DISEASE CHARACTERISTICS: Histologically proven unresectable, recurrent, or refractory squamous cell carcinoma of the head and neck Primarily stage III or IV Tumor accessible to direct injection No tumor involving major blood vessels or obstructing airway

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Life expectancy: At least 3 months Hematopoietic: WBC at least 3,000/mm3 Platelet count at least 50,000/mm3 Hepatic: No prior or concurrent active liver disease SGOT and SGPT no greater than 3 times upper limit of normal (ULN) Renal: Creatinine no greater than 1.5 times ULN Cardiovascular: No New York Heart Association class III or IV heart disease Pulmonary: No respiratory disease that sufficiently influences oxygenation of arterial blood Other: At least 2 weeks since prior infection No concurrent infection No active or clinically relevant viral illness No other malignancies requiring treatment during this study No prior autoimmune disease (e.g., rheumatic disease, Crohn's disease) No allergy to polyvinylpyrrolidone (PVP) or related products No prior psychiatric disability No prior seizures Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior viral based gene therapy, recombinant DNA products, or bacterial plasmids Chemotherapy: At least 28 days since prior chemotherapy No concurrent chemotherapy No chemotherapy during follow up period Endocrine therapy: No concurrent corticosteroids Radiotherapy: At least 28 days since prior radiotherapy No concurrent radiotherapy No radiotherapy during follow up period Surgery: At least 28 days since prior surgery No concurrent surgery No surgery during follow up period Other: At least 30 days since prior investigational drugs No concurrent high dose nonsteroidal antiinflammatory drugs No concurrent immunosuppressive drugs