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Intranasal Delivery of Liposomes-Based Lipopeptide Hookworm Vaccine Diminished its Ability to Protect Mice Against Hookworm Challenge
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Abstract [+]
Background
Hookworm infection is particularly problematic for middle- to low-income countries. While treatment methods are currently available, vaccination may be the ideal intervention, as it could offer cost-effective long-term protection against infection and reinfection.
Methods
Previously established lipopeptide-based vaccine formulations, proven to be effective in an oral application, were adapted for an intranasal administration using a predicted B-cell peptide epitope derived from the hookworm Necator americanus aspartic protease-1 (Na-APR-1) protein and a universal T-helper epitope attached to two lipid moieties, Pam2Cys or lipid core peptide (LCP). The lipopeptides were encapsulated into liposomes or self-assembled into nanoparticles. The intranasal vaccine candidates were evaluated in a rodent hookworm challenge model.
Results
The vaccine candidates were formulated to optimal sizes and charges for uptake by immune cells. However, no significant serum antibody response was elicited, and no protection was demonstrated following hookworm challenge.
Conclusion
In contrast to the previously reported effective oral immunization, intranasal delivery of lipopeptide-based vaccine failed to trigger significant antibody responses in mice against hookworm and had no effect on parasite numbers following challenge infection.
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Self-Adjuvanting Peptide Vaccines Against Cervical Cancer
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Abstract [+]
Background
Cervical cancer is a common cause of cancer-related deaths in women worldwide, with a fatality rate second only to breast cancer. Human papillomaviruses (HPVs) are the main causative agents of cervical cancer, and are therefore obvious targets for vaccine development. Although two prophylactic HPV vaccines have been commercialized, therapeutic vaccines against HPVs have not been developed yet. Current vaccine technologies emphasize the power of small particles in targeting immune cells, and particles of 20-50 nm have been reported to induce optimal immune responses against a variety of pathogens and cancers.
Methods
We synthesized new nanoparticle-based vaccines against cervical cancer by using antigenic 8Qmin peptide epitope derived from HPV-16 E7 protein, a hydrophilic poly-(L-glutamic acid) (PGA) linker, and an 8-arm poly (tert-butyl acrylate) dendrimer-based delivery system (D8).
Results
Four different peptides containing 8Qmin and PGA of different lengths were successfully synthesized with high yield and purity. These were then conjugated to alkyne-functionalized D8 by copper-catalyzed alkyne-azide cycloaddition “click” reaction. The conjugates self-assembled into nanoparticles, with decreased particle size corresponding to a greater number of Glu units. The four vaccine candidates were tested in C57 black 6 (C57BL/6) mice bearing well-established (7-day-old) tumors to examine their therapeutic effects.
Conclusion
Interestingly, only one conjugate delayed tumor growth, and montanide adjuvanted antigen, used as a positive control, failed to demonstrate any therapeutic effect.
Keywords
Peptide-based subunit vaccine; Human papillomavirus; Polyglutamic acid; Therapeutic cancer vaccine; Polymer-peptide conjugate; Self-adjuvanting; Cervical cancer.
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Analysis of Antibiotic Resistance of the Probiotic Bacteria Found in Commercial Food Products
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Aim
The Lactobacillus is an industrially-important group of probiotic organisms that plays an important role in human health by inhibiting harmful and pathogenic bacterial growth, boosting immune function, and increasing resistance to infection. The aim of this study was to identify the probiotic bacteria Lactobacillus based on their phenotypic features and genotypic features. This study also shows the importance of probiotic bacterium, and the effects of their antibiotic resistance to human.
Method
Six different brands were cultured on man, rogosa and sharpe (MRS) agar. The identity of the culture was based on the characteristics of the strains of Lactobacillus spp. which was characterized using their phenotypic features (cell morphology, Gram’s staining tests which are specific for Lactobacillus genus). The bacterial deoxyribonucleic acid (DNA) was extracted by two different methods, boiled cell method and cetyl trimethylammonium bromide (CTAB) method. Furthermore, the extracted DNA yields were compared to determine which gives the best yield. The bacterial genus was detected with using genus specific primers, specific to the Lactobacillus. All the isolates were further subjected to antibiotic resistance test using disc diffusion method against a total of 4 antibiotics (Erythromycin, Tetracycline, Vancomycin and Ampicillin) and the antibiotic resistant genes of tet(M) & erm(B), were analyzed by polymerase chain reaction (PCR).
Results
Five isolates out of six samples (A to E) were found to exhibit multiple resistance against some of the most commonly used antibiotics. The isolates showed resistance toward tetracycline, erythromycin & vancomycin. Besides that, the isolates displayed a low-level of resistance toward ampicillin.
Conclusion
This study proves that antibiotic resistance is present in different species of probiotic strains, which may pose a food safety concern.
Keywords
Lactobacillus; Probiotics; Antibiotics; Tetracycline; Vancomycin; Erythromycin; Ampicillin; Antibiotic resistance.
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Recombinant Protein D from Haemophilus influenzae Induces Mouse Bactericidal Antibodies Against Typeable and Non-Typeable Haemophilus influenzae, which Partially Protect Infant Rats Against Serotype b Bacteraemia
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Abstract [+]
Aim
To evaluate the immunogenicity of a recombinant protein D from Haemophilus Influenzae (Hi) and the functional activities of the induced protein D antibodies in a mouse model.
Methods
Female Balb/c mice were immunised subcutaneously with recombinant protein D in the presence or absence of adjuvants and the serum immunoglobulin G (IgG) response to protein D was assessed by ELISA. The functional activity of the immune sera was evaluated in vitro using bactericidal assay against typeable Hi serotype b (Hib) and non-typeable Hi (NTHi) clinical isolates and in vivo using an infant rat bacteraemia model and a Hib clinical isolate.
Results
A dose-dependent IgG response was induced in mice immunised with the recombinant protein D and this response was further increased by the adjuvants used [CPG, AlPO4 and Al(OH)3], with the latter showing the greatest effect on the antibody response. Immune sera were very effective in bactericidal assay against several Hib and NTHi clinical isolates, with a higher serum bactericidal titre against the NTHi than against the Hib isolates. This is possibly due to the lower expression of protein D on the Hib isolates used in our study, compared to the NTHi isolates. In addition, anti-protein D antibodies were partially protective in vivo infant rat bacteraemia model against a challenge with Hib Eagan strain.
Conclusion
Our results suggest that recombinant protein D is a good vaccine candidate against Hi and should be given in combination with other vaccine candidates to ensure complete protection against Hib and NTHi.
Keywords
Haemophilus influenzae (Hi); Haemophilus influenzae serotype b bacteraemia; Rats.
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Model Liposomal Delivery System for Drugs and Vaccines
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Background
Liposomes have been used for drug delivery since their discovery 60-years-ago. The advantages they provide as carriers have been recognised and exploited to improve the delivery of numerous drugs and eliminate harmful side-effects. Liposomal delivery has been tested for anticancer drugs, anti-tuberculosis drugs, variety of vaccines, just to list a few.
Methods
We developed a series of liposomal formulations with the addition of cholesterol and polyethylene glycol. The uptake of these formulations by human epithelial prostate cancer (PC-3) cells and mouse macrophages was examined and analysed by flow cytometry and confocal microscopy.
Results
Among the liposomes tested, small anionic liposome vesicles (≤200 nm) prepared with egg phosphatidylglycerol as the main lipid were most effectively taken up by PC-3 cells and macrophages.
Conclusion
We produced a liposome formulation that can be used as a model system for the delivery of drugs and vaccines.
Keywords
Liposomes; Drug delivery; Vaccines delivery; Egg phosphatidylglycerol; Polyethylene glycol.
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