USF St. Petersburg campus Honors Program Theses (Undergraduate)

First Advisor

Mya Breitbart Ph.D. Assistant Professor, College of Marine Science

Second Advisor

Karyna Rosario Ph.D. Post-Doctoral Research Assistant, College of Marine Science


University of South Florida St. Petersburg

Document Type


Date Available

May 2012

Publication Date


Date Issued

May 2012


The smallest viruses known to infect eukaryotic organisms contain circular, singlestranded (ssDNA) genomes. Viruses with these characteristics infect economically important animals (Circoviridae) and food crops (Geminiviridae). Circoviruses were traditionally thought to only infect vertebrates; however, recent studies have characterized circoviruses in dragonflies, suggesting that these viruses may be widespread within insect populations. Since there has not been an effort to further characterize circoviruses in these populations, the first objective of this study is to survey various insect species for the presence of circoviruses. A Polymerase Chain Reaction (PCR) assay revealed a novel circovirus genome (~1700 nucleotides) in a Eurycotis floridana (palmetto bug) sampled from Tarpon Springs, Fl, which had a 70% nucleotide identity to circoviruses found in bat and human feces . By describing the second circovirus from insects, this study supports the idea that circoviruses are more widespread in invertebrates than previously recognized. While the presence of circoviruses in insects has only recently been discovered, the role of insect vectors in the transmission of geminiviruses is well established. The feeding behavior of these insect vectors, which feed on both wild and cultivated vegetation, may lead to the transmission and emergence of new virulent plant virus strains. Therefore, surveying wild plants for viruses may serve as a preventive approach for controlling geminivirusrelated outbreaks. For this reason, the second objective of this study is to survey undersampled plants, specifically weeds and grasses, for the presence of geminiviruses. Rolling-circle amplification (RCA) followed by restriction enzyme digest revealed a known Euphorbia mosaic virus (EuMV) in a Euphorbia heterophylla (a wild weed) sampled from Homestead, Florida. This is the first time that the EuMV genome has been sequenced from the United States, as this virus is primarily found in the Caribbean and Mexico. Differences between the Florida EuMV genomic components, DNA-A and DNA-B, and those reported from the Caribbean and Mexico suggests that these two components are exposed to different evolutionary pressures.


A thesis submitted in partial fulfillment of the requirements of the University Honors Program, University of South Florida St. Petersburg.

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