Medical student’s research offers insight into neural changes caused by parasitic infection

According to the Centers for Disease Control and Prevention, 40 million Americans carry a chronic Toxoplasma infection, and most don’t even know it. Caused by the Toxoplasma gondii (T. gondii) parasite, the infection is transmitted most commonly by consuming undercooked meat and unwashed vegetables, as well as exposure to animal droppings. While most people are asymptomatic, there are a small number who can suffer damage to their brain, eyes, or other organs. In addition, research has linked the infection to brain and behavioral abnormalities such as schizophrenia and seizure disorders.

Michael Shlossman, a fourth-year student at the Virginia Tech Carilion School of Medicine, researched Toxoplasma and its effect on alterations in four areas of the brain. His research focused on dopamine, a neurotransmitter made in the body and used to send messages between nerve cells. T. gondii can increase dopamine levels in mice, and Shlossman’s goal was to figure out how.

His project was an expansion of a long-standing study in the lab of Michael Fox at the Fralin Biomedical Research Institute at VTC. Fox is a professor at the institute as well as professor and director of the School of Neuroscience and professor of biological sciences at Virginia Tech.

“Our lab has spent much time trying to understand how infectious agents alter neural circuitry in the brain in the mammalian cerebral cortex and hippocampus,” Fox, who served as Shlossman’s research mentor, said. “But Michael expanded it to other brain regions.”

Shlossman studied four areas in the brains of parasite-infected mice to investigate changes in the genes involved in dopamine production and signaling. He studied each brain area by separating out the genetic material and looking at the levels of genes important to dopamine circuits.

“We wanted to investigate how a T. gondii infection can alter its host environment and explore how these changes may explain behavioral changes,” he said. “We suspected other deviations related to dopamine are caused by the parasite also.”

He added that people with schizophrenia have a much higher likelihood of testing positive for Toxoplasma antibodies, although it’s unknown if there is a direct causal relationship.

Having his research time truncated by new lab protocols that went into effect with the COVID-19 pandemic, Shlossman was not able to investigate as many areas of his research as he would have liked.

He does note, however, that his research showed a pattern of decreases in expression in genes relating to dopamine metabolism, transport, and signaling. This was more pronounced in two of the four areas of the brain he studied.

 “I have a great data set,” he said. “But at this point, drawing any robust conclusions is premature.”

Fox describes Shlossman’s work in his lab as “careful and rigorous.”

“Michael’s discoveries will pave the way for future studies assessing cell type specific circuit changes in these brain regions,” Fox said. “They may shed novel insight into the development of behavioral alterations in response to infection and perhaps a better understanding of why infection by this parasite leads to a higher risk for the development of neuropsychiatric illness.”

This summer, Shlossman will begin a residency in internal medicine. He sees a future in medicine that includes research.

“A research curriculum like the one at the Virginia Tech Carilion School of Medicine is a vital part of our training as clinicians,” he said. “Continuing research after medical school enables us to have a great impact on the medical community. We all rely on each other’s work to continue to make advances in medicine as a whole.

The Virginia Tech Carilion School of Medicine is one of only a few medical schools in the country that requires students to complete a rigorous, multiyear research project as part of their curriculum. This dedicated element of the school’s curriculum has led to its rapidly growing reputation for training exceptional scientist physicians. Since 2014, students have given more than 375 research presentations at regional, national, and international meetings. In addition, there have been 112 research publications with Virginia Tech Carilion School of Medicine students as authors and co-authors.

As a Letter of Distinction recipient, Shlossman is one of eight students in the class of 2021 who will give an oral presentation about their research during the school’s Medical Student Research Symposium on March 26 starting at noon. Other members of the class will present poster sessions of their work in break-out sessions.

In accordance with COVID-19 safety precautions, in-person attendance to the event is limited to the Class of 2021 and select faculty members, though other guests are encouraged to register and attend virtually.