Immunity to the sexual stages of<i>Plasmodium falciparum</i>in mothers, neonates and infants subject to intense and perennial malarial transmission

Akim, N. I. J.; Urassa, Honorathy; Drakeley, Chris; Sauerwein, Robert W.; Kitua, Andrew Y

doi:10.1179/000349802125001861

Cited by 2 publications

(2 citation statements)

References 10 publications

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“…The same is true for anti-Pfs48/45 antibodies where a positive relation was found with TRA in some studies [46,56,63,76,80,82] but not in other studies [73,77,79]. Naturally acquired TRA is found in individuals with recent and/or limited prior exposure to malaria as shown in young children and transmigrants from a malaria non-endemic to an endemic area [76][77][78]82]. In certain epidemiological settings TRA may be negatively related to age [56] although the data are limited and further work is needed [74,76,87].…”

Section: Functional Assaysupporting

confidence: 55%

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Sexual-Stage Antibody Responses to P. falciparum in Endemic Populations

Bousema¹,

Drakeley²,

Sauerwein

2006

CMM

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Gametocytes and sporogonic stages are responsible for the spread of disease and drug resistance in the population. Sexual stage immunity affects the infectiousness of gametocytes to mosquitoes. Specific antibodies including anti-Pfs48/45 and anti-Pfs230 antibodies are found in individuals with limited prior exposure to malaria. Sexual stage antibodies are rapidly acquired after infection and are relatively prevalent in gametocytaemic individuals. Functional transmission reducing activity (TRA) is found after primary infections and in young children and appears to depend on recent rather than cumulative exposure to gametocytes. Exposure to gametocytes decreases with age most likely as a consequence of the acquisition of asexual-stage immunity that controls asexual parasite density and consequently gametocytaemia. This results in lower exposure to the antigenic load of gametocytes in semi-immune individuals. Since sexual stage immunity is probably short-lived in the absence of gametocytes, we hypothesize that sexual stage immunity will wane, resulting in low antibody and TRA prevalences in clinically semi-immune carriers.

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Section: Functional Assaysupporting

confidence: 55%

“…Pfs230 antibody prevalence as detected by IgG1 and competition ELISA is 25-60% and more prevalent than anti-Pfs48/45 antibodies (10-40%) in endemic sera [14,63,76,78]. Seroreactivity against both antigens is higher when measured by immunoprecipitation [48,73,77,79].…”

Section: Antibodies To Pfs48/45 and Pfs230 And Transmission Reducing mentioning

confidence: 95%

Sexual-Stage Antibody Responses to P. falciparum in Endemic Populations

Bousema¹,

Drakeley²,

Sauerwein

2006

CMM

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Evaluation of the standard membrane feeding assay (SMFA) for the determination of malaria transmission-reducing activity using empirical data

Kolk

Vlas

Saul³

et al. 2004

Parasitology

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Host responses to the transmittable stages of the malaria parasite may reduce transmission effectively. Transmission-reducing activity (TRA) of human serum can be determined as a percentage, using the Standard Membrane Feeding Assay (SMFA). This laboratory assay was evaluated using the results of 121 experiments with malaria-endemic sera among which many repeated measurements were obtained. The assay consists of the feeding of Anopheles stephensi mosquitoes with cultured Plasmodium falciparum gametocytes, mixed with human red blood cells, and control and experimental sera. The TRA of individual sera was determined by the comparison of oocyst densities between these sera. Bootstrap data on oocyst densities in individual mosquitoes in control feeds were used to construct confidence limits for TRA percentages of serum feeds. Low (<20%) and high TRA (>90%) values for individual sera were usually reproduced in a second experiment, whereas this was more difficult for values between 20% and 90%. The observed variability of TRA values is explained in part by the variability in oocyst density per mosquito. Oocyst densities in control feeds varied more between experiments than within experiments and showed a slight decline over the 3 years of experiments. Reproducibility of TRA of field sera was low (20%) between experiments, but much higher (61 %) within experiments. A minimum of 35 oocysts per mosquito in control feeds gave optimal reproducibility (44%) between experiments. We recommend that (1) sera are compared within an experiment, or (2) assays are only analysed where controls have at least 35 oocysts per mosquito. The SMFA is under the recommended conditions appropriate for the study of factors that may influence TRA, e.g. transmission blocking vaccines.

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Immunity to the sexual stages ofPlasmodium falciparumin mothers, neonates and infants subject to intense and perennial malarial transmission

Cited by 2 publications

References 10 publications

Sexual-Stage Antibody Responses to P. falciparum in Endemic Populations

Sexual-Stage Antibody Responses to P. falciparum in Endemic Populations

Evaluation of the standard membrane feeding assay (SMFA) for the determination of malaria transmission-reducing activity using empirical data

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