For instance, viruses with truncated or abolished M protein
may survive due to the disruption of their epitopes. Interestingly, we observed a much higher frequency of preS2 deletions in patients treated with NAs compared to long-term immuno-suppressed organ-transplant recipients (Figure 2), suggesting increased immune escape in preS2 deletion mutants. In particular, almost all truncated preS2 mutants had a damaged b10 epitope (aa 120–145), a major envelope epitope whose absence would inhibit HBV clearing by the host [31, 32]. Therefore, larger sample sizes and detailed functional analysis FK506 supplier will be required for further verification. Meanwhile, considering the virulent feature of preS deletion mutants in chronic hepatitis infection, development of diagnostic find more tests
for various deletion mutants would be beneficial for CH patients. Conclusions In this study, we characterized deletion patterns in three hotspots, along the whole HBV genome, that are prevalent in northern China. Except for the BCP region, which influences regulating elements of the core gene, most deletions appear to destroy various epitopes of viral proteins. A comparison of samples with or without antiviral medication demonstrated a correlation between NA treatment and preS deletions, which is also evidenced by the analysis of serial samples before and after ADV treatment. Although preS deletions alone had no effect on drug resistance, the accumulation of preS deletion mutants in patients during antiviral treatment may promote viral immune escape. Methods Patients and blood samples Blood samples were provided by You’an Hospital in Beijing. This study was approved by the Institutional Review Board of the Beijing Institute of Genomics and the Ethics Committee of Beijing You’an Hospital of Capital Medical University. Informed consent was obtained from all patients.
Patients were diagnosed as chronic carrier (CC), chronic hepatitis (CH), liver cirrhosis (LC) and hepatocellular carcinoma (HCC) according to the guidelines on the prevention and treatment of chronic hepatitis B in China (2010) . No patients had co-infections with HCV, HDV, or HIV. Blood samples of 5ml were collected, cells and Astemizole sera were then separated and stored at −20°C. From the few hundred stored samples, we successfully amplified and sequenced 51 whole genomes from 51 individuals. Additionally, preS clone sequencing was performed in another cohort of 52 patients for fine mapping of deletion substructure. DNA quantification and HBV serological marker detection Viral DNA titers were quantified using the FQ-PCR Kit for HBV (DaAn Gene Co., Guangdong, China) on a GeneAmp 5700 Sequence Detection System (PE Applied Biosystems, CA, USA). Serological markers were determined by an Electrochemiluminescence Immunoassay on a Roche E170 Modular Immunoassay Analyzer (Roche Diagnostics, Mannheim, Germany) following the manufacturer’s protocol.