An HIV-1 Envelope Immunogen with W427S Mutation in CD4 Binding Site Induced More T Follicular Helper Memory Cells and Reduced Non-Specific Antibody Responses

AbstractDespite decades of focused research, the field has yet to develop a prophylactic vaccine. In the RV144 vaccine trial, non-neutralizing antibody responses were identified as a correlate for prevention of HIV acquisition. However, factors that predict the development of such antibodies are not fully elucidated. We sought to define the contribution of circulating T follicular helper (cTfh) cell subsets to the development of non-neutralizing antibodies in HIV-1 clade C infection. Study participants were recruited from an acute HIV-1 clade C infection cohort. Plasma anti-gp41, -gp120, -p24 and -p17 antibodies were screened using a customized multivariate Luminex assay. Phenotypic and functional characterization of cTfh were performed using HLA class II tetramers and intracellular cytokine staining. In this study, we found that acute HIV-1 clade C infection skewed differentiation of functional cTfh subsets towards increased Tfh1 (p=0.02) and Tfh2 (p<0.0001) subsets, with a concomitant decrease in overall Tfh1-17 (that shares both Tfh1 and Tfh17 properties) (p=0.01) and Tfh17 subsets (p<0.0001) compared to HIV negative subjects. Interestingly, the frequencies of Tfh1 during acute infection (5.0-8.0 weeks post-infection) correlated negatively with set point viral load (p=0.03, r=-60) and were predictive of p24-specific plasma IgG titers at one year of infection (p=0.003, r=0.85). Taken together, our results suggest that circulating the Tfh1 subset plays an important role in the development of anti-HIV antibody responses and contributes to HIV suppression during acute HIV-1 infection. These results have implications for vaccine studies aimed at inducing long lasting anti-HIV antibody responses.ImportanceThe HIV epidemic in southern Africa accounts for almost half of the global HIV burden with HIV-1 clade C being the predominant strain. It is therefore important to define immune correlates of clade C HIV control that might have implications for vaccine design in this region. T follicular helper (Tfh) cells are critical for the development of HIV-specific antibody responses and could play a role in viral control. Here we showed that the early induction of circulating Tfh1 cells during acute infection correlated positively with the magnitude of p24-specific IgG and was associated with lower set point viral load. This study highlights a key Tfh cell subset that could limit HIV replication by enhancing antibody generation. This study underscores the importance of circulating Tfh cells in promoting non-neutralizing antibodies during HIV-1 infection.

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Neutralization Properties of Simian Immunodeficiency Viruses Infecting Chimpanzees and Gorillas

mBio ◽

10.1128/mbio.00296-15 ◽

2015 ◽

Vol 6 (2) ◽

Cited By ~ 17

Author(s):

Hannah J. Barbian ◽

Julie M. Decker ◽

Frederic Bibollet-Ruche ◽

Rachel P. Galimidi ◽

Anthony P. West ◽

...

Keyword(s):

T Cells ◽

Binding Site ◽

Pan Troglodytes ◽

Neutralizing Antibodies ◽

Gorilla Gorilla ◽

Protective Capacity ◽

Content Type ◽

Ccr5 Receptor ◽

Cd4 Binding Site ◽

Hiv 1

ABSTRACTBroadly cross-reactive neutralizing antibodies (bNabs) represent powerful tools to combat human immunodeficiency virus type 1 (HIV-1) infection. Here, we examined whether HIV-1-specific bNabs are capable of cross-neutralizing distantly related simian immunodeficiency viruses (SIVs) infecting central (Pan troglodytestroglodytes) (SIVcpzPtt) and eastern (Pan troglodytesschweinfurthii) (SIVcpzPts) chimpanzees (n= 11) as well as western gorillas (Gorilla gorilla gorilla) (SIVgor) (n= 1). We found that bNabs directed against the CD4 binding site (n= 10), peptidoglycans at the base of variable loop 3 (V3) (n= 5), and epitopes at the interface of surface (gp120) and membrane-bound (gp41) envelope glycoproteins (n= 5) failed to neutralize SIVcpz and SIVgor strains. In addition, apex V2-directed bNabs (n= 3) as well as llama-derived (heavy chain only) antibodies (n= 6) recognizing both the CD4 binding site and gp41 epitopes were either completely inactive or neutralized only a fraction of SIVcpzPttstrains. In contrast, one antibody targeting the membrane-proximal external region (MPER) of gp41 (10E8), functional CD4 and CCR5 receptor mimetics (eCD4-Ig, eCD4-Igmim2, CD4-218.3-E51, and CD4-218.3-E51-mim2), as well as mono- and bispecific anti-human CD4 (iMab and LM52) and CCR5 (PRO140, PRO140-10E8) receptor antibodies neutralized >90% of SIVcpz and SIVgor strains with low-nanomolar (0.13 to 8.4 nM) potency. Importantly, the latter antibodies blocked virus entry not only in TZM-bl cells but also in Cf2Th cells expressing chimpanzee CD4 and CCR5 and neutralized SIVcpz in chimpanzee CD4+T cells, with 50% inhibitory concentrations (IC50s) ranging from 3.6 to 40.5 nM. These findings provide new insight into the protective capacity of anti-HIV-1 bNabs and identify candidates for further development to combat SIVcpz infection.IMPORTANCESIVcpz is widespread in wild-living chimpanzees and can cause AIDS-like immunopathology and clinical disease. HIV-1 infection of humans can be controlled by antiretroviral therapy; however, treatment of wild-living African apes with current drug regimens is not feasible. Nonetheless, it may be possible to curb the spread of SIVcpz in select ape communities using vectored immunoprophylaxis and/or therapy. Here, we show that antibodies and antibody-like inhibitors developed to combat HIV-1 infection in humans are capable of neutralizing genetically diverse SIVcpz and SIVgor strains with considerable breadth and potency, including in primary chimpanzee CD4+T cells. These reagents provide an important first step toward translating intervention strategies currently developed to treat and prevent AIDS in humans to SIV-infected apes.

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Broad neutralization by a combination of antibodies recognizing the CD4 binding site and a new conformational epitope on the HIV-1 envelope protein

Journal of Experimental Medicine ◽

10.1084/jem.20120423 ◽

2012 ◽

Vol 209 (8) ◽

pp. 1469-1479 ◽

Cited By ~ 123

Author(s):

Florian Klein ◽

Christian Gaebler ◽

Hugo Mouquet ◽

D. Noah Sather ◽

Clara Lehmann ◽

...

Keyword(s):

Binding Site ◽

Envelope Protein ◽

Neutralizing Antibodies ◽

Conformational Epitope ◽

Broadly Neutralizing Antibodies ◽

Cd4 Binding Site ◽

Capture Method ◽

Anti Hiv ◽

Hiv 1 ◽

Viral Isolates

Two to three years after infection, a fraction of HIV-1–infected individuals develop serologic activity that neutralizes most viral isolates. Broadly neutralizing antibodies that recognize the HIV-1 envelope protein have been isolated from these patients by single-cell sorting and by neutralization screens. Here, we report a new method for anti–HIV-1 antibody isolation based on capturing single B cells that recognize the HIV-1 envelope protein expressed on the surface of transfected cells. Although far less efficient than soluble protein baits, the cell-based capture method identified antibodies that bind to a new broadly neutralizing epitope in the vicinity of the V3 loop and the CD4-induced site (CD4i). The new epitope is expressed on the cell surface form of the HIV-1 spike, but not on soluble forms of the same envelope protein. Moreover, the new antibodies complement the neutralization spectrum of potent broadly neutralizing anti-CD4 binding site (CD4bs) antibodies obtained from the same individual. Thus, combinations of potent broadly neutralizing antibodies with complementary activity can account for the breadth and potency of naturally arising anti–HIV-1 serologic activity. Therefore, vaccines aimed at eliciting anti–HIV-1 serologic breadth and potency should not be limited to single epitopes.

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