distribution of hepatitis delta virus genotypes in mashhad, northeast iran

background hepatitis delta virus (hdv) is dependent on the hepatitis b virus for transmission and propagation. based on isolated hdv sequences from different parts of the world, at least three major different genotypes with different geographic distributions are suggested. studies have shown that genotype 1 is the predominant genotype of hdv in different parts of iran; however, the genotype distribution of this virus has not been identified in mashhad, northeast iran. objectives this current study determines the frequency of hdv major genotypes in mashhad, iran. patients and methods twenty-five participants were enrolled in this study. all samples were positive for hbsag (determined by enzyme-linked immunosorbent assay (elisa)) and anti-hdv. rna extraction and cdna synthesis was performed. then, pcr was performed and hdv genotypes were determined by restriction fragment length polymorphism (rflp). results of 25 patients, 12 (48%) were positive for hdv rna. genotype analysis of hdv rna revealed that the prevalence of hdv genotypes i and ii was 83.3% (n = 10) and 16.7% (n = 2), respectively. conclusions this study showed that the most prevalent genotype of hdv in mashhad was genotype i. it was of interest that in contrast to other provinces of iran, hdv genotype 2 was observed in mashhad. similar studies with larger sample sizes could provide valuable information regarding the molecular epidemiology and geographical distribution. it may also help control and prevent the spread of hepatitis d virus infections. in addition, the genotyping of hdv may predict the severity of the disease.