determination of hepatitis delta virus genotype among hbv carriers in southwest of iran

background and aims: hdv is a defective satellite virus and classified in genus deltavirus. its disease is related and limited to hbv-infected patients. acute infection of delta agent occurs in two different patterns simultaneous infection with both hbv & hdv or super infection of chronically hbv infected patients that lead to more sever type of hepatitis. according to genetic diversity of genomic rna of hdv, 8 clades have been classified. the aim of this study was to determine the delta virus genotype among the hbv & hdv infected patients in ahvaz city. materials and methods: sera sample collected from 31 seropositive hdv patients including 21 male and 9 female mean age 46±13.5 suffering from chronic hepatitis and 1 male patient with acute hepatitis. the encoding region for c terminal half of the delta anti gene of the hdv’s genomic rna reverse transcribed and then amplified by nested pcr. the hdv pcr positive samples were sequenced, and the sequences were compared with reference sequences on genbank. all samples were tested for hbv dna, hcv rna and hcv anti body. results: only 15(48%) out of 31 anti hdv seropositive patients were positive for hdv rna by nested rt-pcr. alignment and phylogenic analysis of the present hdv sequences revealed that all sequences belong to clade 1. only 1 hdv rna positive patient was positive for hbv dna by nested pcr. conclusion: according to previous studies the clade 1 (genotype 1) is the predominant clade of hdv in our country. however some (2-hdv-r, 4-hdv-r &11-hdv-r) of our isolates show extensive differences from the two previously isolated hdvs from iran. most of the our isolates were closely related to the iranian hdvs, but egyptian hdv still remains the most relevant foreign isolate. suppression of hbv replication by delta virus is common but mutual suppression of hdv and hcv remains unclear.