AEGiS-11IAC: Induction of mucosal and systemic immune response to HIV gp160 by genetic vaccination.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Induction of mucosal and systemic immune response to HIV gp160 by genetic vaccination.

Int Conf AIDS 1996 Jul 7-12; 11:13 (abstract no. We.A.390)
Mitchell WM, Ding L, Baird C; Department of Pathology, Vanderbilt University, Nashville, TN, USA. Fax: 615 343-7023.

OBJECTIVE: To demonstrate the utility of the calcium mobilizing steroid hormone and immunomodulator, 1alpha, 25-Dihydroxycholecalciferol [1,25(OH)2D3], in the establishment of mucosal as well as systemic humoral immune responses induced by the facilitated transfection of skeletal muscle with a DNA HIV envelope immunogen.

METHODS: A 7742 bp plasmid (pCMVgp160) was constructed containing the full length HIVIIIB envelope sequence under transcriptional control by a CMV early promoter. pCMVgp160 was administered to Balb/c mice at multiple intramuscular (IM) sites at doses of 10 micrograms and 1 microgram and complexed with dioctylglycylspermine (DOGS) in a 5:1:DOGS:DNA charge ratio with or without 1 microgram 1,25(OH)2D3 in the immunizing mixture. Immunoglobulin titers against gp160 were quantitated by ELISA in serum and parotid secretions at 2 1/2 weeks. Binding of gp160 conjugated with biotin to mucosal surfaces was analyzed by immunocytochemistry on formalin fixed tissues using strepavidin-beta-galactosidase mediated decoration of tissue sections.

RESULTS: 100% of the mice seroconverted by 2 1/2 weeks with IgG, IgA, and IgM titers ranging from 1:50 to greater than 1:1250. Specific IgA titers against gp160 in parotid secretions were insignificant in those animals in which 1,25(OH)2D3 was not present in the immunizing mixture. The inclusion of 1,25(OH)2D3 at 1 microgram concentration in the genetic vaccine resulted in significant IgA titers (greater than 1:1250 in 7 animals and 1:250 in a single animal). Specific binding to mucosal surfaces (lung, jejunum, colon, and vagina at the cervical os) was observed in the 1,25(OH)2D3 group.

CONCLUSIONS: 1,25(OH)2D3 stimulates a significant mucosal IgA response to a genetic vaccine encoding the envelope gp160 polyprotein. The use of a cationic lipid (DOGS) to facilitate muscle transfection in vivo results in a significant decrease in the amount of DNA required (approximately two logs) for an immune response to levels that have practical considerations for human use.

Keywords: AEGIS, HIV, HIV Antibodies, HIV Envelope Protein gp160, Immunoglobulin A, AIDS Vaccines, Immunity, Mucosal, HIV-1, Immunoglobulin G, Nasal Mucosa, HIV Antigens, Vaccines, Immunity, Vaccines, DNA, Immunoglobulin M, HIV Infections, Vagina, HIV Envelope Protein gp120, Transfection, HIV Core Protein p24, Vaccines, Synthetic, Plasmids, Immunoglobulins, Female, Dogs, Animal, Human, Mice, immunology, genetics, ICA11

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WeA390