Abstract: Objective The aim of this study was to investigate fluoresce quantity PCR (fq-PCR) assay in monitoring antiviral efficacy in patients with chronic hepatitis B (CHB) with low-level viremia (LLV). Methods A total of 200 patients with CHB were encountered in our hospital between January 2019 and December 2022, and the alleged patients met oral entecavir (ETV) treatment for at least 48 weeks. All patients with complete virologic response (CVR) continued ETV treatment, those without switched to tenofovir alafenamide fumarate (TAF) antiviral treatment, and all patients were followed-up for 48 weeks. Serum HBV DNA loads were detected by quantitative real-time PCR (qPCR) and fq-PCR, respectively. Results Of 200 ETV-treated patient enrolled in this study, fq-PCR assay found CVR in 145 cases (72.5%), serum HBV DNA loads were greater than 2000 IU/mL(PR) in 13 cases (6.5%), and serum HBV DNA loads were at range of 21 to 2000 IU/mL(LLV) in 42 cases (21.0%); by end of 48 week TAF treatment, CVR by qPCR in PR group was found in 13 cases (100.0%), while only in 5 cases(38.5%, P＜0.05) by fq-PCR, and in LLV group were in 41 cases (97.6%) and in 30 cases (71.4%, P＜0.05), in which there was a significant difference between CVR in PR group and in LLV group by fq-PCR (x²=4.662, P＜0.05); there were no significant differences as respect to serum AST and ALT levels in patients with PR and with LLV(P>0.05), while serum HBV DNA loads in LLV group was (125.6±114.2)IU/mL, much lower than [(370.4±217.8)IU/mL, P＜0.05] in those with PR. Conclusion Surveillance of serum HBV DNA loads by high-sensitivity PCR detection could help clinicians find CHB patients receiving nucleos(t)ide analogue treatment at LLV status, and make an appropriate antiviral options as early as possible.

Key words: Hepatitis B, Entecavir, Tenofovir alafenamide fumarate, Low-level viremia, Fluoresce quantity PCR, Quantitative real-time PCR, Efficacy monitoring