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| Hanna J. Laukaitis, Ph.D., and Kevin Macaluso, Ph.D., studied a pathogen that causes spotted fever. |
The research was published in the scientific journal PLoS Pathogens in December 2022 in an article titled “Transposon mutagenesis of Rickettsia felis sca1 confers a distinct phenotype during flea infection.” Hanna J. Laukaitis, Ph.D., a 2022 alumna of the Basic Medical Sciences Graduate Program at the Whiddon College of Medicine and a current postdoctoral fellow at the University of Maryland School of Medicine in Baltimore, was the lead author.
Laukaitis and her collaborators at the University of Minnesota created a mutant form of the pathogen Rickettsia felis to better understand how it infects the cat flea. The flea, Ctenocephalides felis, acts as a vector, or carrier, of the bacterium and can transmit it to pets and humans.
About 5,500 human cases of rickettsial infection in the United States are reported annually to the Centers for Disease Control and Prevention. Infection can produce mild to severe, flu-like symptoms in people, and there is currently no vaccine to prevent it.
“We used gene editing to explore what R. felis uses to infect its vectors,” said Kevin Macaluso, Ph.D., professor and Locke Distinguished Chair of microbiology and immunology at the Whiddon College of Medicine and a co-author of the article. “We were able to identify a factor in the pathogen necessary for flea transmission.”
Macaluso said that altering the genetic sequence in R. felis resulted in significantly reduced pathogen loads during the infection of cat fleas in the lab. “If we can determine the factors necessary for pathogen infection, we can then target these molecules to interfere with transmission to humans,” he said.
The new findings build upon what is already known about the transmission of R. felis, such as the understanding that the pathogen uses multiple routes to infect vertebrate hosts, including skin inoculation via the spit and feces of cat fleas.
The Macaluso laboratory is also doing basic research on the flea. Recently, Macaluso and Monika Danchenko, Ph.D., a postdoctoral fellow in microbiology and immunology at the Whiddon College of Medicine, were co-authors on a paper that examined the salivary gland and saliva composition of cat fleas. In collaboration with colleagues at the National Institutes of Health, the article, “Revisiting the sialmone of the cat flea Ctenocephalides felis,” was published in the scientific journal PLoS One in January.
Macaluso, whose lab is supported by funding from the National Institutes of Health, said the long-term goal of his work is to improve the diagnosis and treatment of diseases transmitted by fleas and other arthropods.
