title: Monoclonal Antibodies Specific for the V2, V3, CD4-Binding Site, and gp41 of HIV-1 Mediate Phagocytosis in a Dose-Dependent Manner.
abstract: In light of the weak or absent neutralizing activity mediated by anti-V2 monoclonal antibodies (MAbs), we tested whether they can mediate Ab-dependent cellular phagocytosis (ADCP), which is an important element of anti-HIV-1 immunity. We tested six anti-V2 MAbs and compared them with 21 MAbs specific for V3, the CD4-binding site (CD4bs), and gp41 derived from chronically HIV-1-infected individuals and produced by hybridoma cells. ADCP activity was measured by flow cytometry using uptake by THP-1 monocytic cells of fluorescent beads coated with gp120, gp41, BG505 SOSIP.664, or BG505 DS-SOSIP.664 complexed with MAbs. The measurement of ADCP activity by the area under the curve showed significantly higher activity of anti-gp41 MAbs than of the members of the three other groups of MAbs tested using beads coated with monomeric gp41 or gp120; anti-V2 MAbs were dominant compared to anti-V3 and anti-CD4bs MAbs against clade C gp120ZM109ADCP activity mediated by V2 and V3 MAbs was positive against stabilized DS-SOSIP.664 trimer but negligible against SOSIP.664 targets, suggesting that a closed envelope conformation better exposes the variable loops. Two IgG3 MAbs against the V2 and V3 regions displayed dominant ADCP activity compared to a panel of IgG1 MAbs. This superior ADCP activity was confirmed when two of three recombinant IgG3 anti-V2 MAbs were compared to their IgG1 counterparts. The study demonstrated dominant ADCP activity of anti-gp41 against monomers but not trimers, with some higher activity of anti-V2 MAbs than of anti-V3 and anti-CD4bs MAbs. The ability to mediate ADCP suggests a mechanism by which anti-HIV-1 envelope Abs can contribute to protective efficacy.IMPORTANCEAnti-V2 antibodies (Abs) correlated with reduced risk of HIV-1 infection in recipients of the RV144 vaccine, suggesting that they play a protective role, but a mechanism providing such protection remains to be determined. The rare and weak neutralizing activities of anti-V2 MAbs prompted us to study Fc-mediated activities. We compared anti-V2 MAbs with other MAbs specific for V3, CD4bs, and gp41 for Ab-dependent cellular phagocytosis (ADCP) activity, implicated in protective immunity. The anti-V2 MAbs displayed stronger activity than other anti-gp120 MAbs in screening against one of two gp120s and against DS-SOSIP, which mimics the native trimer. The activity of anti-gp41 MAbs was superior in targeting monomeric gp41 but was comparable to that seen against trimers, which may not adequately expose gp41 epitopes. While anti-envelope MAbs in general mediated ADCP activity, anti-V2 MAbs displayed some dominance compared to other MAbs. Our demonstration that anti-V2 MAbs mediate ADCP activity suggests a functional mechanism for their contribution to protective efficacy.
authors.affiliation: Vaccine Branch, NCI, NIH, Bethesda, Maryland, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Musich
authors.affiliation: Department of Pathology, New York University School of Medicine, New York, New York, USA.
authors.forename: Liuzhe
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Pathology, New York University School of Medicine, New York, New York, USA.
authors.forename: Lily
authors.initials: L
authors.lastname: Liu
authors.affiliation: Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Susan
authors.identifier: http://orcid.org/0000-0002-0750-2666
authors.initials: S
authors.lastname: Zolla-Pazner
authors.affiliation: Vaccine Branch, NCI, NIH, Bethesda, Maryland, USA.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Robert-Guroff
authors.affiliation: Department of Pathology, New York University School of Medicine, New York, New York, USA mirek.gorny@nyumc.org.
authors.forename: Miroslaw K
authors.initials: MK
authors.lastname: Gorny
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000302:isolation & purification; D001665:Binding Sites; D002460:Cell Line; D005434:Flow Cytometry; D015483:HIV Antibodies / Q000276:immunology* / Q000302:isolation & purification; D015699:HIV Envelope Protein gp120 / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D009000:Monocytes / Q000276:immunology*; D010587:Phagocytosis
chemical_list: D000911:Antibodies, Monoclonal; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D007074:Immunoglobulin G; C514793:gp120 protein, Human immunodeficiency virus 1; C514787:gp41 protein, Human immunodeficiency virus 1
keywords: HIV-1; IgG3; anti-CD4bs MAbs; anti-HIV-1 antibodies; anti-V2 MAbs; anti-V3 MAbs; anti-gp41 MAbs; human monoclonal antibodies; phagocytosis