Interferon in the replication of herpes simplex virus in normal and pathological nerve cells

Previous results obtained in experimental and clinical trials have demonstrated that topical combined thrapy with human interferon (HI) and human colostral secretory immunoglobulin A (S-IgA) is effective against herpetic corneal infection. This therapy prevented encephalitis in rabbits but could not completely prevent recurrences either in rabbits or in patients. A number of in vitro studies were designed to elucidate the role of these factors in herpes simplex virus replication in the nervous system, with the following results: (1) HSV latency in trigeminal ganglia (TG) explanted from rabbits with experimental herpetic keratitis, topically treated with HI or HI/S-IgA: HSV was recovered in 30% TG after 15-19 days co-cultivation on RK-13 cells. (2) HSV replication in nervous ganglia and nerve of newborn rabbits in organ culture; influence of HI or HI plus IgG: a restrictive HSV productive infection was demonstrated in this system, although yields were always higher in nerve cultures. We were unable to demonstrate a direct effect of HI on HSV-1 replication. When explants were treated with HI and IgG before and after infection for 48 hours a delay in the expression of HSV-1 was detected by co-cultivation. (3) Replication of HSV-1 and HSV-2 in a C1300 murine neuroblastoma clone (NB41A3): both HSV types replicated with titres of 10(3.4) for HSV-1 AND 10(4.8) for HSV-2 at 48 hours p.i.; CPE was more marked for HSV-2 at 24 hours. HSV-specific antigens were demonstrated by the immunoperoxidase technique.