We share the world and our bodies with microorganisms, and the ones that live in our gut exert a significant impact on our physiology. Scientists have been learning more about the effects of different types of microbiota, some of which can promote good health and others that can help cause disease. Now scientists have discovered that specific strains of microbes can prevent or cure rotavirus infection. Rotavirus infections can cause a range of symptoms in different people, but is the primary cause of serious or life-threatening diarrhea in children.
The work, reported in Cell, helps explain why rotavirus can lead to death in some people but causes mild symptoms in others. It can also aid in the development of treatments for the infection; right now, the only thing that can be done for people infected with the virus is ensuring that they get enough fluids, so dehydration doesn’t set in. There are vaccines for the virus, but they are not accessible to everyone; the disease tends to impact people in low-income countries.
According to the World Health Organization (WHO), around 215,000 children less than five years of age died from rotavirus infection in 2013. The organization is trying to promote vaccination for the virus, especially in Southeast Asia and sub-Saharan Africa.
The virus is highly contagious, and often occurs when people come into contact with an infected individual or their fecal matter. Rotavirus causes abdominal pain, fever, vomiting, severe diarrhea, and can be fatal. Infected individuals in Central America often experience mild illness from the virus, while many deaths occur from the virus in India and Sub-Saharan Africa. There can be a wide range of symptoms even among individuals in the same society, and susceptibility to the virus has not been well-understood.
Now, scientists at the Institute for Biomedical Sciences at Georgia State University have learned that specific types of microbes in the gut can prevent rotavirus infection or cure the illness.
"This study shows that one big determinant of proneness to rotavirus infection is microbiota composition," said senior study author Dr. Andrew Gewirtz, a professor in the Institute for Biomedical Sciences at Georgia State.
"This discovery was serendipitous," Gewirtz noted. "We were breeding mice and realized that some of them were completely resistant to rotavirus, whereas others were highly susceptible. We investigated why and found that the resistant mice carried distinct microbiota. Fecal microbiota transplant transferred rotavirus resistance to new hosts."
The researchers investigated further and found that Segmented Filamentous Bacteria (SFB) had a major influence on resistance to the virus. They demonstrated that the presence of SFB could reduce and protect against infection from rotavirus by triggering the loss of potentially infected epithelial cells that can then be replaced with new cells that aren’t infected.
"It's a new basic discovery that should help understand proneness to rotavirus infection," Gewirtz said. "It does not yield an immediate treatment for humans but provides a potential mechanism to explain the differential susceptibility of different populations and different people to enteric viral infection. Furthermore, it may lead to new strategies to prevent and treat viral infections."
The first author of the work, Dr. Zhenda Shi, has begun a study at the rotavirus branch of the Centers for Disease Control and Prevention to confirm these findings in humans.