IgG subclass antibodies to three variants of Plasmodium falciparum merozoite surface protein-1 (PfMSP-119) in an area with unstable malaria transmission in Iran

• Published in: Acta tropica Vol. 119; no. 2-3; pp. 84 - 90
• Main Authors: Mehrizi, Akram Abouie, Asgharpour, Sara, Salmanian, Ali-Hatef, Djadid, Navid Dinparast, Zakeri, Sedigheh
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.08.2011; Elsevier
• Subjects: Adolescent; Adult; Aged; antibodies; Antibodies, Protozoan; Antibodies, Protozoan - blood; Antibody; Antibody Affinity; antigens; Biological and medical sciences; Child; Child, Preschool; E/KNG/F; E/TSG/L; enzyme-linked immunosorbent assay; Escherichia coli; Escherichia coli - genetics; Female; General aspects; Genetics; Human protozoal diseases; Humans; immune response; Immunoglobulin G; Immunoglobulin G - blood; Infectious diseases; Iran; Iran - epidemiology; Life Sciences; Malaria; Malaria, Falciparum; Malaria, Falciparum - epidemiology; Malaria, Falciparum - transmission; Male; Medical sciences; Merozoite Surface Protein 1; Merozoite Surface Protein 1 - immunology; merozoites; Middle Aged; morbidity; mortality; parasites; Parasitic diseases; Plasmodium falciparum; Plasmodium falciparum - immunology; Protozoal diseases; Q/KNG/L; Recombinant Proteins; Seroepidemiologic Studies; surface proteins; vaccine development; Young Adult; Iran; Asia; Plasmodium falciparum; Q/KNG/L; E/TSG/L; Antibody; E/KNG/F; Merozoite surface protein 1; Protozoa; Apicomplexa; Protozoal disease; Malaria; Transmission; IgG; Parasitosis; Infection; Tropical medicine; Merozoite surface protein-1
• ISSN: 0001-706X; 1873-6254
• DOI: 10.1016/j.actatropica.2011.04.012

[Display omitted] ► Evaluation of IgG isotype antibodies to E/TSG/L, E/KNG/F and Q/KNG/L of PfMSP-119. ► 72% of the Iranian individuals had antibody responses to three PfMSP-119 variants. ► High-avidity IgG and IgG1 (>50%) were found in positive sera to three variants. ► The prevalence and titers of IgG1 antibody responses to variants increased with age. ► Equal immune response to three variants was developed in falciparum malaria patients. Plasmodium falciparum remains globally an important cause of mortality and morbidity and despite decades of research, no effective vaccine is available against this deadly parasite. The 19-kDa C-terminal fragment of P. falciparum merozoite surface protein 1 (PfMSP-119) is a target for protective immunity against malaria and the major concern in development of vaccine based on this antigen is the presence of polymorphisms. This investigation was designed to evaluate naturally acquired antibodies and antigen-binding avidity of IgG antibodies to three variant forms of PfMSP-119 antigen (E/TSG/L, E/KNG/F and Q/KNG/L) in malaria individuals who are living in hypoendemic areas in Iran (n=92, 4–75years old). The three variant forms of PfMSP-119 were expressed in Escherichia coli and IgG isotype composition and avidity of naturally acquired antibodies to the 19-kDa antigen were measured by ELISA assay. Results showed that almost 72% of the studied individuals had positive antibody responses to three PfMSP-119 variants and the prevalence of responders did not differ significantly (P>0.05). High-avidity IgG (62.7%, 65.7% and 47.76%) and IgG1 (64.2%, 50.75%, and 50.75%) were found in positive sera for E/TSG/L, E/KNG/F and Q/KNG/L variants, respectively. Moreover, the prevalence and titers of IgG1 antibody responses to the three variants increased with age (P<0.05). In summary, individuals in low transmission areas in Iran can develop and maintain equal immune responses with high avidity to the PfMSP-119 variants (E/TSG/L, E/KNG/F and Q/KNG/L); however, the precise role of the total IgG and its isotypes in protection requires further investigation. These results could support the design of a universal PfMSP-119-based vaccine.