Concurrent Exposure of Neutralizing and Non-neutralizing Epitopes on a Single HIV-1 Envelope Structure
Concurrent Exposure of Neutralizing and Non-neutralizing Epitopes on a Single HIV-1 Envelope Structure
The trimeric envelope spikes on the HIV-1 virus surface initiate infection and comprise key targets for antiviral humoral responses. Circulating virions variably present intact envelope spikes, which react with neutralizing antibodies; and altered envelope structures, which bind non-neutralizing antibodies. Once bound, either type of antibody can enable humoral effector mechanisms with the potential to control HIV-1 infection in vivo. However, it is not clear how the presentation of neutralizing vs. non-neutralizing epitopes defines distinct virus populations and/or envelope structures on single particles. Here we used single-virion fluorescence correlation spectroscopy (FCS), fluorescence resonance energy transfer (FRET), and two-color coincidence FCS approaches to examine whether neutralizing and non-neutralizing antibodies are presented by the same envelope structure. Given the spatial requirements for donor-acceptor energy transfer (≤10 nm), FRET signals generated by paired neutralizing and non-neutralizing fluorescent Fabs should occur via proximal binding to the same target antigen. Fluorescent-labeled Fabs of the neutralizing anti-gp120 antibodies 2G12 and b12 were combined with Fabs of the non-neutralizing anti-gp41 antibody F240, previously thought to mainly bind gp41 "stumps." We find that both 2G12-F240 and/or b12-F240 Fab combinations generate FRET signals on multiple types of virions in solution. FRET efficiencies position the neutralizing and non-neutralizing epitopes between 7.1 and 7.8 nm apart; potentially fitting within the spatial dimensions of a single trimer-derived structure. Further, the frequency of FRET detection suggests that at least one of such structures occurs on the majority of particles in a virus population. Thus, there is frequent, overlapping presentation of non-neutralizing and neutralizing epitope on freely circulating HIV-1 surfaces. Such information provides a broader perspective of how anti-HIV humoral immunity interfaces with circulating virions.
single HIV-1 virion, epitope exposure, Immunology, Virion, Antibodies, Monoclonal, HIV Infections, RC581-607, HIV Antibodies, HIV Envelope Protein gp120, Antibodies, Neutralizing, HIV Envelope Protein gp41, Cell Line, Epitopes, two-color coincidence fluorescence correlation spectroscopy (FCS), HEK293 Cells, neutralizing and non-neutralizing epitopes, HIV Seropositivity, HIV-1, Humans, FRET-FCS, Immunologic diseases. Allergy
single HIV-1 virion, epitope exposure, Immunology, Virion, Antibodies, Monoclonal, HIV Infections, RC581-607, HIV Antibodies, HIV Envelope Protein gp120, Antibodies, Neutralizing, HIV Envelope Protein gp41, Cell Line, Epitopes, two-color coincidence fluorescence correlation spectroscopy (FCS), HEK293 Cells, neutralizing and non-neutralizing epitopes, HIV Seropositivity, HIV-1, Humans, FRET-FCS, Immunologic diseases. Allergy
3 Research products, page 1 of 1
- 2008IsRelatedTo
- 2006IsRelatedTo
- 2018IsRelatedTo
citations This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).11 popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.Top 10% influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).Average impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.Average
