Pre-existing chronic or concurrent acute non-A, non-B (NANB) virus infection has been found to interfere with hepatitis B virus (HBV) replication and to delay and moderate markedly the appearance of disease related to HBV infection in chimpanzees. The mechanism for this phenomenon remains unclear. These findings are of practical significance for vaccine safety testing and evaluation of methods for virus inactivation in chimpanzees. The possible occurrence of dual NANB and HBV infection requires that prolonged follow-up be carried out. Attempts to carry out inactivation studies on materials containing both types of virus may also provide misleading observations.

An enzyme-linked immunosorbent assay was applied to the detection of serum antibodies against respiratory syncytial virus. The end points of the various sera tested in the assay were approximately 100 times higher than in the complementfixation test and 2 to 4 times higher than in the plaque reduction test. In addition, the immunosorbent assay appeared to be more efficient than the plaque reduction and complement-fixation techniques for detecting a serological response in young infants (1 to 6 months old) with serious respiratory syncytial virus lower respiratory disease. The simplicity, sensitivity, and rapidity of the enzyme-linked immunosorbent assay make it a useful tool for immunological studies with respiratory syncytial virus.

Induction of RNA "tumor" viruses by 5-iodo-2'-deoxyuridine in mouse fibroblasts is stimulated 5-to 25-fold by glucogenic adrenal corticosteroids. Enhancement of virus production by the hormones is inhibited by low concentration of cordycepin, an inhibitor of poly(A) synthesis.