Genetic diversity in the block 2 region of the merozoite surface protein-1 of Plasmodium falciparum in central India

DNA sequencing analysis was carried out in 71 field isolates collected between July 2005 to November 2005 and in 98 field isolates collected from July 2009 to December 2009. Alleles identified by DNA sequencing were aligned with the strain 3D7 and polymorphism analysis was done by using Edit Sequence tool (DNASTAR).The malaria positivity was 26% in 2005, which rose to 29% in 2009 and P. falciparum prevalence was also increased from 72% in 2005 to 81% in 2009. The overall allelic prevalence was higher in K1 (51%) followed by MAD20 (28%) and RO33 (21%) in 2005 while in 2009, RO33 was highest (40%) followed by K1 (36%) and MAD20 (24%).The present study reports extensive genetic variations and dynamic evolution of block 2 region of MSP-1 in central India. Characterization of antigenic diversity in vaccine candidate antigens are valuable for future vaccine trials as well as understanding the population dynamics of P. falciparum parasites in this area.Madhya Pradesh (MP) is situated in the central part of India, and is a highly malarious state contributing 9% of all malaria cases in the country [1]. Plasmodium falciparum infection has dramatically increased in MP in recent years and is associated with life-threatening complications in both children and adults [2,3].The merozoite surface protein-1 (MSP-1) is a leading vaccine candidate antigen. It is the most abundant surface protein on the blood stage of P. falciparum, and it is thought to play a role in erythrocyte invasion [4]. The primary structure of MSP-1 is polymorphic and 40% of the amino acid residues are different in different allelic forms in P. falciparum [5]. The precursor of MSP-1 is a protein comprising 1,720 amino acids, including a 20-amino-acid signal sequence (SS) and a signal for anchoring the protein at the cellular surface via a GPI moiety (GA). MSP-1 divided into 17 blocks, which were either variable, conserved or semi-conserved [6,7]. Sequences of blocks 1, 3, 5, 12 and 17th are conserved, and block