Distinctiveness of Hepatitis B virus in a primitive population group of Eastern India

September 21, 2010

Clin. Microbiol. doi:10.1128/JCM.01174-10

Authors/Institutions. .

Distinctiveness of Hepatitis B virus in a primitive population group of Eastern

India

Sumantra Ghosh, Priyanka Banerjee, Arindam RoyChoudhury, Sumanta Sarkar, Alip

Ghosh, Amal Santra, Soma Banerjee, Kausik Das, Bhagirathi Dwibedi, Shantanu K.

Kar, Vikas Gangadhar Rao, Jyothi T. Bhat, Neeru Singh, Abhijit Chowdhury, and

Simanti Datta*

Centre for Liver Research, School of Digestive and Liver Diseases, Institute of

Post Graduate Medical Education and Research, Kolkata, INDIA; Department of

Biostatistics, Columbia University, New York, NY 10032, U.S.A.; Regional Medical

Research Centre, Bhubaneswar, India; Regional Medical Research Centre for

Tribals, Jabalpur, India

* To whom correspondence should be addressed. Email: seemdatt@....

Abstract

Hepatitis B virus (HBV) isolated from primitive " Paharia " ethnic community of

Eastern India were studied to gain insight into the genetic diversity and

evolution of the virus. The " Paharia " tribe has remained quite separate from the

rest of the Indians and differs culturally, genetically and linguistically from

mainstream East Indian population, whose HBV strains were previously

characterized. Full length HBV DNA was PCR amplified, cloned and sequenced.

Phylogenetic relationships between the tribal and references sequences from

mainstream population were assessed and divergence time of subgenotypes of HBV

genotype D were estimated. HBV was found in 2% of the Paharias participating in

the study. Predominance of Hepatitis B e-antigen-negative infection (73%) was

observed among the Paharias and the genome sequences of the HBV strains

exhibited a relative homogeneity with very low prevalence of mutations. The

novel feature of Paharia HBV was the exclusive presence of D5 sub-genotype that

was recently identified in Eastern India. Analysis of the four ORFs of these

tribal HBV/D5 and comparison with previously reported D1-D7 sequences enabled

the identification of 27 specific amino acid residues, including six unique ones

that could be considered as D5 signatures. The estimated divergence times among

D1-D5 subgenotypes suggest that D5 was the first to diverge and hence was the

most ancient of the D subgenotypes. The presence of a specific, ancient

sub-genotype of HBV within an ethnically primitive, endogamous population

highlights the importance of studies of HBV genetics from well-separated human

populations to understand viral transmission between communities and genome

evolution.

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