# Outer Membrane Vesicles from Caulobacter crescentus: A Platform for Recombinant Antigen Presentation

## TL;DR

This study shows that OMVs from the nonpathogenic bacterium Caulobacter crescentus are safe, effective, and can be used to deliver vaccines.

## Contribution

The study introduces a novel, safe, and scalable OMV platform for vaccine development using Caulobacter crescentus.

## Key findings

- Caulobacter crescentus OMVs are produced in high yields and induce lower inflammation compared to E. coli OMVs.
- C. crescentus OMVs can be loaded with recombinant proteins and stimulate antibody production with adjuvant effects.
- High-dose C. crescentus OMVs caused only minor pain in mice, indicating their safety.

## Abstract

Bacterial outer membrane vesicles (OMVs) are an emerging
and attractive
technology for the generation of vaccines. Their properties as natural
adjuvants, size, acellularity, and comparative cost of production
favor their use as vaccines. Two major caveats for the use of OMVs
as vaccines are their biological safety, since OMVs can induce a severe
and even fatal inflammatory response and that they are naturally produced
in low amounts. In this study, we show that a strategy to induce the
production of OMVs applied to the nonpathogenic bacterium Caulobacter crescentus results in a strain with good
OMV yields. In comparison with the OMVs derived from Escherichia coli K-12, the OMVs from C. crescentus induce a lower inflammatory response
in an in vivo murine model of acute inflammation
and in a human cell assay. Also, only minor signs of pain in mice
were observed even at high doses. The C. crescentus OMVs can be efficiently loaded with a recombinant protein and induce
antibody production against it with an adjuvant effect, indicating
that these OMVs are viable vehicles for the presentation of recombinant
antigens. These results support the use of the OMVs obtained from C. crescentus as a safe and effective platform for
the development of low-cost vaccines.