Department of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, Guldhedsgatan 10B, 413 46, Gothenburg, Sweden.
Virol J. 2018 May 15;15(1):86. doi: 10.1186/s12985-018-0994-7.
Hepatocytes infected by hepatitis B virus (HBV) produce different HBV RNA species, including pregenomic RNA (pgRNA), which is reverse transcribed during replication. Particles containing HBV RNA are present in serum of infected individuals, and quantification of this HBV RNA could be clinically useful.
In a retrospective study of 95 patients with chronic HBV infection, we characterised HBV RNA in serum in terms of concentration, particle association and sequence. HBV RNA was detected by real-time PCR at levels almost as high as HBV DNA.
The HBV RNA was protected from RNase and it was found in particles of similar density as particles containing HBV DNA after fractionation on a Nycodenz gradient. Sequencing the epsilon region of the RNA did not reveal mutations that would preclude its binding to the viral polymerase before encapsidation. Specific quantification of precore RNA and pgRNA by digital PCR showed almost seven times lower ratio of precore RNA/pgRNA in serum than in liver tissue, which corresponds to poorer encapsidation of this RNA as compared with pgRNA. The serum ratio between HBV DNA and HBV RNA was higher in genotype D as compared with other genotypes.
The results suggest that HBV RNA in serum is present in viral particles with failing reverse transcription activity, which are produced at almost as high rates as viral particles containing DNA. The results encourage further studies of the mechanisms by which these particles are produced, the impact of genotype, and the potential clinical utility of quantifying HBV RNA in serum.
乙型肝炎病毒 (HBV) 感染的肝细胞产生不同的 HBV RNA 物种，包括前基因组 RNA (pgRNA)，其在复制过程中被逆转录。含有 HBV RNA 的颗粒存在于感染个体的血清中，对这种 HBV RNA 的定量可能具有临床意义。
在对 95 例慢性 HBV 感染患者的回顾性研究中，我们从浓度、颗粒关联和序列方面对血清中的 HBV RNA 进行了表征。通过实时 PCR 检测 HBV RNA，其水平几乎与 HBV DNA 一样高。
HBV RNA 能抵抗核糖核酸酶，并在 Nycodenz 梯度分离后发现其存在于与含有 HBV DNA 的颗粒相似密度的颗粒中。对 RNA 的 epsilon 区进行测序并未发现突变，这些突变会阻止其在衣壳化之前与病毒聚合酶结合。通过数字 PCR 对前核心 RNA 和 pgRNA 的特异性定量显示，血清中前核心 RNA/pgRNA 的比值比肝组织低近 7 倍，这表明与 pgRNA 相比，这种 RNA 的衣壳化较差。与其他基因型相比，基因型 D 血清中 HBV DNA 与 HBV RNA 的比值更高。
这些结果表明，血清中的 HBV RNA 存在于逆转录活性丧失的病毒颗粒中，其产生的速率几乎与含有 DNA 的病毒颗粒一样高。这些结果鼓励进一步研究这些颗粒产生的机制、基因型的影响以及定量检测血清中 HBV RNA 的潜在临床应用。
