PubMed Health⌕ Search

Biomedical subjects

R Germanier

Publications and source records attributed to R Germanier.

At least 55 records · Page 3Linked to original sources
PubMed1983

Immunogenicity of Ty21a attenuated "Salmonella typhi" given with sodium bicarbonate or in enteric-coated capsules.

Ty21a, a stable attenuated mutant of Salmonella typhi, is a safe, protective oral vaccine when 3 doses of 10(9) cells in saline are taken after neutralization of gastric acidity by 1 g NaHCO3. To identify a more convenient method to administer vaccine and to determine the feasibility of immunizing with a single dose, we studied the immune response of children and adults to different formulations of Ty21a with a newly developed, sensitive, enzyme-linked immunosorbent assay (ELISA). In this ELISA, a rise in S. typhi O antibody was defined as a change in net optical density of greater than or equal to 0.15 (more than 3 SD from the mean difference in optical density in a negative control population). Three hundred and thirty-five Chilean children were given 3 doses of 10(9) Ty21a in 150 ml of milk with 0.8 g NaHCO3 or in enteric-coated capsules. In each group, 5% seroconverted by Widal O but 41% by IgG ELISA O antibody titers; mean antibody levels by group were identical. Studies were also carried out in healthy college students in a non-endemic area (U.S.A.) who had no history of prior typhoid immunization. In total, 141 U.S. adults received vaccine formulated in either one of two ways: 1) in gelatin capsules administered with two additional gelatin capsules containing a total of 0.8 gm NaHCO3 or 2) in enteric-coated capsules. Thirty-six persons received one dose, 30 got two doses and 16 ingested three doses of enteric-coated vaccines, while 44 persons receiving one dose and 15 got two doses of vaccine in the gelatin capsule formulation. Rates of seroconversion of ELISA O antibody were similar in all the groups. Ty21a vaccine was not recovered from multiple stool, jejunal fluid or blood cultures of the U.S. vaccine recipients. Based on these observations a large-scale field trial of efficacy has been initiated in 90.000 schoolchildren 6-20 years of age in Santiago, Chile, of whom one-third received one dose of enteric-coated vaccine, one-third got two doses and the remainder received placebo.

Adolescent↗
PubMed1983

Protection of piglets against neonatal colibacillosis based on antitoxic immunity.

Substantial protection against colibacillosis in neonatal piglets was provided by transfer of colostral antitoxic antibody to suckling piglets from dams immunized with procholeragenoid. The physical properties of procholeragenoid, an aggregate with a high-molecular weight formed during the heating of cholera toxin, were dependent upon the buffer and the duration of heating used for production. Procholeragenoid possessed a higher molar ratio of subunit A to subunit B than native cholera toxin. The biological activity of procholeragenoid was greatly decreased in several assay systems as compared to cholera toxin. Immunization of pregnant dams with 50 micrograms of procholeragenoid 5 weeks and 2 weeks prior to delivery elicited high titers of antitoxic-IgG and toxin-neutralizing antibody in the serum and colostrum at parturition. In field trials, immunization with procholeragenoid markedly decreased the incidence of diarrhea (85%) and death (84%) due to colibacillosis in neonatal piglets. Reimmunization of dams with procholeragenoid during the following gestation period afforded comparable levels of protection against death in piglets (mortality rate of 0.86% compared to 0.77% following the first immunization schedule). These results demonstrate that only antitoxic immunity can afford a high degree of protection against colibacillosis in neonatal piglets.

Animals↗
PubMed1983

Characteristics of the attenuated oral vaccine strain "S. typhi" Ty 21a.

The lack of a reliable in vitro test or animal model that can predict the potency of typhoid vaccines in man makes it extremely difficult to develop guidelines for the quality control of these vaccines. Attenuated S. typhi strain Ty 21a that has been shown to be safe and efficacious as live oral vaccine in clinical studies and in a controlled field trial, has been extensively characterized by genetical, biochemical and biological data. Production of live oral typhoid vaccine Ty 21a is based on a parent and working seed lot system. Characteristics of the seed lot cultures have to correspond with the original strain. Characteristics of strain Ty 21a relevant to its avirulence and potency are discussed.

Animals↗
PubMed1983

Immunogenicity and protective capacity of inactivated "vibrio cholerae" whole cell vaccines.

The effects of heat and chemical inactivants on the immunogenicity and protective capacity of V. cholerae was studied. ELISA systems, using whole cells of V. cholerae, purified LPS or flagella preparations as immobilized antigens were employed to measure serum antibody titers. The immune response to parenteral vaccination in rabbits with killed whole cell vaccines was dependent upon the inactivation procedure used. Cells inactivated by heat alone or in combination with phenol were found to be comparatively poor immunogens. Formalin, together with heating, produced a much superior immunogen. The concentration of formalin was found to be critical for production of an optimal immunogen. IgG-titers in all ELISA assays were between 10-fold to 100-fold higher when formalin-heat inactivated preparations were employed as compared to phenol-heat inactivated. Additionally, antibody produced in response to a formalin-heat inactivated preparation was capable of reacting with antigen determinants present on the cell surface of several heterologous strains of V. cholerae. The protection afforded by parenteral immunization with several inactivated preparations against live vibrio challenge was determined in the rabbit ileal loop model. A preparation prepared by heating alone offered no detectable protection while a phenol-heat inactivated preparation provided modest levels of protection (approximately 14-fold). In contrast, immunization with a formalin-heat inactivated preparation offered substantial protection (1,400-fold). These results demonstrate that a highly immunogenic inactivated V. cholerae whole cell vaccine can be prepared which provides significant protection against a live V. cholerae challenge.

Animals↗
PubMed1982

A controlled field trial of live Salmonella typhi strain Ty 21a oral vaccine against typhoid: three-year results.

A controlled field trial of Salmonella typhi strain Ty 21a oral vaccine against typhoid was carried out in Alexandria, Egypt, from March 1978 to March 1981. A total of 32,388 children was included in the study. The children were divided in two comparable groups, one given three doses of vaccine and the other three doses of placebo. Each dose of vaccine contained 1-8 X 10(9) live Ty 21a bacteria. The population was monitored, and each suspected case of typhoid was investigated bacteriologically and serologically. The effectiveness of the vaccine was assessed by analyzing the number of confirmed cases of typhoid fever in the two groups. The incidence of typhoid fever was 4.9 cases per 10,000 children per year in the control group and 0.2 cases per 10,000 children per year in the vaccine group. The results indicate that, in the dose schedule used, the Ty 21a mutant strain, which is stable and safe, is protective for a period of at least three years.

Administration, Oral↗
PubMed1982

Protection against colibacillosis in neonatal piglets by immunization of dams with procholeragenoid.

Protection against colibacillosis in neonatal piglets was obtained by immunization of pregnant dams with procholeragenoid. Procholeragenoid is a stable high-molecular-weight aggregate of cholera toxin formed during the heating of cholera toxin. Procholeragenoid retained approximately 1% of the toxicity of native toxin as determined in the rabbit ileal loop and Y-1 adrenal cell assays and 5% of the activity in the rabbit skin assay. Immunization of pregnant dams with 50 micrograms of procholeragenoid 5 and 2 weeks before the expected delivery date elicited high titers of antitoxic immunoglobulin G and toxin-neutralizing antibody in both the colostrum and serum. In three independent field trials, immunization with procholeragenoid resulted in a substantial decrease in diarrhea (73% in controls versus 11% in immunized) and death (4.7% in controls versus 0.77% in immunized) in neonatal piglets. The protection rate in the immunized population was approximately 85% for both diarrhea and death. In the following gestation period, reimmunization of dams with a single dose of procholeragenoid (50 micrograms) 2 weeks before delivery elicited titers of antitoxic immunoglobulin G and toxin-neutralizing antibody comparable to those obtained during the primary immunization. The death rate in neonatal piglets (0.86%) was comparable to that seen after immunization during the first gestation period (0.77%). These results indicate that substantial protection of neonatal piglets against colibacillosis can be obtained by immunization of dams with procholeragenoid. Protection was found to be based solely on antitoxic immunity.

Animals↗
PubMed1982

Effect of chemical and heat inactivation on the antigenicity and immunogenicity of Vibrio cholerae.

The effects of heat and chemical inactivation on the antigenicity and immunogenicity of Vibrio cholerae 1418 in rabbits were studied. V. cholerae 1418 was inactivated with heat and chemical inactivants (phenol or Formalin) alone or in combination. Enzyme-linked immunoassay systems employing whole cells of V. cholerae 1418, lipopolysaccharide, or flagella as immobilized antigens were used to measure the antibody response (immunoglobulins G and M) after parenteral immunization of rabbits with various inactivated whole-cell preparations. The "classical" whole-cell vaccine, produced by phenol treatment, was found to be a comparatively poor immunogen. When Formalin was used instead of phenol, the antibody response to all three enzyme-linked immunosorbent assay antigens was greatly increased. Immunoglobulin G titers to intact V. cholerae cells were as much as 100-fold higher in rabbits immunized with the Formalin-inactivated preparation as compared to the classical phenol-inactivated vaccine. Furthermore, antibody produced against the Formalin-inactivated preparation was capable of recognizing antigenic determinants expressed on the cell surface of several heterologous strains of V. cholerae. These results indicate that the antigenicity and immunogenicity of V. cholerae are greatly affected by the inactivation conditions employed for vaccine production and that Formalin is much superior to phenol as an inactivant under the conditions employed in the present study.

Animals↗
PubMed1982

Development of an enzyme-linked immunosorbent assay for studying Vibrio cholerae cell surface antigens.

An enzyme-linked immunosorbent assay for the measurement of antibodies directed against cell surface antigens of Vibrio cholerae (CSA ELISA) was developed. NaN3-killed whole cells of V. cholerae, adsorbed to polystyrene tubes, were used as immobilized antigens. The assay was capable of detecting antibodies directed against lipopolysaccharide and non-lipopolysaccharide surface antigens. In addition, the CSA ELISA was capable of detecting non-vibriocidal antibody. An antiserum raised in rabbits by immunization with live V. cholerae 1418 (Ogawa, El Tor) was capable of reacting with various heterologous strains of V. cholerae used as immobilized antigens. Therefore, common antigens shared by V. cholerae strains could be detected by using the CSA ELISA.

Antigens, Bacterial↗
PubMed1980

A controlled field trial of liver oral typhoid vaccine Ty21a.

A controlled field trial of a live oral typhoid vaccine was carried out in Alexandria, Egypt, in 1978-79. A total of 32 388 children were included in the study. They were divided in two comparable groups, one given 3 doses of the vaccine and the other 3 doses of the placebo. Each active dose contained 1 x 10(9)-8 x 10(9) live Ty21a bacteria. From March 1978 to March 1979, the population studied was followed up and suspected typhoid cases were investigated bacteriologically and serologically. The effectiveness of the vaccine was assessed by analysis of the incidence of typhoid fever in the two groups. The results of the follow-up indicate that, in the dosage schedule used, the Ty21a mutant strain, found previously to be stable and safe, is protective against typhoid fever for at least one year.

Child↗
PubMed1977

Antigenicity of cholera toxoid in humans.

A cholera toxoid was produced by heating of a purified cholera toxin and treatment of the resulting toxoid procholeragenoid with a formaldehyde solution. When given subcutaneously and intramuscularly to volunteers in doses of 3-100 microng, the toxoid produced no noteworthy side effects, but the injections produced a dose-dependent rise in level of toxin-neutralizing antibodies in serum. Administration of toxoid in combination with whole-cell vaccine induced antitoxin levels that seemed to be higher than those induced by toxoid alone, but statistical analysis revealed a significant difference only between titers after administration of 10 microng of toxoid alone and those after administration of 10 microng of toxoid in combination with whole-cell vaccine.

Antibody Formation↗
PubMed1976

Preparation of a purified antigenic cholera toxoid.

Purified cholera enterotoxin was prepared by methods described by Finkelstein and Lo Spalluto (1970). This toxin was detoxified by treatment with heat and formaldehyde. Heating cholera toxin at 60 C for 25 min resulted in the formation of a polymer named procholeragenoid by Finkelstein et al. (1971). The weak toxic activity of this product was removed by treatment with formalin. No residual toxicity could be demonstrated in formalinized procholeragenoid by the rabbit ileal loop assay and the highly sensitive rabbit skin tests. This toxoid was nevertheless at least as antigenic in the rabbit as was the toxin. No reversion to toxicity was observed in vivo and in vitro at 4 C. The toxicity of formalinized procholeragenoid never exceeded 1/5,000 to 1/10,000 that of the toxin.

Antigens, Bacterial↗
PubMed1976

Vaccination against typhoid fever with a live oral vaccine.

A Salmonella typhi gal E mutant, designated Ty 21a, has been developed on the basis of virulence and protection studies with similar Salmonella typhimurium mutants in mice. Gal E mutants are characterized by a block in the enzyme UDP-4-galactose-epimerase. They owe their outstanding immunizing capacity when used in live oral vaccine to the fact that when galactose is supplied exogenously, as occurs in vivo, wild-type cell wall structures are synthesized. On the other hand, avirulence of these mutants is based upon the fact that when galactose is taken up it is partly accumulated as galactose-1-phosphate and UDP-galactose, which induces lysis of the bacteria. Strain S. typhi Ty 21a does not revert to wild type in vivo and in vitro. Its safety for man has been demonstrated in studies involving 137 adults and 370 children. S. typhi Ty 21a also has been shown to protect against challenge with virulent S. typhi in human volunteers.

Administration, Oral↗
PubMed1975

Isolation and characterization of Gal E mutant Ty 21a of Salmonella typhi: a candidate strain for a live, oral typhoid vaccine.

A gal E mutant of Salmonella typhi was isolated; results obtained with Salmonella typhimurium and the mouse as a model for human typhoid fever indicated that this mutant has the potential for use as a live, oral typhoid vaccine. The mutant, Ty 21a, took up galactose from exogenous sources and accumulated sufficient quantities of galactose-1-phosphate and uridine diphosphate galactose to cause lysis of the cells, an event that resulted in the avirulence of the strain. Galactose was incorporated sufficiently into the cell wall of Ty 21a to allow the synthesis of smooth-type lipopolysaccharides, which are necessary for the proper immunogenicity. Cells of strain Ty 21a, when given intraperitoneally, protected mice against lethal challenge with strain Ty 2 of S. typhi.

Animals↗
PubMed1972

Immunity in experimental salmonellosis. 3. Comparative immunization with viable and heat-inactivated cells of Salmonella typhimurium.

Vaccination with viable cells of an avirulent Salmonella typhimurium galE mutant provides mice with solid specific immunity against subsequent infection with a virulent smooth strain. Such a live vaccine is markedly more potent than one prepared from inactivated cells of the virulent smooth strain. The superiority of the live vaccine is particularly well demonstrated when the oral route of application is used. The protective capacity of the galE mutant is based on its ability to synthesize complete smooth-like cell wall lipopolysaccharide in vivo.

Administration, Oral↗