title: Merozoite surface protein-1 genetic diversity in Plasmodium malariae and Plasmodium brasilianum from Brazil.
abstract: BACKGROUND
  The merozoite surface protein 1 (MSP1) gene encodes the major surface antigen of invasive forms of the Plasmodium erythrocytic stages and is considered a candidate vaccine antigen against malaria. Due to its polymorphisms, MSP1 is also useful for strain discrimination and consists of a good genetic marker. Sequence diversity in MSP1 has been analyzed in field isolates of three human parasites: P. falciparum, P. vivax, and P. ovale. However, the extent of variation in another human parasite, P. malariae, remains unknown. This parasite shows widespread, uneven distribution in tropical and subtropical regions throughout South America, Asia, and Africa. Interestingly, it is genetically indistinguishable from P. brasilianum, a parasite known to infect New World monkeys in Central and South America.
  
  
  METHODS
  Specific fragments (1 to 5) covering 60 % of the MSP1 gene (mainly the putatively polymorphic regions), were amplified by PCR in isolates of P. malariae and P. brasilianum from different geographic origin and hosts. Sequencing of the PCR-amplified products or cloned PCR fragments was performed and the sequences were used to construct a phylogenetic tree by the maximum likelihood method. Data were computed to give insights into the evolutionary and phylogenetic relationships of these parasites.
  
  
  RESULTS
  Except for fragment 4, sequences from all other fragments consisted of unpublished sequences. The most polymorphic gene region was fragment 2, and in samples where this region lacks polymorphism, all other regions are also identical. The low variability of the P. malariae msp1 sequences of these isolates and the identification of the same haplotype in those collected many years apart at different locations is compatible with a low transmission rate. We also found greater diversity among P. brasilianum isolates compared with P. malariae ones. Lastly, the sequences were segregated according to their geographic origins and hosts, showing a strong genetic and geographic structure.
  
  
  CONCLUSIONS
  Our data show that there is a low level of sequence diversity and a possible absence of allelic dimorphism of MSP1 in these parasites as opposed to other Plasmodium species. P. brasilianum strains apparently show greater divergence in comparison to P. malariae, thus P. malariae could derive from P. brasilianum, as it has been proposed.
authors.affiliation: Núcleo de Estudos em Malária, Superintendência de Controle de Endemias/Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil. lilianguimaraes@usp.br.
authors.forename: Lilian O
authors.initials: LO
authors.lastname: Guimarães
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, 05508-900, Brazil. gwunder@usp.br.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wunderlich
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, 05508-900, Brazil. jotajj@usp.br.
authors.forename: João M P
authors.initials: JM
authors.lastname: Alves
authors.affiliation: Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508-270, Brazil. buenomg@gmail.com.
authors.forename: Marina G
authors.initials: MG
authors.lastname: Bueno
authors.affiliation: Wildlife Conservation Society, Rio de Janeiro, RJ, 22461-000, Brazil. fabiorohe@gmail.com.
authors.forename: Fabio
authors.initials: F
authors.lastname: Röhe
authors.affiliation: Departamento de Patologia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508-270, Brazil. zecatao@usp.br.
authors.forename: José L
authors.initials: JL
authors.lastname: Catão-Dias
authors.affiliation: Laboratório de Protozoologia, Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil. amanda.biologia@gmail.com.
authors.forename: Amanda
authors.initials: A
authors.lastname: Neves
authors.affiliation: Laboratório de Protozoologia, Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil. rmalafronte@usp.br.|Departamento de Moléstias Infecciosas e Parasitárias, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, 01246-903, Brazil. rmalafronte@usp.br.
authors.forename: Rosely S
authors.initials: RS
authors.lastname: Malafronte
authors.affiliation: Laboratório de Imunoepidemiologia, Superintendência de Controle de Endemias, São Paulo, SP, 01027-000, Brazil. izcurado@gmail.com.
authors.forename: Izilda
authors.initials: I
authors.lastname: Curado
authors.affiliation: Laboratório de Soroepidemiologia e Imunobiologia, Instituto de Medicina Tropical de São Paulo, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil. will.domingues@hotmail.com.
authors.forename: Wilson
authors.initials: W
authors.lastname: Domingues
authors.affiliation: Núcleo de Estudos em Malária, Superintendência de Controle de Endemias/Instituto de Medicina Tropical, Universidade de São Paulo, São Paulo, SP, 05403-000, Brazil. karink@usp.br.
authors.forename: Karin
authors.initials: K
authors.lastname: Kirchgatter
mesh_terms: D000483:Alleles; D000818:Animals; D001938:Brazil; D009033:Culicidae / Q000469:parasitology; D014644:Genetic Variation; D006801:Humans; D016013:Likelihood Functions; D020066:Merozoite Surface Protein 1 / Q000235:genetics*; D010802:Phylogeny; D010961:Plasmodium / Q000235:genetics* / Q000302:isolation & purification; D010965:Plasmodium malariae / Q000235:genetics; D011110:Polymorphism, Genetic
chemical_list: D020066:Merozoite Surface Protein 1