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Monoclonal antibodies to Mycoplasma gallisepticum membrane proteins.

Monoclonal antibodies (MAbs) were prepared to study the immunogenesis of Mycoplasma gallisepticum. Balb/c mice were immunized with M. gallisepticum immunostimulating complexes and the supernatant of heterokaryotes screened with M. gallisepticum and closely related M. synoviae as antigens in indirect enzyme-linked immunosorbent assay. All selected MAbs proved to be M. gallisepticum species-specific when they were tested against 10 different avian Mycoplasma species. After immunoblotting analysis, five polypeptides were identified with estimated molecular weights of 110,000, 66,000, 64,000, 56,000, and 50,000. Cell membrane localization of the recognized polypeptides was studied by immunoelectron microscopy. None of the MAbs inhibited the hemagglutinating activity of freshly prepared M. gallisepticum. However, one MAb (B3) specific for p56 agglutinated the stained M. gallisepticum antigen in the slide agglutination test. Results seemed to correlate with published information on the protein composition and agglutinating activity of Mycoplasma gallisepticum.

Animals↗
PubMed1993

Effects of adjuvants and multiple antigen peptides on humoral and cellular immune responses to gp160 of HIV-1.

The capacity of five different adjuvants, AlPO4, a muramyldipeptide formulation (MDP.TSL), Freund's adjuvant, immunostimulating complex and its matrix components to elicit humoral and cellular responses in rabbits immunized with the human immunodeficiency virus type 1 (HIV-1) envelope protein rgp160IIIB was compared. The highest antibody titers against gp160 and gp41/gp120 epitopes were seen with rgp160 in MDP.TSL or Freund's adjuvant, whereas the broadest responses were seen in rabbits immunized with rgp160 in matrix or MDP.TSL. The broadest spectrum of high-avidity antibodies was also induced by rgp160 in MDP.TSL. Neutralizing titers against HIV-1IIIB, low titers to HIV-1MN, and the most efficient inhibition of viral cell-to-cell spread was seen with rgp160 in MDP.TSL. The strongest and most persisting cellular responses were induced by rgp160 in AlPO4 or MDP.TSL. Using MDP.TSL as the adjuvant, we also improved the immune response against gp120 epitopes by boosting rgp160-primed rabbits with rgp160, multiple antigenic peptides (MAPs), or unconjugated peptides. The MAPs induced high neutralizing titers and were superior to rgp160 alone in inducing both humoral and cellular reactivity. MAPs are therefore strong candidates for inclusion into future HIV-1 vaccines.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1998

Adjuvants and delivery systems for viral vaccines--mechanisms and potential.

Of the vaccines against viral diseases of man currently available, several are less than satisfactory, and the present surge of interest in improving such vaccines, and in developing new vaccines against viral diseases as yet unchallenged, has led to major developments in three areas. The capacity to identify the nature and form of antigenic epitopes in proteins allows the specific design of molecular entities to promote relevant and protective immune responses. Such entities, although ideal in terms of specificity and purity, may not achieve their goals through failure to reach relevant cells of the immune system due to simple dilution, elimination by host enzymes or lack of specific targeting. Concomitant with the above there has been development of a plethora of adjuvants aimed at enhancing immune responses to these 'new' immunogens, paralleled by an almost equally rapid increase in understanding the complex nature of the immune response, particularly with respect to antigen processing, the nature and role of cytokines and the importance of T-cell subsets in infection. These developments allow exploration of matching the properties and mechanistic action of a given adjuvant to a defined immune response. Adjuvants can be grouped according to their physical characteristics and mode of action. They include particulate adjuvants, oil and emulsifier-based adjuvants, those providing controlled antigen delivery, adjuvants based on specific targeting of antigen, and gel-type adjuvants. They may act non-specifically in promoting an immune response to an antigen through depot formation, or very specifically as in a "delivery system" where an antigen is linked to a cellular protein, targeted to a specific cell receptor. As adjuvant technology develops it is becoming increasingly clear that these differing approaches may be combined, and an adjuvant/delivery system designed, to provide slow release of a targeted antigen. The role of adjuvants in modern viral vaccine technology and their influence on the immune system are the subject of this review.

Adjuvants, Immunologic↗
PubMed1998

Humoral response to HSV-1 subunit vaccines--a statistical analysis.

Following primary infection with HSV, the virus becomes latent in the local sensory ganglia for the lifetime of the host. In some cases, periodic reactivation may occur due to various stimuli and cause a recrudescent lesion at or near the initial site of infection. As yet there is no suitable vaccine to prevent its spread within the human population. We investigated the potential of a large number of commercial and experimental adjuvant preparations to enhance the immunogenicity of an HSV-1 glycoprotein subunit vaccine. Evaluation was based on toxicity, total antibody titre, neutralizing antibody production and protection against lethal challenge. All adjuvants tested increased the titre of antigen specific total and neutralizing lg when compared to subunit vaccine alone, although functional neutralising antibody was only detected in some cases. Following challenge, a broad range of protective responses was noted but no correlation between antibody levels and protection was observed. The results emphasize the requirement of adjuvants when using subunit preparations as vaccine formulations and demonstrate that the magnitude and effectiveness of the induced immune response varies greatly with the choice of adjuvant.

Adjuvants, Immunologic↗
PubMed1998

Induction of a Th1 immune response and simultaneous lack of activation of a Th2 response are required for generation of immunity to leishmaniasis.

Experimental systems based on immunization with plasmid DNA or immune-stimulating complexes were used to delineate the requirements for generation of protective immunity against murine leishmaniasis. Vaccination with plasmid DNA encoding the host-protective Leishmania major parasite surface Ag-2 primed for an essentially exclusive Th1 response that protected mice against L. major infection. In contrast, parasite surface Ag-2 in immune-stimulating complexes generated an immune response with mixed Th1-like and Th2-like properties that was not protective despite the activation of large numbers of CD4+ T cells secreting IFN-gamma. These results indicate that a Th1 response is sufficient to protect against cutaneous leishmaniasis, but the induction of a simultaneous Th2 response abrogates the Th1 effector function. DNA vaccines may therefore have an advantage for diseases in which protection depends on the induction of Th1 responses.

Animals↗
PubMed1997

Immunological adjuvants and their modes of action.

New adjuvant formulations contain a vehicle, which carries antigens to antigen-presenting cells. Examples of vehicles are liposomes, immune-stimulating complexes and microfluidized squalene-in-water emulsions. Adjuvant formulations may contain immunomodulators, which augment cytokine production, such as a synthetic muramyl dipeptide analog or monophosphoryl lipid A. In a primary cascade of cytokine production at the site of antigen + adjuvant injection, TNF-alpha promotes the migration of dendritic cells (DC) to lymphoid tissues while GM-CSF accelerates the differentiation of DC into efficient presenters of antigens to T cells. Adjuvants also up-regulate a secondary cascade of cytokines in lymphoid tissues responding to antigenic stimulation: IL-12 augments the production of IFN-gamma, which favors the production of antibodies of protective isotypes (IgG2a in the mouse). Thus adjuvants can regulate immune responses qualitatively as well as quantitatively. Adjuvant formulations can also activate complement, generating C3d, which binds CD21 on follicular dendritic cells (FDC) and B cells. FDC targeting favors the generation of B lymphocyte memory, which is important for vaccination.

Acetylmuramyl-Alanyl-Isoglutamine↗