Role of the carbohydrate-binding sites of griffithsin in the prevention of DC-SIGN-mediated capture and transmission of HIV-1

• Published in: PloS one 2013-05, Vol.8 (5), p.e64132-e64132
• Main Authors: Hoorelbeke, Bart, Xue, Jie, LiWang, Patricia J, Balzarini, Jan
• Format: Article
• Language: English
• Subjects: Anti-HIV Agents - chemistry; Anti-HIV Agents - pharmacology; Antiviral agents; Binding Sites; Biology; Carbohydrates; CD4 antigen; CD4-Positive T-Lymphocytes - drug effects; CD4-Positive T-Lymphocytes - metabolism; CD4-Positive T-Lymphocytes - virology; Cell Adhesion Molecules - antagonists & inhibitors; Cell Adhesion Molecules - genetics; Cell Adhesion Molecules - metabolism; Cell culture; Cell Line; Cells, Cultured; DC-SIGN protein; Dendritic cells; Disease transmission; Glycan; Glycoprotein gp120; HIV; HIV Envelope Protein gp120 - antagonists & inhibitors; HIV Envelope Protein gp120 - genetics; HIV Envelope Protein gp120 - metabolism; HIV Infections - prevention & control; HIV Infections - transmission; HIV-1 - drug effects; HIV-1 - growth & development; HIV-1 - metabolism; Human immunodeficiency virus; Humans; Infections; Lectins; Lectins, C-Type - antagonists & inhibitors; Lectins, C-Type - genetics; Lectins, C-Type - metabolism; Lymphocytes; Lymphocytes T; Mannose; Medical research; Medicine; Plant Lectins - chemistry; Plant Lectins - pharmacology; Protein Binding; Receptors, Cell Surface - antagonists & inhibitors; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Studies; Surface plasmon resonance; Syncytia; Virus Internalization - drug effects; Viruses
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0064132

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.