There are seven HDV genotypes described, and their nomenclature is defined as type I-VII; various genotypes are reported to be associated with different long term outcomes of infection [11]. Recently Moatter et al reported genotype 1 of HDV and genotype D of HBV from Pakistan http://www.selleckchem.com/products/Roscovitine.html [12], which has also been confirmed on a larger scale by our group (13). HBV infection is associated with a broad spectrum of clinical manifestations, ranging from an asymptomatic carrier (AC) state to acute liver failure. It can also manifest in diverse forms of chronic infection, including the immune tolerant phase (IP), chronic active hepatitis B (CAH), compensated liver cirrhosis (CC), and hepatocellular carcinoma (HCC). Co-infections of hepatitis B with multiple hepatitis viruses are associated with diverse patterns of reciprocal inhibition of viral replication.

Delta hepatitis occurs due to co-infection of HBsAg positive patients with hepatitis delta virus. There are inconsistent reports on the role of each virus in the pathogenicity of HBV/HDV infection. Some reports suggest that the activity of liver disease is mainly due to HDV [13-16] while others implicate hepatitis B virus, regardless of the levels of HBV DNA, in the aggressive nature and progression of disease [17]. In studies from Europe, HDV has frequently been shown to suppress HBV replication [18,19], and 70-90% of patients with hepatitis D are hepatitis B e antigen (HBeAg) negative, with low serum levels of HBV DNA. However, despite this influence of HDV on HBV, 15-30% of patients with hepatitis D are HBeAg and/or HBV DNA positive.

There is no data, to our knowledge, on the characteristics and impact of hepatitis delta virus on hepatitis B virus infection and its spectrum of diseases from South Asia. The aim of this study was to investigate the virological and clinical characteristics of patients infected with HBV/HDV infection in two large tertiary care centers of Pakistan. Methods Patients’ characteristics We conducted this study prospectively in patients seen at the Aga Khan University Hospital (AKUH), Karachi and Isra University Hospital, Hyderabad, Pakistan. Both hospitals are situated in the province of Sindh and serve as main tertiary care centers located in the southern part of Pakistan, which is among the largest countries of South Asia; it represents 30% of the population of this region.

Each year approximately half a million patients visit the out-patient clinics and 45,000 are managed as in-patients in the different wards of these two hospitals. The AKUH laboratory has 189 collection centers all around the country including 07 in Hyderabad where the samples are collected and transported to the central laboratory Drug_discovery in Karachi for processing. We identified 2455 HBsAg positive patients and checked their HBV DNA PCR by qualitative methods from 2005 to 2009 at these two centers.