State Key Laboratory of Veterinary Etiological Biology, National Foot-and-Mouth Disease Reference Laboratory, Lanzhou Veterinary Research Institute Chinese Academy of Agricultural Sciences, Lanzhou, P.R. China.
College of Animal Science, Yangtze University, Jingzhou, P. R. China.
Drug Deliv. 2021 Dec;28(1):957-962. doi: 10.1080/10717544.2021.1909178.
The African swine fever virus (ASFV) is a huge and complex DNA virus that can lead to the acute death of pigs and cause huge losses to the global swine industry. The CD2v protein is a transmembrane protein encoded by the ASFV's gene, which can effectively inhibit the bystander lymphocyte proliferation in response to mitogens and mediate the absorption of red blood cells to ASFV-infected cells. The CD2v protein contains repetitive amino acid sequences ([KPCPPP] labeled as RAAS), which is reported as a genetic marker and an epitope. However, the specific biological function of the RAAS is unknown. Here, we have found that the truncated CD2v protein with RAAS can enter Chinese hamster ovary cells, but the truncated CD2v protein without RAAS cannot enter the cells. Also, the RAAS can carry the macromolecular protein EGFP to enter various cells through multiple endocytic processes that are dependent on time, concentration, and location. Besides, the RAAS enter the cells via the macropinocytosis or the clathrin-mediated endocytosis. These results indicate that the RAAS can function as a cell-penetrating peptide that provides a new insight for ASFV research and has potential application value as a tool for drug delivery.
非洲猪瘟病毒（ASFV）是一种巨大而复杂的 DNA 病毒，可导致猪的急性死亡，并对全球养猪业造成巨大损失。CD2v 蛋白是 ASFV 基因编码的一种跨膜蛋白，可有效抑制有丝分裂原刺激的旁观者淋巴细胞增殖，并介导红细胞对感染 ASFV 的细胞的吸收。CD2v 蛋白含有重复的氨基酸序列（标记为 RAAS 的 [KPCPPP]），被报道为遗传标记和抗原表位。然而，RAAS 的具体生物学功能尚不清楚。在这里，我们发现含有 RAAS 的截短 CD2v 蛋白可以进入中国仓鼠卵巢细胞，但不含 RAAS 的截短 CD2v 蛋白不能进入细胞。此外，RAAS 可以通过多种依赖时间、浓度和位置的内吞作用，携带大分子蛋白 EGFP 进入各种细胞。此外，RAAS 通过巨胞饮或网格蛋白介导的内吞作用进入细胞。这些结果表明，RAAS 可以作为一种细胞穿透肽发挥作用，为 ASFV 研究提供了新的见解，并具有作为药物输送工具的潜在应用价值。
