Plasmodium Ovale ◽  
Coding Region ◽  
Mutant Type ◽  
Double Base

Abstract Background: Nineteen imported ovale malaria patients have been reported in Yunnan Province, China over the past eight years. All of them have been confirmed by morphological examination and 18S small subunit ribosomal RNA gene (18S rRNA) based PCR in YNRL. Nevertheless, the subtypes of P. ovale could not be identified based on 18SrRNA gene test, thus posing challenges on its accurate diagnosis. To help establish a more sensitive and specific method for the detection of P. ovale genes, this study performs sequence analysis on k13-propeller polymorphisms in P. ovale. Methods:The dried blood spots (DBS) of ovale malaria patients in Yunnan Province were collected from January 2013 to December 2018, and the infection sources were confirmed according to epidemiological investigation. The DNAs were extracted, and the coding region (from 206th aa to 725th aa) in k13 gene propeller domain was amplified using nested PCR. Subsequently, the amplified products were sequenced and compared with reference sequence to obtain CDS. The haplotypes and mutation loci of the CDS were analyzed, and the spatial structure of the amino acid peptide chain of k13 gene propeller domain was predicted by SWISS-MODEL. Results:The coding region from 224th aa to 725th aa of k13 gene from P. ovale in 83.3% of collected samples (15/18) were amplified. Three haplotypes were observed in 15 samples, and the values of Ka / Ks, nucleic acid diversity index (π) and expected heterozygosity (He) were 3.784, 0.0095, and 0.4250. Curtisi haplotype, Wallikeri haplotype, and mutant type accounted for 73.3% (11/15), 20.0% (3/15), and 6.7% (1/15). The predominant haplotypes of P. ovale curtisi were determined in all five Myanmar isolates. Of the ten African isolates, six were identified as P. ovale curtisi, three were P. ovale wallikeri and one was mutant type. Base substitutions between the sequences of P. ovale curtisi and P. ovale wallikeri were determined at 38 loci, such as c.711. Moreover, the A > T base substitution at c.1428 was a nonsynonymous mutation, resulting in amino acid variation of T476S in the 476th position. Compared with sequence of P. ovale wallikeri, the double nonsynonymous mutations of G > A and A > T at the sites of c.1186 and c.1428 leads to the variations of D396N and T476S for the 396th and 476th amino acids positions. For P. ovale curtisi and P. ovale wallikeri, the peptide chains in the coding region from 224th aa to 725th aa of k13 gene merely formed a monomeric spatial model, whereas the double-variant peptide chains of D396N and T476S formed homodimeric spatial model. Conclusion:The propeller domain of k13 gene in the P. ovale isolates imported into Yunnan Province from Myanmar and Africa showed high differentiation. The sequences of Myanmar-imported isolates belong to P. ovale curtisi, while the sequences of African isolates showed the sympatric distribution from P. ovale curtisi,P. ovale wallikeri and mutant isolates. The CDS with a double base substitution formed a dimeric spatial model to encode the peptide chain, which is completely different from the monomeric spatial structure to encode the peptide chain from P. ovale curtisi and P. ovale wallikeri.

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