Immunotherapy of acute and recurrent herpes simplex virus type 2 infection with an adjuvant-free form of recombinant glycoprotein D-interleukin-2 fusion protein.

Previous studies demonstrated that the adjuvant-free form of a fusion protein consisting of a truncated herpes simplex virus type 1 (HSV-1) glycoprotein D and human interleukin-2 (tgD-IL-2) elicited superior protective immunity in mice. In this study, the immunotherapeutic efficacy of tgD-IL-2 against vaginal HSV-2 infection was investigated using a guinea pig model. Footpad injections of tgD-IL-2 (12.5 micrograms/dose) after the onset of primary lesions strongly suppressed recurrence in the chronic phase of infection; consequently, the number of days with lesions was reduced 65%. Continuous medication with 100 mg/kg/day acyclovir for 5 days failed to suppress recurrent infection. In a UV radiation-induced recurrence model, prophylactic tgD-IL-2 significantly suppressed both duration and severity of disease. A single injection of tgD-IL-2 plus acyclovir produced an additive effect on the suppression of the disease in the acute phase. These results suggest that tgD-IL-2 is a promising immunotherapeutic agent against HSV-2 genital infections.

Intranasal immunization against herpes simplex virus infection by using a recombinant glycoprotein D fused with immunomodulating proteins, the B subunit of Escherichia coli heat-labile enterotoxin and interleukin-2.

To establish a novel strategy of mucosal immunization against herpes simplex virus type 1 (HSV-1) infection, we studied the immune responses elicited by intranasal immunization with several forms of a recombinant glycoprotein D (gD) of HSV-1. A truncated gD (t-gD) co-administered with heat-labile enterotoxin B subunit (LTB) from Escherichia coli induced both a mucosal immune response involving secretion of anti-gD IgA and serum IgG production. The levels of these responses are comparable to those in mice which have recovered from intranasal HSV-1 infections. The fusion protein (t-gD-LTB), consisting of t-gD and LTB, induced the responses more efficiently than did co-administration of t-gD and LTB, although GM1 ganglioside binding activity was significantly reduced in t-gD-LTB. We found that another fusion protein, consisting of t-gD and human interleukin-2 (t-gD-IL-2), also elicited antibody responses comparable to those induced by t-gD-LTB. Immunity acquired by intranasal immunization with t-gD-IL-2 protected mice from intraperitoneal HSV-1 infections, whereas t-gD-LTB or t-gD alone failed to provide protection against infection. Even in a mouse strain that responded highly to subcutaneously administered gD, intranasally administered t-gD did not elicit antibody responses. The lack of response to gD was clearly abrogated by co-administration with IL-2, and administration of t-gD-IL-2 induced an excellent level of antibody responses in this strain. These results suggest that the IL-2 fusion strategy yields a new type of mucosal immunization, the mechanism of which differs from that speculated for the mucosal adjuvant activity of LTB.

Adjuvant-independent enhanced immune responses to recombinant herpes simplex virus type 1 glycoprotein D by fusion with biologically active interleukin-2.

A truncated herpes simplex virus (HSV) type 1 glycoprotein D (t-gD) gene was fused to the human interleukin-2 (IL-2) gene (t-gD-IL-2 gene) and introduced into mouse myeloma Sp2/0 cells. The gene product, t-gD-IL-2, secreted from the cells was immunoprecipitated with five monoclonal antibodies specific for native gD. Purified t-gD-IL-2 supported the growth of IL-2-dependent cells, with a specific activity almost comparable to that of recombinant human IL-2. Mice immunized with t-gD-IL-2 in an adjuvant-free form showed superior anti-HSV antibody responses, and were completely protected against HSV challenge, whereas immunization with t-gD adsorbed onto aluminum hydroxide (alum) partially failed to prevent the virus infection. The high immunogenicity of t-gD-IL-2 was due to the biological activity of the fused IL-2 rather than to a hapten-carrier effect of the IL-2 moiety, because mice primed with t-gD-IL-2 showed delayed-type hypersensitivity against stimulation with gD, but not against that with IL-2 antigen, and because a booster immunization with t-gD-IL-2 extensively augmented the response of anti-gD antibody, but not that of the anti-human IL-2 antibody. The serological half-life of IL-2 activity in mice injected with t-gD-IL-2 was prolonged to about four times that of rIL-2. However, when t-gD-IL-2 was co-administered with human albumin (HSA), the mouse anti-HSA antibody response was slightly enhanced.(ABSTRACT TRUNCATED AT 250 WORDS)