Department of Biochemistry and Molecular Biology, College of Medicine, Center for Structural Biology, McKnight Brain Institute, University of Florida, Gainesville, FL, 32610-0245, USA.
California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA; Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
Virology. 2022 Jan 2;565:22-28. doi: 10.1016/j.virol.2021.09.010. Epub 2021 Oct 6.
Adeno-associated virus (AAV) are classified as non-enveloped ssDNA viruses. However, AAV capsids embedded within exosomes have been observed, and it has been suggested that the AAV membrane associated accessory protein (MAAP) may play a role in envelope-associated AAV (EA-AAV) capsid formation. Here, we observed and selected sufficient homogeneous EA-AAV capsids of AAV2, produced using the Sf9 baculoviral expression system, to determine the cryo-electron microscopy (cryo-EM) structure at 3.14 Å resolution. The reconstructed map confirmed that the EA-AAV capsid, showed no significant structural variation compared to the non-envelope capsid. In addition, the Sf9 expression system used implies the notion that MAAP may enhance exosome AAV encapsulation. Furthermore, we speculate that these EA-AAV capsids may have therapeutic benefits over the currently used non-envelope AAV capsids, with advantages in immune evasion and/or improved infectivity.
腺相关病毒 (AAV) 被归类为无包膜 ssDNA 病毒。然而，已经观察到嵌入外泌体中的 AAV 衣壳，并且有人提出 AAV 膜相关辅助蛋白 (MAAP) 可能在包膜相关 AAV (EA-AAV) 衣壳形成中发挥作用。在这里，我们观察并选择了足够均匀的 AAV2 的 EA-AAV 衣壳，使用 Sf9 杆状病毒表达系统生产，以确定 3.14 Å 分辨率的冷冻电镜 (cryo-EM) 结构。重建的图谱证实，与非包膜衣壳相比，EA-AAV 衣壳没有明显的结构变化。此外，使用的 Sf9 表达系统暗示 MAAP 可能增强外泌体 AAV 的封装。此外，我们推测这些 EA-AAV 衣壳可能比目前使用的非包膜 AAV 衣壳具有治疗优势，在免疫逃逸和/或提高感染性方面具有优势。
