脊髓灰质炎减毒活疫苗的高效纯化及特性研究

用就Ｑ－Ｓｅｐｈａｒｏｓｅ Ｆａｓｔ Ｆｌｏｗ对Ｖｅｒｏ细胞基质制备的Ｉ型口服脊髓灰质炎减毒活疫苗悬液进行纯化。病毒液经滤过澄清和超浓缩,获得８５％的病毒感染性滴度回收率,而经Ｑ－Ｓｅｐｈａｒｏｓｅ Ｆ．Ｆ．纯化的病毒悬液,病毒感染性滴度回收率达１００％。纯化后的病毒液用α－＾３２ＰｄＡＴＰ标记ＤＮＡ探针膜杂交法测定,宿主Ｖｅｒｏ细胞基质ＤＮＡ残余含量远低于１００ｐｇ／剂量的标准;ｒｃｔ／４０特征     

Population dynamics of live-attenuated virus vaccines

Viruses contained in live-attenuated virus vaccines (LAVV) can be transmitted between individuals, resulting in secondary or contact vaccinations. This fact has been exploited successfully in the use of the Oral Polio Vaccine (OPV) to better control wild-type polio viruses. In this work we analyze general LAVV vaccination models for infections that confer lifelong immunity. We consider both standard (continuous) vaccination strategies and pulse vaccination programs (where mass vaccination is carried out at regular intervals). For continuous vaccination, we provide a complete global analysis of a very general compartmental ordinary differential equation LAVV model. We find that the threshold vaccination level required for the eradication of wild-type virus depends on the basic reproduction numbers of both the wild-type and vaccine viruses, but is otherwise independent of the distributions of the durations in each of the sequence of stages of disease progression (e.g., latent, infectious, etc.). Furthermore, even for vaccine viruses with reproduction numbers below one, which would naturally fade from the population upon cessation of vaccination, there can be a significant reduction in the threshold vaccination level. The dependence of the threshold vaccination level on the virus reproduction numbers largely generalizes to the pulse vaccination model. For shorter pulsing periods there is negligible difference in threshold vaccination level as compared to continuous vaccination campaigns. Thus, we conclude that current policy in many countries to employ annual pulsed OPV vaccination does not significantly diminish the benefits of contact vaccination.     

乙肝疫苗对中小学生的保护效果

为进一步了解中小学生乙肝病毒的感染率及乙肝疫苗的保护效果,用固相放免方法检测1 134名小学生和358名中学生的HBsAg和抗-HBs。判定:S/N≥2.1;以≥10 mIU/mL为阳性。乙肝疫苗接种率,市区小学生高于郊区学生(χ2=54.58,P<0.01),HBsAg的阳性率呈下降趋势,检测到的1 134名小学生中,抗-HBs阳性率平均在89.2%。HBsAg阳性率随乙肝疫苗接种率的增高而下降,但市区学生(2.65%)与郊区学生(2.76%)差异无显著意义(χ2=1.35,P>0.05)。近期加强接种了重组乙肝疫苗的中学生,抗HBS-抗体阳性率97.7%。随着乙肝疫苗接种率和抗-HBs阳性率的增高,HBsAg阳性率呈下降趋势。在乙肝高发区,尽管推行了乙肝疫苗全程免疫规划,但从长远的免疫策略考虑,有必要制定加强免疫计划。     

A、B型流感病毒HA1嵌合基因疫苗的构建及免疫保护研究

为制备能提供交叉保护的疫苗,本研究在证实A型、B型流感病毒HA1 DNA能够提供抗流感病毒保护的基础上,将编码A型和B型流感病毒HA1的基因构建在同一质粒中,制备成嵌合DNA疫苗.将该重组质粒免疫小鼠,并以致死量同种流感病毒A/PR/8/34或B/Ibaraki/2/85攻击,通过测定小鼠的血清抗HA抗体和保护效果(包括存活率、肺部病毒量和体重丢失率)来评价DNA疫苗的免疫效果.结果表明:A、B型流感病毒HAl嵌合DNA疫苗能保护小鼠抵抗两种致死量流感病毒的攻击,具有提供交叉保护的能力.     

Wistar大鼠皮内免疫Sabin株脊髓灰质炎灭活疫苗的免疫持久性及加强免疫效果研究

脊髓灰质炎野毒株消灭后,口服脊髓灰质炎减毒活疫苗(Oral polio vaccine,OPV)将被停止使用,脊髓灰质炎灭活疫苗(Inactivated poliovirus vaccine,IPV)将全面替代OPV,但IPV成本过高,难以满足全球需要。皮内免疫可以降低Sabin株脊髓灰质炎灭活疫苗(Inactivated poliovirus vaccine derived from Sabin strain,sIPV)的免疫剂量,本研究将观察sIPV疫苗皮内免疫大鼠后的免疫持久性及加强免疫效果。本研究采用sIPV,设皮内免疫组、全剂量肌肉免疫组和皮内免疫阴性对照组,接种Wistar大鼠,于3剂基础免疫程序完成后第1个月、12个月采血;第12个月采血后加强免疫1剂,并于加强免疫1个月后采血。中和试验检测各血清抗脊灰病毒中和抗体效价,评价皮内免疫sIPV的免疫持久性及加强免疫效果。Wistar大鼠3剂基础免疫后1个月,1/5、1/3剂量皮内免疫组与全剂量肌肉免疫组Ⅰ、Ⅱ、Ⅲ型抗体阳转率均达到了100%,各型别中和抗体几何平均滴度(Geometric mean titer,GMT)均远高于1∶8保护水平。基础免疫后12个月,sIPV全剂量组各型阳转率均维持在80%以上,1/10剂量皮内免疫组在50%以上,1/5剂量皮内免疫组维持在70%以上,1/3剂量皮内免疫组维持在80%以上,除1/10剂量组Ⅱ型外其余各组各型别GMT均维持在1∶8以上。加强免疫后1个月,1/5剂量皮内免疫组、1/3剂量皮内免疫组及全剂量组的Ⅰ型、Ⅱ型、Ⅲ型各组中和抗体阳转率均达到100%,并能够诱导产生远高于1∶8的抗体水平。本研究结果显示sIPV疫苗皮内免疫具有良好的免疫持久性及加强免疫效果。     

猪繁殖与呼吸综合征病毒GP5蛋白实验性核酸疫苗的构建及其免疫原性的初步研究

扩增了猪繁殖与呼吸综合征病毒(PRRSV)长春分离株ORF5基因,并将其克隆至真核表达载体pVAX1、pVIR-IL-18的CMV启动子下游,构建成真核表达质粒。通过Western blot以及IFA检测方法确认,所构建的2个重组DNA疫苗质粒在真核细胞能进行有效的转录,并表达了目的蛋白(GP5)。同时辅以不同佐剂进行了BALB/c小鼠免疫试验,检测了免疫后的ELISA抗体水平和脾T淋巴细胞亚群数量。结果表明:共表达猪IL-18基因的核酸疫苗pVIR-IL-18-ORF5免疫后的ELISA抗体水平和脾T淋巴细胞亚群数量均优于pVAX1-ORF5,而且加佐剂实验组优于未加佐剂的实验组。