{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T08:23:14Z","timestamp":1787905394929,"version":"build-2784847793"},"reference-count":44,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2024,11,13]],"date-time":"2024-11-13T00:00:00Z","timestamp":1731456000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:p>\n                    This study involves the development and molecular characterization of the isogenic markerless knockout mutant SG \u0394\n                    <jats:italic>purB<\/jats:italic>\n                    , a genetically engineered live attenuated strain aimed at controlling\n                    <jats:italic>Salmonella<\/jats:italic>\n                    Gallinarum (SG) infection in poultry. The mutant was generated by deleting the\n                    <jats:italic>purB<\/jats:italic>\n                    gene using\n                    <jats:italic>\u03bb<\/jats:italic>\n                    -Red recombination technology, impairing adenylosuccinate lyase, necessary for purine biosynthesis. An 1,180\u2009bp deletion was engineered within the\n                    <jats:italic>purB<\/jats:italic>\n                    gene, leaving a residual 298\u2009bp genomic scar resulting in a purine auxotrophic mutant. Phenotypically, SG \u0394\n                    <jats:italic>purB<\/jats:italic>\n                    showed a 66.5% reduction in growth in LB broth compared to the wild-type strain and failed to grow in minimal media without adenosine. Growth was restored to near wild-type levels with 0.3\u2009mM adenosine supplementation, demonstrating the strain\u2019s conditional attenuation.\n                    <jats:italic>In vivo<\/jats:italic>\n                    pathogenicity assessments revealed that oral inoculation of SG \u0394\n                    <jats:italic>purB<\/jats:italic>\n                    into 3-day-old chickens at a dose of 2 \u00d7 10\n                    <jats:sup>8<\/jats:sup>\n                    \u2009CFU resulted in zero mortality, compared to an 80% mortality rate in chickens challenged with the wild-type strain. The SG \u0394\n                    <jats:italic>purB<\/jats:italic>\n                    strain exhibited significantly reduced clinical signs and lesion scores, with clinical sign scores dropping from 2.5\/3 with the wild-type to 0.4\/3 with the \u0394\n                    <jats:italic>purB<\/jats:italic>\n                    mutant, and lesion scores decreasing from 2.9\/3 to 0.3\/3. Additionally, the mutant was efficiently cleared from liver and spleen tissues by 14\u2009days post-inoculation, unlike the wild-type strain, which persisted until the experiment\u2019s end on day 21. The SG \u0394\n                    <jats:italic>purB<\/jats:italic>\n                    mutant shows potential as a safe alternative for preventing fowl typhoid, highlighting the promise of targeted genetic attenuation in developing effective vaccines for poultry diseases.\n                  <\/jats:p>","DOI":"10.3389\/fmicb.2024.1467230","type":"journal-article","created":{"date-parts":[[2024,11,13]],"date-time":"2024-11-13T01:21:06Z","timestamp":1731460866000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":3,"title":["Construction, molecular characterization, and safety assessment of purB mutant of Salmonella Gallinarum"],"prefix":"10.3389","volume":"15","author":[{"given":"Masham","family":"Mukhtar","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aamir","family":"Ghafoor","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"McClelland","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fareeha","family":"Akhtar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Muhammad Adil","family":"Rasheed","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2024,11,13]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"186","DOI":"10.1637\/0005-2086(2002)046[0186:VAOASG]2.0.CO;2","article-title":"Virulence analysis of a Salmonella Gallinarum strain by oral inoculation of 20-day-old chickens","volume":"46","author":"Audisio","year":"2002","journal-title":"Avian Dis."},{"key":"ref2","doi-asserted-by":"publisher","first-page":"39","DOI":"10.1016\/S0165-2427(02)00265-9","article-title":"Effects of live attenuated and killed Salmonella vaccine on T-lymphocyte mediated immunity in laying hens","volume":"91","author":"Babu","year":"2003","journal-title":"Vet. 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