Abstract
Serial passage is a problem among many bacterial species, especially those where strains have been stored (banked) for several decades. Prior to banking with an organization such as ATCC, many bacterial strains were passaged for many years, so the characteristics of each strain may be extremely different. This is in addition to any differences in the original host environment. For Burkholderia pseudomallei, the number of serial passages should be carefully defined for each experiment because it undergoes adaptation during the course of serial passages. In the present study, we found that passaged B. pseudomallei fresh clinical isolates and reference strain in Luria-Bertani broth exhibited increased plaque formation, invasion, intracellular replication, Galleria mellonella killing abilities, and cytokine production of host cells. These bacteria also modulated proteomic profiles during in vitro passage. We presume that the modulation of protein expression during in vitro passage caused changes in virulence and immunogenicity phenotypes. Therefore, we emphasize the need for caution regarding the use of data from passaged B. pseudomallei. These findings of phenotypic adaptation during in vitro serial passage can help researchers working on B. pseudomallei and on other species to better understand disparate findings among strains that have been reported for many years.
Highlights
Serial passage is a problem among many bacterial species, especially those where strains have been stored for several decades
We examined whether serial passage influenced the virulence and immune activation characteristics of fresh clinical isolates of B. pseudomallei and reference strain K96243 using plaque formation, invasion efficiency, intracellular replication, and Galleria mellonella killing assays
We evaluated the pathogenic capacity of passaged B. pseudomallei using the plaque formation assay to determine bacterial abilities regarding invasion, intracellular replication, intracellular survival, and spreading to nearby infected cells
Summary
Serial passage is a problem among many bacterial species, especially those where strains have been stored (banked) for several decades. To the best of our knowledge, phenotypic changes in passaged B. pseudomallei have not been previously reported These prior publications suggest that in vitro serial passages of B. pseudomallei alter phenotypes of the pathogen, both for reference strain K96243, which is extensively used worldwide among multiple laboratories, and for fresh clinical isolates. We hypothesized that B. pseudomallei might alter its protein expression, resulting in phenotypic changes during serial passage To test this hypothesis, we examined whether serial passage influenced the virulence and immune activation characteristics of fresh clinical isolates of B. pseudomallei and reference strain K96243 using plaque formation, invasion efficiency, intracellular replication, and Galleria mellonella killing assays. We examined whether serial passage affected transcription of bacterial genes, using quantitative reverse-transcription polymerase chain reaction (qRT-PCR), in order to validate the proteomic findings
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
