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Association of VH4-59 Antibody Variable Gene Usage with Recognition of an Immunodominant Epitope on the HIV-1 Gag Protein.

Chukwuma VU, Hicar MD, Chen X, Nicholas KJ, Joyner A, Kalams SA, Landucci G, Forthal DN, Spearman PW, Crowe JE - PLoS ONE (2015)

Bottom Line: We found no evidence that mAb 3E4 exhibited any function in laboratory studies aimed at elucidating the immunologic activity, including assays for neutralization, Ab-dependent cell-mediated virus inhibition, or enhanced T cell reactivity caused by Gag-3E4 complexes.The findings suggest this immunodominant epitope in Gag protein, which is associated with VH4-59 germline gene usage, may induce a high level of B cells that encode binding but non-functional antibodies that occupy significant repertoire space following HIV infection.The studies define an additional specific molecular mechanism in the immune distraction activity of the HIV virion.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, Tennessee, United States of America.

ABSTRACT
The human antibody response against HIV-1 infection recognizes diverse antigenic subunits of the virion, and includes a high level of antibodies to the Gag protein. We report here the isolation and characterization of a subset of Gag-specific human monoclonal antibodies (mAbs) that were prevalent in the antibody repertoire of an HIV-infected individual. Several lineages of Gag-specifc mAbs were encoded by a single antibody heavy chain variable region, VH4-59, and a representative antibody from this group designated mAb 3E4 recognized a linear epitope on the globular head of the p17 subunit of Gag. We found no evidence that mAb 3E4 exhibited any function in laboratory studies aimed at elucidating the immunologic activity, including assays for neutralization, Ab-dependent cell-mediated virus inhibition, or enhanced T cell reactivity caused by Gag-3E4 complexes. The findings suggest this immunodominant epitope in Gag protein, which is associated with VH4-59 germline gene usage, may induce a high level of B cells that encode binding but non-functional antibodies that occupy significant repertoire space following HIV infection. The studies define an additional specific molecular mechanism in the immune distraction activity of the HIV virion.

No MeSH data available.


Related in: MedlinePlus

Activation of T cells by Gag in the presence or absence of p17-specific mAb 3E4.(A) Activation of Gag-specific T cells from four subjects in the presence or absence of mAb 3E4. (B) Activation of Gag-specific T cells from one subject, tested in triplicate.
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pone.0133509.g006: Activation of T cells by Gag in the presence or absence of p17-specific mAb 3E4.(A) Activation of Gag-specific T cells from four subjects in the presence or absence of mAb 3E4. (B) Activation of Gag-specific T cells from one subject, tested in triplicate.

Mentions: We next sought to determine if Gag served simply as an antigenic target for these antibodies or, alternatively, if these antibodies mediated some measurable in vitro functional activity that might contribute to the functional immune response in this subject. MAb 3E4 did not exhibit any detectable neutralizing activity against the clade B HIV-1 isolate SF162, and we found no evidence of activity in ADCVI assays (data not shown). We also tested whether incubation of mAb 3E4 with Gag protein would enhance (or abrogate) stimulation of Gag-specific T cells in PBMCs from treatment-naïve HIV-infected donors with known Gag responses. There was no detectable enhancement or inhibition of Gag-specific T cell activation in the presence of mAb 3E4 in any of the individuals as measured by changes in CD69 and CD25 expression (Fig 6). Additionally, cytokine assays measuring IFN-γ, IL-2, and TNF-α and additional activation markers including CD86 and CD40L were performed on PBMC from the subject with the most robust Gag responses. In these assays, incubation with Gag protein and serial dilutions of mAb 3E4 did not yield any differences in Gag-specific responses (data not shown).


Association of VH4-59 Antibody Variable Gene Usage with Recognition of an Immunodominant Epitope on the HIV-1 Gag Protein.

Chukwuma VU, Hicar MD, Chen X, Nicholas KJ, Joyner A, Kalams SA, Landucci G, Forthal DN, Spearman PW, Crowe JE - PLoS ONE (2015)

Activation of T cells by Gag in the presence or absence of p17-specific mAb 3E4.(A) Activation of Gag-specific T cells from four subjects in the presence or absence of mAb 3E4. (B) Activation of Gag-specific T cells from one subject, tested in triplicate.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520566&req=5

pone.0133509.g006: Activation of T cells by Gag in the presence or absence of p17-specific mAb 3E4.(A) Activation of Gag-specific T cells from four subjects in the presence or absence of mAb 3E4. (B) Activation of Gag-specific T cells from one subject, tested in triplicate.
Mentions: We next sought to determine if Gag served simply as an antigenic target for these antibodies or, alternatively, if these antibodies mediated some measurable in vitro functional activity that might contribute to the functional immune response in this subject. MAb 3E4 did not exhibit any detectable neutralizing activity against the clade B HIV-1 isolate SF162, and we found no evidence of activity in ADCVI assays (data not shown). We also tested whether incubation of mAb 3E4 with Gag protein would enhance (or abrogate) stimulation of Gag-specific T cells in PBMCs from treatment-naïve HIV-infected donors with known Gag responses. There was no detectable enhancement or inhibition of Gag-specific T cell activation in the presence of mAb 3E4 in any of the individuals as measured by changes in CD69 and CD25 expression (Fig 6). Additionally, cytokine assays measuring IFN-γ, IL-2, and TNF-α and additional activation markers including CD86 and CD40L were performed on PBMC from the subject with the most robust Gag responses. In these assays, incubation with Gag protein and serial dilutions of mAb 3E4 did not yield any differences in Gag-specific responses (data not shown).

Bottom Line: We found no evidence that mAb 3E4 exhibited any function in laboratory studies aimed at elucidating the immunologic activity, including assays for neutralization, Ab-dependent cell-mediated virus inhibition, or enhanced T cell reactivity caused by Gag-3E4 complexes.The findings suggest this immunodominant epitope in Gag protein, which is associated with VH4-59 germline gene usage, may induce a high level of B cells that encode binding but non-functional antibodies that occupy significant repertoire space following HIV infection.The studies define an additional specific molecular mechanism in the immune distraction activity of the HIV virion.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, Tennessee, United States of America.

ABSTRACT
The human antibody response against HIV-1 infection recognizes diverse antigenic subunits of the virion, and includes a high level of antibodies to the Gag protein. We report here the isolation and characterization of a subset of Gag-specific human monoclonal antibodies (mAbs) that were prevalent in the antibody repertoire of an HIV-infected individual. Several lineages of Gag-specifc mAbs were encoded by a single antibody heavy chain variable region, VH4-59, and a representative antibody from this group designated mAb 3E4 recognized a linear epitope on the globular head of the p17 subunit of Gag. We found no evidence that mAb 3E4 exhibited any function in laboratory studies aimed at elucidating the immunologic activity, including assays for neutralization, Ab-dependent cell-mediated virus inhibition, or enhanced T cell reactivity caused by Gag-3E4 complexes. The findings suggest this immunodominant epitope in Gag protein, which is associated with VH4-59 germline gene usage, may induce a high level of B cells that encode binding but non-functional antibodies that occupy significant repertoire space following HIV infection. The studies define an additional specific molecular mechanism in the immune distraction activity of the HIV virion.

No MeSH data available.


Related in: MedlinePlus