Specificity Differentiation of Herpes Simplex Virus Types 1 and 2 by Indirect Immunofluorescence

Cells infected with herpesviruses develop nuclear and cytoplasmic antigens that are detectable by immunofluorescence. Specific antibodies to a type 1 and a type 2 herpes simplex virus were prepared in rabbits and goats, respectively. Reciprocal cross-titrations of these sera were done on antigens of types 1 and 2 by the indirect immunofluorescence technique. The titers obtained were converted to index numbers and inserted into the formula for specificity differentiation. By this means 11 isolates were typed (seven type 1 and four type 2). Sera from patients with type 1 or 2 herpes simplex virus were titrated against viral antigens of types 1 and 2. The titers were applied to the II/I index formula to type the human sera. By these methods indirect immunofluorescence using intracellular antigens was shown to be a useful additional tool for typing herpes simplex viruses and sera of infected persons.