Procedia in vaccinology最新文献

Neonatal Diarrheal Disease is responsible for significant economic losses to the livestock industries in Canada and around the world. Microbes responsible are diverse and include Escherichia coli, Salmonella, Rotavirus, Coronavirus and Cryptosporidia. While the use of antibiotics as a treatment for bacterial infections and as a prophylactic additive in feed has dramatically improved cattle production in recent decades, the increasing pressure to reduce or eliminate use of antibiotics in animals has caused the livestock industry to seek appropriate alternatives. Antimicrobial/Host Defense Peptides are natural compounds present on skin and in secretions in plants and animals that are microbicidal for bacteria, viruses, and parasites and they stimulate the immune system to combat infectious diseases. Our objective is to establish orally-obtained Host Defense Peptides (HDPs) as an alternative to antibiotics to protect against Neonatal Diarrheal Disease in calves. We devised a method to allow the cow udder to act as a factory to produce HDPs so that suckling calves will receive a continuous oral dose of HDPs over several weeks to protect them against neonatal diarrhea. We will use Adenovirus to deliver a gene coding for several HDPs in-frame into mammary epithelial cells. The epithelial cells will secrete the HDP protein into milk to be consumed by the suckling calves and trypsin in the calf gut will release the HDPs through cleavage. Thus, the novelty of this research lies not only in the proposed alternative to antibiotics to protect neonates against disease, but in the method by which we introduce the peptides to the suckling offspring.

Live vaccines are widely used in the avian industry. Such vaccines can be either injected or delivered on animal mucosa and are usually not adjuvanted. In this study we show that live vaccines efficacy can be improved by formulation with adjuvants in a model of mucosal delivery of live infectious bronchitis vaccine in chicken. Three adjuvant technologies have been tested using intranasal and spray delivery methods to poultry. Those technologies are water in oil in water emulsion, nanoparticles and polymer adjuvants. Intranasal delivery of polymer and nanoparticles adjuvanted live vaccines improved significantly the antibody titer and protection to challenge observed compared to a commercial non-adjuvanted reference. Moreover, spray delivery of the polymer adjuvanted vaccine showed a significantly higher protection compared to the non-adjuvanted reference. Our data demonstrates that the use of MontanideTM adjuvants in the formulation of live poultry vaccines for mucosal delivery can confer to vaccinated animals a significantly improved protection against pathogens.

Tumor-specific gene products such as cancer-testis (CT) antigens are promising targets for the development of T cell vaccines. CT antigens are frequently found in several tumors, but their expression in pituitary adenomas has not been investigated. Here, we immunohistochemically studied the expression of the human Sperm protein 17 (Sp17) CT antigen in disease-free pituitary glands (n = 6) and clinically functioning (n = 22) and non-functioning pituitary adenomas (n = 38). The normal pituitary tissues contained only a few scattered Sp17-immunopositive cells, whereas 30 (79%) non-functioning adenomas and 11 (50%) functioning (p = 0.02) were highly immunopositive. The patients from whom the Sp17-immunopositive samples were taken were older than those whose samples were immunonegative (p= 0.007). The high frequency of Sp17 expression in pituitary adenomas suggests that it might be a potential histopathological biomarker of such tumors and a helpful tool in disease management. Moreover, the results of this study stimulate experimental models for exploring the role of Sp17-immunopositive cells in the pathogenesis of human pituitary adenoma, and evaluating the usefulness of Sp17 as an immunotherapeutic target.

The low immunogenicities exhibited by most soluble proteins are in general due to the absence of any molecular signatures that are recognized by the immune system as dangerous. We show here that electrostatic binding of synthetic branched cationic or anionic lipopeptides that contain the TLR2 agonist Pam2Cys can markedly enhance protein immunogenicity. High protein-specific antibody titres in animals were achieved by vaccination with formulations containing lipopeptide and protein of opposite charge. This response was not totally dependent on electrostatic binding because vaccination with similarly charged constituents also resulted in the induction of strong, albeit lower, antibody titres. The induction of CD8+ T cell-mediated responses, however, was achieved only by vaccination with formulations containing lipopeptide and protein of opposite but not similar charge. These responses also correlated with the ability of the electrostatically associated lipopeptide to facilitate dendritic cell uptake of protein antigen and trafficking into the draining lymph node. Vaccination subsequently resulted in faster viral clearance upon pulmonary infectious challenge with a chimeric influenza virus. The improvement in protein antigen immunogenicity obtained by mixing with lipopeptide led to a 99% reduction in lung viral titres and correlates with the presence of substantial numbers of antigen-specific CD8+ T cells in lung bronchoalveolar washes.

Bovine respiratory syncytial virus (BRSV) and its counterpart in humans (HRSV) are two closely related virus, which are the leading cause of severe respiratory syndrome in calves and young children, respectively. Passive immunization can be a practical alternative to conventional vaccination in order to prevent the disease. In this report the production of chicken egg yolk IgY and its ability to neutralize BRSV in vitro were assessed. Purified IgY against BRSV specifically recognized BRSV in a dot blot assay and was able to neutralize the virus in a viral neutralization assay. These results demonstrate the potential use of IgY as a prophylactic treatment against RSV infection.

It has become increasingly recognized that polymer particle size can have a profound effect on the interactions of particle-based vaccines with antigen presenting cells (APCs) thereby influencing and modulating ensuing immune responses.With the aim of developing chitosan particle-based immunocontraceptive vaccines, we have compared the use of chitosan nano- and microparticles as delivery vehicles for vaccine candidates based on luteinising hormone-releasing hormone (LHRH). Both particle types were taken up effectively by dendritic cells with similar efficacies. Inoculation with nanoand microparticles containing conjugated peptide or protein microparticles also resulted in the induction of high levels of LHRH-specific antibodies. In the case of protein-conjugated particles, the levels of antibodies elicited were similar to those elicited following inoculation with antigen emulsified with complete Freund's adjuvant. The approach to vaccine design that we have described here could represent another useful method for inducing immune responses against microbial, viral and tumorigenic protein antigens.

A two step flow-through chromatography process is proposed as an universal approach to purify viruses. A resin column with reduced surface area was developed for the first step to remove bulk of the host cell protein (HCP) from a viral feed stream while allowing most of the virus to flow-through. For the second step a chromatographic separations strategy using a primary amine membrane adsorber and multivalent ions in the mobile phase was developed. This enabled selective binding of host cell DNA (hcDNA) to the membrane and complete recovery of virus in the flow-through mode. The techniques were evaluated using cell culture grown influenza virus and bacteriophage feed streams. Virus recoveries of >70-80% and 100% were achieved for the column and membrane approaches respectively. The column cleared > 80% of the HCP and the membrane adsorber reduced whole hcDNA levels to <10 ng.

PRRSV live vaccines are widely used in pig farming practice and are usually not adjuvanted. For safety issues, it would be useful to reduce the antigenic load of such vaccines while preserving their efficacy. In this study we show that the addition of polymer or oil adjuvants in a PRRS live vaccine enhanced the protection to challenge of vaccinated animals compared to a non-adjuvanted commercial reference. Moreover, for both types of adjuvants, despite lower antibody titers, the protection to challenge given by the adjuvanted vaccine containing only 50% of the antigen load was equivalent to the protection given by the non-adjuvanted vaccine. These results demonstrate that the addition of relevant adjuvants can enhance the efficacy of the protection conferred to animals by live vaccines.

Live plague vaccines have saved thousands of human lives in the 20th century and have continued to be used in Russia and other countries of the former Soviet Union for prophylaxis of plague. A live attenuated Y. pestis EV strain line NIIEG is used for the routine annual vaccination of plague workers, as well as people from the groups at risk. This vaccination can offer immunity against both bubonic and pneumonic plague. However, serologic markers of the human response to vaccination with EV NIIEG are poorly investigated. It is not clear whether other antigens, in addition to the established capsular antigen F1 and lipopolysaccharide, can elicit specific and long-lasting antibody responses in vaccinees. In this study, a humoral immunity to a panel of recombinant Y. pestis-specific antigens, such as F1, Pla, LcrV, YopM and YscF, was examined in volunteers, who received multiple annual immunizations with EV NIIEG during the period of 5 to 30 years. To evaluate a long-term immune response to these antigens, we chose a cohort of donors, who had their last immunization 4-30 years ago. The immunoblotting technique revealed that sera of 14 out of 17 donors contained antibodies to at least one of the tested antigens. As expected, the occurrence of anti-F1 antibodies was detected in a large group of vaccinees (57%). In contrast, the presence of specific antibodies to either LcrV or YscF was less pronounced (26% and 36%, respectively), and only two donors possessed anti-YopM (10%). Surprisingly, we found that sera of the vast majority of volunteers (82%) gave positive reaction with the outer membrane protease Pla, specific to Y. pestis. This analysis will provide insights into the correlates of immunity elicited in humans by live plague vaccine, aid in the search for markers of exposure to plague, and help to develop new diagnostic protocols.

Influenza virus infections are a serious global health threat, particularly in light of newly emerging strains, such as the avian virus H5N1. In this study, a sample of avian influenza A virus subtype H3N8 inactivated by high hydrostatic pressure was used as a vaccine. Our goal was to study pressurized virus preparations for their ability to induce an immunogenic and protective response when using mice as an animal model. Here, Balb/c mice were treated through the intranasal route with three doses of pressurized virus. After vaccination, the mice were challenged and monitored for virus-specific antibodies (ELISA and neutralization assay), clinical symptoms and death. After immunization, there was an increase of IgG1 and IgG2a in sera and IgA in nasal lavages, which indicated that the serum antibodies were showing neutralizing ability. The viral neutralization assay demonstrated that the produced antibodies were neutralizing. After the challenge, the control group (immunized with saline) showed all measured clinical signs of disease (weight loss, ruffled fur, lethargy and huddling). The vaccinated animals did not develop any clinical signs. The results reveal that the animals were able to produce a satisfactory humoral response after vaccination and protected against the challenge. Our work reaffirms the use of hydrostatic pressure as a means for developing low-cost viral vaccines with good immune response.