Rega Institute for Medical Research, KU Leuven, Leuven, Belgium.
PLoS One. 2013 May 31;8(5):e64132. doi: 10.1371/journal.pone.0064132. Print 2013.
The glycan-targeting C-type DC-SIGN lectin receptor is implicated in the transmission of the human immunodeficiency virus (HIV) by binding the virus and transferring the captured HIV-1 to CD4(+) T lymphocytes. Carbohydrate binding agents (CBAs) have been reported to block HIV-1 infection. We have now investigated the potent mannose-specific anti-HIV CBA griffithsin (GRFT) on its ability to inhibit the capture of HIV-1 to DC-SIGN, its DC-SIGN-directed transmission to CD4(+) T-lymphocytes and the role of the three carbohydrate-binding sites (CBS) of GRFT in these processes.
GRFT inhibited HIV-1(IIIB) infection of CEM and HIV-1(NL4.3) infection of C8166 CD4(+) T-lymphocytes at an EC50 of 0.059 and 0.444 nM, respectively. The single mutant CBS variants of GRFT (in which a key Asp in one of the CBS was mutated to Ala) were about ∼20 to 60-fold less potent to prevent HIV-1 infection and ∼20 to 90-fold less potent to inhibit syncytia formation in co-cultures of persistently HIV-1 infected HuT-78 and uninfected C8166 CD4(+) T-lymphocytes. GRFT prevents DC-SIGN-mediated virus capture and HIV-1 transmission to CD4(+) T-lymphocytes at an EC50 of 1.5 nM and 0.012 nM, respectively. Surface plasmon resonance (SPR) studies revealed that wild-type GRFT efficiently blocked the binding between DC-SIGN and immobilized gp120, whereas the point mutant CBS variants of GRFT were ∼10- to 15-fold less efficient. SPR-analysis also demonstrated that wild-type GRFT and its single mutant CBS variants have the capacity to expel bound gp120 from the gp120-DC-SIGN complex in a dose dependent manner, a property that was not observed for HHA, another mannose-specific potent anti-HIV-1 CBA.
GRFT is inhibitory against HIV gp120 binding to DC-SIGN, efficiently prevents DC-SIGN-mediated transfer of HIV-1 to CD4(+) T-lymphocytes and is able to expel gp120 from the gp120-DC-SIGN complex. Functionally intact CBS of GRFT are important for the optimal action of GRFT.
糖基靶向 C 型 DC-SIGN 凝集素受体通过与病毒结合并将捕获的 HIV-1 转移至 CD4(+)T 淋巴细胞，从而参与人类免疫缺陷病毒（HIV）的传播。已报道碳水化合物结合剂（CBA）可阻断 HIV-1 感染。我们研究了具有强烈抗 HIV 活性的甘露糖特异性 CBA griffithsin（GRFT），观察其抑制 HIV-1 与 DC-SIGN 结合、DC-SIGN 介导的 HIV-1 向 CD4(+)T 淋巴细胞转移的能力，以及 GRFT 的三个碳水化合物结合位点（CBS）在这些过程中的作用。
GRFT 抑制 CEM 细胞感染 HIV-1(IIIB)和 C8166 CD4(+)T 淋巴细胞感染 HIV-1(NL4.3)的 EC50 分别为 0.059 和 0.444 nM。GRFT 的单突变 CBS 变体（其中一个 CBS 中的关键天冬氨酸突变为丙氨酸）对预防 HIV-1 感染的效力约降低 20 至 60 倍，对抑制持续感染 HIV-1 的 HuT-78 和未感染 C8166 CD4(+)T 淋巴细胞共培养物中合胞体形成的效力约降低 20 至 90 倍。GRFT 以 EC50 为 1.5 nM 和 0.012 nM 的浓度，分别抑制 DC-SIGN 介导的病毒捕获和 HIV-1 向 CD4(+)T 淋巴细胞的转移。表面等离子体共振（SPR）研究显示，野生型 GRFT 能有效阻断 DC-SIGN 与固定化 gp120 之间的结合，而 GRFT 的点突变 CBS 变体的效率约降低 10-15 倍。SPR 分析还表明，野生型 GRFT 及其单突变 CBS 变体具有依赖于剂量的能力，可从 gp120-DC-SIGN 复合物中逐出结合的 gp120，而另一种甘露糖特异性强效抗 HIV-1 CBA HHA 则没有这种性质。
GRFT 可抑制 HIV gp120 与 DC-SIGN 的结合，有效阻止 DC-SIGN 介导的 HIV-1 向 CD4(+)T 淋巴细胞的转移，并能从 gp120-DC-SIGN 复合物中逐出 gp120。GRFT 的功能完整的 CBS 对于 GRFT 的最佳作用很重要。
