Department of Biology, College of Science, University of Bahrain, Sakhir, Bahrain.
J Viral Hepat. 2013 Dec;20(12):821-8. doi: 10.1111/jvh.12192.
APOBEC3 (A3) cytidine deaminases are a family of enzymes that have been shown to inhibit the replication of HIV-1 and other retroviruses as part of the innate immune responses to virus infection. They can also hyperedit HBV DNA and inhibit HBV replication. Although A3 proteins are present at low levels in normal liver, A3 gene expression is highly stimulated by both interferon-α and interferon-γ. A3 deaminases are incorporated into nascent HBV capsids where they cleave amino groups from cytidine bases converting them to uracil in newly synthesized DNA following reverse transcription of pregenomic RNA. This modified HBV DNA is susceptible to degradation, or alternatively, numerous G-to-A nucleotide mutations are incorporated into positive-strand viral DNA disrupting coding sequences. A3 proteins in which the cytidine deaminase activity has been lost can also inhibit HBV replication, suggesting that there may be more than one way in which inhibition can occur. There is also evidence that A3 proteins might play a role in the development of hepatocellular carcinoma during chronic HBV infection.
APOBEC3（A3）胞嘧啶脱氨酶是一类酶，已被证明可以抑制 HIV-1 和其他逆转录病毒的复制，作为对病毒感染的固有免疫反应的一部分。它们还可以超编辑 HBV DNA 并抑制 HBV 复制。尽管 A3 蛋白在正常肝脏中含量较低，但干扰素-α和干扰素-γ均可高度刺激 A3 基因表达。A3 脱氨酶被整合到新生的 HBV 衣壳中，在逆转录前基因组 RNA 后，它们从胞嘧啶碱基上切割氨基基团，将其转化为新合成 DNA 中的尿嘧啶。这种修饰的 HBV DNA 容易降解，或者，许多 G 到 A 核苷酸突变被整合到正链病毒 DNA 中，破坏编码序列。失去胞嘧啶脱氨酶活性的 A3 蛋白也可以抑制 HBV 复制，这表明可能有不止一种抑制方式。还有证据表明，A3 蛋白可能在慢性 HBV 感染期间在肝细胞癌的发展中发挥作用。
