m-antigen--brucella-melitensis and Brucellosis

Brucellosis is a serious zoonotic bacterial disease that is ranked by the World Health Organization among the top seven "neglected zoonoses" that threaten human health and cause poverty. It is a costly, highly contagious disease that affects ruminants, cattle, sheep, goats, and other productive animals such as pigs. Symptoms include abortions, infertility, decreased milk production, weight loss, and lameness. Brucellosis is also the most common bacterial disease that is transmitted from animals to humans, with approximately 500 000 new human cases each year. Detection and slaughter of infected animals is required to eradicate the disease, as vaccination alone is currently insufficient. However, as the most protective vaccines compromise serodiagnosis, this creates policy dilemmas, and these often result in the failure of eradication and control programs. Detection of antibodies to the Brucella bacterial cell wall O-polysaccharide (OPS) component of smooth lipopolysaccharide is used in diagnosis of this disease, and the same molecule contributes important protective efficacy to currently deployed veterinary whole-cell vaccines. This has set up a long-standing paradox that while Brucella OPS confers protective efficacy to vaccines, its presence results in similar antibody profiles in infected and vaccinated animals. Consequently, differentiation of infected from vaccinated animals (DIVA) is not possible, and this limits efforts to combat the disease. Recent clarification of the chemical structure of Brucella OPS as a block copolymer of two oligosaccharide sequences has provided an opportunity to utilize unique oligosaccharides only available via chemical synthesis in serodiagnostic tests for the disease. These oligosaccharides show excellent sensitivity and specificity compared with the native polymer used in current commercial tests and have the added advantage of assisting discrimination between brucellosis and infections caused by several bacteria with OPS that share some structural features with those of Brucella. During synthesis and immunochemical evaluation of these synthetic antigens, it became apparent that an opportunity existed to create a polysaccharide-protein conjugate vaccine that would not create antibodies that give false positive results in diagnostic tests for infection. This objective was reduced to practice, and immunization of mice showed that antibodies to the Brucella A antigen could be developed without reacting in a diagnostic test

Topics: Animals; Antibodies, Bacterial; Antigens, Bacterial; Brucella; Brucella Vaccine; Brucellosis; Cattle; Cross Reactions; Epitopes; Humans; Lipopolysaccharides; Mice; Oligosaccharides; Polysaccharides; Polysaccharides, Bacterial; Serum Albumin, Bovine; Tetanus Toxoid; Vaccines, Conjugate

All smooth strains of Brucella bear two lipopolysaccharide (LPS) antigens in a ratio that defines the classification of strains in serovars, A (A greater than M), M (M greater than A) and A.M (A = M). Anti-LPS-A monoclonal antibodies (MAb-A) were previously shown to convey protection to mice against B. abortus (A) strain 544, as shown by lower spleen counts than in controls at days 7 and 21 after challenge. Anti-LPS-M monoclonal antibodies (MAb-M) were obtained and tested for M-specificity with LPS from reference strains by ELISA, by agglutination of LPS-coated latex particles, and by inhibition of this agglutination. Antigens A and M of three strains were quantified by a homologous LPS-latex and MAb agglutination inhibition assay. Protection conferred by MAb-A and MAb-M against three strains, B. abortus 544 (A), B. abortus 292 (M) and B. melitensis H38 (M), was tested at equivalent challenge and MAb doses: intravenous challenge was adjusted to give similar infection at day 7; MAb doses were adjusted to the same specific ELISA titre. Under these conditions, MAb-A and MAb-M conferred both early and late protection, as shown at days 7 and 21, against the strains that bore the homologous major antigen, i.e., strain 544 on one hand and strains H38 and 292 on the other. In contrast, MAb directed against the minor antigen of the challenge strain conferred significant protection at day 7 only with strains 544 and H38 and no or inconsistent protection against strain 292, which expressed the lowest amount of minor antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Agglutination Tests; Animals; Antibodies, Bacterial; Antibodies, Monoclonal; Antibody Formation; Antigens, Bacterial; Brucella; Brucella abortus; Brucellosis; Enzyme-Linked Immunosorbent Assay; Immunoglobulin G; Lipopolysaccharides; Mice; Mice, Inbred BALB C; Species Specificity

Topics: Allergens; Antibodies, Bacterial; Antigens, Bacterial; Brucella; Brucellosis; Endocarditis, Bacterial; Humans; Immunity, Cellular; Intradermal Tests; Lymphocyte Activation

Topics: Antigens, Bacterial; Brucellosis; Diagnosis; Eosinophilia; Humans; Hypersensitivity; Leukocyte Disorders; Lung Diseases

Topics: Antigens, Bacterial; Brucellosis

Topics: Antigens, Bacterial; Brucella melitensis; Brucellosis; Humans; Hypersensitivity; Immunity

Topics: Antigens, Bacterial; Brucella melitensis; Brucellosis; Humans

Topics: Agglutinins; Antigens, Bacterial; Brucella; Brucellosis; Humans; Male