Innovative methods of prevention are needed to stop the more than two million new HIV-1
infections annually, particularly in women. Local application of anti-
HIV antibodies has been shown to be effective at preventing
infection in nonhuman primates; however, the concentrations needed are cost prohibitive. Display of
antibodies on a particulate platform will likely prolong effectiveness of these
anti-HIV agents and lower the cost of goods. Here, we demonstrate that the bacterium Caulobacter crescentus and its highly expressed surface-layer (S-layer)
protein can provide this antibody display platform. Caulobacters displaying
protein G, alone or with CD4 codisplay, successfully captured HIV-1-specific
antibodies and demonstrated functional neutralization. Compared to soluble
antibodies, a neutralizing anti-HIV antibody displayed on Caulobacter was as effective or more effective at neutralizing diverse HIV-1 isolates. Moreover, when an antibody reactive with an
epitope induced by CD4 binding (CD4i) was codisplayed with CD4, there was significant enhancement in HIV-1 neutralization. These results suggest that caulobacters displaying anti-
HIV antibodies offer a distinct improvement in the use of
antibodies as
microbicides. Furthermore, these
reagents can specifically evaluate anti-
HIV antibodies in concert with other HIV-1 blocking agents to assess the most suitable tools for conversion to scFvs, allowing for direct display within the S-layer
protein and further reducing cost of goods. In summary, C. crescentus, which can be easily produced and chemically stabilized at low cost, is well suited for engineering as an effective platform, offering an inexpensive way to produce and deliver HIV-1-specific
microbicides.