Date of Award

Spring 5-20-2016

Degree Type

Honors Thesis



Degree Name

Bachelor of Science

First Advisor

Dr. Juliet Spencer

Second Advisor

Dr. John Paul

Third Advisor

Dr. James Sikes


Human cytomegalovirus (HCMV) is a widespread pathogen that is particularly skilled at evading immune detection and defense mechanisms, largely due to extensive co-evolution with its host’s immune system. One aspect of this co-evolution involves the acquisition of four virally encoded GPCR chemokine receptor homologs, products of the US27, US28, UL33 and UL78 genes. G protein-coupled receptors (GPCR) are the largest family of cell surface proteins, found in organisms from yeast to humans. In this research, phylogenetic analysis was used to investigate the origins of the US27 and US28 genes, which are adjacent in the viral genome. The results indicate that both US27 and US28 share the same common ancestor, the gene for human chemokine receptor CX3CR1, suggesting that a single human gene was captured and that a viral gene duplication event occurred. It also appears that after the gene duplication event, US27 may have undergone neofunctionalization, while US28 maintained the function of their ancestral gene. While the evolutionary advantage of the gene duplication and neofunctionalization event remains unclear, experimental evidence indicates that each gene has evolved distinct, important functions during virus infection.