• Vaccine Name: Arabinomannan-tetanus toxoid conjugate
• Target Pathogen: Mycobacterium tuberculosis
• Target Disease: Tuberculosis
• Vaccine Ontology ID: VO_0000528
• Type: Conjugate vaccine
• Antigen: Arabinomannan (AM) oligosaccharides. They are derived from Lipoarabinomannan (LAM), a carbohydrate antigen expressed on the surface of mycobacteria which contains a manna polysaccharide core attached to a phosphatidyl inositol lipid moiety (Hamasur et al., 2003). The surface carbohydrate was hypothesized to yield CD1-specific immune responses, promote mycobacterial clearance, downregulate T cell proliferation, and interfere with activation of macrophages through interferon gamma intervention (Hamasur et al., 2003).
• Ag85B from M. tuberculosis H37Rv gene engineering:
  • Type: Conjugate protein purified from LAM
  • Description: The 28-kDa AM oligos were pooled and linked to tetanus toxoid (TT) or other M. tuberculosis proteins (Ag85B, 75-kDa protein) with thioether linkage generated by conjugation method. Conjugation consisted of amination of AMO with ammonium chloride and sodium cyanoborohydride, deasalting and treatment with 2-imminothiolane, and end conjugation between thiolated oligsaccharide derivatives with bromoacetylated proteins and tributyl phosphine (Hamasur et al., 2003).
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000127
  • Description: Alum (aluminum hydroxide gel) adjuvant was used initially. Eurocine L3 suspension adjuvant was prepared using 1:1 ratio solid monooleate and oleic acid, Tris buffer with pH adjustment including NaOH, and subsequent sonification. Eurocine L3 emulsion was prepared using 1:1 ratio solid monooleate and oleic acid which were liquified prior to addition of soy bean oil (Hamasur et al., 2003).
• Preparation: Arabinomannan (AM) oligosaccharides derived from LAM of Mycobacterium tuberculosis H37Rv were isolated and covalently conjugated to tetanus toxoid (TT) or to short-term culture filtrate proteins (antigen 85B (Ag85B) or a 75kDa protein) from M. tuberculosis strain Harlingen (Hamasur et al., 2003).

Mouse Response

• Host Strain: C57BL/6, 8-10 wk female
• Vaccination Protocol: Mice were injected subcutaneously in flanks with 100μL or intranasal with 5μL/nostril of antigen plus adjuvant. The control BCG vaccination involved subcutaneous injection of 5x10^5 CFU in 100μL PBS in hind flank. Two formulations of the adjuvant were used, such that mice were either treated at day 0 with AMOs-TT conjugate in Eurocine L3 emulsion or suspension, followed by nasal booster at day 21 (Hamasur et al., 2003).
• Immune Response: Immunization with AMO-TT, AMOs-Ag85B, or AMOs-75kDa conjugate resulted in increased lymphocyte proliferation in spleen when responding to PPD (Hamasur et al., 2003).
• Challenge Protocol: Mice were challenged intranasally with 10^5 M. tuberculosis Harlingen on day 24 (vaccination on day 0).
• Efficacy: All mice started to die after 17 weeks (median time = 36 weeks) (Hamasur et al., 2003). Considerable increases in weight were observed for mice immunized with AMOs-TT conjugate or BCG versus those not vaccinated (Hamasur et al., 2003). Mice immunized with AMOs-TT conjugate and either adjuvant showed longer survival than sham-immunized mice. The emulsion adjuvant showed increased protective efficacy versus the suspension version (Hamasur et al., 2003)
• Information about this animal model: Mouse Model for TB research

Mouse Response

• Host Strain: C57BL/6, 8-10 wk female
• Vaccination Protocol: Mice were immunized subcutaneously on days 0, 28 with 5 or 25 μg of AMO-Ag85B in 1% alum. Control mice were vaccinated s.c. with live BCG on day 0.
• Side Effects: Reduced weight loss observed for BCG and AMO-Ag85B immunized mice versus shams (Hamasur et al., 2003).
• Challenge Protocol: Mice were challenged intravenously with 10^5 CFU M. tuberculosis H37Rv on day 60(Hamasur et al., 2003).
• Efficacy: BCG-immunized mice exhibited best survival versus mice immunized with the AMO-Ag85B vaccine. However, AMO-Ag85B immunized mice also showed significant improvement in survival versus sham-immunized mice.
• Information about this animal model: Mouse Model for TB research

Guinea pig Response

• Host Strain: Dunkin Hartley, female (250-300g)
• Vaccination Protocol: Guinea pigs were immunized s.c. (day 0) and boosted nasally (day 24) with Eurocine L3 emulsion, AMO-TT conjugate, and variable antigen doses and adjuvant concentrations (Hamasur et al., 2003). A protection study included immunization with 15 μg AMO-Ag85B in 10% Eurocine L3 emulsion. Comparison BCG groups were injected s.c. with 5x10^4 CFU live BCG (Hamasur et al., 2003).
• Side Effects: Five of six animals non-vaccinated and two of six AMO-Ag85B vaccinated were killed before 120 days post-challenge if observed >20% loss of starting weight.
• Challenge Protocol: Guinea pigs were aerosol challenged with saline suspension containing 10^6 organisms per ml (~10 CFU/lung).
• Efficacy: BCG vaccinated animals showed reduced counts of M. tuberculosis bacilli in lung and spleen samples versus saline controls. The reduced CFUs in spleen samples along with histological sections analyzed with double blind analysis suggested an overall decrease in disease severity in lung and spleen (Hamasur et al., 2003).

Rabbit Response

• Host Strain: White New Zealand female rabbits (2.5-3kg)
• Vaccination Protocol: Rabbits were immunized with LAM (50 μg), AMO-TT (20 μg), AMO-Ag85B (20 μg), or AMO-75kDA (20 μg) conjugates via i.m. injection with 100 μl PBS and 100 μl FIA emulsifier, and later boosted (weeks 2, 4) with same dose of the previous vaccine.
• Immune Response: LAM alone did not induce LAM IgG antibodies, whereas the three conjugate vaccines induced high IgG antibody titers (Hamasur et al., 2003).
• Challenge Protocol: No challenge protocol implemented for rabbit immunogenicity study.
• Description: Purpose of the experiment with rabbits was to determine immunogenicity response to LAM and AMO-protein conjugates.