Genetic polymorphism and amino acid sequence variation in Plasmodium falciparum GLURP R2 repeat region in Assam, India, at an interval of five years

Abstract

BackgroundThe R2 repeat region of GLURP has been reported as a good genetic marker for Plasmodium falciparum genotyping. Proper knowledge of the extent and nature of P. falciparum genetic diversity using highly immunogenic R2 repeat region in malaria-endemic areas is a crucial element to understand various aspects related to immunity acquisition and disease pathogenesis.MethodsPopulation diversity of P. falciparum GLURP and amino acid sequence repeats in GLURP R2 region was studied in malaria-endemic Assam state, northeast India and compared at an interval of five years during 2005 (Group-A) and 2011 (Group-B).ResultsOf the 66 samples, a total of 55 samples showed positive PCR bands for GLURP R2 region and altogether ten types of alleles with size ranging from 501 bp to 1,050 bp (50 bp bin) were observed and coded as genotypes I-X. In Group-A (n = 29), 24 samples were found infected with single, four with double and one with triple P. falciparum genotype, while in Group-B (n = 26), single genotype was found in 23 samples, double in two samples and triple in one sample. Genotype IV showed significant increase (p = 0.002) during 2011 (Group-B). Genotypes I to V were more common in Group-B (62%), however genotypes VI to X were more frequently distributed in Group-A. The expected heterozygosity was found slightly higher in Group-A (HE = 0.87) than Group-B (HE = 0.85), whereas multiplicity of infection (MOI) in Group-A (MOI = 1.21 ± 0.49) and Group-B (MOI = 1.12 ± 0.43) did not display significant variation. The amino acid repeat sequence unit (AAU) DKNEKGQHEIVEVEEILPE (called ‘a’) was more frequent in the well-conserved part of R2 repeat region.ConclusionThe present study is the first extensive study in India which has generated substantial data for understanding the type and distribution of naturally evolved genetic polymorphism at amino acid sequence level in GLURP R2 repeat region in P. falciparum. There was decrease in the PCR amplicon size as well as the number of AAU [amino acid repeat unit] in Group-B displaying the bottleneck effect. The present study described a new type of AAU ‘d’ which varied from the other previous known AAUs.Electronic supplementary materialThe online version of this article (doi:10.1186/1475-2875-13-450) contains supplementary material, which is available to authorized users.

Genetic diversity and antibody responses against Plasmodium falciparum vaccine candidate genes from Chhattisgarh, Central India: Implication for vaccine development

“…Therefore, this 19 mer peptide of R2 region may be considered as future vaccine candidates either in the combination of other stage-specific antigens or multi-allelic vaccine of some antigens. This finding is consistent with the previous studies [ 13 , 44 ]. R2 repeat region is the immunodominant region and targeted by the human IgG antibody, which is effective in antibody-dependent cellular inhibition (ADCI).…”

“…In present study, P . falciparum msp1 , msp2 and glurp were highly diverse from central India region in respect of length as well as sequence motifs with prevalence of all the allelic families of msp1 and msp2 , which corroborates with earlier reports on Indian isolates [ 9 , 10 , 13 , 14 , 31 , 32 ]. Block-2 region of pfmsp1 exhibit repetitive tri-nucleotides and appears to be subjected to a rapid intra-genic recombination process.…”

Genetic Diversity of the Plasmodium falciparum Glutamate-Rich Protein R2 Region Before and Twelve Years after Introduction of Artemisinin Combination Therapies among Febrile Children in Nigeria

“…The observed number of repeat sequences was less than the 12 reported recently from India. 38 The order of the amino acids in Group B was almost similar to that observed in the NCBI sequences, suggesting sequence homology to parasites from other parts of the world. The study showed some differences in the arrangements of parasite DNA sequences in the two study years, indicating possible responses of the parasite to changes in antimalarial treatment from chloroquine to ACT.…”

“…37 The high number of GLURP alleles (12 in Group A, 11 in Group B) is expected in an area of high malaria endemicity, and this is in agreement with previous reports from Asia, and most especially from Africa where 8-20 GLURP alleles have been reported. 28,38 On the contrary, in low malaria endemic countries such as Honduras, French Guyana, Brazil, and Colombia, low number of alleles ranging from two to five alleles were reported. The fact that high number of alleles were recorded in both study years in our study further corroborate that malaria transmission remains high.…”

Genetic diversity of Plasmodium falciparum merozoite surface protein‐1 (block 2), glutamate‐rich protein and sexual stage antigen Pfs25 from Chandigarh, North India

“…Over time, there is a trend of diagnosing a large number of alleles, which is in direct relationship between the endemicity and number of samples evaluated in case of glurp . There are few reports on the R2 repeat region of glurp from different geographical regions including India . In the present study, a total of 27 haplotypes were found when compared to the reference 3D7 sequence.…”