title: Allele-specific antibodies to Plasmodium vivax merozoite surface protein-1: prevalence and inverse relationship to haemoglobin levels during infection.
abstract: Antigenic polymorphisms are considered as one of the main strategies employed by malaria parasites to escape from the host immune responses after infections. Merozoite surface protein-1 (MSP-1) of Plasmodium vivax, a promising vaccine candidate, is a highly polymorphic protein whose immune recognition is not well understood.
  
  
  
  The IgG responses to conserved (MSP-119) and polymorphic (block 2 and block 10) epitopes of PvMSP-1 were evaluated in 141 P. vivax infected patients. Ten recombinant proteins corresponding to block 2 (variants BR07, BP29, BP39, BP30, BEL) and block 10 (BR07, BP29, BP39, BP01, BP13) often observed in Brazilian P. vivax isolates were assessed by ELISA in order to determine levels of specific antibodies and their respective seroprevalence. The magnitude and the frequency of variant-specific responses were very low, except for BR07 variant (>40%), which was the predominant haplotype as revealed by block 10 PvMSP-1 gene sequencing. By contrast, 89% of patients had IgG against the C-terminal conserved domain (PvMSP-119), confirming the high antigenicity of this protein. Using multiple linear and logistic regression models, there was evidence for a negative association between levels of haemoglobin and several IgG antibodies against block 2 variant antigens, with the strongest association being observed for BP39 allelic version. This variant was also found to increase the odds of anaemia in these patients.
  
  
  
  These findings may have implications for vaccine development and represent an important step towards a better understanding of the polymorphic PvMSP-1 domain as potential targets of vaccine development. These data highlight the importance of extending the study of these polymorphic epitopes of PvMSP-1 to different epidemiological settings.
authors.affiliation: Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK.|Centre for Statistics and Applications of University of Lisbon, Lisbon, Portugal.
authors.forename: Nuno
authors.initials: N
authors.lastname: Sepúlveda
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Cristiane Guimarães
authors.initials: CG
authors.lastname: Morais
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Luiza Carvalho
authors.initials: LC
authors.lastname: Mourão
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Matheus França
authors.initials: MF
authors.lastname: Freire
authors.affiliation: Departamento de Clínica Médica, Hospital Universitário Júlio Müller, Universidade Federal de Mato Grosso, Cuiabá, Brazil.
authors.forename: Cor Jesus F
authors.initials: CJ
authors.lastname: Fontes
authors.affiliation: Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil.
authors.forename: Marcus Vinícius G
authors.initials: MV
authors.lastname: Lacerda
authors.affiliation: Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Drakeley
authors.affiliation: Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK. embraga@icb.ufmg.br.|Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. embraga@icb.ufmg.br.
authors.forename: Érika Martins
authors.identifier: 0000-0001-5550-7157
authors.initials: ÉM
authors.lastname: Braga
mesh_terms: D000328:Adult; D000483:Alleles; D000913:Antibodies, Protozoan / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016780:Malaria, Vivax / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D020066:Merozoite Surface Protein 1 / Q000235:genetics / Q000276:immunology*; D008875:Middle Aged; D010966:Plasmodium vivax / Q000235:genetics / Q000276:immunology*; D016036:Seroepidemiologic Studies
chemical_list: D000913:Antibodies, Protozoan; D000939:Epitopes; D006454:Hemoglobins; D007074:Immunoglobulin G; D020066:Merozoite Surface Protein 1
keywords: Anaemia; Antibodies; MSP-1; Plasmodium vivax; Polymorphism