ABSTRACT
Twenty-four Vi antigen-specific monoclonal antibodies were produced in this study. The MAbs were found to be highly specific to Vi possessing bacteria. Selected MAbs were used in a direct agglutination assay for rapid identification of S. typhi in primary bacterial culture and also used to develop an assay to detect Vi antigen in clinical specimens. The result showed that they could not detect the antigen in urine and serum from acute patients even they could detect as low as 0.02 micrograms/ml of Vi antigen added in normal urine. The study has shown that these MAbs are very useful for rapid identification of S. typhi in primary bacterial culture and they can replace polyclonal anti-Vi antibodies which have been used routinely in bacteriological laboratories.
Subject(s)
Agglutination Tests , Animals , Antibodies, Bacterial/biosynthesis , Antibodies, Monoclonal/biosynthesis , Antibody Specificity/immunology , Antigens, Bacterial/immunology , Enzyme-Linked Immunosorbent Assay , Mice , Mice, Inbred BALB C , Polysaccharides, Bacterial/immunology , Salmonella typhi/immunology , Typhoid Fever/immunologyABSTRACT
The killed whole cell typhoid vaccines, although protective, have limited usefulness because of the adverse reactions they evoke. In contrast, new typhoid vaccines protect without reactogenicity. Attenuated oral vaccine Ty2la has been evaluated in field trials of efficacy in Santiago, Chile. Three doses of Ty2la in an enteric-coated formulation given within one week provided 69% efficacy for at least four years. Ty2la has reached the stage of being a practical public health tool. Two double auxotrophic (Aro-, Pur-) mutant strains of S. typhi (541Ty and 543Ty) were well-tolerated and stimulated cell-mediated immune responses but evoked little serological response. Parenteral purified Vi polysaccharide of S. typhi (single 25 mcg dose) was safe and immunogenic and provided 64-72% protection (for at least 17-21 months) in controlled field trials in Nepal and South Africa.
Subject(s)
Adult , Child , Clinical Trials as Topic , Double-Blind Method , Humans , Pilot Projects , Random Allocation , Salmonella typhi/immunology , Typhoid Fever/prevention & control , Typhoid-Paratyphoid Vaccines/isolation & purification , Vaccines, Attenuated/isolation & purificationABSTRACT
In recent years notable advances have been made in the development of improved vaccines to prevent cholera. These new vaccines are administered orally to maximally stimulate intestinal secretory immunity. Killed vibrios, given in conjunction with purified B subunit or administered alone, in three spaced doses, caused no adverse reactions and have conferred significant protection in volunteer challenge studies and in field trials. Two attenuated mutants of V. cholerae, prepared by recombinant DNA techniques, CVD 103 and CVD 103-HgR are well-tolerated and elicit prominent immune responses and protective immunity after ingestion of a single oral dose. Other modern approaches being pursued include the development of auxotrophic strains and of modifying attenuated S. typhi strain Ty21a to express V. cholerae Inaba and Ogawa LPS antigens.
Subject(s)
Administration, Oral , Cholera Vaccines/administration & dosage , Humans , Intestines/immunology , Secretory Component , Vaccines, Attenuated/isolation & purification , Vibrio cholerae/immunologyABSTRACT
Se estudian los microorganismos enteropatogenos relacionados a diarrea aguda del lactante en muestras de heces tomadas al azar a lo largo de un periodo de 7 meses, durante el ano de 1979, encontrandose E. coli enteroxigenico (14,4%), rotavirus (9,2%) y shigelas (2,6%), en un grupo de 76 ninos.Dentro de este mismo grupo de 25 ninos (8%) y 1 de 25(4%) mostraron ascaris y amebas respectivamente.Los rotavirus se encontraron solo en los meses frios. Los E. coli enterotoxigenicos tanto en los meses frios como calidos. En el 73, 8% de los casos no pudo aislarse un microorganismo sugerente de enteropatogenicidad