Limits...
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.

Show MeSH
Inhibition of HIV-1 Env-mediated fusion by sera from mice immunized with CD4-complexed HIV-1 Env.era from mice immunized with autologous NIH 3T3 cells expressing HIV-1 Ba-L Env in complex or not with soluble CD4 were tested for inhibition of HIV-1 Env-mediated fusion using PM-1 (A) of Sup-T1 (B) cells chronically infected with HIV-1 Ba-L or IIIB, respectively, as effector cells. NIH 3T3 cells expressing human CD4 and the appropriate coreceptor (CXCR4 or CCR5) were used as target cells. Sera from 4 immunized mice were pooled. Fusion inhibition is expressed as percent of the positive control, i.e., the amount of fusion measured when the fusion partners were reacted in the presence of pre-immune sera.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3139607&req=5

pone-0022081-g002: Inhibition of HIV-1 Env-mediated fusion by sera from mice immunized with CD4-complexed HIV-1 Env.era from mice immunized with autologous NIH 3T3 cells expressing HIV-1 Ba-L Env in complex or not with soluble CD4 were tested for inhibition of HIV-1 Env-mediated fusion using PM-1 (A) of Sup-T1 (B) cells chronically infected with HIV-1 Ba-L or IIIB, respectively, as effector cells. NIH 3T3 cells expressing human CD4 and the appropriate coreceptor (CXCR4 or CCR5) were used as target cells. Sera from 4 immunized mice were pooled. Fusion inhibition is expressed as percent of the positive control, i.e., the amount of fusion measured when the fusion partners were reacted in the presence of pre-immune sera.

Mentions: Pooled sera derived from mice injected with autologous NIH-3T3 cells expressing the HIV-1 Ba-L Env in complex or not with 2D-CD4 were tested for inhibition of HIV-1 Env-mediated fusion using PM-1 of Sup-T1 cells chronically infected with HIV-1 Ba-L or IIIB, respectively, as effector cells. As shown in Figure 2, sera obtained from mice immunized with sCD4-complexed Env displayed in both cases a stronger fusion-inhibitory activity compared to those obtained from mice immunized with uncomplexed Env. The spectrum of binding and neutralizing activity of sera derived from mice immunized with sCD4-complexed Env will have to be established with systematic studies on a wide range of genetically diverse HIV-1 strains.


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)

Inhibition of HIV-1 Env-mediated fusion by sera from mice immunized with CD4-complexed HIV-1 Env.era from mice immunized with autologous NIH 3T3 cells expressing HIV-1 Ba-L Env in complex or not with soluble CD4 were tested for inhibition of HIV-1 Env-mediated fusion using PM-1 (A) of Sup-T1 (B) cells chronically infected with HIV-1 Ba-L or IIIB, respectively, as effector cells. NIH 3T3 cells expressing human CD4 and the appropriate coreceptor (CXCR4 or CCR5) were used as target cells. Sera from 4 immunized mice were pooled. Fusion inhibition is expressed as percent of the positive control, i.e., the amount of fusion measured when the fusion partners were reacted in the presence of pre-immune sera.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0022081-g002: Inhibition of HIV-1 Env-mediated fusion by sera from mice immunized with CD4-complexed HIV-1 Env.era from mice immunized with autologous NIH 3T3 cells expressing HIV-1 Ba-L Env in complex or not with soluble CD4 were tested for inhibition of HIV-1 Env-mediated fusion using PM-1 (A) of Sup-T1 (B) cells chronically infected with HIV-1 Ba-L or IIIB, respectively, as effector cells. NIH 3T3 cells expressing human CD4 and the appropriate coreceptor (CXCR4 or CCR5) were used as target cells. Sera from 4 immunized mice were pooled. Fusion inhibition is expressed as percent of the positive control, i.e., the amount of fusion measured when the fusion partners were reacted in the presence of pre-immune sera.
Mentions: Pooled sera derived from mice injected with autologous NIH-3T3 cells expressing the HIV-1 Ba-L Env in complex or not with 2D-CD4 were tested for inhibition of HIV-1 Env-mediated fusion using PM-1 of Sup-T1 cells chronically infected with HIV-1 Ba-L or IIIB, respectively, as effector cells. As shown in Figure 2, sera obtained from mice immunized with sCD4-complexed Env displayed in both cases a stronger fusion-inhibitory activity compared to those obtained from mice immunized with uncomplexed Env. The spectrum of binding and neutralizing activity of sera derived from mice immunized with sCD4-complexed Env will have to be established with systematic studies on a wide range of genetically diverse HIV-1 strains.

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