Researchers funded by the National Institutes of Health have developed an experimental vaccine that reduces stillbirths among rodents born to mothers infected with cytomegalovirus (CMV), a common virus that can also cause mental retardation and hearing loss in newborn children who were infected in early fetal life.

Estimates place the number of US children born with CMV each year at about 40,000, and there is no vaccine or treatment for pregnant women who have the infection. In a 2000 report, the Institute of Medicine of the National Academy of Sciences listed as a top priority the development of a vaccine to prevent cytomegalovirus during pregnancy.

"An effective CMV vaccine for women of childbearing age could greatly reduce the disability caused by the virus," said Duane Alexander, MD, director of the NICHD, the NIH institute that funded the study. "A prototype vaccine is the first step in protecting newborns against the most common viral disease of newborns in the developed world."

The study appears in the March 15, 2007, issue of the "Journal of Infectious Diseases."

Mark Schleiss, MD, American Legion Endowed Chair in Pediatric Infectious Diseases at the University of Minnesota School of Medicine, led a team of researchers at his own and other institutions to conduct the study.

Female guinea pigs given the CMV vaccine before becoming pregnant gave birth to fewer dead pups and were less likely to transmit the infection to their offspring than were female guinea pigs not receiving the vaccine.

The vaccinated group produced 28 live pups and 4 dead pups - a mortality rate of 13 per cent. The control group, which received a vaccine for the flu, produced 9 live pups and 12 dead pups - a mortality rate of 57 per cent.

The surviving pups weighed more than the pups of mothers that had not received the CMV vaccination before becoming pregnant. The vaccine greatly reduced the total amount of virus found in the mothers' blood. The vaccine in the study was developed in collaboration with researchers at AlphaVax, Inc.