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Identification of a soluble Chlamydia trachomatis antigen
Abstract
Chlamydia trachomatis is an obligate intracellular parasite which has a trophism for columnar epithelial cells. It is recognized as a major cause of endemic trachoma and conjunctivitis, as well as being the most prevalent sexually transmitted disease in the United States. The species can be subdivided into two biovars according to their host cell specificity and disease epidemiology. The trachoma biovar is associated with infections of ocular origin, or with the genital epithelia. The lymphogranuloma venereum (LGV) biovar is a sexually transmitted biovar causing a more invasive disease involving the lymphoid tissues. Inguinal and femoral lymph nodes become infected, producing swelling, necrosis and lymphocutaneous fistulae. The differences between biovar infectivity may in part be due to specific membrane antigens of the infectious elementary body and soluble antigens. Soluble antigens released during the infective cycle are likely to be crucial for the organism's survival. The identification of antigenic epitopes present on these molecules can aid in both serodiagnosis and selective immunization procedures which combat this pathogen. A soluble Chlamydia trachomatis esterase has been identified within the supernatant of 48 hour infected McCoy cell tissue cultures. The extraction procedure utilized a combination of ammonium sulfate precipitation, gel filtration, and immunoprecipitation techniques. The isolated protein has an approximate molecular weight of 26,000 to 30,000 M$\sb{\rm r}$ as demonstrated by gel filtration and SDS-PAGE size estimation. The esterase co-isolates with a chlamydial protein, and also contains serovar-specific epitopes. Use of rabbit anti-B serovar antibodies to deplete the esterase activity from the protein fraction confirms this molecule as being a chlamydial protein. Primates infected with B serovar C. trachomatis produce antibodies directed towards this antigen. This indicates that this molecule is immunogenic during infection, and perhaps plays a biological role in the pathogenesis of infection. Isoelectric focusing techniques has enabled the partial purification of a 26,000 M$\sb{\rm r}$ molecule, with a pI value of approximately 6.6, released during chlamydial infection. This molecule co-isolates with fractions containing esterase activity. This molecule is absent in mock-infected McCoy cell supernatants. Guinea pig antisera directed towards this protein is able to recognize specific epitopes present on the surface of infectious chlamydial elementary bodies.
Subject Area
Molecular biology|Microbiology|Immunology
Recommended Citation
Actor, Jeffrey Kenneth, "Identification of a soluble Chlamydia trachomatis antigen" (1991). Doctoral Dissertations Available from Proquest. AAI9132806.
https://scholarworks.umass.edu/dissertations/AAI9132806