Quantitative Analysis of Hepatitis B Virus Precore Mutant in Hepatitis Type B
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TAKESHI ICHIKAWA, HITOSHI TAKAGI, MORITOSHI KINOSHITA,1 RYUYA SHIMODA, TAKEAKI NAGAMINE and MASATOMO MORI
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The First Department of Internal Medicine, Gunma University School of Medicine, Gunma 371-8511, 1Diagnostic Research Institute, Otsuka Pharmaceutical Co., Ltd., Tokushima 771-0132
Active liver disease has been detected in chronic hepatitis B after seroconversion from positive HBe antigen to positive anti-HBe antibody. Active replication of HB virus (HBV) containing a precore stop-codon mutation has been implicated in this condition. The usual methods, such as direct sequencing, to characterize the responsible mutant of HBV are not suitable for routine clinical use. Here we employed the competitive mutation site specific assay (CMSSA) to detect precore mutant HBV-DNA in patients with positive HB surface antigen. In patients with HBe antigen, precore mutant HBV-DNA was significantly higher than in patients with HBe antibody. The level of precore mutant HBV-DNA in patients with elevated serum ALT was significantly higher than in patients with normal serum ALT. Sex, age and the level of serum HBV-associated DNA polymerase levels were not correlated with levels of precore mutant HBV-DNA. Ten of 11 negative patients for the precore mutant by polymerase chain reaction followed by restriction fragment length polymorphism assay (PCR-RFLP) were positive for the precore mutant by CMSSA. These results suggest that the precore mutant has already emerged in the HBeAg-positive phase as determined by CMSSA, which is more sensitive than PCR-RFLP and is useful for evaluating the clinical course of patients with chronic hepatitis B.
Key words---
hepatitis B virus; precore mutant; competitive mutation site specific assay
© 1998 Tohoku University Medical Press
Tohoku J. Exp. Med., 1998, 186, 323-333
Address for reprints:
Takeshi Ichikawa, M.D., The First Department of Internal Medicine, Gunma University School of Medicine, 3-39 Showamachi, Maebashi, Gunma 371-8511, Japan.
e-mail: htakagi@sb.gunma-u.ac.jp
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