Recently, University of Florida Health researchers discovered why an influenza virus was making young people admitted to UF Health Shands Hospital so sick: It contained a mutation that allowed it to infect the patients’ lower respiratory tracts.
Typically, flu settles in the upper airways of the lungs. The researchers knew the virus was settling deeper into the young patients’ lungs but had to determine whether a bacterial pneumonia infection caused the severity of the illness, or whether the viral infection’s penetration deep into the lungs was because of the flu itself. By sequencing samples of this flu’s gene, the researchers discovered that a mutation of the H1N1 flu virus allowed the infection to penetrate deep into the lower respiratory tract.
Knowing about this mutation will help researchers better develop vaccines to combat various forms of flu. The researchers’ findings were published online in the Centers for Disease Control and Prevention’s journal Emerging Infectious Diseases.
Nearly 400 patients with influenza were admitted to UF Health Shands Hospital during winter 2013 to 2014, and the vast majority of them had H1N1. Of these, 15 patients died, and all were younger than 65.
Dr. Nicole Iovine, an epidemiologist for UF Health Shands Hospital and assistant professor of medicine in the College of Medicine, Dr. J. Glenn Morris, director of the Emerging Pathogens Institute at UF and Dr. John Lednicky, an associate professor in the UF College of Public Health and Health Professions department of environmental and global health, sequenced the genes of the virus samples they obtained from patients.
The researchers found a mutation in a viral protein called hemagglutinin. The protein binds to receptors on human cells, allowing the virus to infect the cell. Because of previous, unrelated research published by other scientists, UF Health researchers knew it was this protein mutation that allowed the infection to take hold in the lower respiratory tract.
Even more unusual, the H1N1 virus, including this mutation, targets people between ages 20 and 40. Typically, people who develop severe cases of the flu are those at the extremes of their lifespan: Those who are very young, and those who are very old.
The mystery remains as to why H1N1 — including this variant of H1N1 — hits younger people particularly hard.
Studying the genetics of the virus helps Dr. Lednicky predict whether flu vaccines will protect against particular strains.
“I am interested in how a virus changes and why virulence may change in particular viruses,” said Dr. Lednicky, who studies virology and the airborne transmission of pathogens. “By looking at the virus genes, I can make predictions about whether a vaccine will work.”