Date of Award

5-1-2009

Degree Type

Dissertation

University or Center

Clark Atlanta University(CAU)

School

School of Arts and Sciences

Degree Name

Ph.D.

Department

Biology

First Advisor

Dr. Errol Archilbold

Second Advisor

Dr. David L. Scott

Third Advisor

Dr. Godwin Ananaba

Abstract

The resistance of Stenotrophomonas maltophilia to antimicrobial agents has become a major medical and public health problem. The frequent treatment of S. maltophilia borne infections with the same anti-microbial agent over a period of time inherently results in the pathogen developing resistance to the drug. A polyclonal antibody cocktail, D-Squared David L Scott 01 (D2-DLSO1) was used to recover surface exposed immunogenic polypeptides (SEIP’s) from the cell walls of S. maltophilia. Bioinformatics strategies (Blast analysis, sequence alignment hydrophilicity/hydrophobicity plots) were performed to identify epitopes of ferric enterobactin receptor (Fep A) homolog in S. maltophilia. Data showed that D2-DLSO1 recognized regions along the Fep A peptide sequence that was confirmed in an enzyme linked immunosorbent assay (ELISA) assay. The amino acid sequences of Escherichia coli (E. coli) Fep A Iron receptor could serve as a target for the development of anti S.maltophila IgG that are useful in protection against infections caused by S. maltophilia and other Gram negative bacteria. Individual S. maltophilia surface exposed immunogenic polypeptides were evaluated in growth inhibition studies and ELISA was used to determine applicability as targets for immunological neutralization. The data suggest that serial dilution (100-fold increments) of D2-DLSO 1 antisera (1 02 dilutions) representing ljig/ml showed significant binding ofD2-DLSO1 to S.maltophilia antigens as compared to controls. The data indicated that D2-DLSO1 inhibited the proliferation of S. maltophilia and several Gram negative bacteria. However, D2-DLSO1 did not show any inhibition of proliferation on Gram positive bacteria (Staphiococcus. aureus), suggesting that there are no common conserved sequences among Gram negative and Gram positive bacteria. Human monoclonal antibodies (DLS-10/ DLS-1 1) recovered from transgenic mice were capable of inhibiting the proliferation of S. maltophilia in vitro. These monoclonal antibodies showed potential of being excellent therapeutic agents for infections caused by S. maltophilia and possibly other Gram negative nosocomial pathogens.

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