View clinical trials related to Immunogenicity.
Filter by:Hand, foot, and mouth disease (HFMD) is a common viral illness in infants and children caused by viruses that belong to the enterovirus genus of the picornavirus family. Although most HFMD cases do not result in serious complications, outbreaks of HFMD caused by enterovirus 71 (EV71) can present with a high rate of neurological complications, including meningoencephalitis, pulmonary complications, and can even cause infant death. HFMD caused by EV71 has become a major emerging infectious disease in Asia and the highly pathogenic potential of EV71 clearly requires the attention of world medical community. The phase I study of inactivated vaccine (vero cell) against EV71 has completed last month in Jiangsu Province in China. The data from the phase I study suggested that the inactivated EV71 vaccine had a clinically acceptable safety and good immunogenicity for healthy Chinese children and infants. In order to provide more evidence for the immunogenicity of the vaccine, to further explore the probable immunizing dose and the safety profile of this vaccine, a phase II clinical trial is planed to conduct.
The active ingredient of this Shigella sonnei O-SP-core conjugate vaccine is a saccharide-protein conjugate composed of a fragment of S. sonnei LPS. The saccharide component consists of an average of 3.5 repeat units of the O-SP plus the core region of the LPS (O-SPC). The O-SPC is covalently bound to the recombinant non-toxic exoprotein B of Clostridium difficile. The objective of this phase of the study is to determine if this vaccine is safe and can induce IgG antibody type-specific immunity to shigellosis in adults. The overall objective is to determine if this vaccine can elicit higher levels of IgG antibody than the previous experimental vaccines made with the full length O-SP, shown to be >70% efficacious in greater than or equal to3 year old children, to induce type-specific immunity to shigellosis in younger children. Sixty 18-49 years-old healthy adults will be recruited in Israel. Volunteers will be vaccinated on a random basis with one i.m. injection of 10 or 25 micrograms of the investigational conjugate vaccine. Local and systemic reactions will be observed at 30 minutes, and the volunteers will be instructed to take their temperature and examine the injection site for redness and swelling and fill out a questionnaire at 6, hours and daily for 7 days after vaccination. The volunteers will visit the clinic at 24 or 48 hours following the injection and any time they request it. The study will commence with 5 volunteers injected with the 10ug dose to be followed, if no severe adverse reactions occur, by 5 volunteers injected with the 25ug dose. If a severe adverse reaction occurs on 1 of the 5 volunteers in either group, 5 more will be injected with that dose. If there are no severe adverse reactions the study will proceed. If there is one more severe reaction the study will be halted and re-evaluated by the IRB and the FDA. Vaccine-induced antibodies will be measured at 1 and 6 months after immunization, and compared to those elicited by our previous S. sonnei conjugate vaccines. There is a body of evidence that a critical level of serum IgG antibody to the O-specific polysaccharide domain of LPS confers type-specific immunity to S. sonnei as well as to other Shigella: 1. Shigellosis is rarely observed in infants up to the age of 4-6 months. The most obvious explanation for this is that maternally-derived serum IgG provides this immunity; 2. There is an age-related development of IgG anti-LPS antibodies that, in many instances, is not induced by the homologous bacteria but by non-pathogenic cross-reacting enteric bacteria; 3. The highest incidence, morbidity, and mortality occur during 6 months to 6 years of age when the maternally-derived serum anti-O-SP has waned and the naturally-derived antibodies have not yet appeared; 4. One injection of a S. sonnei-rEPA conjugate showed significant protection against shigellosis in Israeli Defense Force soldiers. Vaccinees who developed shigellosis showed significantly lower serum IgG responses to the homologous LPS than those did not.The high antibody level induced by the conjugate vaccine indicates the positive correlation between the serum IgG anti-LPS levels and immunity to S. sonnei infection; 5. Following Phase 1 and Phase 2 studies that showed safety and age-related immunogenicity, a double-blinded randomized and vaccine-controlled Phase 3 evaluation of S. sonnei and S. flexneri type 2a O-specific polysaccharide (O-SP) protein conjugates was conducted among 1-4 year-olds in Israel. For recipients of the S. sonnei conjugate 71.1% efficacy was shown among 3-4 year-old recipients, no efficacy was shown for recipients of S. flexneri 2a. There was no statistically significant efficacy for either vaccine in the 1-3 year-olds. Levels of serum IgG anti-O-SP were elevated according to the vaccine the children received but G.M. levels declined rapidly several months after the last injection. Our interpretation is that the age-related efficacy of the Shigella conjugates was due to the conjugate-induced O-SP antibody levels. Accordingly, we have developed a method to increase the immunogenicity of the conjugates to approach the antibody levels of Israeli soldiers shown to be protected by our S. sonnei O-SP. Low-molecular-mass O-SP-core (O-SPC) fragments were isolated from S. sonnei LPS, and bound by their reducing ends to the carrier protein. The O-SPC conjugates used oxime linkages between the terminal Kdo residues at the reducing ends of the S. sonnei saccharides and aminooxy linkers bound to the carrier. The coupling reaction was carried out at a neutral pH and room temperature. The carrier protein was a mutant non-toxic Clostridium difficile exotoxin B. IgG antibody levels induced in young outbred mice by this new S. sonnei O-SPC conjugate were significantly higher than those elicited by the O-SP conjugates.
Background: - Gardasil , a recently approved vaccine for the sexually transmitted human papillomavirus (HPV), provides immunity to four types of HPV that are associated with genital warts and cervical, vaginal, and vulvar precancer and cancer. The vaccine has been shown to be highly effective in preventing infection with these HPV types and was approved for use by the Food and Drug Administration. - More research is needed about the vaccine s ability to induce immunity in individuals with suppressed immune systems, such as those who have had other kinds of cancer treatment such as stem cell transplant. Genital warts, precancer, and cancer have been reported as a late complication after stem cell transplant. Researchers are interested in determining whether the HPV vaccine is safe to give and able to induce immunity in female stem cell transplant recipients, their female donors, and healthy female volunteers. Objectives: - To assess the safety and immune response of the HPV vaccine in female recipients of stem cell transplants who are either off or on stable doses of immunosuppression. Eligibility: - Females between 18 and 50 years of age who have had allogenic stem cell transplants. - Healthy female volunteers, including stem cell donors, are also eligible for this study. Design: - Participants will be screened with a physical examination, blood and urine tests, and saliva samples, and will be asked to complete a sexual quality of life questionnaire. - Sexually active participants will also have a routine gynecologic evaluation. - Participants will receive three HPV vaccinations according to the standard vaccination schedule (with the second and third following 2 and 6 months after the first). Participants will record their daily temperature and any reactions to the vaccine on a vaccine report card for 1 week after each vaccination. - Participants will have clinic visits for further testing 2, 6, 7, and 12 months after receiving the first HPV vaccine.