Plasmodium vivax: Recent world expansion and genetic identity to Plasmodium simium

Chae Seung Lim, Loubna Tazi, Francisco J. Ayala

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54 Citations (Scopus)


Plasmodium vivax causes the most geographically widespread human malaria, accounting annually for 70-80 million clinical cases throughout the tropical and subtropical regions of the world's continents. We have analyzed the DNA sequences of the Csp (circumsporozoite protein) gene in 24 geographically representative strains of P. vivax and 2 of P. simium, which parasitizes several species of New World monkeys. The Csp sequences are of two types, VK210 and VK247, which differ by three diagnostic amino acid replacements, one in each of the 5′ and 3′ terminal regions [5′ nonrepeat (NR) and 3′ NR] of the gene and in an insertion sequence that precedes the 3′ NR region. The central region of the gene consists of ≈38 repetitive "motifs," which are alternatively four and five amino acids long, which also are diagnostically different between the VK210 and VK247 types. There are very few synonymous substitutions within and between the two types of strains, which we hypothesize reflects that the worldwide spread of P. vivax is very recent. The two P. simium Csp sequences belong one to each of the two VK types and are genetically indistinguishable from the corresponding P. vivax strains, suggesting that at least two host transfers have occurred between humans and New World monkeys. We exclude as unlikely the possibility that the two types of sequences could have independently arisen in humans and platyrrhines by natural selection. There are reasons favoring each of the two possible directions of host transfer between humans and monkeys.

Original languageEnglish
Pages (from-to)15523-15528
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number43
Publication statusPublished - 2005 Oct 25


  • Circumsporozoite protein
  • Clonal theory
  • Host-parasite interactions
  • Malaria
  • Plasmodium population structure

ASJC Scopus subject areas

  • General


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