Abstract:
:Spotted fever group rickettsiae are known to produce distinct plaque phenotypes. Strains that cause lytic infections in cell culture form clear plaques, while nonlytic strains form opaque plaques in which the cells remain intact. Clear plaques have historically been associated with more-virulent species or strains of spotted fever group rickettsiae. We have selected spontaneous mutant pairs from two independent strains of Rickettsia rickettsii, the virulent R strain and the avirulent Iowa strain. A nonlytic variant of R. rickettsii R, which typically produces clear plaques, was isolated and stably maintained. A lytic variant of the Iowa strain, which characteristically produces opaque plaques, was also selected and maintained. Genomic resequencing of the variants identified only a single gene disrupted in each strain. In both cases, the mutation was in a gene annotated as relA/spoT-like. In the Iowa strain, a single mutation introduced a premature stop codon upstream from region encoding the predicted active site of RelA/SpoT and caused the transition to a lytic plaque phenotype. In R. rickettsii R, the nonlytic plaque phenotype resulted from a single-nucleotide substitution that shifted a tyrosine residue to histidine near the active site of the enzyme. The intact relA/spoT gene thus occurred in variants with the nonlytic plaque phenotype. Complementation of the truncated relA/spoT gene in the Iowa lytic plaque variant restored the nonlytic phenotype. The relA/spoT mutations did not affect the virulence of either strain in a Guinea pig model of infection; R strain lytic and nonlytic variants both induced fever equally, and the mutation in Iowa to a lytic phenotype did not cause them to become virulent.
journal_name
Infect Immunjournal_title
Infection and immunityauthors
Clark TR,Ellison DW,Kleba B,Hackstadt Tdoi
10.1128/IAI.00048-11subject
Has Abstractpub_date
2011-04-01 00:00:00pages
1631-7issue
4eissn
0019-9567issn
1098-5522pii
IAI.00048-11journal_volume
79pub_type
杂志文章abstract::Previous studies have suggested that interleukin-4 (IL-4) has a protective effect in host defense to Borrelia burgdorferi infection, both in limiting the severity of arthritis and in controlling spirochete numbers in tissues, and a mapping study revealed suggestive linkage to a cluster of genes on mouse chromosome 11,...
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journal_title:Infection and immunity
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doi:10.1128/IAI.60.3.845-852.1992
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journal_title:Infection and immunity
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journal_title:Infection and immunity
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更新日期:1985-04-01 00:00:00
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journal_title:Infection and immunity
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journal_title:Infection and immunity
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journal_title:Infection and immunity
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journal_title:Infection and immunity
pub_type: 杂志文章
doi:10.1128/IAI.10.6.1260-1265.1974
更新日期:1974-12-01 00:00:00
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journal_title:Infection and immunity
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doi:
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pub_type: 杂志文章
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journal_title:Infection and immunity
pub_type: 杂志文章
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更新日期:2005-01-01 00:00:00
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journal_title:Infection and immunity
pub_type: 杂志文章
doi:10.1128/IAI.31.3.845-849.1981
更新日期:1981-03-01 00:00:00
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journal_title:Infection and immunity
pub_type: 杂志文章
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journal_title:Infection and immunity
pub_type: 杂志文章
doi:10.1128/IAI.60.2.657-661.1992
更新日期:1992-02-01 00:00:00
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更新日期:2007-01-01 00:00:00
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journal_title:Infection and immunity
pub_type: 杂志文章
doi:10.1128/IAI.61.6.2545-2552.1993
更新日期:1993-06-01 00:00:00
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journal_title:Infection and immunity
pub_type: 杂志文章
doi:10.1128/IAI.55.9.2274-2280.1987
更新日期:1987-09-01 00:00:00
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journal_title:Infection and immunity
pub_type: 杂志文章
doi:10.1128/IAI.67.8.4106-4111.1999
更新日期:1999-08-01 00:00:00
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journal_title:Infection and immunity
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更新日期:2005-06-01 00:00:00
abstract::Subtilase cytotoxin (SubAB) was first isolated from a Shiga toxigenic Escherichia coli (STEC) strain that was responsible for an outbreak of hemolytic-uremic syndrome and is the prototype of a new family of AB(5) cytotoxins. SubAB is a subtilase-like serine protease, and upon uptake by host cells, it is trafficked to ...
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pub_type: 杂志文章
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更新日期:2010-11-01 00:00:00