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Vaccine Detail
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Recombinant MUC1-DHBcAg fusion protein vaccine |
| Vaccine Information |
- Vaccine Name: Recombinant MUC1-DHBcAg fusion protein vaccine
- Target Pathogen: Cancer
- Target Disease: Cancer
- Type: Subunit vaccine
- Status: Research
- Host Species for Licensed Use: Mouse
- Antigen: 2 MUC1 VNTRs, 40aa (likely APPAHGVTSAPDTRPAPGSTAPPAHGVTSAPDTRPAPGST) (Gathuru et al., 2005)
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Adjuvant:
GPI-0100 (Gathuru et al., 2005)
- Immunization Route: subcutaneous injection
- Description: A recombinant subunit vaccine in which two consecutive MUC1 VNTR sequences flanked by KpnI restriction sites were genetically inserted into the Duck Hepatitis B core antigen (DHBcAg) gene (pET3d-DHBcAg vector) and expressed as a soluble intracellular fusion protein in E. coli HMS174, yielding 159–300 mg purified protein per 8-liter culture, offering greater scalability and reproducibility than chemical conjugation approaches. DHBcAg self-assembles into particles of approximately 6.4 × 10⁶ Da, displaying MUC1 VNTR sequences on the particle surface. Formulated with 200 µg saponin adjuvant GPI-0100 and administered subcutaneously in CBF1 mice in two sequential rounds of three weekly immunizations (3 µg MUC1 per dose), separated by a 6-week interval. No detectable anti-MUC1 IgG or IgM antibodies were observed prior to vaccination. After the first three vaccinations, RecMUC1-DHBcAg achieved median IgG ELISA titers of 1/25,600 and IgM titers of 1/6,400. During the 6-week interval before boosting, IgG and IgM titers fell 2–8 fold in all groups (pre-4th bleed: RecMUC1-DHBcAg IgG 1/12,800). After three booster immunizations with the same carrier, IgG titers reached 1/6,553,600 and IgM titers of 1/12,800, equivalent to both MUC1-DHBcAg and MUC1-KLH groups boosted with the same carrier, while groups switched to an alternate carrier achieved significantly lower IgG titers of 1/102,400 and IgM titers of 1/1,600 (p<0.05). Flow cytometry on MUC1-positive MCF7 human breast cancer cells showed IgG surface reactivity of 78% positive cells (MFI 17) and IgM reactivity of 22% post-prime, with IgG declining to 31% (MFI 13) post-boost when the same carrier was used, modestly lower than the chemically conjugated formats. IgM surface reactivity declined across all groups post-boost, ranging 8–32% regardless of carrier sequence. Complement-dependent cytotoxicity against MCF7 cells was not induced despite high ELISA and FACS titers. These results demonstrate that genetic incorporation of MUC1 into DHBcAg particles is an effective recombinant vaccine strategy, achieving booster IgG titers equivalent to chemical conjugate approaches when the same carrier is maintained throughout the immunization schedule (Gathuru et al., 2005).
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| Host Response |
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| References |
Gathuru et al., 2005: Gathuru JK, Koide F, Ragupathi G, Adams JL, Kerns RT, Coleman TP, Livingston PO. Identification of DHBcAg as a potent carrier protein comparable to KLH for augmenting MUC1 antigenicity. Vaccine. 2005; 23(39); 4727-4733. [PubMed: 15978705].
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