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

Abstract

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 Ϸ38 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.circumsporozoite protein ͉ clonal theory ͉ Plasmodium population structure ͉ host-parasite interactions ͉ malaria M alaria's human toll is appalling: 300-500 million clinical cases and 1-3 million deaths per year. Plasmodium falciparum accounts for 80% of human malaria's morbidity and mortality, mostly in sub-Saharan Africa. Most geographically widespread and prevalent in some regions is Plasmodium vivax, which accounts annually for 70-80 million clinical cases across much of the tropics and subtropics of the world.The evolutionary origin of P. vivax has been placed by some authors in Southeast Asia (1-3). However, the high prevalence in sub-Saharan Africa of Duffy negativity (absence of the Duffy blood group antigen) that protects against P. vivax infection has been interpreted as evidence of the African origin of P. vivax (4-6). Most recently, phylogenetic and biogeographical evidence has been advanced supporting a Southeast Asia origin (7-9).Recent investigations have shown a scarcity of selectively neutral genetic polymorphisms in P. vivax (8,10,11), which is consistent with a recent world expansion of P. vivax as a human parasite. The discovery that the platyrrhine parasite P. simium is genetically indistinguishable from P. vivax (2,7,8) manifests that a host transfer between humans and New World monkeys has happened in very recent evolutionary times.The circumsporozoite protein (CSP) has been extensively studied in P. falciparum and other Plasmodium species because of its immune significan...

Diversity, host switching and evolution of Plasmodium vivax infecting African great apes

“…S5). The CR region varies in the number of amino acid motifs, and there is also sequence variation among the oligopeptides (19). Between the 3′ NR and the CR regions, there is an insertion region (IR) of relatively simple structure (Fig.…”

“…Regarding the nature of the repeated amino acid motifs in the CR region, human isolates are of two types, VK 210 and VK 247, distinguished by several diagnostic SNPs in the 5′, 3′, and IR regions (19). In great apes, all isolates displayed SNPs and motifs related to the VK 247 Csp type in human P. vivax (Table S2).…”

Selective sweep suggests transcriptional regulation may underlie Plasmodium vivax resilience to malaria control measures in Cambodia

“…Evidence has shown that both species of malaria are significantly less diverse than primate malarias and likely have undergone genetic bottlenecks associated with host switching and emergence out of Africa, likely less than 10,000 y ago (63,(68)(69)(70)(71)(72). As these species have emerged from the bottleneck, they likely have undergone both sustained and recent selection.…”

Molecular markers and genetic diversity of Plasmodium vivax

“…However, markedly divergent sequence variants were found in isolates from China and North Korea (Mann et al 1994). Although VK210 and VK247-type sequences often occur in sympatric parasite populations, there are no examples of a hybrid repeat array with both repeat types (Lim et al 2005).…”

“…However, markedly divergent sequence variants were found in isolates from China and North Korea (Mann et al 1994). Although VK210 and VK247-type sequences often occur in sympatric parasite populations, there are no examples of a hybrid repeat array with both repeat types (Lim et al 2005).A third type of repeat unit [APGANQ(E/G)GAA], identical to that described for Plasmodium simiovale, characterises the so-called P. vivax-like parasites (Qari et al 1993a). Although P. vivax-like CSP repeats have been found in parasite isolates across the world, its global distribution remains unconfirmed (Gopinath et al 1994).…”