Vaccinating guinea pigs with recombinant glycoprotein D of herpes simplex virus in an efficacious adjuvant formulation elicits protection against vaginal infection

Guinea pigs were immunized with glycoprotein gD-2t in SAF-m or saline, then challenged with herpes simplex virus, type 2 (HSV-2). Animals given gD-2t in SAF-m had higher anti-gD-2t antibodies, fewer and less severe vaginal lesions, and decreased ganglionic latency compared to animals given gD-2t in saline. Leucocytes from animals vaccinated with gD-2t in SAF-m had greater proliferative responses to gD-2t in vitro than cells from control animals. MHC II-restricted, gD-2t-specific cytotoxic T cells were induced in guinea pigs vaccinated with gD-2t in SAF-m. Thus, immunization of guinea pigs with gD-2t in SAF-m markedly reduced the incidence and severity of primary HSV-2 by eliciting both humoral and cell-mediated responses.

Improvement of hepatitis B vaccine by the use of a new adjuvant

Humoral and cellular immune responses of mice and guinea-pigs to hepatitis B virus surface antigen when alum-precipitated or administered with Syntex Adjuvant Formulation (SAF) were compared. Two doses of HBsAg in SAF were sufficient to elicit antibody responses, and using SAF the dose of antigen could be reduced to one-tenth of that required to elicit antibody responses by alum-adjuvanted HBsAg. The use of SAF increased and made more consistent the antibody responses in young mice and in strains of mice with inherited low responses to HBsAg. Cellular responses to HBsAg were more consistently observed when SAF was used than when alum was used. SAF increased the formation of IgG2a antibodies in mice except in the B10.M strain; antibodies of this isotype activate complement and act synergistically with antibody-dependent effector cells more efficiently than antibodies of other isotypes. If SAF proves acceptable for human use it could improve vaccines against hepatitis B virus.

Immunological adjuvants: desirable properties and side-effects

Adjuvants can be used with recombinant antigens to elicit cell-mediated immunity and antibodies of protective isotypes (IgG2a in the mouse and IgG1 in primates). Adjuvants should not produce reactions at injection sites, be pyrogenic or induce anterior uveitis or arthritis. Among 130 analogs of muramyl dipeptides tested, N-acetylmuramyl-L-threonyl-D-isoglutamine showed the greatest separation of potency as an adjuvant from potency in the production of side-effects. A stable emulsion of squalane and the Pluronic polymer L-121 provides a versatile vehicle for targeting of antigens to antigen-presenting cells. The combination of this emulsion with the threonyl analog of MDP is termed Syntex Adjuvant Formulation. This formulation increases the efficacy of influenza, hepatitis B virus, herpes simplex virus, lentivirus and tumor vaccines in experimental animals.

Adjuvant formulations and their mode of action

We have developed an adjuvant formulation (SAF) consisting of a synthetic muramyl dipeptide analogue (N-acetylmuramyl-L-threonyl-D-isoglutamine) in a squalane-Pluronic polymer emulsion. Used with a variety of antigens SAF elicits cell-mediated immunity and antibodies of protective isotypes (IgG2a in the mouse). SAF augments responses to influenza virus haemagglutinin and hepatitis B virus surface antigen. Vaccines using SAF have protected guinea pigs against genital herpes simplex virus infections and subhuman primates against Epstein-Barr virus and simian immunodeficiency virus infections. Properties of SAF are compared with those of other adjuvants, including lipopolysaccharide analogs, ISCOMs and liposomes.

Idiotype vaccination against murine B cell lymphoma. Humoral and cellular requirements for the full expression of antitumor immunity

The roles of humoral and cellular antitumor immune responses induced by immunization with tumor-derived idiotypic IgM were studied in a syngeneic, transplantable B cell lymphoma (38C13) of C3H mice. Id vaccination with keyhole limpet hemocyanin-conjugated Id induced protection against a subsequent lethal tumor challenge. Such immunizations elicited anti-idiotypic antibodies that were cytotoxic in in vitro antibody-dependent cellular cytotoxicity assays as well as in vivo passive transfer experiments. L3T4+ T cells, which proliferated in vitro in response to the specific Id protein, were also induced. However, cells mediating direct cytotoxicity, either in vitro or in vivo, were not observed in the lymph nodes, spleens, or peritoneal cavity of immune mice or at the site of tumor regression as demonstrated by using a tumor sponge implantation model. In addition, in vitro sensitization of immune lymphocytes against 38C13 tumor cells failed to induce cytotoxicity. Immunization with lipid conjugated Id also elicited a T cell proliferative response but failed to induce anti-idiotypic antibodies and did not confer resistance to tumor growth. These results suggest that anti-idiotypic antibodies play the major role in the destruction of 38C13 tumor cells. However, in vivo depletion of L3T4+ or Lyt-2+ cells from 38C-Id-keyhole limpet hemocyanin-immunized mice resulted in diminished protection against a tumor challenge. Thus, although humoral responses appear to play the predominant part in tumor destruction, cellular responses are also required for the full expression of antitumor immunity in this system.

Idiotype vaccination against murine B cell lymphoma. Humoral and cellular requirements for the full expression of antitumor immunity

The roles of humoral and cellular antitumor immune responses induced by immunization with tumor-derived idiotypic IgM were studied in a syngeneic, transplantable B cell lymphoma (38C13) of C3H mice. Id vaccination with keyhole limpet hemocyanin-conjugated Id induced protection against a subsequent lethal tumor challenge. Such immunizations elicited anti-idiotypic antibodies that were cytotoxic in in vitro antibody-dependent cellular cytotoxicity assays as well as in vivo passive transfer experiments. L3T4+ T cells, which proliferated in vitro in response to the specific Id protein, were also induced. However, cells mediating direct cytotoxicity, either in vitro or in vivo, were not observed in the lymph nodes, spleens, or peritoneal cavity of immune mice or at the site of tumor regression as demonstrated by using a tumor sponge implantation model. In addition, in vitro sensitization of immune lymphocytes against 38C13 tumor cells failed to induce cytotoxicity. Immunization with lipid conjugated Id also elicited a T cell proliferative response but failed to induce anti-idiotypic antibodies and did not confer resistance to tumor growth. These results suggest that anti-idiotypic antibodies play the major role in the destruction of 38C13 tumor cells. However, in vivo depletion of L3T4+ or Lyt-2+ cells from 38C-Id-keyhole limpet hemocyanin-immunized mice resulted in diminished protection against a tumor challenge. Thus, although humoral responses appear to play the predominant part in tumor destruction, cellular responses are also required for the full expression of antitumor immunity in this system.

Enhancement of antibody responses to influenza B virus haemagglutinin by use of a new adjuvant formulation

Mice and guinea pigs were immunized with the haemagglutinin (HA) of influenza B-USSR/100 virus, either in Syntex Adjuvant Formulation-1 (SAF-1) or in saline. Antibody titres were determined by ELISA, haemagglutination inhibition and virus neutralization. Animals immunized with HA in SAF-1 had significantly higher antibody titres than did animals immunized with HA in saline. Both 3-week-old and 13 1/2-month-old mice had greater and more uniform antibody responses to HA in SAF-1 than to HA in saline.

Expression of pre-S2 region of hepatitis B surface antigen in Escherichia coli

We constructed a recombinant plasmid that can express the entire pre-S2 sequence of hepatitis B surface antigen (HBsAg) as a fusion protein in E. coli. The hybrid protein, which comprises the bacterial TrpLE protein and the pre-S2 sequence, was the prominent protein that was found in cell extracts. As determined by immune blot analysis, this protein reacted with human HBV convalescent sera, as well as with sera from animals immunized with either purified HBsAg or isolated polypeptides containing pre-S2. It bound specifically to 125I-polymerized human albumin cross-linked with glutaraldehyde but not to 125I-monomeric human albumin. A novel adjuvant formulation was used in place of Freund's adjuvant to immunize guinea pigs with the recombinant product. The antisera obtained from serial bleedings were found to react with HBsAg of both d and y subtypes. These antisera were also shown to react solely with HBsAg polypeptides which contain of HBsAg to solid-phase polymerized the binding of HBsAg to solid-phase polymerized human albumin.

Formulation of vaccine adjuvant muramyldipeptides. 3. Processing optimization, characterization, and bioactivity of an emulsion vehicle

An efficacious vaccine adjuvant which elicits both cell-mediated immunity (CMI) and humoral immune response was developed using [thr1]-Muramyldipeptide (MDP) in an oil-in-water emulsion vehicle containing poloxamer 401, polysorbate 80, and squalane. Processing optimization was performed to increase the physical stability of this adjuvant emulsion which, when prepared by conventional mixing methods, demonstrated good bioactivity but poor physical stability. Various manufacturing methods were compared with a microfluidization process, which produced the most stable and elegant emulsion vehicle. The microfluidized emulsion also elicited equivalent biological response in the animal model tested.

Validation of a first-generation Epstein-Barr virus vaccine preparation suitable for human use

The efficacy of a new vaccine preparation against Epstein-Barr (EB) virus was investigated in cotton-top tamarins. The vaccine consists of fast protein liquid chromatography-purified EB virus membrane antigen glycoprotein of 340 Kd (MA gp340) mixed with a synthetic muramyl dipeptide adjuvant emulsified in squalane containing a pluronic polymer; it is suitable for both scaled-up batch production and eventual administration to man. Vaccinated tamarins rapidly developed ELISA detectable high titre antibodies to MA gp340, and their sera became strongly EB virus-neutralising. After challenge with a massive 100% carcinogenic dose of EB virus, the vaccinated tamarins had a strikingly low level of circulating EB virus-carrying mononuclear cells, in contrast to a control animal, and remained entirely free of tumours. This first-generation vaccine has thus been validated in experimental animals and the way opened for a phase I human trial.

Adjuvant formulation for use in vaccines to elicit both cell-mediated and humoral immunity

Adjuvant formulations which elicit both humoral and cell-mediated immunity will be required for vaccines based on peptides, viral and bacterial subunits and genetically engineered antigens. This report describes an adjuvant formulation which increases both cell-mediated and humoral immunity and is free of significant side effects encountered with other adjuvants or vehicles. The components include the threonyl analogue of muramyl dipeptide, Tween 80, Pluronic L121 and squalane. This formulation was found to be effective with several antigens, in several species, including rodents, cats and monkeys. These results suggest that the formulation will be useful for both human and veterinary vaccines.

An adjuvant formulation that selectively elicits the formation of antibodies of protective isotypes and of cell-mediated immunity

Adjuvants are required to elicit protective immune responses with bacterial toxoids, inactivated viruses and subunit antigens produced by recombinant DNA technology. Some adjuvants, such as muramyl dipeptide (MDP) analog formulations, preferentially induce the formation of antibodies of isotypes that interact with complement and antibody-dependent effector cells, and do not elicit reaginic antibodies. Aluminum salts and mineral oil emulsions increase antibody formation but not cell-mediated immunity (CMI), whereas MDP formulations also elicit CMI. Adjuvants such as MDP and lipopolysaccharide (LPS) stimulate the production by accessory cells of IL-1 that increases the circulation of lymphocytes through draining lymph nodes and act as a growth factor for lymphocytes. Vehicles such as mineral oil emulsions, liposomes and Pluronic polymer formulations provide large surface areas on which antigens can be retained in a two-dimensional matrix, from which they can readily be transferred to antigen-presenting cells. The development of an adjuvant formulation able to elicit the formation of protective antibodies and CMI without unacceptable side effects is described.

Two adjuvant-active muramyl dipeptide analogs induce differential production of lymphocyte-activating factor and a factor causing distress in guinea pigs

Many adjuvant-active analogs of muramyl dipeptide (MDP) have been described. Unfortunately, most have been found to induce pyrexia or other adverse side effects in several species. In the guinea pig, these side effects include the guinea pig distress syndrome, which lasts 24 to 48 h, and enhancement of endotoxin shock. A dose-related response to MDP or N-acetylmuramyl-L-alpha-aminobutyryl-D-isoglutamine [( Abu1]-MDP) was observed. However, we found several adjuvant-active analogs which were completely innocuous in guinea pigs. 2-(2-Acetamido-2-deoxy-D-glucose-3-O-yl)-D-hexanoyl-L-alanyl-D-isoglutam ine (3'-n-propyl-MDP) was one such compound. To understand the differences between the toxic and nontoxic compounds, macrophage stimulation in vitro was studied. Both compounds stimulated guinea pig peritoneal macrophages to produce lymphocyte-activating factor in vitro. However, the supernatant from 3'-n-propyl-MDP-stimulated macrophages had no observable effects on guinea pigs, whereas the dialyzed supernatant from [Abu1]-MDP-stimulated cells readily induced the guinea pig distress syndrome. Sephadex G-150 chromatography showed that both analogs stimulated production of a major (60,000) and minor (11,000) peak of lymphocyte-activating factor activity. The factor causing the guinea pig distress syndrome was found only in the low-molecular-weight fraction of [Abu1]-MDP-treated cell supernatants. Thus, one difference between the nontoxic and toxic compounds is their ability to produce lymphocyte-activating factor in the absence of the toxic factor. The lack of toxicity of 3'-n-propyl-MDP makes it an attractive compound for use in vaccines.

Induction of constant sensitivity to dinitrochlorobenzene in the cynomolgus monkey

A technique for the induction of contact sensitivity in the cynomolgus monkey is described. Seventy percent of the monkeys gave a positive reaction when skin-tested 18 days after sensitization with dinitrochlorobenzene. When re-tested on day 27, both the number of reactors and the intensity of the reactions had increased. Histological examinations showed perivascular leukocytic infiltration with an increased proportion of mononuclear cells, typical of a delayed hypersensitive reaction.

Inhibition of rat intestinal anaphylaxis by various anti-inflammatory agents

Adverse reactions to food may, in some cases, be due to IgE-mediated immune reactions to the ingested antigens. A mast cell protector has been shown to protect patients against challenge with food to which they are sensitive. An IgE-mediated intestinal anaphylaxis reaction in the rat has been developed as a model of some aspects of human food allergy. Using this model, a number of xanthones and other anti-inflammatory agents were tested for activity in inhibiting intestinal anaphylaxis. The compounds were also tested for inhibitory activity against the IgE-mediated rat passive cutaneous anaphylaxis reactions. The xanthones protected against both reactions, as did isoproterenol and cyproheptadine, while aspirin, indomethacin, and dexamethasone inhibited the intestinal but not the cutaneous reaction. This suggests that while IgE-triggered mediator release from mast cells is important in both reactions, other mechanisms may also be operative in the intestinal reaction. Furthermore, the use of xanthones and other anti-inflammatory compounds may be a useful mode of therapy in human food allergy.

Intestinal anaphylaxis in the rat as a model of food allergy

An animal model of food allergy has been developed in which some aspects of the allergic response could be quantified and the effects of various drugs evaluated. The change in permeability of the intestinal tract of actively sensitized rats, after oral challenge with the sensitizing antigen, was the parameter measured. Rats were sensitized by injection of egg albumin and B. pertussis vaccine to induce reaginic antibody to egg albumin. Two weeks after sensitization, 125I-labelled bovine serum albumin (125I-labelled BSA) was injected intravenously, followed by oral challenge with egg albumin. Pieces of intestinal tissue were obtained and the amount of 125I-labelled BSA determined in a gamma counter. The amount of 125I-labelled BSA in the intestinal tissue of sensitized and challenged rats regularly showed an increase of greater than 100% above values for control rats.