Mexican virologist Susana López Charretón unlocks the secrets of rotavirus

Susana López Charretón is one of Mexico’s leading virologists​​. She is the recipient of the UNESCO-Carlos Finlay Prize in Microbiology and the L’Oréal-UNESCO Prize for Women in Science.

She is the only Mexican scientist to edit the Journal of Virology. But winning was not what fueled his science and career. “Awards and recognition are just a result,” he said.

“Actually, they were the ones who embarrassed me the most.” Instead, she was driven by curiosity and a desire to understand and solve problems. “For me, science is a way of life, something that fully fulfills me,” says López Charretón.

For forty years he devoted his life to studying how rotavirus infects human cells. These double-stranded RNA viruses were described by Australian virologist Ruth Bishop and colleagues in 1973 when researchers found a virus particle in the intestinal tissue of children with diarrhea.

Rotavirus causes severe gastroenteritis, including acute diarrhea, vomiting, fever, and dehydration, mainly affecting infants and young children. Worldwide, an estimated 100,000 or more children aged 5 and under die each year from the virus.

Those numbers used to be more than double what they were. A vaccine introduced in 2006 has greatly reduced the burden of disease. The research of the team led by López Charretón and her husband, Carlos Arias Ortiz, and the work of others around the world provided the scientific basis for vaccine development.

López Charretón began studying rotaviruses in the late 1970s, when rotaviruses were still new to science. “They’ve just been discovered, so we’re able to make an important contribution,” he said.

Together with Arias Ortiz, he defined the multistep process and the specific molecular actors by which the virus invades intestinal cells and rapidly replicates its genetic material, the first of its kind in rotavirus infection and gastroenteritis. step.

“Science is primarily a series of small steps to advance knowledge,” says Harry Greenberg, a now-retired American virologist at Stanford University. “During Suzanne’s research on rotavirus, many vaccines were produced,” she said.

Always a scientist López Charretón knew from an early age that he wanted to be a scientist. As a child, she enjoyed doing household experiments like freezing dead flies or opening dead lizards to explore inside.

Unlike the parents of most young women at the time, her parents did not object to her studying throughout her life. With their support, she studied basic biomedical research at the National Autonomous University of Mexico (UNAM) in Mexico City.

Rotavirus was introduced to López Charleton by his mentor, Romilio Espejo, a Chilean virologist who had emigrated to Mexico and was working on rotavirus. She was increasingly fascinated by their intricacies and wanted to understand them. “Rotavirus is causing a very serious problem in the world,” he said.

Around that time, López Charretón also met Carlos Arias, who was working on a master’s degree in Espejo’s lab. She remained at UNAM to pursue her master’s and doctorate degrees, and traveled to California with Carlos Arias between 1981 and 1983 to conduct research sabbaticals in the Caltech laboratory of biologist James Strauss. There they continue the work they started with Espejo. “That’s how I realized that virology was the thing I was most interested in,” he explained.

After returning to Mexico, the couple formed a research group at the Institute of Biotechnology of the National Autonomous University of Mexico to continue their research on rotavirus. At the time, most scientists believed that the process by which rotavirus invades cells is relatively simple, consisting only of viral proteins interacting with cell receptors.

Instead, the group demonstrated that rotavirus entry into host cells is mediated through multiple steps and interactions with the cell surface. These steps take place in specific parts of the cell’s plasma membrane, called lipid rafts, and end with viral entry through endocytosis, a cellular process in which material is surrounded by regions of the cell membrane to form vesicles. transport substances. in the cell.

López Charretón’s research group also describes the molecule that helps rotavirus defeat the body’s innate antiviral system. Two multifunctional viral proteins directly interact with gut cells and prevent antiviral responses. The finding could explain why viruses are so specific to the cells they infect.

Their model is now the leading model describing how rotavirus invades cells. “All viruses set up this type of battle with the host cell, and it’s surprising that each virus has different tools to do it,” says López Charretón.

López Charretón continues to study rotaviruses, trying to discover how they disrupt all the cellular machinery in the cells of the gut. But early in the COVID-19 pandemic, he was part of a team of virologists tasked with monitoring and sequencing the strains of coronavirus circulating in the country.

She and other virologists founded the Mexican Multi-Institutional Genome Surveillance Consortium. Although the group planned to continue monitoring other viruses after the pandemic, it was disbanded due to lack of financial support from the government.

This work underscored to López Charedon the importance of increasing the ranks of Mexican scientists. “With this pandemic, it’s become clear to us that we don’t have enough virology experts to deal with these kinds of problems,” he said.

Mentor for Aspiring Scientists

She has spent her entire career building a scientific pipeline, helping to train motivated young virologists like herself. “(As a scientist) you also have the pleasure of sharing your passion with your students, watching them grow and develop great rigor in their craft,” he said.

Greenberg said that besides being a brilliant scientist, one of Lopez-Charleton’s most outstanding qualities was her willingness to teach. Three of his students completed postdoctoral work in Greenberg’s lab. She observed how close they were to her and how well trained they were; said she was probably the most attentive and caring mentor he had ever met.

Liliana Sánchez Tacuba completed her Ph.D. He had some conversations with López Charretón before heading to Greenberg’s lab as a postdoctoral fellow, and he agreed that, unlike many lab leaders, López Charretón dedicates his time to teaching. “I couldn’t have asked for a better mentor,” said Sánchez Tacuba. “She was my academic mom and I still reach out to her whenever I have difficulties or concerns.”

Sánchez Tacuba is from a small, low-income community in the Mexican state of Guerrero, where most women only go to elementary school. Currently, she is a Research Scientist in the Microbiology Division of Vir Biotechnology, an American immunology company focused on the treatment and prevention of infectious diseases.

Sánchez Tacuba said all this was possible thanks to López Charretón, and the time and dedication of López Charretón in advising her energy. “She changed my life,” Sanchez Takuba said. “Every time I ask myself, I think, if Suzanne Lopez believes in me, then I should be able to do it.”

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