猪链球菌分35种血清型，其中猪链球菌2型(Streptococcus suis type 2, SS2)流行最广，发病率最高，而且可感染人致死，是一种重要的人畜共患病病原。由SS2引起的猪链球菌病常呈散发或地方性爆发，发病率和死亡率均很高，严重危害养猪业的发展。 分离鉴定病原是确诊疾病和开展病原流行病学研究的重要前提。在本病原分离方法上，主要依靠采用将病料直接接种THB培养基或使用选择性培养基提高细菌分离率。临床实践中，由于检测体系中致病菌的相对浓度有时候较低，按照普通分离细菌的方法可能无法分离到致病菌，如果可以富集体系中的目的细菌，并能够将目标细菌浓缩到一定的浓度内，将大大提高细菌的检出率，同时也便于细菌的分离培养，便于SS2进一步研究的展开。因此，探索一种敏感性更高特异性更强的分离SS2的新方法具有现实意义。也可为其它细菌的分离提供借鉴。 免疫磁珠技术是近年来国内外研究的一种新的免疫学技术，免疫磁珠是免疫微球的一种，它具备了固相化试剂特有的优点以及免疫学反应高度专一性的特点，并且分离速度快、效率高和可重复性好；同时操作简单，不需要昂贵的仪器设备。所以它在免疫检测，免疫吸附，细胞分离和培养等领域中得到越来越广泛的应用。 本试验利用HA9801灭活疫苗制备兔抗猪链球菌2型多克隆抗体，纯化抗体，用此抗体包被磁珠制备猪链球菌2型免疫磁珠，确定包被磁珠所需抗体的浓度和包被时间。建立了利用猪链球菌2型免疫磁珠分离鉴定SS2的操作流程，与普通分离细菌的方法相比，在分离临床病料方面，敏感性提高了100倍，特异性方面能特异性的筛选到SS2。本方法也能从人工感染的小鼠的肝脏匀浆中回收到病原。最后用本方法检测了从江苏，四川等地送检的病料，成功地分离到了1株可疑猪链球菌2型，经三重PCR鉴定为2型猪链球菌。结果表明建立的免疫磁珠技术可以用于SS2的分离鉴定。

Streptococcus Suis (SS) has 35 serotypes, in which, SS serotype 2 (SS2) is widespread and can infect human beings, and is regarded as an important zoonosis pathogen both for human beings and animals. Swine streptococcosis caused by SS2 is diverging or endemic, with high disease rate and mortality, and has a severe impact on swine production. Isolation of the pathogen is an important precondition for diagnosis and prevention of the disease and for epidemiological investigation. At present bacterial isolation depends on the direct inoculation of the suspected samples to the normal THB. The selective medium was used to improve the isolation efficiency. However, the vulnerability of actinobacillus pleuropneumoniae, which reduces the number of live pathogen in the samples, limits the traditional methods. And also it is difficult to isolation the SS2 when its’ concentration is very low in the system. Therefore, it will be much easier for the isolation of SS2 if we can highten the comcentration of SS2 in the system and for the further study on SS2. So the study to develope a novel method to improve the bacterial isolation will contribute to the research on this disease and set up an exemplary for the isolation on other disease. Immunomagnetic bead technique has becoming a new popular immunological technology in recent years. It possesses a lot of advantages of solid reagen, such as good specificity, rapidness, highly efficacy, and repeatability. It is also a cost-effective method due to no requirement of expensive instruments during the detection. These merits contribute to its wider application in the fields of lmmunodetectlon, immunoadsorption, cell detachment, cultivation and so on. In this experiment, the rabbit polyclonal antibody against Streptococcus Suis type 2 was produced by using the nactivated vaccine. The purified polyclonal antibody was used for coating the magnetic beads，which was called SS2-IMB. The optimal concentration of the polyclonal antibody and the time for coating magnetic beads were determined. Also the procession for the isolation of SS2 was developed. The analytical sensitivity of the assay was 100 times higher than regular isolation mathods. This technique could also isolated SS2 from the liver of artificial infected mice. Finally, clinical samples were tested by this technique and one suspected SS2 was isolated and then it was identified to be SS2 by treble PCR. These results indicated the establishment of SS2-IMB technique can be used to detect and isolate SS2.