Enhanced Neutralization of HIV by Antibodies Displayed on the S-Layer of Caulobacter crescentus

Abstract

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.

Bioadsorption of Rare Earth Elements through Cell Surface Display of Lanthanide Binding Tags

“…The bacterium Caulobacter crescentus is an ideal biological system for metal adsorption due to its encapsulation by a S-layer that is highly amenable to bioengineering . The S-layer protein, RsaA, is abundant with approximately 40 000 subunits per cell, , providing a convenient anchor for high-density cell surface display of foreign proteins and peptides. − In this study, we used a bioengineering approach to display LBTs in high copy number on the S-layer of C. crescentus . Our results showed that the LBT-displayed cells could effectively extract REEs from REE-containing solutions.…”

Development of an HIV-1 Microbicide Based on Caulobacter crescentus: Blocking Infection by High-Density Display of Virus Entry Inhibitors

“…Using the non-pathogenic, freshwater bacterium Caulobacter crescentus [9], [10] we have generated a system to insert foreign protein sequences into the surface (S)-layer protein RsaA of C. crescentus [11]–[15]. Native expression levels of RsaA exceeds 30% of total cell protein and the insertion of foreign proteins often has minimal impact on expression and assembly of RsaA into the ordered S-layer structure [16].…”

Engineered probiotic Escherichia coli can eliminate and prevent Pseudomonas aeruginosa gut infection in animal models

“…Further, probiotics can prevent colonization of the human intestinal tract by pathogenic E. coli 5 6 . A few studies have exploited engineered probiotics for therapeutic purposes, including site-specific expression and delivery of biomolecules that target bacterial and viral infections 7 8 9 10 11 or as adjuvants to pharmacological therapy 12 . However, the majority of such studies have been validated in vitro , and only a few have been evaluated for therapeutic efficiency using in vivo models 13 14 15 16 .…”