Circumsporozoite protein gene diversity among temperate and tropical Plasmodium vivax isolates from Iran

Abstract

SummaryTo date, there is no information on the genetic diversity of the circumsporozoite protein (CSP), a leading vaccine candidate, in Plasmodium vivax populations circulating in Iran. The gene for this protein, Pvcsp, was amplified from 374 P. vivax isolates collected in the temperate northern, and in the tropical southern endemic areas. PCR-RFLP analysis of the repeated central region revealed that the parasites collected in the northern area were almost exclusively of the VK210 type. Parasites collected in the south-eastern areas were of both VK210 and VK247 types. We detected VK210 parasite in 70.5% of the samples, VK247 parasites in 17.5% and mixed type infections in 12% of the isolates. Sequence analysis of 137 isolates obtained from both areas identified a total of 25 distinct genotypes. The degree of genetic diversity was generally higher for the tropical (21 genotypes) than the temperate (7 genotypes) P. vivax populations, a difference possibly reflecting the high cross-border exchanges between Afghanistan and Pakistan and southern Iran. Interestingly, all but two VK210 type isolates sequenced harboured a 36-bp post-repeat insert previously only observed in North Korea and China. This large-scale survey of parasite diversity in the Eastern Mediterranean Region provides a set of baseline data suitable for future molecular epidemiological studies of P. vivax.

Antigenic Diversity of the Plasmodium vivax Circumsporozoite Protein in Parasite Isolates of Western Colombia

“…Finally, 16 aa found in 12 of the Colombian isolates had also been reported for the P30 isolated (AY632258) in Iran. 10 The origin of the repeats could be the result of meiotic recombination that occurs during the diploid phase of the malaria life cycle. 9 Genetic mechanisms such as slipped-strand mispairing, 27 recombination, and gene conversion can be inferred from the formation and separation of such mutations, 28 including expansion or reduction of repeat sequences.…”

“…9 Both nonapeptides sequences are repeated ~20 times in their corresponding proteins; however, there is extensive polymorphism with regard to the number of repeats. 10 It has been shown that the prevalent phenotype of the P. vivax parasite in the study sites of Colombia is VK247 (59.7%), whereas VK210 accounts for one-third of the cases 32.8%; the remaining 7.5% corresponds to mixed infection. 11 Although previous nucleotide sequence analyses of the flanking regions (3′NR and 5′NR) of P. vivax CS protein have shown high conservation of these regions, recent studies indicated that isolates from Iran, Philippines, China, Brazil, and Korea contained previously undescribed point mutations and an insertion at the beginning of the 3′NR region.…”

“…11 Although previous nucleotide sequence analyses of the flanking regions (3′NR and 5′NR) of P. vivax CS protein have shown high conservation of these regions, recent studies indicated that isolates from Iran, Philippines, China, Brazil, and Korea contained previously undescribed point mutations and an insertion at the beginning of the 3′NR region. 10,[12][13][14] Most studies have reported only partial sequence data, thus limiting complete evaluation of the extent of genetic polymorphism found in the gene encoding P. vivax CS protein. Thus, there is a shortage of information on the polymorphism present in relevant immune epitopes, particularly those localized in the flanking regions.…”

Rapid Dissemination of Newly Introduced Plasmodium vivax Genotypes in South Korea

“…11 All PvCSP variant genotypes have a worldwide distribution. 12,13 We conducted the present study to analyze sequences of these two genes from isolates obtained during 1999-2007 and to identify changes in the genetic diversity of the reemerged P. vivax population in South Korea. This study surveyed previous prevalence and evaluated current prevalence and is useful because it might predict future prevalence.…”

The genetic diversity of Plasmodium vivax: a review

“…This CSP gene sequence is similar to that of P. simiovale, a monkey malaria parasite originally found in Macaca sinica in Sri Lanka (Qari et al 1993a). All CSP variant genotypes have a worldwide distribution (Kain et al 1992, Gonzáles et al 2001, Imwong et al 2005, Zakeri et al 2006.…”