Polymorphism and epitope sharing between the alleles of merozoite surface protein-1 of Plasmodium falciparum among Indian isolates

<p>Abstract</p> <p>Background</p> <p>The C-terminal region of merozoite surface protein-1 (MSP-1) is one of the leading candidates for vaccination against the erythrocytic stages of malaria. However, a major concern in the development of MSP-1 based malaria vaccine is the polymorphism observed in different geographical <it>Plasmodium falciparum </it>isolates. To explore whether the sequence heterogeneity of PfMSP-1 leads to variation in naturally acquired anti-MSP-1₁₉antibodies, the present study was undertaken to study PfMSP-1₁₉sequence polymorphism in malaria-endemic villages in eastern India and also carried out a competition enzyme-linked immunosorbent assay using three PfMSP-1₁₉variant forms.</p> <p>Methods</p> <p>The sequence variations in the C-terminal region of PfMSP-1₁₉were determined in a malaria endemic region. Three PfMSP-1₁₉variants were produced in <it>Escherichia coli </it>(PfMSP1₁₉QKNG-L, PfMSP1₁₉EKNG-L and PfMSP1₁₉ETSR-F) and an immunodepletion assay was carried out using the corresponding patients' sera.</p> <p>Results</p> <p>Results revealed predominance of PfMAD20 allele among Indian field isolates. Seven PfMSP-1₁₉variant forms were isolated in a singe geographical location. Three of PfMSP-1₁₉variant forms when expressed in <it>E. coli </it>showed presence of cross-reaction as well as variant specific antibodies in malaria infected patient sera.</p> <p>Conclusion</p> <p>The present study demonstrates the existence of allele specific antibodies in <it>P. falciparum</it>-infected patient sera, however their role in protection requires further investigation. These results thereby, suggest the importance of a multi-allelic PfMSP-1₁₉based vaccine for an effective malaria control.</p

Assessment of therapeutic efficacy of chloroquine and sulphadoxine-pyrimethamine in uncomplicated falciparum malaria

A standardised protocol has been developed by World Health Organization (CDS/RBM/2002) toassess the efficacy of common antimalarials in the treatment of clinically manifested infection withuncomplicated P. falciparum malaria for areas with low to moderate transmission. The therapeuticefficacy protocol is based on clinical and parasitological responses of the patients and it has thepurpose of determining the practical efficacy of the drug regimen in study areas with the ultimateobjective of ascertaining its continued usefulness or the necessity for replacing it in the routinetreatment. Present study has been conducted at seven sites—Kathiatali and Simonabasti of DistrictNowgaon, Assam; Sonapur and Boko of District Kamrup, Assam; Keonjhar Town, Padampur andBasudebpur of District Keonjhar, Orissa. In order to reduce the patient recruitment time, health centreclose to well-defined community was identified to conduct the activities at peak malaria seasonby selecting local pockets and organising mobile clinics. Microscopically confirmed cases of P. falciparumwere enrolled according to the criteria for inclusion and exclusion. Treatment with recommendeddrug was given under supervision and a follow-up schedule at various intervals for 28days was maintained. In chloroquine (CQ) study areas, wherever patients showed treatment failure,they were treated with second line drug—sulphadoxine-pyrimethamine (SP) combination and thenfollowed-up as per study protocol. It was observed that 30% cases showed treatment failure to CQin District Nowgaon, where revised drug policy has already been introduced. In Kamrup district,treatment failure with CQ was found to be less than 25%, which denotes the said regimen is still effective.Almost all the patients from Padampur and Basudebpur of District Keonjhar responded toCQ, treatment failure was noticed only in two patients (3%). The antifolate combination found to befully effective as second line and also as first line wherever revised drug policy has been introduced

Variations in host genes encoding adhesion molecules and susceptibility to falciparum malaria in India

<p>Abstract</p> <p>Background</p> <p>Host adhesion molecules play a significant role in the pathogenesis of <it>Plasmodium falciparum </it>malaria and changes in their structure or levels in individuals can influence the outcome of infection. The aim of this study was to investigate the association of SNPs of three adhesion molecule genes, <it>ICAM1</it>, <it>PECAM1 </it>and <it>CD36</it>, with severity of falciparum malaria in a malaria-endemic and a non-endemic region of India.</p> <p>Methods</p> <p>The frequency distribution of seven selected SNPs of <it>ICAM1</it>, <it>PECAM1 </it>and <it>CD36 </it>was determined in 552 individuals drawn from 24 populations across India. SNP-disease association was analysed in a case-control study format. Genotyping of the population panel was performed by Sequenom mass spectroscopy and patient/control samples were genotyped by SNaPshot method. Haplotypes and linkage disequilibrium (LD) plots were generated using PHASE and Haploview, respectively. Odds-ratio (OR) for risk assessment was estimated using EpiInfo™ version 3.4.</p> <p>Results</p> <p>Association of the ICAM1 rs5498 (exon 6) G allele and the CD36 exon 1a A allele with increased risk of severe malaria was observed (severe versus control, OR = 1.91 and 2.66, P = 0.02 and 0.0012, respectively). The CD36 rs1334512 (-53) T allele as well as the TT genotype associated with protection from severe disease (severe versus control, TT versus GG, OR = 0.37, P = 0.004). Interestingly, a SNP of the <it>PECAM1 </it>gene (rs668, exon 3, C/G) with low minor allele frequency in populations of the endemic region compared to the non-endemic region exhibited differential association with disease in these regions; the G allele was a risk factor for malaria in the endemic region, but exhibited significant association with protection from disease in the non-endemic region.</p> <p>Conclusion</p> <p>The data highlights the significance of variations in the <it>ICAM1</it>, <it>PECAM1 </it>and <it>CD36 </it>genes in the manifestation of falciparum malaria in India. The <it>PECAM1 </it>exon 3 SNP exhibits altered association with disease in the endemic and non-endemic region.</p

Therapeutic efficacy of artemether-lumefantrine in uncomplicated falciparum malaria in India

<p>Abstract</p> <p>Background</p> <p>Artemisinin-based combination therapy (ACT) is the treatment of choice for uncomplicated falciparum malaria. Artemether-lumefantrine (AL), a fixed dose co-formulation, has recently been approved for marketing in India, although it is not included in the National Drug Policy for treatment of malaria. Efficacy of short course regimen (4 × 4 tablets of 20 mg artemether plus 120 mg lumefantrine over 48 h) was demonstrated in India in the year 2000. However, low cure rates in Thailand and better plasma lumefantrine concentration profile with a six-dose regimen over three days, led to the recommendation of higher dose globally. This is the first report on the therapeutic efficacy of the six-dose regimen of AL in Indian uncomplicated falciparum malaria patients. The data generated will help in keeping the alternative ACT ready for use in the National Programme as and when required.</p> <p>Methods</p> <p>One hundred and twenty four subjects between two and fifty-five years of age living in two highly endemic areas of the country (Assam and Orissa) were enrolled for single arm, open label prospective study. The standard six-dose regimen of AL was administered over three days and was followed-up with clinical and parasitological evaluations over 28 days. Molecular markers <it>msp</it>-<it>1 </it>and <it>msp</it>-2 were used to differentiate the recrudescence and reinfection among the study subjects. In addition, polymorphism in <it>pfmdr</it>1 was also carried out in the samples obtained from patients before and after the treatment.</p> <p>Results</p> <p>The PCR corrected cure rates were high at both the sites viz. 100% (n = 53) in Assam and 98.6% (n = 71) in Orissa. The only treatment failure case on D7 was a malnourished child. The drug was well tolerated with no adverse events. Patients had pre-treatment carriage of wild type codons at positions 86 (41.7%, n = 91) and 184 (91.3%, n = 91) of <it>pfmdr1 </it>gene.</p> <p>Conclusion</p> <p>AL is safe and effective drug for the treatment of acute uncomplicated falciparum malaria in India. The polymorphism in <it>pfmdr</it>1 gene is not co-related with clinical outcome. However, treatment failure can also occur due to incomplete absorption of the drug as is suspected in one case of failure at D7 in the study. AL can be a viable alternative of artesunate plus sulphadoxine/pyrimethamine (AS + SP), however, the drug should be used rationally and efficacy needs to be monitored periodically.</p

Correction: The Impact of Artemisinin Combination Therapy and Long-Lasting Insecticidal Nets on Forest Malaria Incidence in Tribal Villages of India, 2006–2011

INTRODUCTION: New tools for malaria control, artemisinin combination therapy (ACT) and long-lasting insecticidal nets (LLINs) were recently introduced across India. We estimated the impact of universal coverage of ACT and ACT plus LLINs in a setting of hyperendemic, forest malaria transmission. METHODS: We reviewed data collected through active and passive case detection in a vaccine trial cohort of 2,204 tribal people residing in Sundargarh district, Odisha between 2006 and 2011. We compared measures of transmission at the village and individual level in 2006–2009 versus 2010–2011 after ACT (in all villages) and LLINs (in three villages) were implemented. RESULTS: During 2006–2009 malaria incidence per village ranged from 156–512 per 1000 persons per year and slide prevalence ranged from 28–53%. Routine indoor residual spray did not prevent seasonal peaks of malaria. Post-intervention impact in 2010–2011 was dramatic with ranges of 14–71 per 1000 persons per year and 6–16% respectively. When adjusted for village, ACT alone decreased the incidence of malaria by 83% (IRR 0.17, 95%CI: 0.10, 0.27) and areas using ACT and LLINs decreased the incidence of malaria by 86% (IRR 0.14, 95%CI: 0.05, 0.38). After intervention, the age of malaria cases, their parasite density, and proportion with fever at the time of screening increased. CONCLUSIONS: ACT, and LLINs along with ACT, effectively reduced malaria incidence in a closely monitored population living in a forest ecotype. It is unclear whether LLINs were impactful when prompt and quality antimalarial treatment was available. In spite of universal coverage, substantial malaria burden remained

The impact of malaria control interventions (IRS - small arrows, ACT and LLINs - big arrow) on malaria cases (positive slides) and total slide collection (positive plus negative slides) by month in forest villages of Odisha, India 2006–2011.

<p>The impact of malaria control interventions (IRS - small arrows, ACT and LLINs - big arrow) on malaria cases (positive slides) and total slide collection (positive plus negative slides) by month in forest villages of Odisha, India 2006–2011.</p

Sequence polymorphisms in the receptor-binding domain of Plasmodium falciparum EBA-175: implications for malaria vaccine development

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