A Longitudinal Systems Biological Analysis of Naturally Acquired Malaria Immunity in Mali

Study Overview
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Brief Summary
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Plasmodium falciparum (Pf) malaria remains a major cause of morbidity and mortality worldwide. A malaria vaccine would contribute towards efforts to control and eliminate malaria. Optimism that an effective malaria vaccine can be developed is derived in part from the observation that repeated Pf infections can induce protective immunity; however, the mechanisms underlying acquired malaria immunity remain unclear. The goal of the current study is to apply systems biological tools to an observational cohort in an area of intense seasonal Pf transmission to gain insight into the mechanisms underlying naturally acquired malaria immunity. This year-long observational-cohort study of 700 individuals (3 months and 25 years of age) will be conducted in the rural village of Kalifabougou, Mali, where Pf transmission is intense and seasonal. Asymptomatic Pf infection and malaria episodes will be detected by passive and active surveillance. Immune parameters of malaria-protected and -susceptible individuals will be assayed from blood samples collected at strategic time points relative to the malaria season. The primary objective is to identify genome-wide expression profiles induced by Pf infection that are associated with protection from malaria. Secondary objectives include identifying age-related (surrogate for cumulative Pf exposure) changes in Pf-induced gene-expression and serum cytokine profiles, and examining Pf-specific antibody profiles that are associated with protection from malaria using a protein microarray representing 2000 Pf proteins (40 percent of the Pf proteome). Exploratory objectives for this study are to compare the magnitude and quality of the Pf-specific CD4 plus T cell response in malaria-protected and -susceptible individuals and determine how this response varies with age and among individuals before, during, and after malaria season, as well as compare various immune parameters in Pf-infected and uninfected individuals at the end of the dry season to investigate host immune factors associated with chronic asymptomatic Pf infection....

Detailed Description
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Plasmodium falciparum (Pf) malaria remains a major cause of morbidity and mortality worldwide. A malaria vaccine would contribute towards efforts to control and eliminate malaria. Optimism that an effective malaria vaccine can be developed is derived in part from the observation that repeated Pf infections can induce protective immunity; however, the mechanisms underlying acquired malaria immunity remain unclear. The goal of the current study is to apply systems biological tools to an observational cohort in an area of intense seasonal Pf transmission to gain insight into the mechanisms underlying naturally acquired malaria immunity. This observational-cohort study of individuals (3 months and 40 years of age) will be conducted in the rural village of Kalifabougou, Mali, where Pf transmission is intense and seasonal. Asymptomatic Pf infection and malaria episodes will be detected by passive and active surveillance. Immune parameters of malaria-protected and -susceptible individuals will be assayed from blood samples collected at strategic time points relative to the malaria season. The primary objective is to identify genome-wide expression profiles induced by Pf infection that are associated with protection from malaria. Secondary objectives include identifying age-related (surrogate for cumulative Pf exposure) changes in Pf-induced gene-expression and serum cytokine profiles, and examining Pf-specific antibody profiles that are associated with protection from malaria using a protein microarray representing 2000 Pf proteins (approximately 40% of the Pf proteome). Exploratory objectives for this study are to compare the magnitude and quality of the Pf-specific CD4+ T cell response in malaria-protected and -susceptible individuals and determine how this response varies with age and among individuals before, during, and after malaria season, as well as compare various immune parameters in Pf-infected and uninfected individuals at the end of the dry season to investigate host immune factors associated with chronic asymptomatic Pf infection.

Official Title
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A Longitudinal Systems Biological Analysis of Naturally Acquired Malaria Immunity in Mali

Conditions
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Malaria

Participation Criteria
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Eligibility Criteria
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INCLUSION CRITERIA: Individuals 3 months to 40 years of age are eligible to enter the study if they agree to: Live in Kalifabougou for the duration of the study (12 months). Have blood specimens stored for future studies. EXCLUSION CRITERIA: The following eligibility criteria are exclusionary: Anemia (hemoglobin less than 7 g/dL). Current use of antimalarials, corticosteroids, or other immuno-suppressants. Underlying heart disease, bleeding disorder, or other conditions that, in the judgment of the clinical investigators, could increase the risk to the study subjects. Fever greater than or equal to 37.5 degrees Celsius or evidence of an acute infection. Currently pregnant or planning to become pregnant during the study period. (Asymptomatic Pf infection at enrollment is not exclusionary).

Ages Eligible for Study
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Minimum Age: 3 Months
Maximum Age: 40 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| observational cohort<br>This observational-cohort study of individuals (3 months and 40 years of age) will be conducted in the rural village of Kalifabougou, Mali, where Pf transmission is intense and seasonal | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pf expression profiles | Identify genome-wide progression profiles induced by Plasmonium falciparum infection that are assocaited with malaria immunity | Triannual cross-sectional surveys and convalescence visits | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| serum cytokine profiles | Examine the relationship between age (surrogate for cumulative Pf exposure) and the gene-expression and serum cytokine profilesinduced by Pf infection. | Triannual cross-sectional surveys and convalescence visits | 
| Pf-specific antibody profiles | Identify Pf-specific antibody profiles that are associated with malaria immunity by using a protein microarray representing 2000 Pf proteins (approx. 40% of the Pf proteome), and determine how these profiles change with age. The objective is to validate and extend findings from a preliminary study performed in the nearby village of Kambila, Mali, where a protein microarray containing approx. 23% of the Pf proteome was used to profile Pf-specific antibody responses in children and adults before and after the 6-month malaria season | Triannual cross-sectional surveys and convalescence visits | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Plasmodium, PBMC, Natural History, Malaria