暹罗鳄外周血白细胞提取物抗海豚链球菌感染的效果

通过细胞破碎和沉淀的方法从暹罗鳄(Crocodylus siamensis)外周血白细胞中获得提取物,并将此提取物以3种不同的方式注射小鼠,测定其在小鼠体内抗御海豚链球菌感染的效果。实验结果表明,若用海豚链球菌以腹腔注射感染小鼠,小鼠表现出明显病理症状,然后用不同浓度(2.2×103、2.2×102、2.2×101μg/ml)的提取物以腹腔注射小鼠,可使小鼠分别获得77.8％、55.6％、44.4％的相对保护率;若将海豚链球菌与不同浓度(2.2×103、2.2×102、2.2×101μg/ml)的提取物在体外等体积混合,然后将混合物以腹腔注射小鼠,可使小鼠分别获得55.6％、88.9％、77.8％的相对保护率;若将海豚链球菌以肌肉注射小鼠左腿,同时以不同浓度(2.2×103、2.2×102、2.2×101μg/ml)的提取物以肌肉注射小鼠右腿,可使小鼠分别获得77.8％、66.7％、44.4％的相对保护率。本实验的结论是：暹罗鳄外周血白细胞内存在一种或数种高效的抗菌物质,在小鼠体内能有效的防御由某些细菌导致的感染。     

猪链球菌2型分离株对野生斑马鱼的致病性

以野生斑马鱼为模式动物,对6株mrp＋epf＋sly＋猪链球菌2型（SS2）分离株进行致病性比较。斑马鱼经腹腔接种不同稀释度的SS2分离株,连续观察5d,Kaplan-Meier生存曲线分析并统计半数致死量（LD50）。结果显示,6个分离株对斑马鱼的LD50在10^5cfu-10^6cfu之间,临床株与非临床株的毒力差异不显著（P〉0.05）。从攻毒后死亡的鱼腹腔和脑可分离到SS2,并伴有腹腔出血及肝、肠、脑部炎性病变。表明SS2可感染斑马鱼,为进一步研究SS2的体内感染机制及毒力因子功能等奠定了基础。     

Early pathogenesis of equine Streptococcus equi infection (strangles)

Reasons for performing study: Little is known about entry and subsequent multiplication of Streptococcus equi following exposure of a susceptible horse. This information would have value in design of intranasal vaccines and understanding of shedding and protective immune responses. Objectives: To determine entry points and sites of subsequent replication and dispersion of S. equi at different times after intranasal infection or commingling exposure. Methods: Previously unexposed horses and ponies were subjected to euthanasia 1, 3, 20 or 48 h following intranasal inoculation with biotin labelled or unlabelled S. equi CF32. Some ponies were inoculated with suspensions of equal numbers of CF32 and its mutants lacking capsule, S. equi M‐like protein or streptolysin S. Others were infected by commingling exposure and subjected to euthanasia after onset of fever. Tonsils and lymph nodes were cultured for S. equi and tissues sectioned for histopathological examination and fluorescent microscopy. Results: Tonsillar tissues of both the oro‐ and nasopharynx served as portals of entry. Entry was unexpectedly rapid but involved few bacteria. Small numbers of organisms were detected in tonsillar crypts, in adjacent subepithelial follicular tissue and draining lymph nodes 3 h after inoculation. By 48 h, clumps of S. equi were visible in the lamina propria. At onset of fever, tonsillar tissues and one or more mandibular and retropharyngeal lymph nodes were heavily infiltrated by neutrophils and long chains of extracellular S. equi. Mutant S. equi lacking virulence factors were not seen in draining lymph nodes. Conclusions: Although very small numbers of S. equi entered the lingual and nasopharyngeal tonsils, carriage to regional lymph nodes occurred within hours of inoculation. This observation, together with visual evidence of intracellular and extracellular multiplication of S. equi in tonsillar lymphoid tissue and lymph nodes over the following days, indicates involvement of potent antiphagocytic activity and failure of innate immune defences. Relevance: Future research should logically address the tonsillar immune mechanisms involved including identification of effector cell(s) and antigens.     

Streptococcus zooepidemicus Myocardial Abscessation in a 1-Month-Old Thoroughbred Foal

A 1-month-old male Thoroughbred foal was presented at necropsy. A focal purulent lesion was observed in the right ventricular free wall of the myocardium. To the authors' knowledge, this is the first report of Streptococcus zooepidemicus myocardial abscessation in an equine.     

无乳链球菌检测及其奶牛乳腺炎防治的研究进展

本文就近年来国内外在无乳链球菌的鉴定、检测方法、防御等方面的研究进展进行了系统性的综述,为控制该病原微生物的传播、蔓延和由无乳链球菌引起的奶牛乳腺炎的防治提供参考。无乳链球菌（Streptococcus agalactiae）属于B群链球菌,是影响人畜健康的重要病原微生物之一。它可以引起新生儿脑膜炎、肺炎、败血病等,又是奶牛乳腺炎的主要病原体之一,给奶牛业造成了巨大的损失。     

猪链球菌35个血清型标准抗血清的制备及应用

用猪链球菌35个血清型的标准菌株免疫新西兰白兔制备标准抗血清,经试管凝集测定抗血清的效价均在1:32以上,吸附处理后抗血清具有良好的特异性和敏感性。对12株猪链球菌的试验结果表明:抗血清只与相同血清型的菌株出现凝集,可以区分出PCR方法无法区分的1型和14型以及2型和1/2型,并在国内首次鉴定出猪链球菌13型。     

猪链球菌2型38 000蛋白主要功能区基因的克隆与表达

根据GenBank中已发表的猪链球菌2型38000蛋白基因核苷酸序列,设计合成1对特异性引物,采用PCR方法,以四川分离株猪链球菌2型基因组DNA为模板扩增38000蛋白主要功能区基因。将PCR产物纯化后与pMD18-T连接转化宿主菌DH5α,提取阳性质粒,进行PCR和酶切鉴定。将目的片段定向克隆到表达载体pET32a中,经测序正确后,重组质粒转化入大肠杆菌BL21(DE3),于37℃、0.8mmol/LIPTG条件下进行诱导表达,结果重组菌菌体裂解物经SDS-PAGE电泳可检测到相对分子质量约为35000的重组蛋白,表达产物经纯化后,免疫印迹法(Western blotting)证实该重组蛋白可以与猪链球菌2型阳性血清发生特异性反应。     

The redox potential of growing cultures of Streptococcus bovis Orla-Jensen compared with other facultative anaerobes.

The changes of redox potential were measured in growing cultures of three strains of Streptococcus bovis, together with three strains of Staphylococcus aureus and one strain of each of Lactobacillus plantaram, Lactobacillus casei, and Eschericia coli. It was found that both S. aureus and E. coli could reduce the redox potential of the growth medium to very low values (between —400 mv and —600 mv), whereas the streptococci and lactobacilli were able to cause only slight or insignificant changes of the redox potential. Respirometric measurements confirmed that the capacity of oxygen consumption of S. bovis was very small compared to that of E. coli and S. aureus. On this basis the authors conclude that S. bovis in all probability is unable to contribute significantly to maintenance of the low redox potential of its natural habitat, the rumen. This function must be carried out by other bacteria, such as enterobacteria or staphylococci, which are capable of performing a true, aerobic respiration.