Honors College Theses

Publication Date

5-5-2023

Major

Biology (B.S.B.)

Document Type and Release Option

Thesis (archived)

Faculty Mentor

Dr. Marina Eremeeva

Abstract

Bartonella bacilliformis (BB) is the etiological agent of Carrion’s Disease, a neglected disease that occurs within the Andean Mountains. Previous animal studies involving BB have had limited success due to an inability to characterize BBs pathogenesis. The purpose of this study was to determine if Galleria mellonella larvae (GML) could be a model for BB infection and to characterize the antimicrobial peptide response of GML. BB was grown on 5% rabbits blood agar, harvested, and enumerated using a qPCR assay developed for this study. 5th instar GML kept at 28°C were injected with 104 to 107 live or heat-treated BB and observed for 96 hours. Hemolymph and fat body were harvested, and total DNA and total RNA were prepared, respectively. cDNA was generated using RT-PCR; gene expression was quantified using gene specific SYBR-Green qPCR. GML inoculated with 104 -107 live heat-killed BB exhibited dose-dependent melanization, health score decline, and lethality compared to control groups. BB was detected and observed microscopically in hemolymph of infected GML at 2- and 24- hours post infection. GML also exhibited dose-dependent melanization and lethality when inoculated with heat-treated BB. The antimicrobial peptides prophenoloxidase (PPO), peptidoglycan recognition protein B (PRPB), and apolipophorin-III (ApoLp-III) were upregulated in infected GML compared to control larvae. PPO gene was upregulated at 2 hours, while PRPB and apoLp-III genes reached max expression at 24 hours before declining at 48 hours post-infection. In conclusion, GML is a suitable model of infection for BB study and useful for early characterization of innate immune system responses.

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Available for download on Tuesday, April 30, 2030

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