Document Type

Honors Thesis

Publication Date

Spring 2019

Abstract

The Center for Disease Control approximates that one out of every four women carries Group B Streptococcus (GBS) bacteria. GBS can be passed to the neonate from the pregnant mother during vaginal delivery or in utero by the ascending route1. Some notable diseases that are caused by GBS are sepsis, meningitis, pneumonia, certain skin infections, and types of bone and joint infections2. One of the most important virulence factors for GBS is capsule, which has sialic acid residues attached to the polysaccharide chains helping to prevent the host immune system from being triggered when the pathogen is present. CpsA is a protein found in Streptococcus agalactiae, GBS, that plays a role in production and ligation of the capsule to the cell wall. This research aims to understand the mechanisms used by the CpsA protein to create and attach the capsule. Previous research in this lab has specifically focused on the two aspartic acid residues in the metal binding site of CpsA. This research showed that changing negatively charged aspartic acid residues to a different neutral amino acid resulted in decreased capsule expression. To continue the experiment, this project will be focusing on the third residue within this metal binding domain, arginine, and mutating it to an alanine. Some hypothesized results include that the mutation will cause less capsule production or attachment, increased resistance in zebrafish, and a possible difference between the single mutation compared to the double mutation in the metal binding site.

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