title: Naturally Acquired Antibody Responses to Plasmodium vivax and Plasmodium falciparum Merozoite Surface Protein 1 (MSP1) C-Terminal 19 kDa Domains in an Area of Unstable Malaria Transmission in Southeast Asia.
abstract: Understanding naturally acquired immunity to infections caused by Plasmodia in different malaria endemicity settings is needed for better vaccine designs and for exploring antibody responses as a proxy marker of malaria transmission intensity. This study investigated the sero-epidemiology of malaria along the international border between China and Myanmar, where malaria elimination action plans are in place. This study recruited 233 P. vivax and 156 P. falciparum infected subjects with acute malaria at the malaria clinics and hospitals. In addition, 93 and 67 healthy individuals from the same endemic region or from non-endemic region, respectively, were used as controls. Acute malaria infections were identified by microscopy. Anti-recombinant PfMSP119 and PvMSP119 antibody levels were measured by ELISA. Antibody responses to respective MSP119 were detected in 50.9% and 78.2% patients with acute P. vivax and P. falciparum infections, respectively. There were cross-reacting antibodies in Plasmodium patients against these two recombinant proteins, though we could not exclude the possibility of submicroscopic mixed-species infections. IgG1, IgG3 and IgG4 were the major subclasses. Interestingly, 43.2% of the healthy endemic population also had antibodies against PfMSP119, whereas only 3.9% of this population had antibodies against PvMSP119. Higher antibody levels were correlated with age and parasite density, but not with season, gender or malaria history. Both total IgG and individual IgG subclasses underwent substantial declines during the convalescent period in three months. This study demonstrated that individuals in a hypoendemic area with coexistence of P. vivax and P. falciparum can mount rapid antibody responses against both PfMSP119 and PvMSP119. The significantly higher proportion of responders to PfMSP119 in the healthy endemic population indicates higher prevalence of P. falciparum in the recent past. Specific antibodies against PvMSP119 could serve as a marker of recent exposure to P. vivax in epidemiological studies.
authors.affiliation: Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China.
authors.forename: Qinghui
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Dalian Institute of Biotechnology, Dalian, Liaoning, China.
authors.forename: Zhenjun
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China.
authors.forename: Xuexing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Epidemiology, School of Public Health, China Medical University, Shenyang, Liaoning, China.
authors.forename: Xuelian
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Humanities and Social Science, China Medical University, Shenyang, Liaoning, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Dalian Institute of Biotechnology, Dalian, Liaoning, China.
authors.forename: Peipei
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China.
authors.forename: Zhaoqing
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Institute of Tropical Medicine, Third Military Medical University, Chongqing, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Program in Public Health, University of California Irvine, Irvine, CA, United States of America.
authors.forename: Guiyun
authors.initials: G
authors.lastname: Yan
authors.affiliation: Department of Laboratory Medicine, the First Hospital of China Medical University, Shenyang, Liaoning, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Shang
authors.affiliation: Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, China.
authors.forename: Yaming
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Dalian Institute of Biotechnology, Dalian, Liaoning, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Fan
authors.affiliation: Department of Entomology, Pennsylvania State University, 501 ASI Building, University Park, PA, 16802, United States of America.
authors.forename: Liwang
authors.initials: L
authors.lastname: Cui
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000595:Amino Acid Sequence; D000913:Antibodies, Protozoan / Q000276:immunology*; D000917:Antibody Formation / Q000276:immunology*; D001210:Asia, Southeastern / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003710:Demography; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007223:Infant; D016015:Logistic Models; D016778:Malaria, Falciparum / Q000097:blood / Q000276:immunology / Q000469:parasitology / Q000635:transmission*; D016780:Malaria, Vivax / Q000097:blood / Q000276:immunology / Q000469:parasitology / Q000635:transmission*; D020066:Merozoite Surface Protein 1 / Q000737:chemistry / Q000276:immunology*; D008970:Molecular Weight; D010963:Plasmodium falciparum / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D020066:Merozoite Surface Protein 1; D011994:Recombinant Proteins