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Broad-spectrum inhibition of HIV-1 by a monoclonal antibody directed against a gp120-induced epitope of CD4.

Burastero SE, Frigerio B, Lopalco L, Sironi F, Breda D, Longhi R, Scarlatti G, Canevari S, Figini M, Lusso P - PLoS ONE (2011)

Bottom Line: In particular, a CD4-specific MAb designated DB81 (IgG1Κ) was found to preferentially bind to a complex-enhanced epitope on the D2 domain of human CD4.Functionally, MAb DB81 displayed broad HIV-1-inhibitory activity, but it did not exert suppressive effects on T-cell activation in vitro.Due to its broad-spectrum anti-HIV-1 activity and lack of immunosuppressive effects, a humanized derivative of MAb DB81 could provide a useful complement to current preventive or therapeutic strategies against HIV-1.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy. s.burastero@hsr.it

ABSTRACT
To penetrate susceptible cells, HIV-1 sequentially interacts with two highly conserved cellular receptors, CD4 and a chemokine receptor like CCR5 or CXCR4. Monoclonal antibodies (MAbs) directed against such receptors are currently under clinical investigation as potential preventive or therapeutic agents. We immunized Balb/c mice with molecular complexes of the native, trimeric HIV-1 envelope (Env) bound to a soluble form of the human CD4 receptor. Sera from immunized mice were found to contain gp120-CD4 complex-enhanced antibodies and showed broad-spectrum HIV-1-inhibitory activity. A proportion of MAbs derived from these mice preferentially recognized complex-enhanced epitopes. In particular, a CD4-specific MAb designated DB81 (IgG1Κ) was found to preferentially bind to a complex-enhanced epitope on the D2 domain of human CD4. MAb DB81 also recognized chimpanzee CD4, but not baboon or macaque CD4, which exhibit sequence divergence in the D2 domain. Functionally, MAb DB81 displayed broad HIV-1-inhibitory activity, but it did not exert suppressive effects on T-cell activation in vitro. The variable regions of the heavy and light chains of MAb DB81 were sequenced. Due to its broad-spectrum anti-HIV-1 activity and lack of immunosuppressive effects, a humanized derivative of MAb DB81 could provide a useful complement to current preventive or therapeutic strategies against HIV-1.

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BIACORE® sensogram of interactions between MAb DB81 (bound to the chip) and 2D-CD4 (light blue), gp120 IIIB (violet), CD4-gp120 IIIB complex (green) or the FLSC chiimeric protein (dark blue).
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pone-0022081-g006: BIACORE® sensogram of interactions between MAb DB81 (bound to the chip) and 2D-CD4 (light blue), gp120 IIIB (violet), CD4-gp120 IIIB complex (green) or the FLSC chiimeric protein (dark blue).

Mentions: By surface plasmon resonance, we measured the specificity and kinetic rates of binding and dissociation of MAb DB81 to either sCD4, gp120, the sCD4-gp120 complex, or a previously described chimeric single-chain molecule, designated FLSC, encompassing full-length HIV-1Ba-L gp120 and the D1D2 domains of CD4 joined by a 20-amino-acid linker. Figure 6 depicts the sensogram of these interactions, which were measured with MAb DB81 bound to the solid-phase chip. Binding of MAb DB81 to 2D-CD4 was clearly increased when CD4 was complexed with gp120 from isolate IIIB (45 versus 16 resonance units), confirming the results obtained by ELISA (Figure S2). When gp120 from isolate Ba-L was used, a lower increase was observed (not shown). The chimeric FLSC peptide was also recognized but showed a much slower slope of association with MAb DB81 compared to the CD4-gp120 complex. In contrast, no binding was measured with gp120 alone either from isolate IIIB (Figure 5) or from isolate Ba-L (not shown).


Broad-spectrum inhibition of HIV-1 by a monoclonal antibody directed against a gp120-induced epitope of CD4.

Burastero SE, Frigerio B, Lopalco L, Sironi F, Breda D, Longhi R, Scarlatti G, Canevari S, Figini M, Lusso P - PLoS ONE (2011)

BIACORE® sensogram of interactions between MAb DB81 (bound to the chip) and 2D-CD4 (light blue), gp120 IIIB (violet), CD4-gp120 IIIB complex (green) or the FLSC chiimeric protein (dark blue).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3139607&req=5

pone-0022081-g006: BIACORE® sensogram of interactions between MAb DB81 (bound to the chip) and 2D-CD4 (light blue), gp120 IIIB (violet), CD4-gp120 IIIB complex (green) or the FLSC chiimeric protein (dark blue).
Mentions: By surface plasmon resonance, we measured the specificity and kinetic rates of binding and dissociation of MAb DB81 to either sCD4, gp120, the sCD4-gp120 complex, or a previously described chimeric single-chain molecule, designated FLSC, encompassing full-length HIV-1Ba-L gp120 and the D1D2 domains of CD4 joined by a 20-amino-acid linker. Figure 6 depicts the sensogram of these interactions, which were measured with MAb DB81 bound to the solid-phase chip. Binding of MAb DB81 to 2D-CD4 was clearly increased when CD4 was complexed with gp120 from isolate IIIB (45 versus 16 resonance units), confirming the results obtained by ELISA (Figure S2). When gp120 from isolate Ba-L was used, a lower increase was observed (not shown). The chimeric FLSC peptide was also recognized but showed a much slower slope of association with MAb DB81 compared to the CD4-gp120 complex. In contrast, no binding was measured with gp120 alone either from isolate IIIB (Figure 5) or from isolate Ba-L (not shown).

Bottom Line: In particular, a CD4-specific MAb designated DB81 (IgG1Κ) was found to preferentially bind to a complex-enhanced epitope on the D2 domain of human CD4.Functionally, MAb DB81 displayed broad HIV-1-inhibitory activity, but it did not exert suppressive effects on T-cell activation in vitro.Due to its broad-spectrum anti-HIV-1 activity and lack of immunosuppressive effects, a humanized derivative of MAb DB81 could provide a useful complement to current preventive or therapeutic strategies against HIV-1.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy. s.burastero@hsr.it

ABSTRACT
To penetrate susceptible cells, HIV-1 sequentially interacts with two highly conserved cellular receptors, CD4 and a chemokine receptor like CCR5 or CXCR4. Monoclonal antibodies (MAbs) directed against such receptors are currently under clinical investigation as potential preventive or therapeutic agents. We immunized Balb/c mice with molecular complexes of the native, trimeric HIV-1 envelope (Env) bound to a soluble form of the human CD4 receptor. Sera from immunized mice were found to contain gp120-CD4 complex-enhanced antibodies and showed broad-spectrum HIV-1-inhibitory activity. A proportion of MAbs derived from these mice preferentially recognized complex-enhanced epitopes. In particular, a CD4-specific MAb designated DB81 (IgG1Κ) was found to preferentially bind to a complex-enhanced epitope on the D2 domain of human CD4. MAb DB81 also recognized chimpanzee CD4, but not baboon or macaque CD4, which exhibit sequence divergence in the D2 domain. Functionally, MAb DB81 displayed broad HIV-1-inhibitory activity, but it did not exert suppressive effects on T-cell activation in vitro. The variable regions of the heavy and light chains of MAb DB81 were sequenced. Due to its broad-spectrum anti-HIV-1 activity and lack of immunosuppressive effects, a humanized derivative of MAb DB81 could provide a useful complement to current preventive or therapeutic strategies against HIV-1.

Show MeSH