Neutralizing Antibody Titer (neutralizing + antibody_titer)

Distribution by Scientific Domains

Selected Abstracts

Enhancement of protective humoral immune responses against Herpes simplex virus-2 in DNA-immunized guinea-pigs using protein boosting

Fatemeh Fotouhi
Abstract Genital Herpes is a common sexually transmitted disease that is caused mostly by Herpes simplex virus type 2 (HSV-2). Its prevalence has increased in developing countries in spite of the availability of valuable antiviral drug therapy. Considering the importance of HSV-2 infections, effective vaccines remain the most likely hope for controlling the spread of HSV diseases. In the present study, the complete HSV-2 glycoprotein D gene was isolated and cloned into different plasmid vectors to construct a DNA vaccine and prepare recombinant subunit vaccines using a baculovirus expression system. The vaccines were tested alone or in combination to evaluate their ability to induce protective immunity in guinea-pigs against genital HSV infections. Immunization elicited humoral responses as measured by neutralization tests and enzyme-linked immunosorbent assay, and immunized animals had less severe genital skin disease as well as reduced replication of the challenging virus in the genital tract during experimental infection. Our results further demonstrate that DNA priming-protein boosting induced a neutralizing antibody titer higher than that obtained with DNA,DNA vaccination. The massive increase of antibody titer following DNA priming-protein boosting might be attributed to a recall of B cell memory. [source]

Neutralizing antibody response variation against dengue 3 strains

Mayling Alvarez
Abstract To evaluate the neutralizing antibody activity of a human sera panel against seven strains of the homotypic virus. Sera were collected from DENV-3 immune individuals. Two DENV-3 genotypes and strains isolated at different time-points during the 2000 and 2001,2002 Havana epidemics were included. A panel of 20 late convalescent sera collected 16,18 months after acute illness from DF and DHF patients are studied. These individuals were infected during the 2001,2002 Havana DENV-3 epidemic. All but four sera collected from DF cases had a secondary DENV-1/DENV-3 infection. Sera neutralizing antibody titer against the seven DENV-3 strains were determined by plaque reduction neutralization technique. Sera samples were tested simultaneously. Studied sera showed higher levels of neutralizing antibodies to DENV-3 strains of genotype III compared to genotype V. Interesting, higher levels of neutralizing antibodies were detected to DENV-3 strain isolated at the end of the epidemic 2001,2002. An increased tendency of GMT of neutralizing antibodies according to epidemic evolution was observed for the 2001,2002 outbreak. In general, antibody levels in sera collected from DF cases were higher. Differences in the neutralization capacity of immune DENV-3 sera tested against two homologous genotypes including strains of the same genotype are demonstrated. Observed results suggest that virus changed in the course of the epidemic. The implications of this finding in terms of dengue pathogenesis and vaccine development need to be considered. J. Med. Virol. 80:1783,1789, 2008. 2008 Wiley-Liss, Inc. [source]

Neutralizing antibody against severe acute respiratory syndrome (SARS)-coronavirus spike is highly effective for the protection of mice in the murine SARS model

Koji Ishii
ABSTRACT We evaluated the efficacy of three SARS vaccine candidates in a murine SARS model utilizing low-virulence Pp and SARS-CoV coinfection. Vaccinated mice were protected from severe respiratory disease in parallel with a low virus titer in the lungs and a high neutralizing antibody titer in the plasma. Importantly, the administration of spike protein-specific neutralizing monoclonal antibody protected mice from the disease, indicating that the neutralization is sufficient for protection. Moreover, a high level of IL-6 and MCP-1 production, but not other 18 cytokines tested, on days 2 and 3 after SARS-CoV infection was closely linked to the virus replication and disease severity, suggesting the importance of these cytokines in the lung pathogenicity of SARS-CoV infection. [source]

Cellular and humoral immune responses to measles in immune adults re-immunized with measles vaccine

Rosa Maria Wong-Chew
Abstract The objective of this study was to characterize the kinetics of the cellular and humoral immune responses elicited by measles vaccine given to previously immune adults. The cellular and humoral immune responses to measles were measured in seven healthy adults, before vaccination and at 1, 2, 3, and 4 weeks and 3 months after vaccination, using measles-specific T-cell proliferation and plaque reduction neutralization assays. All study subjects had detectable measles antibodies, but only six (85%) showed protective titers, defined as >1:120, before immunization. However measles-specific T-cell proliferation was not detectable before vaccination in any of the subjects. The six subjects with protective titers showed a positive stimulation index (SI) of >3.0 within the first 4 weeks after vaccination, an SI of 5 at the 4th week, and an SI of 3 at 3 months after vaccination. The subject with a low antibody titer (1:99) before vaccination developed a high SI at 3 months after vaccination. This subject was the only participant whose neutralizing antibody titers increased more than 4-fold by 3 months after vaccination. No significant increases in geometric mean titers were detected in the other six subjects during the follow-up period. These data suggest that high measles antibody titers interfere with the humoral response in subjects who receive a booster immunization, whereas the cellular response is boosted at least transiently, after revaccination. J. Med. Virol. 70: 276,280, 2003. 2003 Wiley-Liss, Inc. [source]

Protective effect of nasal immunization of influenza virus hemagglutinin with recombinant cholera toxin B subunit as a mucosal adjuvant in mice

Masanori Isaka
ABSTRACT To develop an efficient nasal influenza vaccine, influenza A and B virus HA with rCTB as a mucosal adjuvant were administered to mice intranasally. Serum anti-HA IgG and IgA antibody responses for both HA vaccines were significantly increased in the presence of rCTB. Higher HI and neutralizing antibody titers and higher mucosal IgA antibody responses in the respiratory tract were detected when rCTB was added than without rCTB. When mice were immunized with HA vaccine with or without rCTB and challenged by intranasal administration of mouse-adapted pathogenic influenza A virus, all mice immunized with HA plus rCTB survived for seven days without any inflammatory changes in the lungs, while not all the mice immunized with HA without rCTB survived, and all of them had lung consolidations. These results demonstrate that intranasal co-administration of rCTB as a mucosal adjuvant with influenza virus HA is necessary not only for the induction of systemic and mucosal HA antibodies, but also for the protection of mice from morbidity and mortality resulting from virus infection. [source]