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Sedigheh Zakeri

Publications and source records attributed to Sedigheh Zakeri.

10 recordsLinked to original sources
PubMed2006

Identification and typing of Cameroonian isolates of P. malariae using monoclonal antibodies against P. brasilianum.

In the present study, monoclonal antibodies raised against Plasmodium brasilianum were used to demonstrate, for the first time, antigenic diversity in natural populations of Plasmodium malariae isolates and as diagnostic tool to detect low parasitaemia P. malariae infection. Seventeen McAbs reacting by indirect immunoflorescence antibody (IFA) assay with no other Plasmodium species than P. brasilianum, were shown to react with P. malariae and were used for typing 29 P. malariae isolates from hyperendemic areas in Yaounde and in three villages of South Cameroon with parasitaemia ranging from 0.01% to 1.8%. All 29 isolates were distinguished by their ability to react with certain antibodies and considered as representing different isolates of P. malariae. One of these McAbs (No. 14) recognized P. malariae isolates to both in Yaounde and from Mengang but not in Edou or in Nkol Mvae, which may recognize a specific epitope that is less common in strains found in these villages and provide evidence of regional variation within the P. malariae parasites. The McAbs Nos. 16 and 17 were used to determine their usefulness as diagnostic tools for 30 suspected blood samples that were collected from patients with fever and it became clear that they could detect sub-microscopical infections of P. malariae. This study supports the concept of using of P. brasilianum as a substitute for P. malariae during immuno-diagnosis of malaria in endemic areas where PCR assay cannot be used for identification of the P. malariae parasites. In addition our results for the first time provide evidence of considerable antigenic diversity of clinical P. malariae isolates in Cameroon.

Adolescent↗
PubMed2006

Merozoite surface protein-3alpha is a reliable marker for population genetic analysis of Plasmodium vivax.

BACKGROUND: The knowledge on population structure of the parasite isolates has contributed greatly to understanding the dynamics of the disease transmission for designing and evaluating malaria vaccines as well as for drug applications. msp-1 and msp-3alpha genes have been used as a genetic marker in population studies of Plasmodium vivax isolates. In this study, msp-3alpha was compared and assessed with msp-1 marker in order to find whether msp-3alpha is a reliable genetic marker for P. vivax population studies. METHODS: This comparative study was designed and carried out as the first assessment of diversity in Pvmsp-3alpha gene by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in the 50 northern and 94 southern P. vivax isolates from Iran, which had been analysed before for msp-1 gene. RESULTS: Three allele size as, Type A (1.8 kb), Type B (1.5 kb) and Type C (1.2 kb) have been detected among both northern and southern isolates based on PCR results. Type C (70%) and Type A (68.7%) were the predominant fragments among northern and southern parasites, respectively. 99 distinct Pvmsp-3alpha fragments defined by the size were detected in the 94 southern samples by PCR analysis. However, no mixed genotype infections have been detected among northern isolates. Based on restriction pattern from digestion with Hha I and Alu I 12 and 49 distinct allelic variants have been detected among 50 northern and 94 southern isolates. However, based on msp-1 gene, 30 distinct variants identified in all 146-sequenced Iranian P. vivax isolate. CONCLUSION: The results suggested that PCR-RFLP on msp-3alpha gene is an adequate, applicable and easily used technique for molecular epidemiology studies of P. vivax isolates without the need for further sequencing analysis.

Alleles↗
PubMed2006

Circumsporozoite protein gene diversity among temperate and tropical Plasmodium vivax isolates from Iran.

To date, there is no information on the genetic diversity of the circumsporozoite protein (CSP), a leading vaccine candidate, in Plasmodium vivax populations circulating in Iran. The gene for this protein, Pvcsp, was amplified from 374 P. vivax isolates collected in the temperate northern, and in the tropical southern endemic areas. PCR-RFLP analysis of the repeated central region revealed that the parasites collected in the northern area were almost exclusively of the VK210 type. Parasites collected in the south-eastern areas were of both VK210 and VK247 types. We detected VK210 parasite in 70.5% of the samples, VK247 parasites in 17.5% and mixed type infections in 12% of the isolates. Sequence analysis of 137 isolates obtained from both areas identified a total of 25 distinct genotypes. The degree of genetic diversity was generally higher for the tropical (21 genotypes) than the temperate (7 genotypes) P. vivax populations, a difference possibly reflecting the high cross-border exchanges between Afghanistan and Pakistan and southern Iran. Interestingly, all but two VK210 type isolates sequenced harboured a 36-bp post-repeat insert previously only observed in North Korea and China. This large-scale survey of parasite diversity in the Eastern Mediterranean Region provides a set of baseline data suitable for future molecular epidemiological studies of P. vivax.

Adolescent↗
PubMed2006

Identification, sequence analysis, and comparative study on GSTe2 insecticide resistance gene in three main world malaria vectors: Anopheles stephensi, Anopheles culicifacies, and Anopheles fluviatilis.

Glutathione S-transferases (GSTs) are soluble dimeric proteins that are involved in the metabolism, detoxification, and excretion of a large number of endogenous and exogenous compounds such as insecticides from the cell. In the current study, field specimens of Anopheles stephensi Liston, Anopheles fluviatilis James, and Anopheles culicifacies Giles collected from Sistan and Baluchistan province in Iran and subjected to World Health Organization susceptibility test. Only An. stephensi was resistant to 4% DDT. DNA extraction and rDNA-ITS2-polymerase chain reaction (PCR) for correct species identification, followed by amplification of GSTe2 gene, including exon I and II and full sequence of intron I, identified a 500-bp fragment in these three species. These fragments were purified and sequenced from both ends. The comparison of coding sequence of GSTe2 gene between these species and with Anopheles gambiae Giles showed 82 to 86% similarity at nucleic acid levels and identified nucleotide polymorphisms within An. culicifacies and An. stephensi populations. Species-specific differences have been detected in intron I of GSTe2 gene. This is in concordance with the previous studies and confirmed the conserved nature of intron sequence in GSTe2 gene of each species, probably useful as a molecular marker for species-specific identification. Phylogenetic analysis based on rDNA-ITS2, and coding (exon I and II) and noncoding sequences of GSTe2, showed the systematic relatedness between Iranian malaria vectors and the possibility of using these sequences in both differentiation of Anopheles species and defining their evolutionary relationship with the only available GSTe2 sequence of An. gambiae. These data may be useful for implementation and evaluation of malaria control programs in aspects of population genetics and molecular resistance.

Animals↗
PubMed2006

Population structure analysis of Plasmodium vivax in areas of iran with different malaria endemicity.

To obtain the genetic structure of Plasmodium vivax populations in the northern and southern malaria-endemic areas in Iran, which differ in endemicity, sequence diversity in the variable block 5 and the C-terminal part of P. vivax merozoite surface protein 1 (Pvmsp 1) was analyzed. The variable block 5 fragment from 52 northern and 94 southern isolates was amplified and sequenced. Type 1, type 2, and recombinant type 3 allelic variants were found in both northern and southern isolates, with type 1 predominant in parasites from the north and type 2 in those from the south. A total of 7 and 27 distinct variants were detected among northern and southern isolates, respectively. A single variant predominated (71%) in the northern isolates, whereas variants were evenly distributed among southern isolates, with only two exceeding 10%. Thus, parasites from the southern malaria-endemic area were more polymorphic than those circulating in the northern area, where malaria is a re-emerging disease. Sequence alignments showed that although some variants were found only in northern or southern isolates, some were common to both and had also been observed in parasites from Azerbaijan, Turkey, Thailand, Bangladesh, and China. The Pvmsp 1 fragment corresponding to the C-terminal region was also amplified and the sequences derived from 20 northern and 50 southern isolates were identical. This high degree of conservation reinforces the potential of this polypeptide fragment for inclusion in synthetic vaccines being developed against P. vivax.

Adult↗
PubMed2005

Genetic analysis of rDNA-ITS2 and RAPD loci in field populations of the malaria vector, Anopheles stephensi (Diptera: Culicidae): implications for the control program in Iran.

Anopheles stephensi is one of the most important malaria vectors in the Middle-East, the Indian subcontinent, the Far-East and is the main malaria vector in south of Iran. This vector is thought to be a single but polytypic species, despite its enormous geographical range. To examine this hypothesis, we analyzed the rDNA-ITS2 and RAPD loci in different populations of An. stephensi from Iran. rDNA-ITS2 region in all sequenced specimens of An. stephensi contained a (CA)7 microsatellite sequence. Construction of phylogenetic tree based on rDNA-ITS2 sequences revealed that there only is a minor polymorphism between the different populations, despite their vast geographical distances. RAPD-PCR could differentiate rural and urban populations of An. stephensi, but it is unclear whether these two samples represent mysorensis and the type form. Further characterization of interested RAPD fragments by cloning; have shown the nature of inverted repeats and the presence of microsatellite region (GT) in both ends near to inverted repeat sequences of primers. These results showed that An. stephensi in Iran could be considered a single species with different biological and ecological forms in different zoogeographical zones. Further studies are needed to demonstrate the relation between RAPD and microsatellite sequences and the differences seen in the field for this species. This data will serve as first report on the sequence of rDNA-ITS2 and a microsatellite-containing RAPD region, which could be used for species-specific diagnosis and differentiation of urban and rural populations in An. stephensi.

Animals↗
PubMed2005

Multiple genotypes of the merozoite surface proteins 1 and 2 in Plasmodium falciparum infections in a hypoendemic area in Iran.

In Iran, malaria transmission mainly occurs in south-eastern regions through both Plasmodium falciparum and P. vivax. The genetic diversity of P. falciparum isolates was analysed in 108 patients attending the regional hospital in Chabahar District, using the molecular markers msp1 and msp2. Multiple genotypes were detected in 87% of patients and the mean numbers of msp1 and msp2 genotypes were 2.51 (95% CI: 2.29-2.73) and 2.61 (95% CI: 2.39-2.83) respectively. Various allelic types of msp1 and msp2 were found, with msp2 3D7/IC type detected in 94% of infections. Plasmodium falciparum infections in south-east Iran appear to have a higher genetic diversity than expected for an area of low transmission. A situation of higher transmission in this area may be emerging, possibly because of reduced efficacy of first-line treatments.

Adolescent↗
PubMed2003

Sequence heterogeneity of the merozoite surface protein-1 gene (MSP-1) of Plasmodium vivax wild isolates in southeastern Iran.

The merozoite surface protein of Plasmodium vivax (PvMSP-1) has been considered as a vaccine candidate, which exhibits antigenic diversity among isolates. We investigated the extent of sequence variation in the polymorphic region 5 of PvMSP-1 in order to characterize the genetic structure and composition of P. vivax in clinical isolates from Iranshahr and Chahbahar districts of Sistan and Baluchistan province, Iran. The PvMSP-1 gene amplification revealed size variation among the isolates, ranging from 430 to 550 bp. Sequences were obtained for 15 Iranian and one Pakistani isolates and 14 different alleles were detected. Results also showed three distinct sequence types of the polymorphic region. Sequence analysis has shown several single nucleotide polymorphisms to occur in this block of PvMSP-1, creating different alleles in the progeny and also microheterogeneity in the region. Thus, this study provides preliminary evidence of sequence heterogeneity in the Iranian P. vivax population.

Adolescent↗
PubMed2002

Detection of malaria parasites by nested PCR in south-eastern, Iran: evidence of highly mixed infections in Chahbahar district.

BACKGROUND: Rapid diagnosis and correct treatment of cases are the main objectives of control programs in malaria-endemic areas. METHODS AND RESULTS: To evaluate these criteria and in a comparative study, blood specimens were collected from 120 volunteers seeking care at the Malaria Health Center in Chahbahar district. One hundred and seven out of 120 Giemsa-stained slides were positive for malaria parasites by microscopy. Eighty-four (70%) and 20 (16.7%) were identified as having only Plasmodium vivax and Plasmodium falciparum infections, respectively, while only 3 (2.5%) were interpreted as having mixed P. vivax-P. falciparum infections. The target DNA sequence of the 18S small sub-unit ribosomal RNA (ssrRNA) gene was amplified by Polymerase Chain Reaction (PCR) and used for the diagnosis of malaria in south-eastern Iran. One hundred twenty blood samples were submitted and the results were compared to those of routine microscopy. The sensitivity of PCR for detection of P. vivax and P. falciparum malaria was higher than that of microscopy: nested PCR detected 31 more mixed infections than microscopy and parasite positive reactions in 9 out of the 13 microscopically negative samples. The results also confirmed the presence of P. vivax and P. falciparum. CONCLUSIONS: These results suggest that, in places where transmission of both P. vivax and P. falciparum occurs, nested PCR detection of malaria parasites can be a very useful complement to microscopical diagnosis.

Adolescent↗