Herpes simplex type 1 defective interfering particles do not affect the antiviral activity of acyclovir, foscarnet and adenine arabinoside.

The concentration of defective interfering particles (DI-particles) of herpes simplex type 1 virus was analysed by electron microscopy and plaque titration. Fifteen consecutive passages of undiluted virus in green monkey kidney cells were followed. No relationship was found between the concentration of DI-particles and the activity of antiviral substances such as acyclovir, foscarnet and adenine arabinoside.