Prophylaxis against adenovirus pneumonia : a laboratory investigation

Abstract

Adenovirus type 7 (Ad?) is the sub-species of adenovirus most frequently associated with serious illness. In Cape Town, the strain predominantly responsible for infantile pneumonia due to adenovirus is adenovirus type 7c (Ad7c), and it has been the cause of several outbreaks of nosocomial infection in the respiratory unit at the Red Cross War Memorial Hospital for Children.. This study explored two strategies which could possibly assist in the prevention of the spread of adenovirus infection in the hospital environment. The guanosine analog, 9-(1,3-dihydroxy-2-propoxymethyl) guanine (DHPG) is a highly effective antiviral agent against herpesviruses. It has also been reported that this drug could have therapeutic potential with regard to adenovirus infections. Based on this postulate, it was decided to perform in vitro studies to evaluate the antiviral activity of DHPG against Ad7c. DHPG was tested for it's inhibitory potential against the replication of Ad7c in cell culture. The virus was propagated in the presence of drug concentrations ranging from 2 pM to 150 pM and the manifestation of cytopathic effect was monitored. Ad7c replication in cell culture was not inhibited by the drug at those concentrations that were tested, although growth ~f herpes simplex virus, used as a control, was significantly impaired. The value of passive immunization in the prevention or amelioration of disease has been well recognized. Commercial preparations of immunoglobulin are not routinely monitored for the presence of antibodies to Ad7c. In this study, 17 batches of intramuscular and intravenous globulin were tested for the presence of neutralizing antibodies specific for Ad7c. The batches, which were randomly selected, were all found to contain high levels of neutralizing antibodies to Ad7c. The conclusions reached were that DHPG will not be an efficacious antiviral agent for treatment of Ad7c infections, but that the implementation of passive immunization to children who are infected or exposed to Ad7c in a hospital ward, may be of help to control the spread of nosocomial infections.