High level of specific anti-plasmodium falciparum merozoite IgG1 antibodies in rural asymptomatic individuals of dienga, south-eastern Gabon

Abstract

Plasmodium falciparum merozoite antigens (PfMAgs) play an essential role in the development of immunity to malaria. Currently, P. falciparum: protein 113 (Pf 113), apical membrane antigen 1 (AMA1), erythrocyte binding antigens (EBA175), and reticulocyte binding protein homologue 5 (RH5) are among the most PfMAgs studied. A comparative analysis of naturally acquired antibodies against these antigens in children would increase our knowledge about the development of protective immunity.Analysis of antibodies to Pf113, PfAMA1, PfEBA175, and PfRH5 was conducted in rural population during 2013 and 2014. Both prevalence and levels of total IgG anti-PfAMA1 were higher than that of IgG anti-PfEBA175, anti-PfRH5, and anti-Pf113. Seroconversion to PfAMA1 and PfEBA175 occurred moderately in young children and reached to the maximum in adolescent and in adults. High prevalence of IgG anti-Pf113 was observed in young children of 3 to 6 years old in 2013. The four antigens were recognized by IgG 1, 2, 3, and 4 antibodies from a large proportion of the subjects, and all of them induced high levels of specific IgG1 against PfAMA1, PfEBA175, fewer by Pf113 and PfRH5.Many asymptomatic children had specific IgG1 recognizing multiple antigens, and these IgG1 antibodies could be associated with a reduced risk of developing malaria symptoms.

IgG antibody response against Plasmodium falciparum aminopeptidase 1 antigen in Gabonese children living in Makokou and Franceville

“…Our previous studies, comparing the humoral response against plasmodial antigens among Gabonese children from urban and rural areas, support this idea by revealing high levels of immunoglobulin (Ig)G antibodies against Pf113 antigen in children from rural areas and more exposed to plasmodial infection. . Unlike IgG, IgM responses are not influenced by either clinical or parasitological status in malaria in Gabonese children .…”

The role of naturally acquired antimalarial antibodies in subclinicalPlasmodiumspp. infection

“…Recent studies have demonstrated an association between Abs and protection from PCR‐detectable subclinical infection. 70 , 71 However, these findings have been reported mostly in serial cross‐sectional surveys, which may fail to capture individual infection dynamics.…”

“… 82 However, several other cross‐sectional studies investigating the same common blood‐stage antigenic targets have found little or no differences in the overall prevalence and breadth of antimalarial IgG between individuals with and without subclinical infection. 70 , 83 , 84 , 85 Many studies assessing Ab responses and the occurrence of subclinical infection performed to date have not been designed with the primary goal of assessing this association and are frequently performed as secondary outcomes in field surveys designed to assess some other primary outcome. The challenge of all serological surveys in malaria is the confounding effect of prior exposure, which in the vast majority of studies cannot be quantified and likely differs significantly between exposed populations.…”

“…Indeed, Abs can predict hot spots of infection in discrete regions, 80,81 and are being pursued as surveillance tools in many settings for detection of subclinical reservoirs 82 . However, several other cross‐sectional studies investigating the same common blood‐stage antigenic targets have found little or no differences in the overall prevalence and breadth of antimalarial IgG between individuals with and without subclinical infection 70,83–85 . Many studies assessing Ab responses and the occurrence of subclinical infection performed to date have not been designed with the primary goal of assessing this association and are frequently performed as secondary outcomes in field surveys designed to assess some other primary outcome.…”