Document Type

Honors Thesis

Publication Date

Spring 2019

Abstract

Streptococcus agalactiae or Group B Streptococcus (GBS), is a Gram-positive commensal bacterium that is harmless in healthy adults, yet causes systemic diseases in neonates, the elderly, and immunocompromised individuals. Neonates are at risk of GBS infection in utero or during delivery due to the colonization of the organism in the vaginal canal of between 15-30% of adult females. GBS can cause severe neonatal sepsis and meningitis, as well as chorioamnionitis, which can cause premature birth and stillbirth. GBS infection is greatly facilitated by the presence of a bacterial capsule; a protective, polysaccharide matrix surrounding the cell that plays a key role in the pathogen’s ability to evade host immune responses. Antibiotics are effective in reducing the chances of neonatal infection by GBS; however, they also increase the likelihood of the organism developing antibiotic resistance. An approach to manipulate GBS and reduce its functionality would be beneficial to counter the potential of antibiotic resistance developments, while avoiding the cytotoxic effects that antibiotics can impose on the host.

The GBS CpsA protein, a putative transcriptional regulator of the capsule locus within the GBS genome, plays a significant role in capsule production. Without CpsA, GBS displays reduced capsule production, and thus, reduced virulence. In this study Aspartic Acid-375 and Arginine-378 were targeted in the LytR domain of CpsA, a domain proposed to be responsible for the ligation of capsule to the cell wall of GBS. This work will provide insight into which amino acids are the key residues required for the function of CpsA.

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