Viral Photoinactivation and Oncogenesis

To the Editor.—  Photoinactivation therapy for herpes simplex has become a controversial issue since the publication of an observation that herpesvirus photoinactivated by neutral red dye still retained its oncogenicity.¹ The Medical Letter on Drugs and Therapeutics cautioned practicing physicians that the use of photoinactivation therapy for herpes simplex might be risky because of the possibility of cancer production.²Time magazine picked up the issue and introduced it to the public. A drug bulletin was issued by the Food and Drug Administration echoing the potential risk of this new form of therapy.³ These warnings made it sound as if it was an established fact that photoinactivation therapy could lead to oncogenesis.On the other hand, Melnick and Wallis tried to repeat the experiments of Rapp et al and were unable to confirm the observation that herpesvirus photoinactivated by neutral red dye still retained its oncogenicity.⁴Thus,