title: Genetic structure of Plasmodium falciparum field isolates in eastern and north-eastern India.
abstract: BACKGROUND
  Molecular techniques have facilitated the studies on genetic diversity of Plasmodium species particularly from field isolates collected directly from patients. The msp-1 and msp-2 are highly polymorphic markers and the large allelic polymorphism has been reported in the block 2 of the msp-1 gene and the central repetitive domain (block3) of the msp-2 gene. Families differing in nucleotide sequences and in number of repetitive sequences (length variation) were used for genotyping purposes. As limited reports are available on the genetic diversity existing among Plasmodium falciparum population of India, this report evaluates the extent of genetic diversity in the field isolates of P. falciparum in eastern and north-eastern regions of India.
  
  
  METHODS
  A study was designed to assess the diversity of msp-1 and msp-2 among the field isolates from India using allele specific nested PCR assays and sequence analysis. Field isolates were collected from five sites distributed in three states namely, Assam, West Bengal and Orissa.
  
  
  RESULTS
  P. falciparum isolates of the study sites are highly diverse in respect of length as well as sequence motifs with prevalence of all the reported allelic families of msp-1 and msp-2. Prevalence of identical allelic composition as well as high level of sequence identity of alleles suggest a considerable amount of gene flow between the P. falciparum populations of different states. A comparatively higher proportion of multiclonal isolates as well as multiplicity of infection (MOI) was observed among isolates of highly malarious districts Karbi Anglong (Assam) and Sundergarh (Orissa). In all the five sites, R033 family of msp-1 was observed to be monomorphic with an allele size of 150/160 bp. The observed 80-90% sequence identity of Indian isolates with data of other regions suggests that Indian P. falciparum population is a mixture of different strains.
  
  
  CONCLUSIONS
  The present study shows that the field isolates of eastern and north-eastern regions of India are highly diverse in respect of msp-1 (block 2) and msp-2 (central repeat region, block 3). As expected Indian isolates present a picture of diversity closer to southeast Asia, Papua New Guinea and Latin American countries, regions with low to meso-endemicity of malaria in comparison to African regions of hyper- to holo-endemicity.
authors.affiliation: National Institute of Malaria Research (ICMR), 22-Sham Nath Marg, Delhi, India. hema_joshi_mrc@yahoo.com
authors.forename: Hema
authors.initials: H
authors.lastname: Joshi
authors.forename: Neena
authors.initials: N
authors.lastname: Valecha
authors.forename: Anju
authors.initials: A
authors.lastname: Verma
authors.forename: Asha
authors.initials: A
authors.lastname: Kaul
authors.forename: Prashant K
authors.initials: PK
authors.lastname: Mallick
authors.forename: Sneh
authors.initials: S
authors.lastname: Shalini
authors.forename: Surendra K
authors.initials: SK
authors.lastname: Prajapati
authors.forename: Surya K
authors.initials: SK
authors.lastname: Sharma
authors.forename: Vas
authors.initials: V
authors.lastname: Dev
authors.forename: Sukla
authors.initials: S
authors.lastname: Biswas
authors.forename: Nutan
authors.initials: N
authors.lastname: Nanda
authors.forename: M S
authors.initials: MS
authors.lastname: Malhotra
authors.forename: Sarala K
authors.initials: SK
authors.lastname: Subbarao
authors.forename: Aditya P
authors.initials: AP
authors.lastname: Dash
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000469:parasitology*; D020066:Merozoite Surface Protein 1 / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics* / Q000302:isolation & purification*; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D000953:Antigens, Protozoan; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium