Capsid allosteric modulators（CpAMs）對B型肝炎病毒之核心蛋白相關第一型干擾素反應的影響

Abstract

B型肝炎病毒（Hepatitis B virus, HBV）是一種可引發B型肝炎的DNA病毒，其核心蛋白（HBV-core protein, HBc protein）在合成後會自我組裝形成HBV capsid，並在此過程中包裹病毒的前基因體RNA（pregenomic RNA, pgRNA）。在capsid內，pgRNA經反轉錄作用轉化為鬆弛環狀DNA（relaxed-circular DNA, rcDNA）。成熟的capsid可被包裹形成完整的HBV病毒顆粒，亦可輸送至細胞核以促進病毒的基因轉錄。因此，HBc protein與capsid在HBV的複製中扮演關鍵角色。先前研究顯示，第一型干擾素（Type I interferons）可能透過抑制包裹病毒RNA的HBV capsid形成，或可能導致HBV capsid的降解，進而降低感染細胞中具有複製能力的nucleocapsid數量。而近二十年來，針對HBV capsid的小分子化合物- capsid allosteric modulators（CpAMs）的研究逐年增加。這類化合物可藉由干擾capsid組裝來降低pgRNA的包裹以達到抑制HBV複製的目的。根據其對HBV capsid與HBc protein的影響機制，CpAMs可以粗略地分為兩大類：capsid disruptors與capsid enhancers。其中，capsid disruptors會導致HBc protein錯誤組裝，形成結構異常的HBc polymer；而capsid enhancers則促進不含pgRNA之empty capsid形成。而由於CpAMs與type I interferons皆可影響HBV capsid，但其作用機制各不相同，因此本研究將首先利用HepG2細胞的轉染模型（transfection model）探討不同CpAMs對細胞內HBV capsid之影響，進而評估其是否影響HBc protein相關的type I interferon反應。並希望可以藉由CpAMs來探討type I interferon對於HBV core protein影響的機制。

Hepatitis B virus (HBV) is a DNA virus whose core protein (HBc) self-assembles into a capsid, encapsidating pregenomic RNA (pgRNA) for reverse transcription into relaxed-circular DNA (rcDNA). The mature capsid can either be enveloped to form infectious virions or transported to the nucleus to support viral transcription. Thus, HBc protein and capsid formation are essential for HBV replication. Type I interferons have been shown to inhibit HBV replication, potentially by blocking pgRNA encapsidation or promoting capsid degradation, thereby reducing nucleocapsid levels in infected cells. In recent years, capsid allosteric modulators (CpAMs), small molecules that disrupt normal capsid assembly, have emerged as promising antiviral agents. Depending on their mode of action, CpAMs are broadly categorized into capsid disruptors, which lead to misassembled HBc polymers, and capsid enhancers, which promote the formation of empty capsids lacking pgRNA. Since CpAMs and type I interferons both affect capsid dynamics through different mechanisms, this study uses a HepG2 transfection model to examine the effects of distinct CpAMs on intracellular HBV capsid formation and evaluate their impact on type I interferon responses associated with HBc protein. Furthermore, CpAMs are used as mechanistic probes to elucidate how type I interferons influence HBV core protein.