• Vaccine Name: Murine Cytomegalovirus Inactivated Vaccine FI-MCMV - Chitosan adjuvant
• Target Pathogen: Murine Cytomegalovirus
• Type: Inactivated or "killed" vaccine
• Status: Research
• Host Species for Licensed Use: None
• Antigen: MCMV Smith strain (Wang et al., 2014)
• Preparation: Inactivated vaccine was prepared with tissue culture-derived extracellular MCMV. Briefly, 3T3 cells were infected by MCMV and incubated at 37°C for 4–5 days. When the monolayer exhibited 100% cytopathic effect, the medium from the infected cells was harvested and the cell debris removed by centrifugation at 6,500 × g at 4°C for 20 min. The total volume of crude virus stock was quantified and inactivated by mixing with 37% formalin at a 1/4000 ratio. (Wang et al., 2014)
• Immunization Route: Intraperitoneal injection (i.p.)
• Description: Adjuvanted inactivated murine cytomegalovirus (MCMV) vaccine with chitosan induces potent and long-term protective immunity against a lethal challenge with virulent MCMV. (Wang et al., 2014)

Mouse Response

• Vaccination Protocol: Each experimental group had 10 mice. The inactivated vaccines, at doses of 4 μg, 1 μg, and 0.25 μg with or without an adjuvant (MF59, alum, or chitosan), were prepared for immunization by intraperitoneal (i.p.) injection. Immunizations were performed twice, 3 weeks apart. The volume of each dose was 200 μl. The adjuvant-only group of mice was administered with MF59, alum, or chitosan only and the control group of mice received PBS. In addition, one group of mice was immunized with formalin-treated mock virus preparation (Mock). To test whether the FI-MCMV vaccine could provide long-term protection, immunizations were performed with 4 μg FI-MCMV and adjuvants, three times by i.p. injection. (Wang et al., 2014)
• Immune Response: Antibody titers after the immunization boost were higher than those after priming. IgG antibody levels correlated positively with the vaccine dose. The antibody titer was greater and the elicited immune response stronger with a higher vaccine dose. When the vaccines were formulated with an adjuvant, the antibody levels increased significantly compared with adjuvant-free vaccines. No anti-MCMV IgG was detected in MF59, alum, and chitosan alone or in mock vaccine-treated mice, which suggested that neither the adjuvant-only treatment nor the Mock vaccine could induce specific anti-MCMV immune response. MF59-adjuvanted groups had the best antibody response. (Wang et al., 2014)
• Challenge Protocol: At 3 weeks after the second immunization, or 6 months after the third immunization, mice were challenged with a lethal dose (5 × LD50, 200 μl/mouse) of SG-MCMV by i.p. injection. (Wang et al., 2014)
• Efficacy: All mice in the control group (including mock vaccine) and adjuvant-alone treatment groups died within 8 days after a lethal challenge with SG-MCMV. Immunization with FI-MCMV vaccine (no adjuvant) at all three doses did not provide sufficient protection, but immunization with adjuvanted FI-MCMV significantly improved protection. At a low dose (0.25 μg), the survival rate in the FI-MCMV plus MF59 group reached 83.3%, while mice immunized with FI-MCMV plus alum or chitosan were not protected. At the 1 μg dose, all mice in the FI-MCMV plus MF59 group survived, while mice in the alum- or chitosan-adjuvanted groups were not completely protected. At the 4 μg dose, all three adjuvanted groups had full protection. These results indicated that immunizing twice with adjuvanted FI-MCMV vaccine could achieve excellent protection. (Wang et al., 2014)