Effect of saponin from Quillaja saponaria (molina) on antibody, tumour necrosis factor and interferon-gamma production.

Saponin has been described to contain adjuvant activity in vaccination protocols, in protection against disease, and on humoral immune response. In this paper we describe the effect of a pure saponin from Quillaja saponaria (molina) on the immune response elicited in mice by two antigens, BSA and Crotalus durissus terrificus (South American rattlesnake) venom. Antibody production as measured by ELISA shows that saponin was able to increase antibody synthesis to both antigens. Moreover, mice immunized with verom plus saponin were completely protected against the lethal effects of the venom. The effect of saponin was also evaluated for cytokine production. Tumour necrosis factor activity about 2.9 times higher than in control mice was detectable in sera from animals immunized with saponin. Interferon-gamma was produced only when BSA and saponin were injected together into the mice.

PsaA (pneumococcal surface adhesin A) and PspA (pneumococcal surface protein A) DNA vaccines induce humoral and cellular immune responses against Streptococcus pneumoniae.

Streptococcus pneumoniae is one of the most important human pathogens and improvement of the currently used polysaccharide vaccines is being pursued. We constructed DNA vaccine vectors containing either the full-length psaA (pneumococcal surface adhesin A) or a truncated pspA (pneumococcal surface protein A--pspA') gene. Both constructs showed transient expression of the antigens in vertebrate cells and induced significant antibody response to the pneumococcal antigens in BALB/c mice injected intramuscularly (i.m.). Fusion with an N-terminal cytoplasmatic SV40 T-antigen (CT-Ag), which was previously shown to stabilize poorly expressed antigens through association with Hsp73, also induced anti-PspA antibody response. The induction of antibodies with a low IgG1:IgG2a ratio and elevated gamma interferon (IFN-gamma) production by spleen cells elicited by DNA vaccination indicate preferential priming of Th1 immunity. Since induction of antibodies against both PsaA and PspA was previously shown to correlate with protection against fatal infection with S. pneumoniae and cell-mediated immune responses could contribute to protection, further evaluation of PsaA and PspA as antigens for a DNA vaccine against S. pneumoniae could be promising.

Susceptibility to murine hepatitis virus (type 3)-induced paralysis is influenced by class I genes of the MHC.

Using H-2 recombinant congenic strains of mice, genetic analysis of resistance to murine hepatitis virus type 3 (MHV3)-induced paralysis was performed. It appeared that both H-2K and H-2D, two class I gene regions of the mouse major histocompatibility complex (MHC), can play independent significant roles in the establishment of such resistance.

Recombinant Mycobacterium bovis BCG expressing pertussis toxin subunit S1 induces protection against an intracerebral challenge with live Bordetella pertussis in mice.

The recent development of acellular pertussis vaccines has been a significant improvement in the conventional whole-cell diphtheria-pertussis-tetanus toxoid vaccines, but high production costs will limit its widespread use in developing countries. Since Mycobacterium bovis BCG vaccination against tuberculosis is used in most developing countries, a recombinant BCG-pertussis vaccine could be a more viable alternative. We have constructed recombinant BCG (rBCG) strains expressing the genetically detoxified S1 subunit of pertussis toxin 9K/129G (S1PT) in fusion with either the beta-lactamase signal sequence or the whole beta-lactamase protein, under control of the upregulated M. fortuitum beta-lactamase promoter, pBlaF*. Expression levels were higher in the fusion with the whole beta-lactamase protein, and both were localized to the mycobacterial cell wall. The expression vectors were relatively stable in vivo, since at two months 85% of the BCG recovered from the spleens of vaccinated mice maintained kanamycin resistance. Spleen cells from rBCG-S1PT-vaccinated mice showed elevated gamma interferon (IFN-gamma) and low interleukin-4 (IL-4) production, as well as increased proliferation, upon pertussis toxin (PT) stimulation, characterizing a strong antigen-specific Th1-dominant cellular response. The rBCG-S1PT strains induced a low humoral response against PT after 2 months. Mice immunized with rBCG-S1PT strains displayed high-level protection against an intracerebral challenge with live Bordetella pertussis, which correlated with the induction of a PT-specific cellular immune response, reinforcing the importance of cell-mediated immunity in the protection against B. pertussis infection. Our results suggest that rBCG-expressing pertussis antigens could constitute an effective, low-cost combined vaccine against tuberculosis and pertussis.

Vitamin A as adjuvant to the mouse immune response to pertussis, tetanus and diphtheria vaccines

Vitamin A was used as adjuvant, comparatively with Al(OH)3, in pertussis, tetanus and diphtheria vaccines. Both groups induced a primary immune response in mice, and one single booster dose elevated the antibodies titers in average 554 times to vitamin A groups and 104 times to Al(OH)3. These antibodies titers correlate with sera IL-4 in immunized animals, suggesting a Th2 response. Other cytokines detected in the sera and/or lymphocytes culture supernatants (IL-2 and IFN- ) indicated that vitamin A could also modulate a Th1 response in DPT and acellular pertussis vaccines.