婴儿脊灰母传抗体对Sabin株脊髓灰质炎灭活疫苗不同序贯免疫接种程序效果的影响

目的探讨婴儿脊髓灰质炎(简称脊灰)母传抗体对Sabin株脊髓灰质炎灭活疫苗(Sabin inactivated poliovirus vaccine,s IPV)与不同剂型脊髓灰质炎减毒活疫苗(oral poliovirus vaccine,OPV)采用不同序贯免疫程序接种效果的影响。方法选取柳州市600名2月龄无脊髓灰质炎疫苗免疫史的常住健康婴儿,分为6个序贯免疫组,其中1剂s IPV+2剂b OPV 2组:s IPV+2b OPV(糖丸)组、s IPV+2b OPV(液体)组;2剂s IPV+1剂b OPV 2组:2s IPV+b OPV(糖丸)组、2s IPV+b OPV(液体)组;2剂s IPV+1剂t OPV 2组:2s IPV+t OPV(糖丸)组,2s IPV+t OPV(液体)组。每组100人。按照0、28、56 d程序,分别在婴儿2、3、4月龄时接种相应疫苗。检测免前、全程免后28 d血清中脊灰中和抗体滴度,计算阳转率及GMT。结果 6个序贯免疫组免前各项指标分布均匀,各型脊灰抗体阳性率、抗体水平及分布均无明显差异。共有518例免前和免后配对血清抗体检测结果的研究对象进入免疫原性分析。s IPV+2b OPV组与2s IPV+b OPV组Ⅱ型抗体、2s IPV+t OPV(糖丸)组Ⅲ型抗体免前阴性和免前阳性者接种疫苗后阳转率差异均有统计学意义;s IPV+2b OPV(糖丸)组Ⅲ型抗体,2s IPV+b OPV(糖丸)组与2s IPV+b OPV(液体)组Ⅱ型抗体,2s IPV+t OPV(糖丸)组Ⅰ、Ⅱ型抗体的免前阳性与免前阴性者接种疫苗后的GMT差异均有统计学意义;2s IPV+t OPV(糖丸)Ⅰ型抗体组与2s IPV+t OPV(液体)Ⅱ型抗体组中,免前8~32、≥32两种滴度水平的免后GMT差异均有统计学意义。结论脊灰疫苗序贯免疫效果受脊灰母传抗体干扰。     

中山市2011年健康儿童脊髓灰质炎、麻疹和乙型肝炎抗体水平监测

目的了解中山市1~14岁健康儿童脊髓灰质炎(脊灰)病毒、麻疹病毒和乙型肝炎(乙肝)病毒抗体水平状况,为维持无脊灰、消除麻疹和控制乙肝提供依据。方法采用多阶段整群抽样方法,随机选择220名1~14岁健康儿童抽取静脉血,采用ELISA法检测麻疹病毒抗体Ig G、乙肝病毒表面抗原和抗体;用中和试验检测脊灰(Ⅰ、Ⅱ、Ⅲ)型病毒中和抗体。结果脊灰、麻疹和乙肝病毒抗体阳性率分别为91.36%、93.18%和66.36%,脊灰病毒Ⅰ、Ⅱ、Ⅲ型和麻疹病毒抗体几何平均滴度(GMT)分别为1∶215.90、1∶119.05、1∶31.40和1∶1 254.45;乙肝病毒表面抗原阳性率为1.36%。结论中山市1~14岁健康儿童对脊灰病毒具有较高的免疫水平,已形成对脊灰病毒有效的免疫屏障;乙肝得到有效控制;但麻疹未能形成有效的免疫屏障。     

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。     

2018年河南省健康人群脊髓灰质炎抗体水平监测结果分析

目的了解2018年河南省健康人群脊髓灰质炎(poliomyelitis,简称脊灰)抗体水平,为评价脊灰疫苗免疫效果、保持河南省无脊灰状态提供科学依据。方法选取漯河市舞阳县、许昌市建安区和濮阳市清丰县作为监测点,通过中和抗体测定法对健康人群进行脊灰抗体检测。结果共检测636份健康人血标本,其中脊灰I型和III型抗体阳性率分别为96.54%和93.55%,抗体几何平均滴度(geometric mean titer,GMT)分别为1∶137.70和1∶47.27,I型、III型抗体阳性率和GMT之间差异均有统计学意义(P0.05),I型抗体阳性率和GMT均高于III型。不同年龄组之间脊灰I型、III型抗体阳性率和GMT差异均有统计学意义(P0.05),GMT随着年龄的增加而降低。不同免疫史之间脊灰I型、III型抗体阳性率和GMT差异有统计学意义(P0.05),接种过脊灰疫苗人群的抗体阳性率和GMT均高于未接种或者免疫史不详人群。不同性别和不同地区之间脊灰I型、III型抗体阳性率和GMT差异均无统计学意义(P0.05)。结论 2018年河南省健康人群脊灰抗体处于较高水平,已形成了有效的免疫屏障,但保持河南省无脊灰的发生工作依然严峻。脊灰防治需加强人群的疫苗免疫规划和常规免疫,定期对健康人群脊灰抗体的检测是防止脊灰病毒传播较为有效的方法之一。     

湘西少数民族健康人群脊髓灰质炎疫苗免疫效果监测分析

目的了解湘西少数民族地区健康人群脊髓灰质炎(poliomyelitis,以下简称脊灰)免疫水平及1岁内儿童完成脊灰疫苗基础免疫后的免疫效果,为制定脊灰免疫策略提供科学依据。方法随机抽取湘西土家族苗族自治州345名健康人群调查脊髓灰质炎免疫水平,同时选择50名1岁内完成脊灰疫苗基础免疫1个月后的婴幼儿调查免疫成功率,采用微细胞中和试验检测脊灰中和抗体水平。结果 1岁内婴幼儿脊灰I型和III型中和抗体阳性率均为100%,I型和III型抗体几何平均滴度(GMT)分别为1∶916.51和1∶724.09。健康人群中脊灰I型和III型中和抗体阳性率分别为92.26%和97.39%,脊灰I型和III型GMT分别为1∶174.03和1∶95.84;同年龄组中I型GMT均高于III型,0～3岁组I型和III型GMT最高,各型GMT随着年龄的增长均呈现下降趋势。结论湘西土家族苗族自治州针对脊灰疫苗冷链运转情况好,疫苗接种质量与效果好,脊灰疫苗接种免疫成功率高,健康人群免疫状况良好,已形成牢固的免疫屏障,能有效地控制和阻断脊灰野病毒的传播。     

湘西少数民族健康人群脊灰疫苗免疫效果监测

目的 了解湘西少数民族地区健康人群脊髓灰质炎(poliomyelitis,本文简称脊灰)免疫水平及1岁内儿童完成脊灰疫苗基础免疫后的免疫效果,为制定脊灰免疫策略提供科学依据。方法 随机抽取湘西土家族苗族自治州345名健康人群调查脊髓灰质炎免疫水平,同时选择50名1岁内完成脊灰疫苗基础免疫1个月后的婴幼儿调查免疫成功率,采用微细胞中和试验检测脊灰中和抗体水平。结果 1岁内婴幼儿脊灰I型和III型中和抗体阳性率均为100%,I型和III型抗体几何平均滴度(GMT)分别为1∶916.51和1∶724.09。健康人群中脊灰I型和III型中和抗体阳性率分别为92.26%和97.39%,脊灰I型和III型GMT分别为1∶174.03和1∶95.84;同年龄组中I型GMT均高于III型,0~3岁组I型和III型GMT最高,各型GMT随着年龄的增长均呈现下降趋势。结论 湘西土家族苗族自治州冷链运转情况好,疫苗接种质量与效果好,脊灰疫苗接种免疫成功率高,健康人群免疫状况良好,已形牢固的免疫屏障,能有效地控制和阻断脊灰野病毒的传播。     

Sabin IPV疫苗在版纳小耳猪体内的免疫原性及安全性研究

目的评价Sabin株脊髓灰质炎灭活疫苗(inactivated poliovirus vaccine derived from Sabin strain,s IPV)在版纳小耳猪体内的免疫原性及安全性,为新型动物模型提供实验依据。方法采用中国医学科学院医学生物学研究所已经上市的s IPV疫苗,设计s IPV肌肉免疫实验组与野毒株IPV(IPV derived from wild strain,w IPV)肌肉免疫对照组,以及生理盐水阴性对照组,按0、1、2月基础免疫程序,接种版纳小耳猪,于免疫接种前及每剂免疫接种后第30天釆血,检测各组的血清中和抗体水平,评价免疫原性,并通过观察小耳猪的状态及体重情况,评价安全性。结果版纳小耳猪3剂免疫后,s IPV试验组与w IPV对照组Ⅰ、Ⅱ、Ⅲ型抗体阳转率均达到了100%,各型中和抗体几何平均滴度(GMT)均远高于1∶8保护水平。版纳小耳猪接种疫苗后体重增加,结果表明s IPV疫苗在版纳小耳猪动物模型中具有良好的安全性。结论 s IPV疫苗在版纳小耳猪体内具有良好的免疫原性及安全性,版纳小耳猪可作为评价s IPV疫苗的新型实验动物模型。     

无针皮内免疫接种Sabin IPV疫苗的安全性及免疫原性研究

全球消灭脊髓灰质炎野病毒后,必须全面使用脊髓灰质炎灭活疫苗(Inactivated poliovirus vaccine,IPV)才能维持无脊灰状态,然而IPV成本较高,难以满足全球需要。皮内免疫途径能够降低Sabin株脊髓灰质炎灭活疫苗(Vero细胞)(Inactivated poliovirus vaccine derived from Sabin strains,sIPV)的抗原量,本研究将评估无针皮内免疫sIPV的安全性及免疫原性。本研究采用中国医学科学院医学生物学研究所生产的sIPV进行1/5(0.1 ml)剂量无针皮内免疫接种Wistar大鼠,并设计全剂量肌肉免疫对照组以及无针皮内免疫阴性对照组,按0月、1月、2月基础免疫程序,于免疫前及每剂免疫后第30 d釆血,检测血清中和抗体水平,评价免疫原性,并通过观察大鼠的皮肤刺激反应及豚鼠的全身过敏反应,评价安全性。Wistar大鼠3剂免疫后,1/5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。大白鼠接种疫苗后体重增加,皮肤刺激试验及全身过敏反应试验结果表明无针皮内免疫sIPV具有良好的安全性。本研究结果表明sIPV疫苗无针皮内注射免疫安全、有效,并可降低sIPV的抗原量,可为全球消灭脊髓灰质炎提供可负担得起的疫苗。     

中国急性弛缓性麻痹(AFP)病例中脊髓灰质炎病毒疫苗株VP1区基因变异的研究

为研究中国急性弛缓性麻痹(AFP)病例中脊髓灰质炎(简称脊灰)病毒分离株的分子特征,为中国继续维持"无脊灰野毒状态"提供理论依据,对2002年所有省级疾病预防控制中心送检的脊灰分离株,用PCR-RFLP法及ELISA法进行型内鉴定.用PCR-RFLP法筛查出与疫苗株相比有异常酶切图谱的毒株共24株,其中Ⅰ型毒株1株,Ⅱ型毒株21株,Ⅲ型毒株2株;用ELISA法筛查出与疫苗株相比有不同的抗原抗体反应的毒株共22株,其中Ⅰ型毒株7株,Ⅱ型毒株4株,Ⅲ型毒株11株,在7株Ⅰ型毒株中有3株为非疫苗类似株(NSL),其余为双反应毒株(DRV).随后对这46株毒株进行了全VP1区的基因序列分析.结果表明:2002年脊灰分离株都是疫苗株或疫苗衍生株,没有发现野毒株,中国继续保持着"无脊灰野毒状态";口服减毒活疫苗(OPV)株与其它野毒株在稳定性性质方面是类似的,即通常是不稳定的,在人体肠道内有很强的选择性;在人体肠道内,病毒复制产生的基因变异导致毒力升高,是引起疫苗相关麻痹病例(VAPP)的重要原因,但宿主本身的因素也有很大的作用;在局部地区有疫苗株的循环或脊灰疫苗衍生株(VDPV)的存在;最终消除疫苗株引起的AFP病例可能还需要脊灰灭活疫苗(IPV)的介入.     

流行性出血热(EHF)Ⅱ型(家鼠型)纯化灭活疫苗Ⅰ期临床观察

根据卫生部(91)特申体第02号文,92年完成了Ⅱ型纯化疫苗Ⅰ期临床反应及血清效果观察,免疫程序为0,1,2月,分原倍疫苗组和1∶2稀释组,各免15人,每针次免疫后连续观察3天,结果均无不良反应,仅在注射时稍有微胀痛感。二针次免疫后均能产生较高的免疫抗体:原倍疫苗免疫抗体滴度,ELISA1∶181(GET),PRNT中和抗体≥1∶10;1∶2稀释疫苗,ELISA1∶169(GMT),PRNT≥1∶10。三针次免疫后抗体滴度高于二针次;原倍疫苗,ELISA1∶478(GMT),PRNT1∶10～1∶20;稀释疫苗,ELISA1∶446(GMT),PRNT1∶10～1∶20,但原倍疫苗和稀释疫苗的抗体水平之间无显著性差异。半年后仍保持一定抗体水平。可采用二针次总量2ml免疫。     

Circulating Vaccine Derived Polio Viruses and their Impact on Global Polio Eradication

Poliomyelitis vaccination via live Oral Polio Vaccine (OPV) suffers from the inherent problem of reversion: the vaccine may, upon replication in the human gut, mutate back to virulence and transmissibility resulting in circulating vaccine derived polio viruses (cVDPVs). We formulate a general mathematical model to assess the impact of cVDPVs on prospects for polio eradication. We find that for OPV coverage levels below a certain threshold, cVDPVs have a small impact in comparison to the expected endemic level of the disease in the absence of reversion. Above this threshold, the model predicts a small but significant endemic level of the disease, even where standard models predict eradication. In light of this, we consider and analyze three alternative eradication strategies involving a transition from continuous OPV vaccination to either continuous Inactivated Polio Vaccine (IPV), pulsed OPV vaccination, or a one-time IPV pulse vaccination. Stochastic modeling shows continuous IPV vaccination is effective at achieving eradication for moderate coverage levels, while pulsed OPV is effective if higher coverage levels are maintained. The one-time pulse IPV method may also be a viable strategy, especially in terms of the number of vaccinations required and time to eradication, provided that a sufficiently large pulse is practically feasible. More investigation is needed regarding the frequency of revertant virus infection resulting directly from vaccination, the ability of IPV to induce gut immunity, and the potential role of spatial transmission dynamics in eradication efforts. B.G. Wagner’s research is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Doctoral Scholarship. D.J.D. Earn’s research is supported by the Canadian Institutes of Health Research (CIHR), Natural Sciences and Engineering Research Council of Canada (NSERC) and the J.S. McDonnell Foundation.     

Cold chain and virus‐free chloroplast‐made booster vaccine to confer immunity against different poliovirus serotypes

The WHO recommends complete withdrawal of oral polio vaccine (OPV) type 2 by April 2016 globally and replacing with at least one dose of inactivated poliovirus vaccine (IPV). However, high‐cost, limited supply of IPV, persistent circulating vaccine‐derived polioviruses transmission and need for subsequent boosters remain unresolved. To meet this critical need, a novel strategy of a low‐cost cold chain‐free plant‐made viral protein 1 (VP1) subunit oral booster vaccine after single IPV dose is reported. Codon optimization of the VP1 gene enhanced expression by 50‐fold in chloroplasts. Oral boosting of VP1 expressed in plant cells with plant‐derived adjuvants after single priming with IPV significantly increased VP1‐IgG1 and VP1‐IgA titres when compared to lower IgG1 or negligible IgA titres with IPV injections. IgA plays a pivotal role in polio eradication because of its transmission through contaminated water or sewer systems. Neutralizing antibody titres (~3.17–10.17 log₂ titre) and seropositivity (70–90%) against all three poliovirus Sabin serotypes were observed with two doses of IPV and plant‐cell oral boosters but single dose of IPV resulted in poor neutralization. Lyophilized plant cells expressing VP1 stored at ambient temperature maintained efficacy and preserved antigen folding/assembly indefinitely, thereby eliminating cold chain currently required for all vaccines. Replacement of OPV with this booster vaccine and the next steps in clinical translation of FDA‐approved antigens and adjuvants are discussed.     

A vision of a world without polio: the OPV cessation strategy.

Once the eradication of wild poliovirus has been confirmed, the public health benefits of routine immunization with OPV will no longer outweigh the burden of disease either due to paralysis caused by OPV (vaccine associated paralytic polio), or by outbreaks caused by circulating vaccine-derived polioviruses. The eventual cessation of OPV use in routine immunization programmes worldwide will become necessary to assure a lasting eradication of polio. As the world moves towards polio eradication and its certification, preparations are therefore being intensified for OPV cessation, and the risk management framework for safe OPV cessation is being put in place. The framework includes bio-containment of all known poliovirus and potentially infected substances, development of an international stockpile of oral polio vaccine, ensuring a mechanism for continued global surveillance and response for polio after eradication has been certified, and national policies if countries decide to continue vaccinating with inactivated polio vaccine (IPV). It is ironic that the vaccine on which the world has depended for polio eradication will itself become a risk to eradication once the transmission of wild poliovirus has been interrupted. Final preparations for the eventual global and simultaneous cessation of OPV will require the same level of international cooperation and coordination that has brought the world to the verge of polio eradication.     

Evaluation of poliovirus antibody titers in orally vaccinated semi‐captive chimpanzees in Uganda

Background To understand immunological responses in chimpanzees vaccinated with live‐attenuated vaccine (oral polio vaccine; OPV), serum neutralizing antibodies against poliovirus types 1, 2, and 3 were investigated over time. Methods The neutralizing antibody titers against poliovirus types 1, 2, and 3 were determined by microneutralization test using 100 ID₅₀ of poliovirus types 1, 2, and 3 (Sabin strains). Results Neutralizing antibodies against poliovirus types 1, 2, and 3 were detected in 85.7%, 71.4%, and 65% of the serum from 42 chimpanzees tested 9 years post‐vaccination. The neutralizing antibody titers in chimpanzees were similar to the documented levels in human studies as an indicator of vaccine efficacy. Conclusions This study reveals persistence of neutralizing antibodies in chimpanzees for at least 9 years after vaccination with OPV. This first study in chimpanzees provides useful information for the evaluation of the success of vaccination with OPV in other captive apes.     

Human Circulating Antibody-Producing B Cell as a Predictive Measure of Mucosal Immunity to Poliovirus

Background

The “gold standard” for assessing mucosal immunity after vaccination with poliovirus vaccines consists in measuring virus excretion in stool after challenge with oral poliovirus vaccine (OPV). This testing is time and resource intensive, and development of alternative methods is a priority for accelerating polio eradication. We therefore evaluated circulating antibody-secreting cells (ASCs) as a potential means to evaluate mucosal immunity to poliovirus vaccine.

Methods

199 subjects, aged 10 years, and previously immunized repeatedly with OPV, were selected. Subjects were assigned to receive either a booster dose of inactivated poliovirus vaccine (IPV), bivalent OPV (bOPV), or no vaccine. Using a micro-modified whole blood-based ELISPOT assay designed for field setting, circulating poliovirus type-specific IgA- and IgG-ASCs, including gut homing α4β7+ ASCs, were enumerated on days 0 and 7 after booster immunization. In addition, serum samples collected on days 0, 28 and 56 were tested for neutralizing antibody titers against poliovirus types 1, 2, and 3. Stool specimens were collected on day 28 (day of bOPV challenge), and on days 31, 35 and 42 and processed for poliovirus isolation.

Results

An IPV dose elicited blood IgA- and IgG-ASC responses in 84.8 to 94.9% of subjects, respectively. In comparison, a bOPV dose evoked corresponding blood ASC responses in 20.0 to 48.6% of subjects. A significant association was found between IgA- and IgG-ASC responses and serum neutralizing antibody titers for poliovirus type 1, 2, 3 (p<0.001). In the IPV group, α4β7⁺ ASCs accounted for a substantial proportion of IgA-ASCs and the proportion of subjects with a positive α4β7⁺ IgA-ASC response to poliovirus types 1, 2 and 3 was 62.7%, 89.8% and 45.8%, respectively. A significant association was observed between virus excretion and α4β7⁺ IgA^- and/or IgG-ASC responses to poliovirus type 3 among immunized children; however, only a weak association was found for type 1 poliovirus.

Discussion

Our results suggest that virus-specific blood ASCs, especially for type 3 poliovirus, can serve as surrogate of mucosal immunity after vaccination. Further studies are needed to evaluate the duration of such memory responses and to assess the programmatic utility of this whole blood-based mucosal ASC testing for the polio eradication program.     

The final stages of the global eradication of poliomyelitis

The global incidence of poliomyelitis has dropped by more than 99 per cent since the governments of the world committed to eradication in 1988. One of the three serotypes of wild poliovirus has been eradicated and the remaining two serotypes are limited to just a small number of endemic regions. However, the Global Polio Eradication Initiative (GPEI) has faced a number of challenges in eradicating the last 1 per cent of wild-virus transmission. The polio endgame has also been complicated by the recognition that vaccination with the oral poliovirus vaccine (OPV) must eventually cease because of the risk of outbreaks of vaccine-derived polioviruses. I describe the major challenges to wild poliovirus eradication, focusing on the poor immunogenicity of OPV in lower-income countries, the inherent limitations to the sensitivity and specificity of surveillance, the international spread of poliovirus and resulting outbreaks, and the potential significance of waning intestinal immunity induced by OPV. I then focus on the challenges to eradicating all polioviruses, the problem of vaccine-derived polioviruses and the risk of wild-type or vaccine-derived poliovirus re-emergence after the cessation of oral vaccination. I document the role of research in the GPEI''s response to these challenges and ultimately the feasibility of achieving a world without poliomyelitis.     

Developments in the production and quality control of poliovirus vaccines -- historical perspectives.

Using virus grown in monkey kidney cells, Salk and his colleagues developed an inactivated poliovirus vaccine (IPV) in 1952. A large-scale field trial showed the vaccine to be safe and highly immunogenic in children, but soon after the vaccine became generally available in 1955, cases of paralytic disease were reported in recipients. Investigations showed that almost all the cases occurred in children who had received vaccine from one particular manufacturer. Extensive studies attributed the disaster to problems with inactivation. Addition of a Seitz filtration step midway during formalin inactivation and extension of the inactivation period resulted in a safe vaccine. No further paralytic cases were observed following the use of several hundred million doses of this improved vaccine. Thus, IPV was safe and caused a dramatic decline in the incidence of poliomyelitis in countries where it was used. A second generation IPV is produced in fermentors using well-characterized cell strains or continuous cell lines. The major breakthrough in the development of live poliovirus vaccine was the application of tissue culture methods for virus attenuation. By 1959 several candidate live oral poliovirus vaccines (OPV) had been developed. These were clinically tested in millions of individuals and found to be safe and effective. Since the attenuated virus strains developed by Koprowski and Cox were more neurotropic in monkeys than the Sabin strains, only the latter was licensed in the USA in 1961 and endorsed shortly after by the World Health Organization (WHO). The widespread use of Sabin's OPV in many countries hastened the development of International Requirements by WHO for OPV in 1962 to define the criteria that ensured the uniformity of batches produced by different manufacturers. These have been updated continuously in light of new information and quality control procedures. Extensive field trials have shown the risk of OPV associated polio to be less than 0.3 per million doses administered.     

Systematic Review of Mucosal Immunity Induced by Oral and Inactivated Poliovirus Vaccines against Virus Shedding following Oral Poliovirus Challenge

Inactivated poliovirus vaccine (IPV) may be used in mass vaccination campaigns during the final stages of polio eradication. It is also likely to be adopted by many countries following the coordinated global cessation of vaccination with oral poliovirus vaccine (OPV) after eradication. The success of IPV in the control of poliomyelitis outbreaks will depend on the degree of nasopharyngeal and intestinal mucosal immunity induced against poliovirus infection. We performed a systematic review of studies published through May 2011 that recorded the prevalence of poliovirus shedding in stool samples or nasopharyngeal secretions collected 5–30 days after a “challenge” dose of OPV. Studies were combined in a meta-analysis of the odds of shedding among children vaccinated according to IPV, OPV, and combination schedules. We identified 31 studies of shedding in stool and four in nasopharyngeal samples that met the inclusion criteria. Individuals vaccinated with OPV were protected against infection and shedding of poliovirus in stool samples collected after challenge compared with unvaccinated individuals (summary odds ratio [OR] for shedding 0.13 (95% confidence interval [CI] 0.08–0.24)). In contrast, IPV provided no protection against shedding compared with unvaccinated individuals (summary OR 0.81 [95% CI 0.59–1.11]) or when given in addition to OPV, compared with individuals given OPV alone (summary OR 1.14 [95% CI 0.82–1.58]). There were insufficient studies of nasopharyngeal shedding to draw a conclusion. IPV does not induce sufficient intestinal mucosal immunity to reduce the prevalence of fecal poliovirus shedding after challenge, although there was some evidence that it can reduce the quantity of virus shed. The impact of IPV on poliovirus transmission in countries where fecal-oral spread is common is unknown but is likely to be limited compared with OPV.     

Polio antibody outfit of newborns and infants born after 20 years of mass vaccination with live poliovaccine

Antibodies against type 1 and 2 poliovirus were tested in 250 infants and against type 3 poliovirus in 341 infants aged 0-13 months to compare the polio antibody outfit of newborns and infants born to three groups of mothers: (a) nonvaccinated, above 35 years of age; (b) vaccinated with attenuated poliovirus but having had chance of contact with wild poliovirus during childhood, age 22-35 years, and (c) vaccinated but not having had contact with wild poliovirus, below 22 years of age. Over 90% of newborns had specific neutralizing antibodies against all three poliovirus types. With increasing infant age the percentage of antibody-positive infants decreased: by age 9-11 months only 46%, 27% and 14% of infants displayed antibodies to polio-virus types 1, 2 and 3, respectively. Geometric mean titres decreased accordingly. Differences between infants born to mothers of the above three groups were nonsignificant: the results obtained suggest that future newborns will also possess satisfactory levels of antibodies acquired from mothers who have only had contact with attenuated vaccine poliovirus.