Viral Heterogeneity and Genotypes
There are at least 8 genotypes (genetic variants) of HDV based on 14-38% sequence variation. These genotypes are associated with different long-term outcomes. Genotype 1 chronic HDV super-infection (HDV infection superimposed on chronic HBV infection) usually exacerbates pre-existing HBV mediated liver disease and this in turn leads to a rapid progression to cirrhosis. There are lower rates of remission with this genotype. Genotypes 2 and 4 cause a milder disease over a longer time course. Genotype 3 is associated with advanced necroinflammatory (inflammation that causes uncontrolled cell death) activity, fibrosis, and poor prognosis but it responds better to the pegylated interferon treatment as compared to genotype 1. Genotypes 5 to 8 have been only noted in Africa and in African migrant populations, and are associated with mild disease and good response to interferon therapy.
Author: Minaam Abbas