Sequence Variation in Hepatitis B Virus Variants of Chronically Infected Saudi Patients and Their Interaction with Host Genetic Factors

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Hepatitis B virus (HBV) continues to be o‐‐‐‐‐‐‐‐‐ne of the most important viral pathogens in humans. Approximately 350–400 million individuals worldwide are estimated to be chronically infected with HBV. In Saudi Arabia, the prevalence and dynamics of HBV infection is far from being unambiguously clear. The current study was designed to explore: i) the epidemiology of HBV in Riyadh and the different risk factors’ impact, ii) the genetic diversity among circulating Saudi variants, iii) the interaction between mutant proteins of Saudi HBV variants and host genetic factors. A total of 123 blood samples were collected from HBV infected patients (114 at chronic stage and 9 at cirrhotic stage) at Riyadh during 2012–2013. Clinical and biochemical parameters, serological markers and HBV viral load were evaluated in all patients. HBV Pre‐core/Core (P/C), HBsAg (S) and X gene mutations were determined in different disease categories by sequence and phylogenetic analysis. Two representative mutant open reading frames were cloned for both P/C and X genes. Cloned genes were transfected in Huh7 cells and the expression of different host factors including uPA, TIMP‐2, MMP‐2, TGF‐β1and CXCR4 was in‐vitro evaluated as compared to wild‐type genes on both transcriptional level (by real‐time RT‐PCR) and translational level (by ELISA). All clinical samples were tested positive for HBV infection using HBsAg ELISA and real‐time PCR. Of these samples, 28.5% were positive for HBeAg and negative for anti‐HBeAg antibodies. The rate of HBV infection and viral load was higher in males (68.3% and 8.5×106 IU/mL, respectively) than in females (31.7% and 1.9×104 IU/mL, respectively). Sequence analysis of Saudi HBV variants has identified a collective number of 33, 21 and 5 unique mutations in the P/C, S and X genes, respectively. Phylogenetic analysis revealed that all Saudi variants are members of genotype D, with the majority located in subgenotypes D1 and D3. Studying the effect of mutant genes on the expression of host factors demonstrated that both mutant and wild‐type forms have the same effect. HBx gene upregulated the expression of all host genetic factors, whereas P/C gene only up‐regulated MMP‐2 and slightly TGF‐β1. HBV is circulating in Saudi Arabia in males more than females with no correlation between the viral load and disease severity. This study is the first to classify Saudi HBV variants as members of genotype D. The positive regulatory effect of mutant and wild‐type genes on host genetic factors necessitates a series of comprehensive studies to characterize the nature of this protein‐protein interaction.