INVESTIGADORES
CUESTAS Maria Lujan
libros
Título:
Genetic diversity and variability of Hepatitis B virus.
Autor/es:
MATHET VL; CUESTAS ML
Editorial:
Nova Biomedical
Referencias:
Lugar: Nueva York; Año: 2012 p. 115
ISSN:
1604568887
Resumen:
In spite of the progress made in vaccine and antiviral therapy development,
hepatitis B virus (HBV) infection still remains a major health care problem.
Over 350 million people are chronically infected worldwide, showing differences
in the severity of liver disease, clinical outcome and response to immune and
antiviral-therapy. Parameters associated to the host immune system (HBV specific
T and/or B-cell repertoires, defective antigen presentation and diminished
Th1/Th2 response ratio) and viral factors, such as the HBV genotypes and their
evolving variants, have largely contributed to the explanation of such
differences. The unique genomic structure and replication cycle of HBV
contribute to the occurrence of mutations in any of its genes undergoing
selection pressures.The selection of one mutant over the others warrants a
biological advantage to the prevalent mutation during the replication cycle of
the virus or a selective advantage to the mutant over wild-type virus in
host-virus interactions as the authors observed in Argentina where mutated HBsAg
were detected, even in the presence of specific anti-HBs antibodies. Reports
from USA, as well as from several European and Asian countries have focused on
mutations within the HBV genome that may be associated with the hepatitis B
vaccine and/or hepatitis B immune globulin (HBIG) failure, diagnostic escape
mutants, antiviral therapy resistance, and differential outcomes in liver
disease. In contrast, studies regarding these topics are almost lacking in Latin
America. Within this context, it should be emphasised that the already known
mutants circulating in other parts of the world could not necessarily be
mirroring those strains circulating in this part of the American
continent.Emerging data is filling the gap in our knowledge of HBV genotypes in
several Latin American countries. While genotypes F and H of HBV are considered
to be indigenous in this continent, genotypes A and D might be a mere reflection
of a past European migration, and genotypes B and C could represent a
consequence of a recent Asian migration. Few years ago, genotype G was detected
in Mexico as previously identified in the USA and France. Unexpectedly, some
strains ascribed to HBV genotype E (widely considered an African restricted
genotype) have been observed in Argentina, even though genotypes F, A and D
appear to be the most prevalent in this country. Co-circulation of all the
already known genotypes and certain HBV variants in Latin America offers a
unique opportunity to study basic viral and clinical features of this
infection.