目的 检测福氏志贺菌喹诺酮类耐药临床分离株DNA旋转酶gyrA和拓扑异构酶ⅣparC基因的突变情况，探讨GyrA和ParC氨基酸改变与喹诺酮类耐药的相关性。方法 根据药敏实验结果选取47株福氏志贺菌临床分离菌，对其gyrA、parC喹诺酮耐药决定区（QRDR）进行聚合酶链反应（PCR）扩增和测序分析，并采用SAS（V8.2）软件分析GyrA和ParC改变和喹诺酮类耐药性的关联程度。结果 44株喹诺酮类耐药菌在gyrA、parC基因QRDR均发生有义突变，gyrA83位密码子突变（TCG→TTG）最为常见，存在于43株耐药菌。混合模型分析结果显示GyrA83位、ParC80位氨基酸改变与萘啶酸的耐药性密切相关（P<0.01，R2=0.999），GyrA83、87位氨基酸改变与环丙沙星的耐药性密切相关（P<0.05，R2=0.872）。结论 GyrASer83→Leu突变是导致福氏志贺菌临床株对喹诺酮类耐药的关键突变，此单位点突变即可介导福氏志贺菌对萘啶酸的耐药，但对环丙沙星耐药需同时存在GyrA和/或ParC多个位点突变或其他耐药机制。

目的：研究两种不同的IL-15真核表达质粒对乙肝蛋白疫殁苗诱导的免殁应答的影响。方法：构建IL-15真核表达质粒（简称pIL-15）和含有IL-12信号肽的IL-15真核表达质粒（简称pIL-2s-15），CfLL-2细胞增殖实验验证两种质粒真核表达产物的生物学活性。将这两种质粒分别与HBsAg共免疫BALB/C小鼠，用ELISA法检测小鼠血清抗-HBsigG及igGl、igG2a亚类的效价。结果：与HBsAg蛋白疫苗共免疫时，pIL-15可使FIBsAg诱导的抗-HBslgG效价升高，显著高于载体pcDNA3.l与HB-sAg共免疫对照组，pIL-2s-15对HBsAg诱导抗-HBslgG效价没有明显影响。与HBsAg+pcDNA3.l组相比，FIBsAg+pIL-2s-15组和HBsAg+piL-15组诱生的抗HBsigG2a亚类均升高，但前者igG2a/lgGl比值最高，与HBsAg+pcDNA3.l组相比差别有显著性；HBsAg+pIL-15组igG2a/lgGl比值与HBsAg+pcDNA3.l组相比差别无显著性。结论：piL-15真核表达质粒可增强蛋白疫苗诱导的体液免疫应答，pIL-2s-15真核表达质粒则主要使免疫应答趋向Thl型。

目的：研究乙肝病毒核心抗原（HBcAg）DNA疫苗诱导的细胞免疫应答。方法：用表达乙肝病毒核心抗原N端144个氨基酸的重组质粒DNA（简称pHBc144）100μg免疫C57BL/6小鼠，用细胞内细胞因子染色技术检测小鼠体内抗原特异性CD8+T细胞的动态变化。结果：pHBc144免疫后抗原特异性CD8+细胞逐渐增多，在初次免疫的第14天出现第一个免疫应答高峰，此后抗原特异性CD8+细胞数量逐渐下降进入免疫记忆期并在1年内维持在稳定水平。加强免疫后在第10天抗原特异性CD8+T细胞数量达到高峰，约是初次免疫应答高峰的2倍，此后抗原特异性CD8+T细胞数量逐渐下降，但下降的速度比初次免疫应答减缓。结论：pHBc144DNA疫苗可诱导有效的细胞免疫应答。

In order to compare and evaluate three animal models for studying the pathogenicity of Staphylococcus epidermidis strains, three experimental animal models, namely, murine intra2venous LD50, mouse foreign body infection and rat central venous catheter (CVC) infection models were used to assess the relative virulence of two S. epidermidis strains, ATCC 12228 and 972337. The results from three animal models were comparable, indicating S. epidermidis 972337 was more viru-lent than strain ATCC 12228. The rat CVC infection model best mimicked the conditions of clinical patients with intra2venous catheters, and more information could be obtained from this model. We conclude that different in vivo models serve for dif-ferent purposes, and the rat CVC infection model is most suitable for studying specific characteristics of catheter related in-fections caused by S. epidermidis strains.

Sixteen pairs of two-component regulatory systems are identified in the genome of Staphylococcus epidermidis ATCC12228 strain, which is newly sequenced by our laboratory for Medical Molecular Virology and Chinese National Human Genome Center at Shanghai, by using bio-informatics analysis. Comparative analysis of the two-component regulatory systems in S. epidermidis and that of S. aureus and Bacillus subtilis shows that these systems may regulate some important biological functions, e.g. growth, biofilm formation, and expression of virulence factors in S. epidermidis. Two conserved domains, i.e. HATPase-c and REC domains, are found in all 16 pairs of two-component proteins. Homologous modelling analysis indicates that there are 4 similar HATPase-c domain structures of histidine kinases and 13 similar REC domain structures of response regulators, and there is one AMP-PNP binding pocket in the HATPase-c domain and three active aspartate residues in the REC domain. Preliminary experiment reveals that the bioinfor-matics analysis of the conserved domain structures in the two-component regulatory systems in S. epidermidis may provide useful information for discovery of potential drug target.