Defense Date

6-7-2022

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Biological Sciences

First Advisor

Aurelien Tartar

Second Advisor

Robert Smith

Third Advisor

William Morgan

Keywords

entomopathogen, transcriptomics, oral infection, virulence, pathogenicity

Abstract

Culicinomyces clavisporus is an entomopathogenic fungus that can infect mosquito larvae, such as Culex quinquefasciatus, Aedes aegypti, and Anopheles stephensi. Whereas most fungal entomopathogens infect hosts through the cuticle, C. clavisporus initiates infection through ingestion. This suggests that the C. clavisporus genome may be mined for novel pathogenicity factors with the potential for vector control. To this end, a transcriptome analysis was initiated. The strain C. clavisporus ARSEF 582 was grown in modified PYG liquid cultures that was supplemented with whole, insect larvae (Galleria mellonella) to elicit the expression of genes involved in host-pathogen relationships. Total RNA samples were extracted and processed for cDNA library construction and Single Molecule Real Time (SMRT) sequencing (PacBio platform). A total of 3,512,145 reads were produced. Assembly of these reads was completed using CD-HIT-EST and revealed 8,266 unigenes. A phylogenetic analysis using actin gene sequences showed the C. clavisporus is closely related to both D. coniospora and H. rhossiliensis. The transcriptome annotation revealed 10 genes of interest to entomopathogenic fungi infection methods, including those potentially linked to the oral infection method. Of those 10 genes, 4 genes have functions related to cellular processes aiding in virulence, 4 genes linked to cuticle degradation, and 2 genes with potential links to the oral infection process. Overall, the number of unigenes identified from the transcriptomic analysis showed greater abundance of unigenes with possible link to oral infection than compared to cuticular degradation. This suggests that C. clavisporus utilizes oral infection as its main mode of infection.

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