Competing interests
- Molecular analysis of hepatitis B virus "a" determinant in asymptomatic and symptomatic Mexican carriers

The authors declare that they have no competing interests.

Authors' contributions

MERT: Designed and supervised most of the molecular studies; analyzed sequences and interpreted results. Participated in the preparation of the manuscript.

HAVS: carried out molecular techniques and participated in the analysis of results.

VJB: carried out immunoassays and interpreted the results.

MDV: responsible for the clinical aspects of the study, including the recruitment of patients; participated in the writing of the manuscript.

JT: Participated in the designed of the study and in the analyses and interpretation of the results. Critical review and edition of the manuscript.

OMH: Participated in the clinical designed of the study and in obtaining financial support for the study.

MTAM: responsible for the design of the study and for acquiring financial support. Supervision of the experimental work. Participated in the drafting of the manuscript.

Acknowledgements

This work was supported by the Instituto Mexicano del Seguro Social (IMSS), Coordinación de Investigación en Salud (grant FP2003-040). The authors are grateful to Juan Burgueño-Ferreira, Ph.D. for statistical analysis; Othón Rojas-Montes, Mario Valle-Aguirre, Ma.-Carmen Real-Rosas for technical support.