Date of Award


Degree Type


Degree Name



Department of Biology

First Advisor

Dr. Judith Rae Lumb

Second Advisor

Dr. Roger M. McKinney


Legionellosis is an acute respiratory disease which occurs throughout the United States and other areas of the world. The etiologic agent of this disease is a gram-negative, fastidious bacterium that belongs to the genus Legionella. The most common species, L. pneumophila, has been divided into 7 serogroups. Strains of serogroups 3 and 6 show common antigens as indicated by cross-reactivity which has been obtained with rabbit antisera. The objective of this research is to produce monoclonal antibody against cell surface antigens of L. pneumophila serogroup 6 (Chicago 2 strain), to determine whether there is antigenic heterogeneity among strains of _L. pneumophila serogroup 6, and to determine whether monoclonal antibodies to serogroup 6 might be useful as diagnostic reagents for detecting legionellosis. Hybridoma cell lines producing monoclonal antibodies for the determinants of L^. pneumophila serogroup 6 were derived from the fusion of mouse myeloma cells and spleen cells from mice immunized with pneumophila Chicago 2 strain. Test sera of mice immunized with Chicago 2 strain were negative against the Bloomington 2 reference strain of L^. pneumophila serogroup 3. After fusion, the suspension was plated in 10 plates. Screening of Chicago 2 antibody-producing clones by indirect fluorescent antibody (IFA) was performed throughout the project. The clones producing the highest fluorescence in each plate were recloned twice to insure monoclonality. Ten clones producing monoclonal antibodies against Chicago 2, the representative strain of L^. pneumophila serogroup 6, were isolated. These were tested by IFA against 30 strains of JL. pneumophila serogroup 6 and 6 strains of L. pneumophila serogroup 3. All ten of the monoclonal antibodies gave positive results to 30 strains of serogroup 6 but not to 6 strains of serogroup 3. It is concluded that monoclonal antibody is superior to the conventional antisera because of the specificity demonstrated. The reaction of monoclonal antibodies with 30 strains of L^. pneumophila serogroup 6 demonstrated that 3 strains showed antigenic variation. These results also indicate the potential of monoclonal antibodies as diagnostic reagents for identification of L^. pneumophila.