Research
Allelic dimorphism of Plasmodium vivax gam-1 in the Indian subcontinent
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* Corresponding author: Hema Joshi hema_joshi_mrc@yahoo.com
1 National Institute of Malaria Research (ICMR), 22-Sham Nath Marg, Delhi, India
2 National Institute of Malaria Research (Field Unit Nadiad), Gujarat, India
3 National Institute of Malaria Research (Field Unit Goa), Goa, India
4 National Institute of Malaria Research (Field Unit Chennai), Tamil Nadu, India
5 National Institute of Malaria Research (Field Unit Car Nicobar), Andaman & Nicobar Island, India
6 National Institute of Malaria Research (Field Unit Jabalpur), Madhya Pradesh, India
7 National Institute of Malaria Research (Field Unit Rourkela), Orissa, India
8 Department of Biosciences, Jamia Millia Islamia University, Delhi, India
Malaria Journal 2006, 5:90 doi:10.1186/1475-2875-5-90
Published: 24 October 2006Abstract
Background
Genetic polymorphism is an inevitable component of a complex organism especially in multistage infectious organisms such as malaria parasites. Understanding the population genetic structure of the parasites would provide valuable information for effective malaria control strategies. Recently, the development of molecular tools like PCR has made analysis of field samples possible and easier and research on Plasmodium vivax has also been strengthened. Not many reports are available on the genetic polymorphism of P. vivax from the Indian sub-continent. This study evaluates the extent of diversity in field isolates of India with respect to Pvgam-1.
Methods
A study was designed to assess the diversity of Pvgam-1 among field isolates from India, using a nested PCR assay. Field isolates were collected from different regions of the country and the observed variability was confirmed by sequencing data.
Results
Both Belem and Chesson type alleles were present either exclusively or in mixed form among isolates of all 10 study sites. The Belem type allele was predominant, occurring in 67% of isolates. The proportion of isolates showing the mixed form (both Belem and Chesson type alleles occurring together in the same isolate) was about 13 overall (up to 38.5% in some isolates). Sequencing of the PCR-amplified Belem and Chesson type alleles confirmed the PCR results. Among the 10 study sequences, 11 polymorphic sites and four singleton variations were observed. All the nucleotide substitutions were non-synonymous.
Conclusion
Study shows limited diversity of Pvgam-1 marker in Indian isolates with well representation of both Belem and Chesson type alleles.