Immunoglobulin response to the low polymorphic Pf113 antigen in children from Lastoursville, South-East of Gabon

• Published in: Acta tropica Vol. 163; pp. 149 - 156
• Main Authors: Imboumy-Limoukou, Roméo Karl, Maghendi-Nzondo, Sidney, Kouna, Charlene Lady, Bounaadja, Lotfi, Mbang, Sophie, Biteghe, Jean Claude, Eboumbou, Carole, Prugnolle, Franck, Florent, Isabelle, Lekana-Douki, Jean-Bernard
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-11-2016; Elsevier
• Subjects: Adolescent; Animals; Antibodies, Protozoan - immunology; Antigens, Protozoan - genetics; Antigens, Protozoan - immunology; Antigens, Protozoan - metabolism; Child; Child, Preschool; Enzyme-Linked Immunosorbent Assay; Female; Gabon - epidemiology; Humans; Immunogenicity; Immunoglobulin; Immunoglobulin G - immunology; Immunology; Infant; Life Sciences; Malaria Vaccines - immunology; Malaria, Falciparum - epidemiology; Malaria, Falciparum - immunology; Male; Merozoites - immunology; Merozoites - metabolism; P. falciparum; Pf113; Plasmodium falciparum - immunology; Polymorphism; Polymorphism, Genetic; Prevalence; Protein Binding; Protozoan Proteins; Recombinant Proteins - genetics; Immunoglobulin; Pf113; Immunogenicity; P. falciparum; Polymorphism
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2016.08.014

•Fifty one percent (51%) of the studied sera recognized the recombinant Pf113.•High IgG3 and IgG1 response antibodies (respectively 84% and 50%) were found in sera which tested positive.•A high level of IgG4 was also found.•Polymorphism of this protein, evaluated in field isolates, is low.
Pf113 is a P. falciparum putatively GPI-anchored protein that has been so far localized at the surface of merozoites, suggesting it could interact with RBC surface during merozoite invasion. Previous studies conducted in Papua New Guinea and in Kenya have revealed that this protein is recognized by natural antibodies in individuals living in malaria-endemic areas and is associated with protective immunity in malaria, further supporting the potential of Pf113 for the development of anti-malaria vaccines. However, in Central Africa, no study on the immunogenicity of this protein has been conducted. Here, we report the characterization of the Pf113 immune response in 103 children by Enzyme-Linked Immunoabsorbent Assay (ELISA), using a recombinant form of Pf113 expressed in Escherichia coli, together with the study of the Pf113 polymorphism, after amplification and sequencing of 40 field isolates. Data showed that almost 51% of the studied individuals had positive antibody responses to the recombinant Pf113 protein, and that IgG subclass response was dominated by IgG3 (84%) followed by IgG1 (50%). Surprisingly the prevalence of IgG4 was 92%. In addition, gene analysis in field isolates from this region indicated that Pf113 was not highly polymorphic, in particular regarding high-activity binding peptides (HABPs). Our data reinforce the idea that Pf113 may be considered for inclusion in multicomponent blood-stage vaccines.