Enzymatic treatment of formalin-fixed and paraffin-embedded specimens for detection of antigens of herpes simplex, varicella-zoster and human cytomegaloviruses.

Attempts were made to detect antigens of herpes simplex (HS), varicella-zoster (VZ) and human cytomegalo (CM) viruses in pathological preparations made by formalin fixation and paraffin embedding as well as in infected culture cells by means of enzymatic treatment followed by indirect immunofluorescent staining, and the following results were obtained. 1) Specimens from autopsy cases, in which diagnosis was established by detection of viral antigens or virus isolation, showed specific antigens in specimens of various organs of all cases of HS (6 cases), VZ (3 cases) and CM (2 cases). In 17 other cases, which were suspected for those viral infections on the basis of ordinary light microscopic observation, also demonstrated respective viral antigens specifically, enabling differential diagnosis. In one case, HS antigen was detected in the esophagus and CM antigen in the liver, testifying occurrence of a double infection. 2) The time spun during which the specific antigens could be preserved was tested, and it was learned that preservation of stainable antigens was better in paraffin-embedded specimens than in specimens kept in formalin. It was possible to detect HS and VZ antigens in paraffin-embedded specimens prepared 20 and 18 years ago, respectively. 3) The optimal conditions of trypsin treatment varied depending upon the organ as well as upon each individual specimen, but a commonly recommendable procedure was found to by warming at 37 degrees C for 3 hours with 0.25% trypsin. A test with HS virus-infected Vero cells indicated that the effect of trypsin treatment was influenced by the concentration of formalin and the time of fixation.