Wang Scarlet Xiaoyan, Michiels Johan, Ariën Kevin K, New Roger, Vanham Guido, Roitt Ivan
Department of Natural Sciences, Middlesex University, London, UK.
Institute of Tropical Medicine, Antwerp, Belgium.
Nanoscale Res Lett. 2016 Dec;11(1):350. doi: 10.1186/s11671-016-1558-7. Epub 2016 Jul 28.
Although highly active antiretroviral therapy (HAART) has greatly improved the life expectancy of HIV/AIDS patients, the treatment is not curative. It is a global challenge which fosters an urgent need to develop an effective drug or neutralizing antibody delivery approach for the prevention and treatment of this disease. Due to the low density of envelope spikes with restricted mobility present on the surface of HIV virus, which limit the antibody potency and allow virus mutation and escape from the immune system, it is important for a neutralizing antibody to form bivalent or multivalent bonds with the virus. Liposome constructs could fulfil this need due to the flexible mobility of the membrane with its attached antibodies and the capacity for drug encapsulation. In this study, we evaluated the neutralization activity of a range of liposome formulations in different sizes coated with anti-gp120 llama antibody fragments (Vhhs) conjugated via either non-covalent metal chelation or a covalent linkage. The non-covalent construct demonstrated identical binding affinity to HIV-1 envelope glycoprotein gp120 and neutralizing ability for HIV virus as free Vhh. Although covalently linked Vhh showed significant binding affinity to gp120, it unexpectedly had a lower neutralization potency. This may be due to the comparability in size of the viral and liposome particles restricting the number which can be bound to the liposome surface so involving only a fraction of the antibodies, whereas non-covalently attached antibodies dissociate from the surface after acting with gp120 and free the remainder to bind further viruses. Covalently conjugated Vhh might also trigger the cellular uptake of a liposome-virion complex. To explore the possible ability of the antibody-coated liposomes to have a further function, we encapsulated the hydrophobic antiviral drug dapivirine into both of the non-covalently and covalently conjugated liposome formulations, both of which revealed high efficacy in reducing viral replication in vitro. Thus, dual function liposomes may lead to a novel strategy for the prophylaxis of HIV/AIDS by combining the neutralizing activity of Vhh with antiviral effects of high drug concentrations.
尽管高效抗逆转录病毒疗法（HAART）极大地提高了HIV/AIDS患者的预期寿命，但该治疗方法并不能治愈疾病。这是一项全球性挑战，迫切需要开发一种有效的药物或中和抗体递送方法来预防和治疗这种疾病。由于HIV病毒表面包膜刺突密度低且流动性受限，限制了抗体效力，并使病毒发生突变并逃避免疫系统，因此中和抗体与病毒形成二价或多价键很重要。脂质体构建体可以满足这一需求，因为其膜与附着抗体具有灵活的流动性以及药物包封能力。在本研究中，我们评估了一系列不同大小的脂质体制剂的中和活性，这些脂质体用通过非共价金属螯合或共价连接缀合的抗gp120羊驼抗体片段（Vhhs）包被。非共价构建体显示出与HIV-1包膜糖蛋白gp120相同的结合亲和力以及与游离Vhh对HIV病毒相同的中和能力。尽管共价连接的Vhh对gp120显示出显著的结合亲和力，但出乎意料的是其具有较低的中和效力。这可能是由于病毒颗粒和脂质体颗粒大小相当，限制了可结合到脂质体表面的数量，因此仅涉及一部分抗体，而非共价附着的抗体在与gp120作用后从表面解离，释放其余抗体以进一步结合病毒。共价缀合的Vhh也可能触发脂质体 - 病毒体复合物的细胞摄取。为了探索抗体包被的脂质体可能具有的进一步功能，我们将疏水性抗病毒药物达匹韦林包封到非共价和共价缀合的脂质体制剂中，两者在体外均显示出在降低病毒复制方面的高效性。因此，双功能脂质体可能通过将Vhh的中和活性与高药物浓度的抗病毒作用相结合，为预防HIV/AIDS带来一种新策略。
