Neutralizing Activity of Saliva Against Cytomegalovirus

ABSTRACT

Congenital cytomegalovirus (CMV) disease is the leading cause of permanent disability in neonates in the U.S. Neutralizing antibodies in saliva may protect against maternal CMV infection by blocking viral entry into oral epithelial cells, but the antibody response to CMV in the saliva following natural infection is not well characterized. Salivas from naturally infected individuals were tested for CMV neutralizing activity using epithelial and fibroblast cells. Salivas from seronegative adults had no inherent anti-CMV activity. Neutralizing activity of saliva from naturally infected adults was not detectable using fibroblast cells, and salivas from young children, adolescents, and Towne vaccine recipients did not have activity using either cell type. However, using epithelial cells neutralizing activity was present in salivas from 50% of seropositive adults, correlated with serum neutralizing activity, and was more prevalent in mothers of children in daycare than non-daycare-associated adults. Three daycare mothers with high salivary neutralizing activities (>1:20) had exceptionally high serum neutralizing titers (3-8 fold higher than typical seropositives) and were immunoblot positive for serum antibodies to the epithelial entry mediator UL130. These results suggest that salivary neutralizing activities are attainable by induction of high serum IgG levels and could be utilized to evaluate candidate cytomegalovirus vaccines.