Procedia in vaccinology最新文献

Salmonella have many advantages as a vaccine delivery vector, they are easy to produce, easy to administer (orally), and able to elicit humoral immunity which induces serum and secretory IgA antibody. In addition, they induce robust cell-mediated immune responses such as cytotoxic and memory T lymphocytes. Moreover, when Salmonella is being used as a vaccine vector, immune responses against both Salmonella and the heterologous antigen will be induced, providing protection against infection by Salmonella and the heterologous pathogen. In this study, Salmonella STM-1, an attenuated strain which was developed at RMIT and licensed for the prevention of salmonellosis in poultry, is used as a delivery vector for an influenza antigen. Different strategies are used to display the influenza hemagglutinin (HA) antigen in various destinations to optimise protein expression and immunogenicity. Comparing the immune responses in a mouse trial, mice which were vaccinated with Salmonella to express the HA protein inside cell (under the control of the starvation induced S. enterica sspA promoter) did not show robust T cell and humoral responses in comparison to mice vaccinated with HA protein expressed in yeast. Therefore other systems are being engineered, including one to display the HA antigen on the outer membrane of Salmonella and another to secrete it into the media. Directing heterologous antigen for surface display or secretion may increase humoral responses. Expression of HA protein in these systems was detected by western blot analysis. An animal trial is underway to examine the immunogenicity of these promising systems.

Prevention and control of rabies in the world will require international efforts to increase the availability and use of high quality cell-culture rabies vaccines for use in human and veterinary. An important aspect of activities to ensure such availability is transfer of technologies to developing countries for production of these vaccines. Methods for Rabies Virus manipulation have changed fundamentally from random attenuation to defined modifications. In 2001, WHO issued a resolution for the complete replacement of nerve tissue vaccines by 2006 with cell-culture rabies vaccines. However, sheep brain derived Fermi type rabies vaccine is still being manufactured and utilized for the majority of exposed patients in Ethiopia. Therefore, production of a safer and effective cell culture based anti-rabies vaccine is needed. Currently the Ethiopian government has heavily invested in upgrading the facilities required to produce a rabies vaccine in keeping with WHO recommendation. Rabies virus suspensions were obtained from vero cells cultivated on roller bottles after infection with the Pasteur virus strain (PV) and Evelyn Rokitniki Abelseth (ERA). Initially the titer of the obtained virus and multiplicity of infection of the viruses had to be optimized; therefore in rabies virus infected cultures, higher virus yields was obtained when infected with 0.001ERA virus/cell and incubated at 37 °C in 5% CO₂ for 96hr and 0.01PV/cell incubated at 37 °C in 5% CO₂ for 48hr. Based on the results it is conclude that, ERA virus 0.001ID/cell with incubation period of 96 h and was selected as best titer for rabies vaccine production.

For the sake of exploring a safe and effective immune potentiator to promote the immune responses of swine to Pseudorabies vaccine, the chitosan nanoparticles (CNP) were prepared by use of ionotropic gelation method to encapsulate the recombinant VR1020 eukaryotic plasmids which respectively containing pig interleukin-6 gene (VPIL6) and the combination of PIL-6 gene and immunostimulatory sequences consisted of 11 CpG motifs (VPIL6C), designated respectively as VPIL6-CNP and VPIL6C-CNP. Then forty 21-day-old hybrid piglets were divided into four groups and intramuscularly injected respectively with 0.5 mg the VPIL6C-CNP, VPIL6-CNP, CpG and VR1020- CNP together with the attenuated Pseudorabies vaccine. The bloods were collected from the vaccinated piglets to detect the changes of immunoglobulin, specific antibody, IL-2, IL-4, IL-6, IFN-γ and immune cells. The results were found that in comparison with the control groups with VR1020-CNP, the content of immunoglobulin, and specific antibody significantly increased in the sera from the VPIL6C-CNP and VPIL6-CNP groups from 14 to 56 days post inoculation (P<0.05), and so did the level of IL-2, IL-4, IL-6 and IFN-γ of the treated groups. Meanwhile, the number of lymphocytes and monocytes also markedly elevated in the treated groups (P<0.05). The immune responses of VPIL6C-CNP piglets were notably stronger than group VRIL6-CNP and VRCpG. These suggested that VPIL6C-CNP could significantly enhance the immunity of piglets to Pseudorabies vaccine and is a promising effective adjuvant to promote the protection of pig against Pseudorabies.

The novel reco mbinant euka ryotic VRPIL4/ 6 p lasmid, the secretory VR1020 vector containing fused pig IL-6 and IL-4 genes, was encapsulated with chitosan nanoparticles (CNP) prepared by use of ionotropic gelat ion method and then used to inoculate intramuscularly forty 14-day-old piglets using 0.5, 1.0 or 1.5 mg/per anima l, which were simu ltaneously injected with inactivated Mycoplasma hyopneumoniae vaccine and challenged on 10 weeks post vaccination, which were designated as group A1, A2 and A3. Blood was collected every two weeks fro m the piglets after vaccination to detect the changes in immunoglobulin, specific antibod y, IL-2, IL-4, IL-6, IFN-γ and immune ce lls. Co mpared to the control piglets with VR1020-CNP, the concentration of Ig G, IgA and IgM, specific antibody, interleukins and IFN-γ significantly increased in the sera of the groups treated with the fusion genes fro m 14 to 70 days after vaccination (P<0.05); furthermore, the nu mber of T_H, T_C and CD3⁺ T ce lls was raised significantly in the blood of the treated piglets (P<0.05). Meanwhile, the ly mphocytes and monocytes also significantly rose in the treated groups (P<0.05). The hu mora l and ce llu lar immune inde xes of the A3 group increased to different e xtents in co mparison with those of A 1 and A 2 group fro m 14 to 56 days post inoculation (P>0.05 or P<0.05). The protection against challenge with viru lent M hyo and growth performance of the treated pigs is markedly better than those of the control anima l (P<0.05). These results indicated that VRPIL4/6 entrapped with CNP can enhance the humora l and cellu lar immunity of pigs to Mycoplasma hyopneumoniae vaccine, and elevate the immunoprotection level of treated anima l, wh ich could facilitate the development of effective immunoadjuvant against Mycoplasma hyopneumoniae of pig.

Water-in-mineral oil adjuvants induce a strong long-term humoral immune response and are widely used in poultry vaccines. New adjuvants that also increase the cellular immune response could help to extend the vaccinal cross- protection against different viral strains or serotypes. We have developed a new water-in-oil adjuvant, Montanide^TM ISA 71 VG, based on a specific enriched light mineral oil which stimulates both humoral and cellular immune responses. Here, using a Newcastle Disease vaccine model, we demonstrate that this new adjuvant is safe, can improve vaccine efficacy in poultry and could allow the reduction of injection doses of inactivated poultry vaccines.

The RV144 efficacy trial conducted in Thailand provided the first evidence that an HIV vaccine could provide a modest level of protection against HIV acquisition (31.2% at 42 months of follow-up) in populations at low risk for HIV infection. Vaccine efficacy appeared to be higher (60%) at 12 months post vaccination, suggesting an early, but nondurable, vaccine effect. This breakthrough finding led to identification of immune correlates of risk, antibodies directed against the V2 loop, paving the way to new vaccine designs and clinical trials to better characterization of the vaccine-induced adaptive and innate humoral and cell-mediated immune responses in peripheral and mucosal compartments. Whether the RV144 correlates of risk are universal and apply to other populations at higher risk for HIV acquisition and other modes of transmission (rectal, injecting drug users) is unknown and remains to be explored. Future efficacy trials using a similar vaccine concept tested in high-risk heterosexual populations and in men having sex with men are planned.

Porcine circovirus associated diseases (PCVADs) are economically important diseases of domestic pigs caused by porcine circovirus type 2 (PCV2). PCV2 vaccination is usually performed with adjuvanted inactivated formulations and is necessary to control PCVADs and subclinical PCV2 related body weight losses in pig farming. An important issue with PCV2 vaccine formulation is that PCV2 antigenic media often have properties which destabilize vaccine formulations. Vaccine adjuvants are a key parameter in modern vaccination closely linked to galenic properties of vaccine formulations, and galenic stability is necessary to insure efficacy stability during vaccine shelf life. Here we show that especially designed formulations based on Montanide^TM ISA 11R VG (Oil in water) and Montanide^TM ESSAI Gel R (polymer) adjuvants are able to resist to very destabilizing antigenic media and conditions while keeping safety parameters and efficacy at requested levels.

Campylobacter jejuni is a gram negative bacterium which is one of the leading causes of bacterial related acute entritis in the developing world. C. jejuni is also linked to auto- immune diseases such as Miller- Fisher syndrome and Guillain- Barre Syndrome. C. jejuni is highly effective in colonizing chicken intestinal mucosa without causing any clinical symptoms and the consumption of poultry meat is the major source of transmission of bacteria to humans. One of the approaches to reduce Campylobacter related illnesses is to reduce the burden of Campylobacters in chickens. This can be achieved by vaccinating chickens against Campylobacter; however, various approaches to develop a vaccine against Campylobacter have yet to yield a commercial vaccine. One approach to develop a new class of vaccines against Campylobacter or other pathogens is to use an attenuated Salmonella autotrophic mutant as a vector to deliver antigens of Campylobacter origin to chickens. Our results indicate that Salmonella mutants can be effectively used as vector to deliver antigens of Campylobacter origin for vaccine purposes. However, before this method can be commercialized several parameters including the choice of suitable antigen or antigens needs to be evaluated.

Several vaccines, diagnostic tests, and medications are currently delivered intradermally, and it is likely that this route of administration will grow in importance. A phase I clinical study was conducted to evaluate the intradermal (ID) adapter, a prototype intradermal delivery aid, for safety and precision of injection. Healthy adult volunteers received two injections each of 0.1 mL of sterile saline solution in the upper deltoid region of the arm using the ID adapter. Injection performance was determined by the proportion of injections delivered to the dermal layer by measuring wheals and fluid leakage, and through ultrasound imaging. Of the 40 study injections, 100% were determined to be successful intradermal injections. Leakage of liquid at the injection site was negligible. Performance was similar with the bevel orientation both upward and downward. Minor bleeding and skin abrasions were the only reported adverse events. Injections were well tolerated based on self-reporting of pain of injection. Based on these results, the ID adapter appears to be safe and effective as an alternative to the Mantoux method of ID delivery for future use in clinical evaluations of ID delivery of vaccines, skin tests, and other drugs.

Protective antigens are targeted by host acquired immunity and able to induce protection against infectious diseases. To identify enriched features that do not typically exist in non-protective protein antigens, this study analyzed 201 protective protein antigens from Gram-negative bacteria and 69 protective protein antigens from Gram-positive bacteria available in the manually curated Protegen protective antigen database. Our study found that 64% of Gram+ protective antigens are extracellular or cell wall proteins and 48% of protective antigens in Gram^-bacteria belong to extracellular or outer membrane proteins. Approximately 54% and 40% protective antigens in Gram+ and Gram-, respectively, are adhesins or adhesin-like proteins. Many conserved domains (motifs), such as Autotransporter and TonB domains, are enriched in protective antigens. A protection method based on SVM (Support Vector Machine) classification demonstrates 92% of true positive rate of sequence-based protection. This study represents a pioneer effort in the identification and prediction of specific patterns in protective antigens.