Imagine a virus that has been around for centuries. It's the the most common infectious disease, but also the least well known.
The infection is cytomegalovirus, or CMV. CMV is a member of the Herpesvirus family of viruses. And it’s also a leading cause of birth defects and disabilities in newborns in the United States.
The infection is spread from person-to-person, through contact with bodily fluids, and causes few problems for healthy adults, other than a mononucleosis-like illness. However, like any other member of the Herpesvirus family, once a person contracts the infection, he or she will have it for the rest of his or her life.
By the time adults are 40 years old, 50 to 80 percent of them will have contracted the virus. And it is the complexity of the virus that makes it so prevalent in the population, and so hard to control.
How the virus works
No one is ever really “immune” to CMV. No two strains of CMV are alike, making it possible to get re-infected over and over with new variants of the virus. It’s a virus that is genetically more complex than the common cold, or even HIV (the AIDS virus), and it has the largest genome of any virus.
The virus has been around for hundreds of thousands of years—since the beginning of mankind. And over the course of its evolution, CMV has “stolen” and made copies of the genes in our bodies that regulate our immune system.
By expressing genes that mimic our own immune system control genes, CMV is camouflaged from our immune system, and our bodies don’t recognize it (and don’t eliminate it) as happens with most other viral infections. Since even a healthy, normal immune systems is “tricked” into not fighting the virus, CMV can be shed in body fluids and secretions, sometimes for years, ensuring its ability to spread from person-to-person.
For healthy individuals, the chronic persistence of CMV usually doesn’t cause health problems. However, if a pregnant woman has CMV and it infects the fetus, it may cause life-altering effects on the baby, including deafness, seizures, blindness, mental retardation, and death.
“One in every 100 babies is born with CMV,” says Mark R. Schleiss, M.D., “and in the medical world, that’s huge.”
Schleiss is professor of pediatrics and co-director for the Center for Infectious Disease and Microbiology Translational Research. He is on the Board of Directors for non-profit Brendan B. McGinnis Foundation, a non-profit with the mission of promoting awareness of congenital CMV and enabling vaccine research for junior investigators. Schleiss' CMV research is currently supported by the National Institutes of Health, the March of Dimes Birth Defects Foundation, and an endowment from the McNew Family of Irvine, California.
Schleiss is on a mission: to find a vaccine strategy to prevent CMV. And with a 5-year, $2.9 million grant from the National Institute of Child Health and Human Development, he is on his way.
Developing a vaccine
So, how will Schleiss and his collaborators (scientists at the Fred Hutchinson Cancer Research Center in Seattle and Virginia Commonwealth University) go about developing a vaccine? Using genetic techniques in the laboratory, they’ll delete specific genes in the virus—the ones that trick the immune system into thinking there is no virus. The hope is that—once the virus has been altered and turned into a vaccine—the immune system will be able to recognize that CMV is present in the body and then be able to fight it off more effectively, and that the immune system will retain a long-term to fight off wild-type strains of CMV when they are encountered in day-to-day life.
“We do have some treatments we use for babies infected with CMV, and they provide a modest degree of benefit, but the greatest benefit would be a vaccine for prevention,” says Schleiss.
Researchers like Schleiss continue to make strides in infectious disease research at the University of Minnesota. For more information, and to find the latest research breakthroughs coming out of the U, visit our infectious disease corridors webpage.
-- Emily Jensen