Induction of mucosal and systemic humoral immune responses in murine system by intranasal immunization with peptide antigens of P. vivax and CpG oligodeoxynucleotide (ODN) in microparticle delivery

In the present study we have investigated the immunomodulatory effects of two adjuvants, CpG 1826 (two copies of CpG motifs) and CpG 2006 (three copies of CpG motifs) to the five peptide antigens of Plasmodium vivax derived from circumsporozoite protein (CSP), merozoite surface protein-1 (MSP1#1, MSP1#23), apical membrane antigen-1 (AMA-1) and gametocyte surface antigen (Pvs24) in alum and microparticle formulations, using intramuscular and intranasal routes of immunization. Alum formulation without CpG ODN generated low serum IgG and IgA antibody titers and the predominant IgG isotypes were IgG1 but with the addition of CpG ODN (1826 or 2006), the antibody titers were increased by four fold with the predominance of IgG2a/2b isotypes. The SIgA peak titers in lung and intestinal washes were significantly increased with the intranasal mode of administration. Specific activity measurement was done to calculate for the accurate amounts of total serum IgG, IgA and SIgA in washes and showed direct correlation between antibody titer and its concentration. High titer anti-Pvs24 antibodies have significant inhibitory effects on parasite development in the mosquito midgut when tested in membrane feeding assays. The immunofluorescence results show that the peptide specific antisera reacted with the air-dried parasite antigens isolated from P. vivax patients. The present study demonstrates that intranasal route of immunization appears to be an alternate mode of inducing protective immunity in P. vivax malaria.     

免疫规划策略与艾滋病防制

文章作者结合免疫规划多年的实践经验,探讨防控艾滋病的有效措施。与免疫规划策略作对照,建议将免疫规划的成熟经验与手段应用在艾滋病防控中。     

1999—2007年保定市麻疹流行病学特征分析

目的了解保定市1999-2007年麻疹发病情况,分析流行原因。方法对1999—2007年麻疹监测数据进行描述流行病学分析。结果保定市1999-2007年麻疹监测系统共报告麻疹疑似病例4591例,确诊3033例,年均发病率为3．17／10万;1999—2002年,发病率维持在0．5／10万左右,从2003年开始发病率有所回升,2006年达11．73／10万。病例呈散发分布,有明显季节性高峰,3～5月份病例占全年的68．13％,男性发病高于女性,发病年龄有向大年龄和未到免疫年龄人群转移的趋势,麻疹病例中有免疫史、无免疫史和免疫史不详的分别占24．58％、38．15％和37．27％。结论保定市近几年麻疹发病有回升的趋势,8月龄以下儿童发病问题需进行免疫策略研究。     

无锡市乙型肝炎防制和成人免疫策略研究

目的阐述无锡市乙型肝炎发病特点,开展成人乙肝免疫策略研究。方法收集无锡市19年乙型肝炎年发病率和新生儿乙肝疫苗接种率,用横断面整群抽样的方法选择城区二个调查点、部分幼儿园和中小学校学生,开展入户问卷调查,采集空腹血样,用ELISA方法检测乙肝抗-HBs。结果19年乙肝发病率下降趋势明显,新生儿乙肝疫苗接种率保持在98%以上,20岁以上年龄组人群乙肝疫苗接种率经标化后为20.20%,2007年全人群标化后的乙肝抗-HBs阳性率为46.00%,其中15岁年龄组乙肝抗-HBs阳性率为30.77%,乙肝发病率以20～40岁年龄组为高峰。结论无锡市乙肝防制工作成效显著,但成人发病率仍较高,成人乙肝疫苗接种率低,全人群乙肝免疫水平低,对15岁以下儿童补种乙肝疫苗和成人开展乙肝免疫策略研究意义重大。     

Transcutaneous immunization with a synthetic hexasaccharide-protein conjugate induces anti-Vibrio cholerae lipopolysaccharide responses in mice

Antibodies specific for Vibrio cholerae lipopolysaccaride (LPS) are common in humans recovering from cholera, and constitute a primary component of the vibriocidal response, a serum complement-mediated bacteriocidal response correlated with protection against cholera. In order to determine whether transcutaneous immunization (TCI) with a V. cholerae neoglycoconjugate (CHO-BSA) comprised of a synthetic terminal hexasaccharide of the O-specific polysaccharide of V. cholerae O1 (Ogawa) conjugated with bovine serum albumin (BSA) could induce anti-V. cholerae LPS and vibriocidal responses, we applied CHO-BSA transcutaneously in the presence or absence of the immune adjuvant cholera toxin (CT) to mice. Transcutaneously applied neoglycoconjugate elicited prominent V. cholerae specific LPS IgG responses in the presence of CT, but not IgM or IgA responses. CT applied on the skin induced strong IgG and IgA serum responses. TCI with neoglycoconjugate did not elicit detectable vibriocidal responses, protection in a mouse challenge assay, or stool anti-V. cholerae IgA responses, irrespective of the presence or absence of CT. Our results suggest that transcutaneously applied synthetic V. cholerae neoglycoconjugate is safe and immunogenic, but predominantly induces systemic LPS responses of the IgG isotype.     

Development of a live-attenuated influenza B ΔNS1 intranasal vaccine candidate

We discovered a unique, single amino acid mutation in the influenza B M1 protein promoting viral growth of NS1 truncation mutants in Vero cells. Due to this mutation, we were able to generate an influenza B virus lacking the complete NS1 open reading frame (ΔNS1-B virus) by reverse genetics, which was growing to titers of 8 log₁₀ TCID₅₀/ml in a Vero cell culture-based micro-carrier fermenter. The ΔNS1-B vaccine candidate was attenuated in IFN-competent hosts such as human alveolar epithelial cells (A549) similar to influenza A ΔNS1 viruses. In ferrets, the ΔNS1-B virus was replication-deficient and did not provoke any clinical symptoms. Importantly, a single intranasal immunization of ferrets at a dose as low as 6 log₁₀ TCID₅₀/animal induced a significant HAI response and provided protection against challenge with wild-type influenza B virus. So far, the lack of a ΔNS1-B virus component growing to high titers in cell culture has been limiting the possibility to formulate a trivalent vaccine based on deletion of the NS1 gene. Our study closes this gap and paves the way for the clinical evaluation of a seasonal, trivalent, live replication-deficient ΔNS1 intranasal influenza vaccine.     

Redesigned immunization card and center-based education to reduce childhood immunization dropouts in urban Pakistan: a randomized controlled trial

In Pakistan during 2000-2004, about 11-13% of children who received the first dose of diphtheria-pertussis-tetanus (DPT1) failed to complete its third dose (DPT3). We assessed the effect of a redesigned immunization card and center-based education to mothers on DPT3 completion. We enrolled 1500 mother-child units at DPT1, randomized them to three intervention and one standard care groups, and recorded their DPT3 visits during a 90-day follow-up. In multivariable analysis, a significant increase of 31% (adjusted RR=1.31, 95% CI=1.18-1.46) in DPT3 completion was estimated in the group that received both redesigned card and center-based education compared with the standard care group.     

Delivery to the lower respiratory tract is required for effective immunization with Newcastle disease virus-vectored vaccines intended for humans

Newcastle disease virus (NDV), an avian virus, is being evaluated for the development of vectored human vaccines against emerging pathogens. Previous studies of NDV-vectored vaccines in a mouse model suggested their potency after delivery by injection or by the intranasal route. We compared the efficacy of various routes of delivery of NDV-vectored vaccines in a non-human primate model. While delivery of an NDV-vectored vaccine by the combined intranasal/intratracheal route elicited protective immune responses, delivery by the subcutaneous route or the intranasal route alone elicited limited or no protective immune responses, suggesting the necessity for vaccine delivery to the lower respiratory tract. Furthermore, direct comparison of a vaccine based on an NDV mesogenic strain (NDV-BC) with a similarly designed NDV vector based on a modified lentogenic strain carrying a polybasic F cleavage site (NDV-VF) suggested that the two NDV strains were similar in immunogenicity and were equally protective.     

Pulmonary delivery of DNA encoding Mycobacterium tuberculosis latency antigen Rv1733c associated to PLGA–PEI nanoparticles enhances T cell responses in a DNA prime/protein boost vaccination regimen in mice

During persistent infection and hypoxic-stress, Mycobacterium tuberculosis (Mtb) expresses a series of Mtb latency antigens. The aim of this study was to evaluate the immunogenicity of a DNA vaccine encoding the Mtb latency antigen Rv1733c and to explore the effect of pulmonary delivery and co-formulation with poly (d,l-lactide-co-glycolide) (PLGA)–polyethyleneimine (PEI) nanoparticles (np) on host immunity. Characterization studies indicated that PLGA–PEI np kept their nanometer size after concentration and were positively charged. The np were able to mature human dendritic cells and stimulated them to secrete IL-12 and TNF-α comparable to levels observed after lipopolysaccharide (LPS) stimulation. Mtb latency antigen Rv1733c DNA prime combined with Rv1733c protein boost enhanced T cell proliferation and IFN-γ secretion in mice in response to Rv1733c and Mtb hypoxic lysate. Rv1733c DNA adsorbed to PLGA–PEI np and applied to the lungs increased T cell proliferation and IFN-γ production more potently compared to the same vaccinations given intramuscularly. The strongest immunogenicity was obtained by pulmonary priming with np-adsorbed Rv1733c DNA followed by boosting with Rv1733c protein. These results confirm that PLGA–PEI np are an efficient DNA vaccine delivery system to enhance T cell responses through pulmonary delivery in a DNA prime/protein boost vaccine regimen.     

Evidence of effectiveness from a large county-wide school-based influenza immunization campaign

A school-based campaign in Knox County, TN immunized 41% and 48% of school children with live attenuated influenza vaccine in 2005 and 2006, respectively. We computed the relative risk (RR) of a positive rapid influenza test in Knox compared to Knox-surrounding county children (controls) during five baseline and two campaign seasons. Among children aged <5 years, the RR for a positive test remained relatively constant throughout the study seasons. Among children aged 5–17 years (target population), the RR was 1 during baseline and declined by 21% (RR, 0.79; 95% CI, 0.59–1.05) and 27% (RR, 0.73; 95% CI, 0.60–0.87) during the first and second campaign season, respectively. These findings suggest a direct beneficial effect of the immunization campaign.