Overexpression of the Bam Complex Improves the Production of MOMP in the Outer Membrane.

A licensed vaccine is not yet available. Recombinant major outer membrane protein (-MOMP), the most abundant constituent of the chlamydial outer membrane complex, is considered the most attractive candidate for subunit-based vaccine formulations. Unfortunately, -MOMP is difficult to express in its native structure in the outer membrane (OM). Here, by co-expression of the Bam complex, we improved the expression and localization of recombinant -MOMP in the OM. Under these conditions, recombinant -MOMP appeared to assemble into a β-barrel conformation and express domains at the cell surface indicative of correct folding. The data indicate that limited availability of the Bam complex can be a bottleneck for the production of heterologous OM vaccine antigens, information that is also relevant for strategies aimed at producing recombinant OMV-based vaccines.