Characterization of the post-entry anti-HBV properties of nucleic acid polymers

人们已经研究了几种聚合物的广谱抗病毒活性。这些抗病毒聚合物，如聚乙烯醇硫酸酯(PVAS)、硫酸多糖(SPS)和聚萘硫酸酯(PNS)被认为主要通过抑制病毒进入发挥作用。它们的抗病毒活性与它们的两亲性相关，并呈长度依赖关系，并通过阻断病毒与细胞的相互作用或融合发挥作用。最近，一种由修饰的核酸衍生的新型抗病毒聚合物被称为核酸聚合物(NAP)，也被证明具有强大的、广谱的抗病毒活性。尽管NAP在大多数病毒中的抗病毒活性仅限于阻止病毒进入和/或融合，但在乙肝病毒(HBV)感染的情况下，还观察到了额外的进入后的抗病毒作用。这种进入后的活动具有重要的治疗潜力，因为它与血清乙肝病毒表面抗原(HBs Ag)的清除有关，这是在抗病毒治疗停止后患者实现感染控制的关键事件。由于其良好的安全性，Replicor Inc.(加拿大蒙特雷亚尔)已在孟加拉国和摩尔多瓦患者的三项概念验证II期临床试验中对NAP的抗乙肝病毒活性进行了评估。当与常规免疫疗法(聚乙二醇化干扰素-α2a)联合使用时，所有患者的血清乙肝表面抗原水平都下降了几个对数。在接受目前批准的任何一种治疗乙肝病毒感染的患者中，如此降低的乙肝表面抗原是罕见的。由于乙肝病毒感染的慢性性质，NAP的进入后的抗病毒作用被认为是治疗患者中观察到的乙肝表面抗原显著降低的原因。因此，更好地从机制上了解NAPs进入后的抗乙肝病毒作用将有助于揭示这些作用所涉及的分子机制，因为它们有望揭示乙肝病毒复制周期中以前未知的生物学行为。在此，我提出了一种策略，用于研究NAPs在体外对表达乙肝病毒的细胞的作用机制。

Several polymers have been studied for their broad spectrum antiviral activity. These antiviral polymers such as polyvinyl alcohol sulfate (PVAS), sulfated polysaccharides (SPS) and polynapthalene sulfate (PNS) are believed to act primarily through inhibition of viral entry. Their antiviral activities were shown to correlate with their amphipathic character and to be length dependent and were shown to act by blocking virus-cell interaction or fusion. Recently, a new type of antiviral polymer, derived from modified nucleic acids and called nucleic acid polymers (NAPs), has also been shown to have potent, broad spectrum antiviral activity.Although the antiviral activity of NAPs in most viruses is confined to blocking viral entry and or fusion, an additional post-entry antiviral effect has been observed specifically in the case of Hepatitis B Virus (HBV) infection. This post entry activity is of important therapeutic potential as it is correlated with the elimination of serum HBV surface antigen (HBsAg), a critical event always observed in patients achieving control of their infection after antiviral therapy is stopped. Due to their good safety profile, the anti-HBV activity of NAPs has been evaluated in three proof-of-concept phase II clinical trials in patients from Bangladesh and Moldova by Replicor Inc (Montréal, Canada). When used in conjunction with a conventional immunotherapy (pegylated-interferon-alpha2a), the serum level of HBsAg declined by several logs in all patients. Such reduction in HBsAg is rarely seen in patients treated with any of the currently approved therapies for HBV infection. Due to the chronic nature of the HBV infection, the post-entry antiviral effect of NAPs is thought to be responsible for the profound reduction in HBsAg observed in treated patients. Therefore a better mechanistic understanding of the post-entry anti-HBV effects of NAPs would be beneficial to uncover the molecular machinery involved in these effects as they promise to reveal previously unknown biology in the replication cycle of HBV. Here I present a strategy for the investigation of the mechanism of action of NAPs in vitro in HBV expressing cells.