Augmented immunogenicity of Lewis lung carcinoma by infection with herpes simplex virus type 2

In vitro, LLT cells sustain HSV-2 replication without evidence of lysis. Simultaneously, multiplication of the cells is stimulated. These xenogenized cells were tested for their immunopotentiating capacity: three-step immunization with xenogenized viable cells conferred significantly augmented transplantation resistance to a challenge graft with 4 x 10(4) intact LLT cells. Latency periods preceding tumor formation were increased and 15% of the mice failed to form primary tumors. Metastasis was likewise decreased and 25% of the mice had healthy lungs. Immunopotentiation, however, did not suffice to significantly protect against a challenge with 6 x 10(4) intact cells. The presence of virus-specific neoantigens on HSV-2-infected viable cells was demonstrated by the progressively increasing number of rejections of 4 x 10(4) xenogenized cells during the successive immunization steps. Immunization with non-viable LLT cells did not augment resistance to challenge.