Porcine reproductive and respiratory syndrome virus infection at the time of porcine circovirus type 2 vaccination has no impact on vaccine efficacy

Several porcine circovirus type 2 (PCV2) vaccines are now commercially available and have been shown to be effective at decreasing the occurrence of porcine circovirus-associated disease (PCVAD). Many herds are coinfected with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV). Some producers and veterinarians are concerned that if pigs are vaccinated for PCV2 at or near the time that they are typically infected with PRRSV, the efficacy of the PCV2 vaccine will be compromised. The impact of PRRSV on PCV2 vaccination is unclear and has not been investigated under controlled conditions. The objective of the present study was to determine whether the presence of PRRSV viremia has an effect on the efficacy of commercial PCV2 vaccinations. Three-week-old PCV2-negative conventional pigs with passively derived anti-PCV2 antibodies were either vaccinated with one of three commercial PCV2 vaccines or left nonvaccinated. A portion of the pigs were infected with PRRSV 1 week prior to PCV2 vaccination. To determine vaccine efficacy, a PCV2 challenge was conducted at 8 weeks of age. PCV2 vaccination, regardless of PRRSV infection status at the time of vaccination, was similarly effective in inducing an anti-PCV2 IgG response in the presence of maternally derived immunity and in protecting the pigs from PCV2 challenge, as determined by a reduction in the level of PCV2 viremia and a reduction in the prevalence and amount of PCV2 antigen in lymphoid tissues in vaccinated pigs compared to nonvaccinated pigs. The results indicate that acute PRRSV infection at the time of PCV2 vaccination has no adverse effect on PCV2 vaccine efficacy.     

水痘-带状疱疹病毒抗原的ELISA定量检测方法的建立

目的:建立水痘-带状疱疹病毒(VZV)抗原的双抗体夹心ELISA定量检测方法,用于质控VZV灭活疫苗研发和生产中抗原含量.方法:以VZV中和单抗5F6C8为包被抗体、8H5D1为酶标抗体,构建定量检测VZV抗原的双抗体夹心ELISA方法,并对本方法的特异性、灵敏度、准确性、线性和稳定性等性能进行分析.结果:建立的双抗体夹心定量检测VZV抗原的ELISA方法,线性范围为0.4 μg～13 μg/ml,相关系数为R2=0.994,定量限度为0.4.μg/ml;变异系数CV＜ 15％、准确性回收率介于87.5％ ～ 111.6％之间,稳定性37℃6天的回收率＞80％.与VZV以外的相关病毒样本没有交叉反应.结论:构建的VZV抗原ELISA定量检测方法的各项性能符合定量检测需要,可用于VZV灭活疫苗的研发和生产过程的抗原含量检测.     

Postlicensure epidemiology of childhood vaccination: the Danish experience

The efficacy, the ability to confer protection against a target disease and the safety of a vaccine are assessed in great detail before licensure. However, inherent limitations in the prelicensure assessment necessitate continued epidemiological evaluations of efficacy and safety issues after the introduction of vaccines into use. In Denmark, the opportunities available for epidemiological research are unique. In 2001, an initiative was undertaken to take advantage of these opportunities to study the postlicensure epidemiology of childhood vaccination with respect to effectiveness and safety. First, we describe the unique opportunities for postlicensure research in Denmark with respect to the data sources available and the epidemiological and statistical methods used. We then describe a number of recent postlicensure studies of effectiveness and safety that took advantage of these opportunities. Specifically, studies on the effectiveness of Haemophilus influenzae type b vaccination, the effectiveness of pertussis vaccination, the impact of a preschool pertussis booster on infant pertussis, measles-mumps-rubella vaccine and autism, thimerosal-containing vaccine and autism, measles-mumps-rubella vaccine and febrile seizures, childhood vaccination and Type 1 diabetes, and childhood vaccination and nontargeted infectious disease are discussed.     

Pathophysiology of environmental enteric dysfunction and its impact on oral vaccine efficacy

Environmental enteric dysfunction (EED) refers to a subclinical disorder of intestinal function common in tropical countries and in settings of poverty and economic disadvantage. The enteropathy that underlies this syndrome is characterized by mucosal inflammation and villus blunting mediated by T cell activation. Epithelial cell disruption and microbial translocation drive systemic inflammation. EED in young children is associated geographically with growth failure, malnutrition, and greatly impaired responses to oral vaccines, notably rotavirus and poliovirus vaccines. In this review, we describe the pathophysiology of EED and examine the evidence linking EED and oral vaccine failure. This evidence is far from conclusive. Although our understanding of EED is still sketchy, there is limited evidence of disturbed innate immunity, B cell disturbances including aggregation into lymphoid follicles, and autoantibody generation. Pathways of T cell activation and the possibility of dendritic cell anergy, which could help explain oral vaccine failure, require further work.     

Varicella zoster virus: vaccination and implications in children with renal failure

The varicella zoster virus is associated with significant disease in those with chronic kidney disease, both pre- and postrenal transplantation. With the advent of the varicella vaccine, the opportunity to prevent significant morbidity and mortality exists. Despite the secondary immune defects associated with renal failure, the varicella vaccine has been demonstrated to be immunogenic, safe and efficacious in pediatric patients with kidney disease.     

Influence of vaccine deposition site on post-vaccinal viraemia and vaccine efficacy in broiler chickens following in ovo vaccination against Marek's disease

In ovo vaccination against Marek's disease is a widely used technology in the broiler industry.A series of experiments was carried out to determine the site of vaccine deposition in the egg during automated in ovo vaccination, and the effect of vaccine deposition site and dose on vaccine responses following vaccination with cell-associated herpesvirus of turkeys in commercial broiler chickens. Vaccine deposition site following automated in ovo vaccination was principally influenced by the age of embryo, with egg size having a smaller effect. The frequency of vaccine deposition inside the embryo body increased as incubation progressed from day 17.5 to 19.5. In experiments using manual vaccine deposition intra-embryonically (IE) or extra-embryonically (EE) at day 18.5, EE vaccine deposition resulted in a significantly delayed development of post-vaccinal viraemia relative to both IE vaccination and subcutaneous vaccination at hatch. There were no effects of vaccine dose (2000, 4000 or 8000 plaque forming units) on the timing of post-vaccinal viraemia. The timing of post-vaccinal viraemia was found to be a good indicator of the level of protection provided by the vaccine against challenge with earlier viraemia associated with better protection. IE vaccine deposition induced significantly greater protection than EE deposition against challenge with a virulent strain of Marek's disease virus. IE deposition consistently produced a high level of protection (68 to 84%) irrespective of vaccine dose or challenge day, while EE vaccine deposition produced no or low levels of protection (0 to 27%) depending on the vaccine dose and day of challenge. The growth of challenged chickens was also affected by site of vaccine deposition, with significantly higher live weights at day 56 of age in IE compared with EE vaccinated groups. These data suggest that the site of vaccine deposition within the embryo is an important determinant of the success of in ovo vaccination.     

Varicella vaccination in pediatric oncology patients without interruption of chemotherapy

BackgroundMorbidity and mortality from primary varicella-zoster virus (VZV) infection is increased in immunocompromised children. Vaccination of VZV-seronegative cancer patients with live-attenuated varicella vaccine is safe when chemotherapy is interrupted. However, VZV vaccination without interruption of chemotherapy would be preferable.ObjectiveTo vaccinate VZV-seronegative pediatric oncology patients with live-attenuated VZV vaccine without interrupting their chemotherapy.Study-designWe performed a single-center prospective cohort study.ResultsThirty-one patients with either a hematological malignancy (n = 24) or a solid tumor (n = 7) were vaccinated early during their course of chemotherapy. VZV IgG seroconversion occurred in 14 of the 31 patients (45%) after one vaccination. Only 20 patients were revaccinated after 3 months. These were patients who did not seroconvert (5 patients) and patients who serocoverted (15 patients) to induce or sustain seropositivity. Of these 20 patients the final seroconversion rate was 70%. Seven out of the 31 patients (23%) developed a mild rash of which 5 were treated with antivirals and recovered completely without interrupting chemotherapy, and 2 recovered untreated. Of these 31 immunized patients 26 were available for cellular testing. After one vaccination 20 of 26 patients (77%) tested positive for VZV-specific CD4⁺ T cells, of which 7 patients had remained VZV-seronegative. After the second vaccination 11 of 11 patients showed VZV-specific CD4⁺ T cells to sustain positivity, although 4 remained VZV-seronegative.ConclusionsThis study indicates that live-attenuated VZV vaccine can be safely administered to closely monitored pediatric oncology patients without interruption of chemotherapy and adaptive immunity was induced despite incomplete seroconversion.     

水痘-带状疱疹病毒疫苗株ORF62碱基突变及ORF62编码IE62反式激活力的分析

目的 分析水痘-带状疱疹病毒(VZV)疫苗株(vOka)ORF62碱基突变及ORF62编码即刻早期蛋白(IE62)对VZV基因启动子的反式激活力.方法 分别以vOka及其亲本株(pOka)基因组DNA为模板,PCR扩增获得ORF62全序列,克隆到高效表达质粒pCAGGS中构建vOka和pOka ORF62表达质粒;采用双脱氧核苷酸链末端终止法对表达质粒中ORF62测序;应用基因转染瞬时表达技术比较vOka和pOka IE62在MeWo和CV1细胞中对VZV基因启动子的反式激活力差别.结果 成功构建vOka和pOka ORF62表达质粒pCAG-vOka62和pCAG-pOka62;测序结果发现,与pOka比较,vOka ORF62至少有9个碱基突变,其中106262、107136和107262位点碱基突变后分别产生Sma Ⅰ、BssH Ⅱ和Nae Ⅰ酶切位点.vOka IE62在MeWo细胞中对ORF4、ORF10和ORF61启动子的反式激活力低于pOka IE62,但在CV1细胞中对ORF9启动子的反式激活力高于poka IE62.结论 利用vOka ORF62碱基突变产生的酶切位点可鉴别vOka和pOka,vOka和poka IE62对VZV基因启动子的反式激活力差别可能与转染细胞类型有关.     

Varicella seroprevalence and molecular epidemiology of varicella-zoster virus in Argentina, 2002

There is limited data on immunity against varicella-zoster virus (VZV) in adults in different parts of Argentina, and it is not known which VZV strains are circulating in Argentina. The objectives of this study were as follows: (i) to evaluate seroprevalence of varicella among adults, assessing the accuracy of clinical history and determining the sociodemographic factors associated with seropositivity; and (ii) to determine the VZV strains circulating in Argentina. A cross-sectional serological survey enrolling 2,807 women aged 15 to 49 years attending public health-care settings in four cities in Argentina (i.e., Buenos Aires, Salta, Mendoza, and Rosario) and one rural area was conducted from August to November 2002. Specimens for identification of VZV strains were obtained from vesicular lesions from 13 pediatric patients with varicella from different areas of the country. PCR amplification was used for genotyping. The overall seroprevalence of varicella antibodies was 98.5% (95% confidence interval, 98.0 to 98.9), ranging from 97.2% in central Buenos Aires to 99.3% in southern Buenos Aires and Salta. Varicella seroprevalence increased with age. Crowding and length of residence in the same place were associated with seropositivity. The positive predictive value of varicella history for immunity to varicella was 99.4%; however, the negative predictive value was 2.5%. The European genotype was identified in all viral specimens. In Argentina, seroprevalence in women more than 15 years old was high regardless of the area of residence. Negative or uncertain varicella history was not a good predictor of immunity. VZV genotype was stable in all areas of the country.     

Varicella vaccination of children in the United States: assessment after the first decade 1995-2005.

Live attenuated varicella vaccine (strain Oka) was approved for administration to healthy children in the United States in 1995. Over the past 10 years, varicella vaccine has been given to millions of children, usually at ages between 12 and 18 months. In states such as California, Michigan, and Texas, there has been a marked decline in the number of reported cases of varicella. Furthermore, there has been a 75% decrease in varicella-related hospitalizations across the United States, as well as a similar decrease in the number of deaths caused by complications of chickenpox. The main unanticipated result has been a growing number of outbreaks of varicella among immunized children ("breakthrough varicella"). The most cited risk factors for breakthrough varicella include the following: (1) 3-5-year interval since immunization and (2) immunization at the youngest ages, especially 12 months. Explanations for breakthrough varicella include a lessened immune response among the youngest recipients of the vaccine. Another possibility is genetic variation among circulating VZV strains. VZV strains can be separated into two geographic clades called European/North American and Asian, based on single nucleotide polymorphisms. Two mutant North American strains have been isolated from patients in the last 10 years. Several genomic differences between Oka vaccine strain and other strains have also been identified, including one site at the DNA origin of replication. Since breakthrough disease among vaccine recipients appears to be more common in the United States than in Japan, further comparisons between the varicella vaccination programs in Japan and the United States are warranted. In addition, data from varicella vaccination programs in Europe should provide further insight into the effectiveness of varicella vaccination in different geographic and ethnic populations.     

Animal studies on the efficacy of vaccination against recurrent herpes

Guinea pigs, latently infected with herpes simplex virus type 2 (HSV 2), were immunized with an HSV 2 vaccine derived from extracts of infected cells and either formol inactivated or detergent treated. Although such postinfection vaccination could significantly increase the titers of neutralizing anitbodies, it had no effect on the course of recurrent herpes in these animals.     

IL-15增强小鼠卵透明带3DNA疫苗的滴鼻免疫效果

目的:观察以细胞因子IL-15作为DNA疫苗的免疫佐剂,壳聚糖作为发送载体,增强经滴鼻途径接种的小鼠卵透明带3(mZP3)DNA疫苗的免疫效果。方法:将壳聚糖包裹的mZP3 DNA疫苗(pcD-mZP3)单独或IL-15+pcD-mZP3通过滴鼻途径免疫雌性C57BL/6 36只小鼠后。用ELISA法检测小鼠体内特异性抗mZP3抗体IgG和sIgA的水平。免疫后的雌鼠和有生育能力的雄鼠合笼后进行生育实验。观察小鼠免疫和生育后的肺脏和卵巢病理切片。结果:ELISA法检测结果显示,IL-15能够增加免疫小鼠抗mZP3 IgG的水平,生育率有一定的下降。结论:IL-15与壳聚糖可以增强mZP3DNA疫苗诱导的抗体水平,可一定程度上降低小鼠的生育率。     

The impact of European vaccination policies on seasonal influenza vaccination coverage rates in the elderly

Despite strong recommendations, seasonal influenza vaccination coverage rates (VCRs) remain limited in Europe, even in high-priority groups. There is a need for understanding the impact of vaccination-related policy elements and barriers toward vaccination. We aimed at assessing essential elements of vaccination policies and the influence of policy-related driving factors on VCRs among elderly. Sixteen European National Vaccine Industry Groups (NVIGs) were included in a survey to make an inventory of vaccination policies implemented at national level (2009). The questionnaire was structured around four topics: management of vaccination programs; influence of health care workers (HCWs); role of information/ communication campaigns; and access to vaccine. The information retrieved was put in relation to current VCRs among the elderly (≥65 y). Correlation coefficients between policy elements and vaccination rates were calculated. Several policy elements may be suitable to increase influenza vaccination uptake in the elderly, but only few countries make use of all alternatives. Countries with good monitoring systems regarding vaccine uptake rates (Spearman's rho = 0.639, p = 0.010) or sending personal letters offering free vaccination (Sp = 0.728, p = 0.002) showed on average higher coverage among the elderly than countries with less developed vaccine management systems. The presence of additional policy elements (setting national objectives, HCW incentives, vaccination reimbursement systems, awareness campaigns and clear VCR objectives) led to numerically increased VCRs. The presence of several elements of vaccination policies at national level, including broad information and reminding systems, strong official recommendations and good access to the vaccine may help to achieve improved influenza vaccine coverage rates among elderly.     

Effect of previous vaccination with pneumococcal conjugate vaccine on pneumococcal polysaccharide vaccine antibody responses

During the past 10 years, pneumococcal conjugate vaccine (PCV) has become part of the standard childhood vaccination programme. This may impact upon the diagnosis of polysaccharide antibody deficiency by measurement of anti‐polysaccharide immunoglobulin (Ig)G after immunization with unconjugated pneumococcal polysaccharide vaccine (PPV). Indeed, contrary to PPV, PCV induces a T‐dependent, more pronounced memory response. The antibody response to PPV was studied retrospectively in patients referred for suspected humoral immunodeficiency. The study population was divided into four subgroups based on age (2–5 years versus ≥ 10 years) and time tested (1998–2005 versus 2010–12). Only 2–5‐year‐old children tested in 2010–12 had been vaccinated with PCV prior to PPV. The PCV primed group showed higher antibody responses for PCV–PPV shared serotypes 4 and 18C than the unprimed groups. To a lesser extent, this was also found for non‐PCV serotype 9N, but not for non‐PCV serotypes 19A and 8. Furthermore, PCV‐priming elicited a higher IgG2 response. In conclusion, previous PCV vaccination affects antibody response to PPV for shared serotypes, but can also influence antibody response to some non‐PCV serotypes (9N). With increasing number of serotypes included in PCV, the diagnostic assessment for polysaccharide antibody deficiency requires careful selection of serotypes that are not influenced by prior PCV (e.g. serotype 8). Further research is needed to identify more serotypes that are not influenced.