453. Development of GBV-C E2 Monoclonal Antibodies that Precipitate HIV-1 Particles and Neutralize Diverse HIV-1 Isolates
Session: Poster Abstract Session: HIV Pathogenesis and Immunity
Friday, October 21, 2011
Room: Poster Hall B1
Background: Persistent GB virus C (GBV-C) viremia is associated with prolonged survival in HIV-infected cohorts. When GBV-C viremia is cleared, antibody against the E2 protein is detected. In HIV-infected people without GBV-C viremia, the presence of E2 antibody is associated with prolonged survival. Several monoclonal E2 antibodies (MAbs) were previously available, and polyclonal E2 antibodies were shown to neutralize HIV infectivity in vitro.  Unfortunately, no GBV-C E2 MAbs remain available and there is no commercial anti-E2 assay sold in the U.S. This study was designed to generate GBV-C E2 MAbs.

Methods: Murine MAbs were generated against a 17 amino acid E2 peptide using standard methods. Cell lines producing E2 antibodies were cloned and adapted to serum free media.  MAbs were examined for E2 reactivity by EIA and western blot. and E2 MAb interactions with HIV were determined by immune precipitation (IP) and HIV neutralization using replication competent and single-cycle methods previously described (J.Immunol, 185:4496-4505, 2010).

Results: Two GBV-C E2 MAbs were cloned and characterized.  Both were IgG1k and specifically reacted with the E2 peptide and recombinant E2 protein. The MAbs were able to capture E2 to the solid phase and detect E2 by immunoblot.  The antibodies were useful in a MAb capture assay for detecting human anti-E2 antibodies, documenting seroconversion during viremia clearance in sera characterized by the previously available commercial Roche E2 antibody test. MAb 1C4-10 precipitated HIV-1 particles and neutralized six HIV-1 isolates representing 3 Clades.

Conclusion: Two GBV-C E2 MAbs were generated that react with recombinant E2 protein.  One of these has been further characterized and it interacts with HIV by IP and neutralization assays. The MAbs do not neutralize HIV as well as the polyclonal anti-E2 antibodies generated previously, suggesting that additional GBV-C epitopes are required to potently inhibit HIV.  Further studies to evaluate the MAbs for efficacy in animal models of HIV-1 infection, and to identify additional epitopes involved in the cross-neutralization effects with HIV are underway. In addition, the MAbs will facilitate detection of human anti-E2 antibodies in clinical samples by use in MAb-capture EIAs.


Subject Category: H. HIV/AIDS and other retroviruses

James McLinden, PhD, Jinhua Xiang, MD, Thomas M Kaufman, B.S., Qing Chang, B.S. and Jack T. Stapleton, MD, University of Iowa and Iowa City VAMC, Iowa City, IA

Disclosures:

J. McLinden, None

J. Xiang, None

T. M. Kaufman, None

Q. Chang, None

J. T. Stapleton, None

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