Antibody responses to a C-terminal fragment of the Plasmodium falciparum blood-stage antigen Pf332 in Senegalese individuals naturally primed to the parasite

Abstract

SummaryPrevious studies have shown that antibodies from humans exposed continuously to malaria recognize the Plasmodium falciparum asexual blood-stage antigen Pf332. Here we analysed the antibody responses to a C-terminal fragment of Pf332, designated C231, in individuals from Senegal, by measuring the serum levels of immunoglobulin M (IgM), IgG class and subclass and IgE antibodies. IgG antibody reactivity with crude P. falciparum antigen was detected in all the donors, while many of the children lacked or had low levels of such antibodies against C231. The antibody levels increased significantly with age for both crude P. falciparum antigen and C231, and in the older age groups most of the donors displayed antibodies to C231. This was also true for IgM, IgE and IgG subclass reactivity against C231. Moreover, the ratio of IgG1/IgG2 was considerably lower for C231 than for crude P. falciparum antigen, and in age groups 10-14 and 15-19 years the levels of IgG2 against C231 even exceeded that of IgG1. The IgG2/IgG3 ratios suggest that C231 gives similar levels of IgG2 and IgG3, except for children aged 4-9 years, where IgG3 was higher. Raw IgM, IgG class and subclass and IgE antibody levels to C231 tended to be higher in those who did not experience a malaria attack, but following linear multivariate analysis the trends were not significant.

Characterization of the Duffy-Binding-Like Domain ofPlasmodium falciparumBlood-Stage Antigen 332

“…Previous studies using recombinant protein of the Pf332 regions EB200 and C231 (a C-terminally located region of Pf332, less rich in degenerate-repeats [ 47 ]), have reported that children lack antibodies against both parts of the molecule. However, antibodies were frequently found in older individuals, indicating a slow acquisition of Pf332 antibodies [ 14 , 48 ]. Our results show that children living in Apac, a highly endemic region in Uganda experiencing the highest entomological inoculation rate reported in Africa [ 29 ], had developed antibodies to both Pf332-DBL and PfEMP1-DBL already at a very young age.…”

Development of quantitative suspension array assays for six immunoglobulin isotypes and subclasses to multiple Plasmodium falciparum antigens

“…Traditionally, the measurement of specific antibodies has been done by the enzyme-linked immunosorbent assay (ELISA) 23–25 . Although this classical technique has been very useful over the years, it demands significant amount of time, the use of relatively large sample volumes and, importantly, only allows quantifying antibodies against a single antigen at a time.…”