Advancing toward Cytomegalovirus vaccination

It’s among the most common infectious diseases, difficult to detect and is the leading cause of deafness in children. This relatively unknown disease is called Cytomegalovirus (CMV).

By age 40, the majority of adults have contracted the virus, according to the Centers for Disease Control and Prevention. For most people, it doesn’t present a problem.

But for women who contract the disease while pregnant, their babies have a huge risk of long-term complications because they can acquire the infection in a process called congenital transmission. This causes many long-term problems for the newborn, particularly cognitive deficiencies and hearing loss.

While there’s no current vaccine for CMV, new research in Clinical and Vaccine Immunology shows there now may be a viable path forward for future immunization to prevent congenital transmission to the newborn.

The study, led by Mark R. Schleiss, MD, professor in the University of Minnesota Medical School’s Department of Pediatrics, found that two proteins when used together during vaccination significantly decreased guinea pig fetuses’ chances of contracting CMV in utero.

“No one knows how to protect against this common disease that has potential to hurt many people’s quality of life,” said Schleiss. “So discovering a possible way to achieve immunity down the road is an advancement for the field of infectious disease.”

More specifically, a non-replicating “vector“ virus was used to deliver the CMV gene products, or antigens, to the immune system as a vaccine. While the vector virus is incapable of causing disease, it delivers the antigens and bolsters the immune system. Schleiss compared the previous leading protein candidate vaccine glycoprotein B (gB) delivered alone, and a novel combination with a CMV protein pp65 (a T cell target). This combination approach known as a bivalent vaccine was more effective in protecting against congenital CMV infection than either individual protein given alone, likely because the combination approach induced both B & T cells. The combination improved guinea pig pup survival and reduced infection when compared to either monovalent vaccine.

In the animal model, the control group that did not receive the bivalent vaccine had a mortality rate of about 93 percent. However, mortality rate for the group that received the bivalent vaccine was just 8 percent.

Beyond testing safety and efficacy, Schleiss added that the infectious disease community will explore the duration of its benefits in the animal model, as well as whether the immunity protects across the multiple strains of CMV.

“Like all science, this finding represents another ’building block’ toward the goal of an optimized vaccine”, he said. “But it’s a building block that we think could be very helpful in figuring out how to protect kids and improve their chances at a happy, healthy life.”
University of Minnesota, Twin Cities