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. 2014 Sep 26;3(9):e24.
doi: 10.1038/cti.2014.22. eCollection 2014 Sep.

Designer antigens for elicitation of broadly neutralizing antibodies against HIV

Affiliations

Designer antigens for elicitation of broadly neutralizing antibodies against HIV

Tuckweng Kok et al. Clin Transl Immunology. .

Abstract

Broadly neutralizing antibodies (bNAbs) are a consistent protective immune correlate in human immunodeficiency virus (HIV) patients as well as in passive immunotherapy studies. The inability to elicit bNAbs is the core reason underlining the repeated failures in traditional HIV vaccine research. Rare monoclonal bNAbs against HIV, however, have been produced. The significance of producing and studying more monoclonal bNAbs against HIV is underlined by its capability of defining critical epitopes for antigen designs aimed at the development of a serum-neutralizing HIV vaccine. In this regard, traditional antigen preparations have failed. There is a need to clearly advocate the concept, and systematic study, of more sophisticated 'designer antigens' (DAGs), which carry epitopes that can lead to the elicitation of bNAbs. Using an extremely efficient cell-to-cell HIV infection model for the preparation of HIV prefusion intermediates, we have investigated a novel and systematic approach to produce (not screen for) potential bNAbs against HIV. We have established the concept and the experimental system for producing formaldehyde-fixed HIV DAGs that carry temperature-arrested prefusion intermediates. These prefusion intermediates are structures on the cell surface after viral attachment and receptor engagement but before fully functional viral entry. Using defined HIV prefusion DAGs, we have produced monoclonal antibodies (mAbs) specific to novel epitopes on HIV prefusion intermediates. These mAbs do not react with the static/native surface HIV or cellular antigens, but react with the DAGs. This is a paradigm shift from the current mainstream approach of screening elite patients' bNAbs.

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Figures

Figure 1
Figure 1
Cell-to-cell HIV infection temperature-arrested at 23 °C.
Figure 2
Figure 2
Temperature-arrested HIV infection followed by incubation at 37 °C. Functional viral entry was monitored by reverse transcription, as judged by estimation of HIV episomal DNA copies. Error bars represent ranges of duplicate infections. *Statistical significance (P<0.05, Student's t-test) between time point samples denoted at the ends of each horizontal line. Grey columns: Cell processing time. Black columns: co-culture mix temperature arrested for 3 h. (A. Davis and P. Li (unpublished))
Figure 3
Figure 3
Absorbed (grey columns) and depleted guinea pig sera (black columns) at 1:10 dilution were tested for their ability to neutralize the infectivity of T-cell tropic HIV-HXB2 (a, b) and macrophage tropic HIV-Bal (c, d) on TZM-b1 cells. Columns with error bars represent the average if HIV-infected cell numbers from triplicate 48th post infection.
Figure 4
Figure 4
Immunofluorescence staining with mAb 8B3 (HIV native/static antigen) and a pre-fusion DAG19-specific mAb 5E1 against DAG19, H3B and Hut78. (a) IF: mAb 8B3 (static/native HIV specific). (b) IF: mAb 5E1 (novel DAG specific).
Figure 5
Figure 5
(a) Confocal trifluorophore IF staining of DAG19 and H3B cells with 5E1 mAb, patient's HIV serum and anti-human CD4. (b) Confocal trifluorophore IF staining of DAG19 and H3B cells with 8B3 mAb, patient's HIV serum and anti-human CD4.

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