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Isolation and characterization of the MSP1 genes from Plasmodium malariae and Plasmodium ovale.

ABSTRACT: The merozoite surface protein 1 (MSP1) is the principal surface antigen of the blood stage form of the Plasmodium parasite. Antibodies recognizing MSP1 are frequently detected following Plasmodium infection, making this protein a significant component of malaria vaccines and diagnostic tests. Although the MSP1 gene sequence has been reported for Plasmodium falciparum and Plasmodium vivax, this gene has not been identified for the other two major human-infectious species, Plasmodium malariae and Plasmodium ovale. MSP1 genes from these two species were isolated from Cameroon blood donor samples. The genes are similar in size to known MSP1 genes and encode proteins with interspecies conserved domains homologous to those identified in other Plasmodium species. Sequence and phylogenetic analysis of all available Plasmodium MSP1 amino acid sequences clearly shows that the Po and Pm MSP1 sequences are truly unique within the Plasmodium genus and not simply Pf or Pv variants.

SUBMITTER: Birkenmeyer L

PROVIDER: S-EPMC2877440 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Isolation and characterization of the MSP1 genes from Plasmodium malariae and Plasmodium ovale.

Birkenmeyer Larry L Muerhoff A Scott AS Dawson George J GJ Desai Suresh M SM

The American journal of tropical medicine and hygiene 20100601 6

The merozoite surface protein 1 (MSP1) is the principal surface antigen of the blood stage form of the Plasmodium parasite. Antibodies recognizing MSP1 are frequently detected following Plasmodium infection, making this protein a significant component of malaria vaccines and diagnostic tests. Although the MSP1 gene sequence has been reported for Plasmodium falciparum and Plasmodium vivax, this gene has not been identified for the other two major human-infectious species, Plasmodium malariae and ...[more]

PMID: 20519591

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Project description:BackgroundMultiplex bead assays (MBA) that measure IgG antibodies to the carboxy-terminal 19-kDa sub-unit of the merozoite surface protein 1 (MSP119) are currently used to determine malaria seroprevalence in human populations living in areas with both stable and unstable transmission. However, the species specificities of the IgG antibody responses to the malaria MSP119 antigens have not been extensively characterized using MBA.MethodsRecombinant Plasmodium falciparum (3D7), Plasmodium malariae (China I), Plasmodium ovale (Nigeria I), and Plasmodium vivax (Belem) MSP119 proteins were covalently coupled to beads for MBA. Threshold cut-off values for the assays were estimated using sera from US citizens with no history of foreign travel and by receiver operator characteristic curve analysis using diagnostic samples. Banked sera from experimentally infected chimpanzees, sera from humans from low transmission regions of Haiti and Cambodia (N = 12), and elutions from blood spots from humans selected from a high transmission region of Mozambique (N = 20) were used to develop an antigen competition MBA for antibody cross-reactivity studies. A sub-set of samples was further characterized using antibody capture/elution MBA, IgG subclass determination, and antibody avidity measurement.ResultsTotal IgG antibody responses in experimentally infected chimpanzees were species specific and could be completely suppressed by homologous competitor protein at a concentration of 10 μg/ml. Eleven of 12 samples from the low transmission regions and 12 of 20 samples from the high transmission area had antibody responses that were completely species specific. For 7 additional samples, the P. falciparum MSP119 responses were species specific, but various levels of incomplete heterologous competition were observed for the non-P. falciparum assays. A pan-malaria MSP119 cross-reactive antibody response was observed in elutions of blood spots from two 20-30 years old Mozambique donors. The antibody response from one of these two donors had low avidity and skewed almost entirely to the IgG3 subclass.ConclusionsEven when P. falciparum, P. malariae, P. ovale, and P. vivax are co-endemic in a high transmission setting, most antibody responses to MSP119 antigens are species-specific and are likely indicative of previous infection history. True pan-malaria cross-reactive responses were found to occur rarely.

Project description:The Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has been recently documented, the transmission of the two minor Plasmodium species, Plasmodium malariae and Plasmodium ovale spp., is poorly characterized in the region. This study aims to determine the prevalence of these minor species in the China-Myanmar border area and their genetic diversity.Epidemiology study was conducted during passive case detection in hospitals and clinics in Myanmar and four counties in China along the China-Myanmar border. Cross-sectional surveys were conducted in villages and camps for internally displaced persons to determine the prevalence of malaria infections. Malaria infections were diagnosed initially by microscopy and later in the laboratory using nested PCR for the SSU rRNA genes. Plasmodium malariae and P. ovale infections were confirmed by sequencing the PCR products. The P. ovale subtypes were determined by sequencing the Pocytb, Pocox1 and Pog3p genes. Parasite populations were evaluated by PCR amplification and sequencing of the MSP-1 genes. Antifolate sensitivity was assessed by sequencing the dhfr-ts and dhps genes from the P. malariae and P. ovale isolates.Analysis of 2701 blood samples collected from the China-Myanmar border by nested PCR targeting the parasite SSU rRNA genes identified 561 malaria cases, including 161 Plasmodium falciparum, 327 P. vivax, 66 P. falciparum/P. vivax mixed infections, 4 P. malariae and 3 P. ovale spp. P. vivax and P. falciparum accounted for >60 and ~30% of all malaria cases, respectively. In comparison, the prevalence of P. malariae and P. ovale spp. was very low and only made up ~1% of all PCR-positive cases. Nevertheless, these two species were often misidentified as P. vivax infections or completely missed by microscopy even among symptomatic patients. Phylogenetic analysis of the SSU rRNA, Pocytb, Pocox1 and Pog3p genes confirmed that the three P. ovale spp. isolates belonged to the subtype P. ovale curtisi. Low-level genetic diversity was detected in the MSP-1, dhfr and dhps genes of these minor parasite species, potentially stemming from the low prevalence of these parasites preventing their mixing. Whereas most of the dhfr and dhps positions equivalent to those conferring antifolate resistance in P. falciparum and P. vivax were wild type, a new mutation S113C corresponding to the S108 position in pfdhfr was identified in two P. ovale curtisi isolates.The four human malaria parasite species all occurred sympatrically at the China-Myanmar border. While P. vivax has become the predominant species, the two minor parasite species also occurred at very low prevalence but were often misidentified or missed by conventional microscopy. These minor parasite species displayed low levels of polymorphisms in the msp-1, dhfr and dhps genes.

Project description:Since several malaria parasite species are usually present in a particular area, co-infections with more than one species of Plasmodium are more likely to occur in humans infected in these areas. In many mixed infections, parasite densities of the cryptic species may be low and often not recognized in clinical practice.Two children (3 and 6 years old) adopted recently from Central African Republic were admitted to hospital because of intermittent fever. Thin blood smears stained with Giemsa showed Plasmodium falciparum and Plasmodium malariae co-infection for both children at admission. They were both treated with atovaquone-proguanil combination for 3 days. At day 7, both thin blood smears examination remained negative but at day 28, thin blood smear was positive for P. malariae trophozoites and for Plasmodium ovale for the girl and her brother, respectively. Samples collected at day 1 and day 28 were submitted to real-time PCR showing the presence of the three parasite species (P. falciparum, P malariae and P. ovale) in admission blood samples from the two children and only P. ovale at day 28.Twenty-eight days follow-up after treatment led to detection of a third parasite species in the blood of these two patients suggesting covert co-infection and a delayed appearance of one cryptic species following treatment. Concurrently infecting malaria species could be mutually suppressive, with P. falciparum tending to dominate other species. These observations provide more evidence that recommendations for treatment of imported malaria should take into account the risk of concurrent or cryptic infection with Plasmodium species. Clinicians and biologists should be aware of the underestimated frequency of mixed infections with cryptic species and of the importance of patient follow-up at day 28. Future guidelines should shed more light on the treatment of mixed infection and on the interest of using artemisinin-based combinations for falciparum and non-falciparum species.

Dataset Information

Isolation and characterization of the MSP1 genes from Plasmodium malariae and Plasmodium ovale.

Publications

Isolation and characterization of the MSP1 genes from Plasmodium malariae and Plasmodium ovale.

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