Human adenovirus infections: update and consideration of mechanisms of viral persistence

Purpose of review To provide an update on recent studies of human adenoviral (HAdV) infections and to explore the mechanisms of viral persistence and the role of persistent infection in disseminated disease in immunocompromised patients. Recent findings Human adenoviruses continue to be a problem in ophthalmology clinics and to cause periodic, limited, global outbreaks of respiratory disease. Ad14p1 remains in worldwide circulation and continues to result in miniepidemics of severe respiratory infections. New variants of Ad4 and Ad7 have emerged in both the United States and Asia. The severity of Ad4 infections in outbreaks appears to depend more on preexisting conditions in patients than on genetically determined, viral virulence factors, in contrast to limited evidence of Ad7 mutations that may convey increased viral pathogenesis. Reactivation of persistent adenovirus infection appears to be the primary source of disseminated infections in immunocompromised patients. New studies suggest that establishment of persistent infection and reactivation are related to variations in interferon-mediated control of viral replication. Summary Innate immune responses can create a state of adenoviral persistence, and repression of these host defenses can result in reactivation and dissemination of infection. A better definition of the molecular mechanisms of immune-mediated control of viral replication might lead to new strategies for treatment of HAdV reactivation and dissemination.