Incorporating the Cluster A and V1V2 Targets into a Minimal Structural Unit of the HIV-1 Envelope to Elicit a Cross-Clade Response with Potent Fc-Effector Functions

Abstract

The generation of a potent vaccine for the prevention and/or control of HIV-1 has been unsuccessful to date, despite decades of research. Existing evidence from both infected individuals and clinical trials support a role for non-neutralizing or weakly neutralizing antibodies with potent Fc-effector functions in the prevention and control of HIV-1 infection. Vaccination strategies that induce such antibodies have proven partially successful in preventing HIV-1 infection. This is largely thought to be due to the polyclonal response that is induced in a vaccine setting, as opposed to the infusion of a single therapeutic antibody, which is capable of diverse Fc-effector functions and targets multiple but highly conserved epitopes. Here, we build on the success of our inner domain antigen, ID2, which incorporates conformational CD4-inducible (CD4i) epitopes of constant region 1 and 2 (C1C2 or Cluster A), in the absence of neutralizing antibody epitopes, into a minimal structural unit of gp120. ID2 has been shown to induce Cluster A-specific antibodies in a BALB/c mouse model with Fc-effector functions against CD4i targets. In order to generate an immunogen that incorporates both epitope targets implicated in the protective Fc-effector functions of antibodies from the only partially successful human vaccine trial, RV144, we incorporated the V1V2 domain into our ID2 antigen generating ID2-V1V2, which we used to immunize in combination with ID2. Immunized BALB/c mice generated both Cluster A- and V1V2-specific antibodies, which synergized to significantly improve the Fc-mediated effector functions compared to mice immunized with ID2 alone. The sera were able to mediate both antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). We therefore conclude that ID2-V1V2 + ID2 represents a promising vaccine immunogen candidate for the induction of antibodies with optimal Fc-mediated effector functions against HIV-1.

Characterization of antibody‐dependent cellular phagocytosis in patients infected with hepatitis C virus with different clinical outcomes

“…Moreover, we found that patients with anti‐E2 antibodies targeting Domain B and D that are known to be associated with effective neutralization 55–59 are also the ones that had antibodies strongly associated with high ADCP, further supporting the notion that there may be overlapping protective functions via dually acting antibodies. This is consistent with reports on HIV in which overlapping ADCP and neutralizing functions were observed, 24 and antibodies that maintain broad neutralization function against several HIV variants also possessed potent Fc receptor‐dependent effector functions including ADCP 14,17,24,25 . However, future studies aimed at defining the significance of ADCP in HCV, namely its role in viral clearance and clinical outcomes using live viruses, is warranted.…”

“…This is consistent with reports on HIV in which overlapping ADCP and neutralizing functions were observed, 24 and antibodies that maintain broad neutralization function against several HIV variants also possessed potent Fc receptor‐dependent effector functions including ADCP. 14 , 17 , 24 , 25 However, future studies aimed at defining the significance of ADCP in HCV, namely its role in viral clearance and clinical outcomes using live viruses, is warranted.…”

“… 14 , 15 , 16 , 17 Among these effector functions, ADCP has been shown to correlate with immune protection against several RNA viruses, including HIV, 18 ebola, 19 dengue, 20 and influenza. 21 Importantly, in patients with HIV infection, antibodies that neutralize broader HIV variants 22 , 23 also possess potent Fc receptor‐dependent effector functions, including ADCP, 24 , 25 and antibodies that maintain broadly neutralizing function at later stages of the disease showed an early and stronger Fc‐receptor‐dependent effector function. 14 , 17 , 26 , 27 A positive relationship between neutralization and ADCP was also observed in patients with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) 15 , 28 and influenza virus 29 infections.…”

Engineered ACE2-Fc counters murine lethal SARS-CoV-2 infection through direct neutralization and Fc-effector activities

“…The binding capacity of the purified ACE2-Fcs to various viral antigens was measured by indirect ELISA, as described in ( 61 ). Ninety-six–well Nunc Maxisorp plates (Sigma-Aldrich) were coated with SARS-CoV-2 RBD wt (residues 319 to 541) (50 ng), RBD B.1.351 (50 ng), S-2P (75 ng), S B.1.1.7 (75 ng), S B.1.351 (75 ng), S P.1 (75 ng), S B.1.526 (75 ng), and SARS-CoV-1 RBD (50 ng) per well in tris-buffered saline (TBS) at 4°C overnight.…”

Plasmatic HIV-1 soluble gp120 is associated with immune dysfunction and inflammation in ART-treated individuals with undetectable viremia

“…We have previously reported that the release of sgp120 from infected cells sensitizes uninfected bystander CD4 + T cells to ADCC mediated by HIV+ plasma in vitro, whether this happens in PLWH remains unclear [15][16][17]. We therefore measured the levels of anti-cluster A antibodies using an engineered stabilized gp120 inner domain protein (ID2) only exposing the cluster A region [24,31]. Figure 2 and Table S1, present the associations between anti-cluster A antibodies and absolute CD4 cell counts or the CD4:CD8 ratio (Figure S1).…”