Hepatitis delta virus genotype-1 alone cocirculates with hepatitis B virus genotypes A and D in Pakistan

Hepatitis delta virus (HDV) and hepatitis B virus (HBV) have been identified as major causes of morbidity and mortality in Pakistan because HDV causes infection only in the presence of HBV. Coinfection with both hepatitis viruses can lead to a more severe acute form of disease and to an increased risk of fulminant hepatitis. HDV infection differs in its distribution and severity depending on the geographical distribution, and several genotypes of HDV have been identified so far.

The aim of the present study was to establish the HDV and HBV genotypes in chronically infected Pakistani patients and to determine whether there is any correlation between HDV and HBV genotypes.

We studied samples from a total of 46 chronically infected HBV and HDV patients for HBV and HDV genotype analysis out of a total of 75 chronic HBV carriers enrolled. HBV and HDV genotypes were determined using type-specific PCR, followed by sequencing of PCR amplified products.

The results of HBV genotyping showed that 33 of 46 (71.7%) patients had genotype D, five (10.9%) had A+D mixed genotypes, whereas eight (17.3) samples were untypable. We could detect only one HDV genotype (HDV-1) prevalent in the Pakistani population. The HDV-1 genotype isolate was associated with HBV genotype D alone or in combination with A (HBV-A+D).

The present study concludes that HDV/HBV coinfection is very high in the Pakistani population and was previously underestimated. The most prevalent circulating genotypes of HBV and HDV are HDV-1 and HBV-D, respectively, in the studied area. There is no specific interaction between HBV and HDV genotypes as suggested by HDV-1/HBV-D or HDV-1/HBV-A+D coinfection. Coinfection of HDV-1 and HBV-D simply reflects the most frequent genotypes circulating in this specific geographical region of the world.