{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T05:12:19Z","timestamp":1772169139561,"version":"3.50.1"},"reference-count":33,"publisher":"F1000 Research Ltd","license":[{"start":{"date-parts":[[2018,3,8]],"date-time":"2018-03-08T00:00:00Z","timestamp":1520467200000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004440","name":"Wellcome Trust","doi-asserted-by":"publisher","award":["101502"],"award-info":[{"award-number":["101502"]}],"id":[{"id":"10.13039\/100004440","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100004440","name":"Wellcome Trust","doi-asserted-by":"publisher","award":["202755"],"award-info":[{"award-number":["202755"]}],"id":[{"id":"10.13039\/100004440","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["wellcomeopenresearch.org"],"crossmark-restriction":false},"short-container-title":["Wellcome Open Res"],"abstract":"<ns4:p>\n                    <ns4:bold>Background:<\/ns4:bold>\n                    Research in chlamydial genetics is challenging because of its obligate intracellular developmental cycle.\n                    <ns4:italic>In vivo<\/ns4:italic>\n                    systems exist that allow studies of different aspects of basic biology of chlamydiae, the murine\n                    <ns4:italic>Chlamydia muridarum<\/ns4:italic>\n                    model is one of great importance and thus an essential research tool.\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    carries a plasmid that has a role in virulence.\u00a0 Our aim was to compare and contrast the\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    plasmid-free phenotype with that of a chromosomally isogenic plasmid-bearing strain, through the inclusion phase of the developmental cycle.\n                  <\/ns4:p>\n                  <ns4:p>\n                    <ns4:bold>Methods:<\/ns4:bold>\n                    We measured infectivity for plasmid bearing and plasmid-cured\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    by inclusion forming assays in McCoy cells and in parallel bacterial chromosome replication by quantitative PCR, throughout the developmental cycle. In addition to these studies, we have carefully monitored chlamydial inclusion formation by confocal microscopy and transmission electron microscopy. A new\n                    <ns4:italic>E.coli<\/ns4:italic>\n                    \/chlamydial shuttle vector (pNigg::GFP) was constructed using standard cloning technology and used to transform\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    for further phenotypic studies.\n                  <\/ns4:p>\n                  <ns4:p>\n                    <ns4:bold>Results:<\/ns4:bold>\n                    We have advanced the definition of the chlamydial phenotype away from the simple static observation of mature inclusions and redefined the\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    plasmid-based phenotype on growth profile and inclusion morphology. Our observations on the growth properties of plasmid-cured\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    challenge the established interpretations, especially with regard to inclusion growth kinetics. Introduction of the shuttle plasmid pNigg::GFP into plasmid-cured\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    restored the wild-type plasmid-bearing phenotype and confirmed that loss of the plasmid was the sole cause for the changes in growth and chromosomal replication.\n                  <\/ns4:p>\n                  <ns4:p>\n                    <ns4:bold>Conclusions:<\/ns4:bold>\n                    Accurate growth curves and sampling at multiple time points throughout the developmental cycle is necessary to define plasmid phenotypes.\u00a0 There are subtle but important (previously unnoticed) differences in the overall growth profile of plasmid-bearing and plasmid-free\n                    <ns4:italic>C. muridarum<\/ns4:italic>\n                    .\u00a0 We have proven that the differences described are solely due to the plasmid pNigg.\n                  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indexed","URL":"https:\/\/wellcomeopenresearch.org\/articles\/3-25\/v1#referee-response-31735","order":1,"name":"referee-response-31735","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"10.21956\/wellcomeopenres.15117.r31736, Derek J. Fisher, Department of Microbiology, Southern Illinois University, Carbondale, IL, USA, 26 Mar 2018, version 1, indexed","URL":"https:\/\/wellcomeopenresearch.org\/articles\/3-25\/v1#referee-response-31736","order":2,"name":"referee-response-31736","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"This work was supported by the Wellcome Trust [grants 101502, 202755]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.","order":3,"name":"grant-information","label":"Grant Information"},{"value":"This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.","order":0,"name":"copyright-info","label":"Copyright"}]}}