VIRULENCE OF STREPTOCOCCUS-MUTANS - INVIVO REVERSION OF A LOW-VIRULENCE MUTANT RESULTS IN PARTIAL DISPLACEMENT AND PATHOGENESIS
VIRULENCE OF STREPTOCOCCUS-MUTANS - INVIVO REVERSION OF A LOW-VIRULENCE MUTANT RESULTS IN PARTIAL DISPLACEMENT AND PATHOGENESIS
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DOI：
10.1128/iai.27.3.1003-1011.1980
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发表时间：
1980-01-01
影响因子：
3.1
通讯作者：
MCGHEE, JR
中科院分区：
文献类型：
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作者：
HIRASAWA, M;KIYONO, H;MCGHEE, JR
突变链球菌6715野生型(WT)的一个突变体C4对不溶性葡聚糖的葡糖转移酶合成有缺陷，对单关联生药大鼠的毒力较低。报告了在单相关大鼠中检测到C4的WT样变异体，用这些WT样生物体替代C4，以及这些WT样生物体在共生大鼠中的致病潜力。在第一组与C4单相关大鼠的纵向研究中，在感染后第7天(27日龄)动物的4个笼子中有1个口腔拭子样本中检测到WT样生物，频率较低(0.001%)。从1个笼子里的动物身上分离出的变异体的频率增加，到45天时，这些微生物约占下颌菌斑菌群的1%。对4个鼠笼(45日龄)进行随机再分配后，对60日龄大鼠口腔拭子标本进行微生物分析，结果表明，4个鼠笼中均存在变异体。在年龄较大的动物(90天龄)中，可恢复变异的频率增加，并与高龋齿活动相关。WT类生物是可传播的，因为这些动物的后代(45d龄)具有高水平的变异和高龋齿活动。在第二项研究中，虽然在所有4个笼子中都存在变异，但直到45天大鼠才被检测到。所有变异株的形态、生化和体内毒力特征更接近变形链球菌6715WT，而不是C4。与C4和WT的体外混合实验表明，WT生物迅速取代了C4。葡萄糖基转移酶缺陷、低毒力的C4在体内恢复为毒性类似WT的生物，这些生物比C4更有利于争夺光滑的表面。这些变异在与龋齿增加相关的斑块中达到了显着的数量。
A mutant of S. mutans 6715 wild type (WT), designated C4, is defective in glucosyltransferase synthesis of insoluble glucan and has low virulence in monoassociated gnotobiotic rats. Detection of WT-like variants of C4 in monoassociated rats, supplantation of C4 by these WT-like organisms and pathogenic potential of these WT-like organisms in gnotobiotic rats are reported. In the 1st series of longitudinal studies with C4-monoassociated rats, WT-like organisms were detected at a low frequency (0.001%) in oral swab samples from 1 of 4 cages of animals analyzed on day 7 after infection (age 27 days). The frequency of variants isolated from animals in the 1 cage increased and by age 45 days these organisms represented approximately 1% of the mandibular plaque flora. After random redistribution of rats in the 4 cages (age 45 days), microbial analysis of oral swab samples (age 60 days) demonstrated the presence of variants in samples taken from rats in all 4 cages. The frequency of recoverable variants increased in older animals (age 90 days) and correlated with high caries activity. WT-like organisms were transmissible, since offspring (age 45 days) from these animals had high levels of variants and high caries activity. Variants in a 2nd study, although present in all 4 cages, were not detected until rats were 45 days old. All variant isolates exhibited morphological, biochemical and in vivo virulence characteristics more similar to S. mutans 6715 WT than to C4. In vitro mixing experiments with C4 and WT or a selected variant suggested that C4 was rapidly displaced by WT organisms. The glucosyltransferase-defective, low-virulence C4 reverts to virulent WT-like organisms in vivo which compete more favorably for smooth surfaces than C4. These variants reached significant numbers in plaque which correlated with increased dental caries.