An Extremely Aberrant Subtype of Hepatitis BVirus Genotype D in Iran

Background and Aims: Hepatitis B virus (HBY) infection is a global health problem, with more than 350 million people hronically infected worldwide. Previous studies revealed that ayw2 is the predominant subtype in Iran. There are also some reports on other HBY subtypes including ayw1, ayw3 and ayw4 which are widespread subtypes of genotype D. In this study, we reported an exceptional and extremely rare subtype of HBY genotype D in an Iranian patient chronically infected with HBY who was also co-infected with hepatitis delta virus (HDY). Methods: The HBY and HDY genotypes and sub-genotypes were determined by polymerase chain reaction (peR) followed by direct sequencing and phylogenetic analysis. The HBY subtype was determined from the amino acid sequence of the region of viral genome encoding the hepatitis B surface antigen (HBsAg). Results: Phylogenetic analysis based on the HBY S gene revealed that the patient was infected with HBY genotype D and sub-genotype Dl. Further amino acid mapping on the amino acid of the HBY S gene sequence showed that the patient who was chronically infected with HBY was infected by an unusual subtype ayt of the virus which is not typical for the genotype D of HBY. HDY phylogenetic analysis also revealed that the patient was co-infected with HDY c1adel. Conclusions: The results indicated the presence of the uncommon subtype ayt of HBY genotype D in Iran. This may show that the virus is going further evolution by changing its genome, though the importance of this atypical subtype in genotype D of HBY is still not clear and needs longitudinal studies