Accumulation of virulence-associated proteins in Campylobacter jejuni Outer Membrane Vesicles at human body temperature.

Campylobacter jejuni is the major cause of bacterial gastroenteritis in humans. In contrast, colonization in avian hosts is asymptomatic. Body temperature differs between human (37 °C) and avian (42 °C) hosts, and bacterial growth in 37 °C is therefore a potential cue for higher virulence properties during human infection. The proteome of the bacteria was previously shown to be altered by temperature. Here we investigated whether temperature has an effect on the C. jejuni outer membrane vesicle (OMV) proteome, as OMVs are considered to be bacterial vehicles for protein delivery and might play a role during infection. OMVs isolated from C. jejuni strain 81-176 grown at 37 °C and 42 °C were analyzed by LC-ESI-MS/MS. 181 proteins were detected in both sample groups, one protein was exclusively present, and three were absent in OMVs from 37 °C. Of the 181 proteins, 59 were differentially expressed; 30 proteins were detected with higher abundance, and 29 proteins with lower abundance at 37 °C. Among the more highly abundant proteins, significantly more proteins were predicted to be associated with virulence. These data show that temperature has an impact on the property of the OMVs, and this might affect the outcome of colonization/infection by C. jejuni in different hosts. SIGNIFICANCE: While C. jejuni is considered as a commensal bacterium in avian hosts, it causes symptomatic infection in humans. As the host body temperature is one differentiating factor, the growth temperature can potentially affect the virulence properties of the bacteria, but also OMVs that are released during growth. By using a proteomic approach, in this study, we observed that the protein content of OMVs isolated from C. jejuni is affected by growth temperature and that more proteins related to virulence are associated with OMVs at 37°C growth temperature. This property indicates that C. jejuni OMVs have a potential role for the outcome of human infection.

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