A study on sequence variations in preS/S regions of hepatitis B virus in occult infective patients
Objective To assess the sequence variations in preS/S regions of occult hepatitis B virus (OHB) and their relationship to severe chronic hepatic injury. Methods We collected samples from HBsAg negative patients, and evaluated their HBV-DNA by nest-PCR. HBV-DNA positive samples were used for analysis of preS/S region by PCR sequencing. Results Sixty-nine cases with HBV-DNA were identified in 468 cases without HBsAg. The positive percents were 16％, 8.7％, 36.4％, 18.3％ and 0％in group of only HBcAb positive, only HBeAb positive, only HBeAg positive, both HBcAb and HBsAb positive and all indexes negative, respectively. The level of HBV-DNA of OHB was significant lower than that in HBsAg positive patients. Compared with HBsAg positive controls, preS/S deletion, M1I and Q2K in preS2 region, Q129N/R/P,G185R and S210R in S region were more common in OHB. Moreover, M1I and Q2K in preS2 region, G185R and S210R in S region in OHB with severe chronic hepatic injury were more common that those in OHB without severe chronic hepatic injury. Compared with HBsAg positive patients with severe chronic hepatic injury, the level of HBV-DNA was lower, while the frequency of M1I and Q2K mutation in preS2 region, G185R and S210R in S region were more common in OHB patients with severe chronic hepatic injury. Conclusion The virological factors were different between OHB and HBsAg positive patients. The M1I and Q2K in preS2 region, G185R and S210R in S region might be useful for prognosis evaluation of OHB patients. 
 
Key words: 
Hepatitis B virus;  PreS/S region;  Variation analysis;  Hepatic injury