US researchers have uncovered the key to how a prolific virus is able to reinfect individuals despite a strong immune response, possibly opening the way for vaccines to deadly pathogens including HIV and malaria.
In a study of monkeys, scientists at Oregon Health Sciences University found that the common cytomegalovirus (CMV), which has infected up to 80 percent of the adult population, can overcome the body's ability to clean out infected cells unlike most viruses.
"In essence, CMV is able to cutoff an infected cell's call for elimination. This allows CMV to overcome this critical immune barrier during re-infection," explained Klaus Frueh, a senior scientist at the university.
CMV infection is not very serious in adults, but can be deadly in infants, transplant patients and others with suppressed immune systems.
The ability of CMV to bypass the body's immune response makes it difficult to make a vaccine against it, but this study shows how the virus might be useful as a viral vaccine vector, which would carry genetic material from other pathogens into the body.
Most viral vaccine vectors can be used only once, but the ability of CMV to reinfect could make it useful as a vector for vaccines to a number of diseases, including HIV, hepatitis C, malaria parasites and tuberculosis bacteria.