Protective effects of pertussis immunoglobulin (P-IGIV) in the aerosol challenge model.

Pertussis in infants is often severe, resulting in prolonged hospitalization. Treatment is limited to supportive care. Antibiotics do not significantly alter the course of the disease unless administered during the catarrhal phase. Therapies directed at pertussis toxin, a major virulence factor of Bordetella pertussis, may be beneficial. This study uses the aerosol challenge model to further examine the protective effects of P-IGIV, a new intravenous immunoglobulin product, which has high levels of pertussis toxin antibodies. P-IGIV was prepared as a 4% immunoglobulin G (IgG) solution from the pooled donor plasma from donors immunized with inactivated pertussis toxoid. The IgG pertussis toxin antibody concentration in P-IGIV is >7-fold higher than conventional intravenous immunoglobulin products. In the aerosol challenge model, P-IGIV-treated mice exhibited a dose-dependent decrease in mortality when monitored for 28 days postchallenge. P-IGIV in doses of 2,800, 1,400, and 350 mg/kg significantly reduced mortality compared to saline (P < 0.01)- and human IGIV (P < 0.01)-treated controls. The 50% protective dose of pertussis toxin antibodies in P-IGIV was 147 microg/ml. Recovery of weight gain and normalization of leukocyte counts occurred in all P-IGIV-treated groups but did not exhibit dose-dependent characteristics. Even after 7 days of infection, P-IGIV reversed the effects of pertussis in mice. This study provides further evidence that pertussis toxin antibodies not only play a role in passive protection but can also reverse symptoms of established disease in mice. We feel that P-IGIV deserves further evaluation in children hospitalized with severe pertussis.     

Protection afforded against aerosol challenge by systemic immunisation with inactivated Francisella tularensis live vaccine strain (LVS)

BALB/c mice were immunised with inactivated Francisella tularensis live vaccine strain (LVS) and the level of protection afforded against aerosol challenge with virulent strains of F. tularensis ascertained. Intramuscular (IM) injection of inactivated LVS with an aluminium-hydroxide-based adjuvant-stimulated IgG1-biased LVS-specific antibody responses and afforded no protection against aerosol challenge with subspecies holarctica (strain HN63). Conversely, IM injection of inactivated LVS adjuvanted with preformed immune-stimulating complexes (ISCOMS) admixed with immunostimulatory CpG oligonucleotides afforded robust protection against aerosol-initiated infection with HN63. However, despite a significantly extended time-to-death relative to naïve controls, the majority of mice immunised with the most potent vaccine formulation were not protected against a low-dose aerosol challenge with subspecies tularensis (strain Schu S4). These data indicate that parenterally administered non-living vaccines can be used for effective immunisation against aerosol challenges with subspecies holarctica, although not high virulence strains of F. tularensis.     

DTaP-sIPV联合疫苗中SabinIPV 免疫原性研究

目的 探讨吸附无细胞百白破-Sabin株脊髓灰质炎联合疫苗（DTaP-sIPV）的制备工艺,并比较不同配比的DTaP-sIPV中Sabin株脊髓灰质炎灭活疫苗（SabinIPV）三针基础免疫大鼠的中和抗体效价,为确定联合疫苗的最佳制备工艺及抗原剂量配比提供参考.方法 用不同配比的SabinIPV,制备两批DTaP-sIPV,进行各项指标的检定及稳定性试验,并联合单独的Sabin IPV和GSK制备的DTaP-wIPV对56只Wistar大鼠进行3针免疫,每针间隔1个月,每次免疫后30 d采血并分离血清,采用微量中和试验测定血清中抗脊髓灰质炎病毒3个型别的中和抗体效价.结果 两批DTaPsIPV的各项检定指标均符合〈中国药典〉三部（2005版）要求,且稳定性良好.大鼠经3针基础免疫后,其Ⅰ、Ⅱ、Ⅲ型脊髓灰质炎病毒中和抗体的几何平均滴度均显著上升,3针免疫后抗体阳转率已经达到100%.结论 经此制备的DTaP-sIPV安全、稳定、有效,且DTaP-sIPV中的SabinIPV在大鼠中有良好的免疫效果,经3针免疫可产生高水平的中和抗体.     

Murine aerosol challenge model of anthrax

The availability of relevant and useful animal models is critical for progress in the development of effective vaccines and therapeutics. The infection of rabbits and non-human primates with fully virulent Bacillus anthracis spores provides two excellent models of anthrax disease. However, the high cost of procuring and housing these animals and the specialized facilities required to deliver fully virulent spores limit their practical use in early stages of product development. Conversely, the small size and low cost associated with using mice makes this animal model more practical for conducting experiments in which large numbers of animals are required. In addition, the availability of knockout strains and well-characterized immunological reagents makes it possible to perform studies in mice that cannot be performed easily in other species. Although we, along with others, have used the mouse aerosol challenge model to examine the outcome of B. anthracis infection, a detailed characterization of the disease is lacking. The current study utilizes a murine aerosol challenge model to investigate disease progression, innate cytokine responses, and histological changes during the course of anthrax after challenge with aerosolized spores. Our results show that anthrax disease progression in a complement-deficient mouse after challenge with aerosolized Sterne spores is similar to that described for other species, including rabbits and non-human primates, challenged with fully virulent B. anthracis. Thus, the murine aerosol challenge model is both useful and relevant and provides a means to further investigate the host response and mechanisms of B. anthracis pathogenesis.     

Protective effect of an inactivated avian coronavirus vaccine administered by aerosol

Summary The antigenicity and protective effect of 3 strains of avian infectious bronchitis virus inactivated by beta-propiolactone were studied. Chickens administered 2 doses of the inactivated Connecticut strain (IBV-46) vaccine by aerosol at 3-week intervals had significant levels of virus-neutralizing antibodies and were resistant to infection by the Massachusetts strain (IBV-41) as determined by virus isolation attempts. Antibody levels in chickens given inactivated Iowa 33 and Iowa 609 were not significant and they were not resistant to infection by IBV-41.     

A live, attenuated Bordetella pertussis vaccine provides long-term protection against virulent challenge in a murine model

Despite successful mass vaccination programs, whooping cough remains a significant cause of neonatal mortality. Immunity induced by current vaccines wanes in adolescence, requiring additional immunizations to prevent resurgence. There is a need for a new generation of vaccines capable of conferring long-lasting immunity from birth. Recently, a live, attenuated whooping cough vaccine, BPZE1, has been developed. Here, an established murine immunization model was used to examine the induction and longevity of immunological memory. In this predictive model, BPZE1 conferred a level of protection against virulent bacterial challenge comparable to that conferred by recovery from prior infection, up to 1 year after immunization. One year after immunization with BPZE1, a pertussis-specific persistent response, with high levels of gamma interferon (IFN-γ), could be detected from spleen cells restimulated with inactivated Bordetella pertussis. BPZE1 induced low levels of interleukin-17 (IL-17) and no IL-10 or IL-5. BPZE1 immunization induced long-lasting, efficacious memory B-cell and specific antibody responses dominated by IgG2a, which were boosted by subsequent challenge. Finally, the antibody induced by BPZE1 was functionally relevant and could clear a virulent B. pertussis infection in antibody-deficient mice following passive transfer. This study suggests that BPZE1 is capable of conferring a high level of long-lived effective protection against virulent B. pertussis.     

High dose interleukin-12 exacerbates Bordetella pertussis infection and is associated with suppression of cell-mediated immunity in a murine aerosol challenge model

The in-vivo clearance of Bordetella pertussis infections in murine models in naive mice and animals vaccinated with whole-cell vaccine is considered to be via a Th-1-dependent mechanism in which interleukin-12 (IL)-12 may play a prominent role. It has also been demonstrated clearly that the treatment of animals with macrophage-derived IL-12 administered with an acellular vaccine can increase the efficacy of this vaccine preparation to levels seen with the whole-cell vaccine. However, the effects of exogenously added IL-12 on immune responses in non-vaccinated B. pertussis-challenged mice remain unclear, with two studies giving contradictory findings. In this study we have treated mice with escalating doses of mIL-12 (0.1-10 microg/mouse) prior to challenge with B. pertussis (using an aerosol challenge model of infection). The ability of mice to clear infection was assessed in IL-12 treated and in phosphate buffered saline (PBS) control animals at days 6 and 13 post-challenge. Lymphoid cells were isolated from spleen and cell-mediated immune responses assessed at days 1, 6 and 13 post-challenge. In addition, the direct effects of high-dose IL-12 on challenged mice was assessed by checking natural killer (NK) activity from isolated lung and spleen lymphoid cells as well as interferon-gamma (IFN-gamma) generation from isolated cells and serum at day 1 post-challenge. The results from this study show that bacterial colonization of the lungs is actually enhanced following treatment with high-dose IL-12. This is associated with impaired cellular immune responses. The mechanisms associated with the immunosuppressive effects of IL-12 are discussed.     

Subclass compositions of immunoglobulin G to pertussis toxin in patients with whooping cough, in healthy individuals, and in recipients of a pertussis toxoid vaccine

The subclass composition of serum immunoglobulin G (IgG) antibodies against pertussis toxin was studied in 108 serum samples obtained during various stages of disease from 75 patients with whooping cough. IgG1 and IgG3 antibodies were detected in 92 and 42% of the samples, respectively, while only a few contained IgG2 or IgG4 antibodies. Similarly, IgG1 antibodies were predominant in serum samples from healthy children and adults, many of whom had a history of whooping cough several years earlier. Of 85 children and 30 adults with detectable levels of total IgG, 65 and 14 had IgG1 antibodies, respectively, while only 9 of them had IgG3 antibodies. Again, very few sera contained IgG2 or IgG4 antibodies. In contrast, 13 children vaccinated with an acellular aluminum-adsorbed pertussis toxoid vaccine responded mainly with IgG1 and IgG4 antibodies. In conclusion, this study showed that the subclass composition of IgG antibodies to pertussis toxin after natural infection consists mainly of IgG1 and to a certain extent of IgG3, while an aluminum-adsorbed pertussis toxoid induces IgG1 and IgG4 antibodies.     

候选无细胞百白破-Sabin株灭活脊髓灰质炎联合疫苗在大鼠上的免疫保护效果研究

目的观察候选无细胞百白破-Sabin株灭活脊髓灰质炎联合疫苗(DTaP-sIPV)在大鼠中的免疫保护效果,为疫苗临床前研究提供依据。方法将候选疫苗DTaP-sIPV、无细胞百白破-灭活脊髓灰质炎-b型流感嗜血杆菌联合疫苗(DTaP-IPV/Hib)、吸附无细胞百白破-b型流感嗜血杆菌联合疫苗(DTaP/Hib)、百日咳疫苗效力参考品(全细胞疫苗,wP)按0、30、60 d 3剂免疫程序免疫Wistar大鼠,检测各组大鼠每剂免疫后的血清中各组分抗体水平。在免疫完成后3周,用百日咳18323株通过气雾攻击的方式感染大鼠。在感染后的第3、7、14、21和28天检测各组白细胞数、肺部菌落克隆形成数以及百日咳疫苗组分抗体变化水平。结果候选疫苗组3剂次免疫完成后PT抗体几何平均滴度(GMT,log2)为16.74,FHA抗体GMT为18.44,PRN抗体GMT为10.75,DT抗体GMT为17.34,TT抗体GMT为17.84,针对3种Sabin脊髓灰质炎病毒株(Ⅰ、Ⅱ和Ⅲ型)的抗体的GMT分别为7.57、8.41和9.70,均达到100%阳转。候选疫苗抗原组分抗体除了PRN和I型IPV外,其他组分抗体水平均与疫苗对照组相比无显著性差异。在基础免疫完成后3周对大鼠进行百日咳杆菌气雾攻击,各疫苗组均表现较好的保护效果,白细胞水平都呈现平稳状态,虽然在肺部也检测到少量细菌定植,但各疫苗组间差异不明显,且在感染后第28天都清除至检测限;而空白对照组在肺部则检测到了大量细菌定植,且在感染后第28天都并未清除至检测限,百日咳特异性的FHA和PRN抗体在感染后的第14天也出现了相应的升高。结论候选疫苗在Wistar大鼠模型上具有较好的免疫保护效果。     

Genetic evolution under vaccine pressure: the Bordetella pertussis model

A possible genetic selective pressure related to the long-term use of vaccines has been the object of recent theoretical thought and publications. For more than thirty years, an effective vaccine has been in use against whooping cough on a wide scale basis in several countries. Thus, the Bordetella pertussis model may contribute to the analysis of an evolutionary risk linked to the vaccine. To maintain and improve the control of whooping cough, better vaccination coverage must be achieved in countries where prevalence is low. In countries where high vaccination coverage has been achieved over a long period, a trend toward the resurgence of the disease has been observed. Efforts are therefore now being directed toward primary vaccination and boosters. These two targets require new vaccines with fewer side effects. Outbreaks in highly vaccinated populations have been reported, raising the issues of vaccine efficacy, of the long-term effect of vaccines on the transmission of the disease, and of genetic selective pressure. Time trend modifications of circulating strains related to vaccination practices and vaccine types have been observed and are compatible with a selective pressure of the vaccine on related pathogens. However, evidence for a causal relation is lacking. In order to monitor and understand the various effects the vaccine may be having on the effectiveness of immunisation against whooping cough, further surveillance is needed, integrating a standardised characterisation of circulating strains and vaccines by way of a space-time sampling model.     

Safety and effectiveness study of the aerosol method of administering inactivated influenza chromatographic vaccine in an experiment

Experiments in laboratory animals demonstrated safety, areactogenicity, and low allergenic potential of inactivated influenza chromatographic vaccine (IICV) administered by aerosol method. Aerosol immunization of white rats resulted in the development of the same level of secretory antibody as after intraperitoneal inoculation of IICV but the immunizing aspirational dose was 10-20 times as low as parenteral. Marked protection of mice was achieved after triple aerosol immunization of immunologically experienced animals.     

Time since last vaccine dose in PCR-positive and PCR-negative children with suspected pertussis to monitor pertussis vaccine effectiveness

We evaluated whether the results of diagnostic polymerase chain reaction (PCR) testing combined with time since last vaccine dose could be used to monitor the effectiveness of acellular pertussis vaccines. In 258 consecutive nasopharyngeal swabs from children and adolescents with typical pertussis symptoms, 80 were positive and 178 were negative in PCR for Bordetella pertussis DNA (IS 481). Time since last vaccine dose was available for 152 patients, of which 120 were fully immunised. Among the fully vaccinated patients, the median age of 41 PCR-positive patients was 8.4 years (range 0.9–12.3) and that of 79 PCR-negative cases was 3.3 years (range 0.4–14.1) (p?<?0.01). The median time since last pertussis vaccine dose was 6.05 years [95 % confidence interval (CI): 0.5–10.9] in PCR-positive cases and 2.22 years (95 % CI: 0.04–9.23) in PCR-negative cases (p?<?0.001). The use of diagnostic PCR results from pertussis cases together with time since last vaccine dose permits estimates of the duration of protection after vaccination with acellular pertussis vaccines that are in keeping with more complex studies.     

Resistance of adults to challenge with influenza A wild-type virus after receiving live or inactivated virus vaccine.

The efficacy of live attenuated cold-adapted (ca) reassortant influenza A H3N2 and H1N1 virus vaccines against experimental challenge with homologous wild-type virus 7 months after vaccination was compared with that of licensed inactivated virus vaccine in 106 seronegative (hemagglutination-inhibiting antibody titer less than or equal to 1:8) college students. The live attenuated virus vaccines induced as much resistance against illness as did the inactivated vaccine. Vaccine efficacy, measured by reduction in febrile or systemic illness in vaccines, compared with that in controls was 100% for ca H3N2 vaccine, 84% for inactivated H3N2 vaccine, 79% for ca H1N1 vaccine, and 67% for inactivated H1N1 vaccine. Less protection was conferred against upper respiratory tract illness; there was 50 and 77% protection in ca and inactivated H3N2 vaccines, respectively, but there was no protection in ca or inactivated H1N1 vaccinees. The duration, but not the magnitude, of H1N1 wild-type virus shedding in both ca and inactivated vaccinees was significantly reduced compared with controls. In contrast, a significant reduction in the duration and magnitude of H3N2 virus shedding was observed in ca vaccinees but not in inactivated vaccines. After wild-type virus challenge, live ca virus vaccinees demonstrated resistance at least as great 7 months postvaccination as did inactivated virus vaccinees. These observations indicate that live virus vaccines may be a satisfactory alternative to inactivated vaccines for healthy persons.     

Acellular pertussis vaccine protects against exacerbation of allergic asthma due to Bordetella pertussis in a murine model

The prevalence of asthma and allergic disease has increased in many countries, and there has been speculation that immunization promotes allergic sensitization. Bordetella pertussis infection exacerbates allergic asthmatic responses. We investigated whether acellular pertussis vaccine (Pa) enhanced or prevented B. pertussis-induced exacerbation of allergic asthma. Groups of mice were immunized with Pa, infected with B. pertussis, and/or sensitized to ovalbumin. Immunological, pathological, and physiological changes were measured to assess the impact of immunization on immune deviation and airway function. We demonstrate that immunization did not enhance ovalbumin-specific serum immunoglobulin E production. Histopathological examination revealed that immunization reduced the severity of airway pathology associated with sensitization in the context of infection and decreased bronchial hyperreactivity upon methacholine exposure of infected and sensitized mice. These data demonstrate unequivocally the benefit of Pa immunization to health and justify selection of Pa in mass vaccination protocols. In the absence of infection, the Pa used in this study enhanced the interleukin-10 (IL-10) and IL-13 responses and influenced airway hyperresponsiveness to sensitizing antigen; however, these data do not suggest that Pa contributes to childhood asthma overall. On the contrary, wild-type virulent B. pertussis is still circulating in most countries, and our data suggest that the major influence of Pa is to protect against the powerful exacerbation of asthma-like pathology induced by B. pertussis.     

Characterization of genetically inactivated pertussis toxin mutants: candidates for a new vaccine against whooping cough.

the introduction of two amino acid substitutions within the enzymatically active subunit S1 of pertussis toxin (PT) abolishes its ADP-ribosyltransferase activity and toxicity on CHO cells (Pizza et al., Science 246:497-500, 1989). These genetically inactivated molecules are also devoid of other in vivo adverse reactions typical of PT, such as induction of leukocytosis, potentiation of anaphylaxis, stimulation of insulin secretion, and histamine sensitivity. However, the mutant PT molecules are indistinguishable from wild-type PT in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and maintain all the physical and chemical properties of PT, including affinity for toxin-neutralizing poly- and monoclonal antibodies. Either alone or stabilized with formaldehyde, PT mutants are able to induce high levels of neutralizing antibodies and to protect mice in a dose-dependent fashion against intracerebral challenge with virulent B. pertussis. These results clearly show that these genetically inactivated PT molecules are nontoxic but still immunogenic and justify their development as a component of a new, safer acellular vaccine against whooping cough.     

Bordetella pertussis infection in mice: correlation of specific antibodies against two antigens, pertussis toxin, and filamentous hemagglutinin with mouse protectivity in an intracerebral or aerosol challenge system

The correlation of titers of specific serum immunoglobulin G antibodies against two antigens, pertussis toxin (PT), and filamentous hemagglutinin (FHA), which are the main components of pertussis vaccine in Japan, with mouse protectivity was examined by both intracerebral and aerosol challenge systems with virulent Bordetella pertussis cells. Titer of the antibodies was calculated from the enzyme-linked immunosorbent assay (ELISA) unit given arbitrarily to reference antibodies. PT antibody titer which protected 50% of mice was indistinguishable in both active immunization followed by intracerebral challenge and passive immunization followed by aerosol challenge. The 50% effective dose was 23 ELISA U/ml in the former mice and 24 ELISA U/mouse in the latter. In the intracerebral challenge system, FHA did not elicit a protective response but was very helpful for PT as an immunizing antigen. When anti-FHA immunoglobulin G coexisted with anti-PT immunoglobulin G in mice, the 50% effective dose of PT antibody was 4.4 or 10 ELISA U/mouse in intracerebral or aerosol challenge systems, respectively. In this active immunization system, pertussis toxoid of 1 micrograms or 0.1 microgram/mouse produced PT antibody of ca. 20 or 5 ELISA U/ml, respectively. It was concluded that pertussis toxoid or its antibody was much more potent than Formalin-treated FHA or its antibody; Formalin-treated FHA or its antibody was helpful when it was administered with pertussis toxoid toxoid or its antibody, however.