• Vaccine Name: Nontypeable H. influenzae protein P6 with cholera toxin
• Target Pathogen: Haemophilus influenzae
• Target Disease: Meningitis
• Vaccine Ontology ID: VO_0000614
• Type: Subunit vaccine
• Antigen: outer membrane protein P6 (Sabirov et al., 2004)
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000143
• Preparation: NTHI was grown on chocolate agar plates and suspended in phosphate-buffered saline (PBS). The suspension was sonicated and centrifuged at 21,000 × g for 30 min at room temperature. The pellet was resuspended in 1% sodium dodecyl sulfate with 0.1 M Tris, 0.5 M NaCl, and 0.1% 2-mercaptoethanol (buffer B, pH 8.0) with RNase (10 mg/ml), sonicated, incubated, and centrifuged. This procedure was repeated twice. The pellet was then suspended in buffer B without RNase, sonicated, incubated, and centrifuged again. The pellet was finally suspended in buffer A (0.01 M Tris, 0.15 M NaCl; pH 7.4) and incubated at 65°C for 30 min. The insoluble material was removed by centrifugation at 100,000 × g for 60 min at 30°C. The protein contained in the supernatant was thought to be pure P6 (Sabirov et al., 2004).

Rat Response

• Host Strain: White Wistar male rats
• Vaccination Protocol: White Wistar rats were randomly assigned to four experimental groups: intranasal immunization with P6 plus CT or CT alone, intraperitoneal immunization with P6 plus CT or CT alone. Rats were immunized intranasally 5 times, on days 0, 7, 14, 21 and 28 with 60 μl of antigen solution containing 50 μg of P6 and 10 μg of cholera toxin (CT; Sigma, St. Louis, MO) as a mucosal adjuvant or 60 μl of PBS containing 10 μg of CT alone into the left nasal cavity. Control rats were given PBS without antigen.In the experiments on systemic immunization, animals were intraperitoneally injected with 60 μl of the same vaccine on days 0, 7, 14, 21 and 28 (Sabirov et al., 2004).
• Immune Response: Intranasal immunization induced P6-specific sinus mucosal and systemic immunological responses, mainly of the IgA and IgG isotype.
• Challenge Protocol: At day 35, 50 μl (10^9 CFU) of the live NTHi suspension was injected slowly through exposed fibrous tissue into left or right maxillary sinus using a microsyringe. Six rats from each group were sacrificed at 12 and 24 h after the inoculation. Thereafter, the nose was lengthwise split in the equal halves and challenged sinuses were washed with PBS. The sinus wash samples were serially diluted 10-fold, and 10 μl aliquots of the diluted samples were spread on chocolate agar plates to determine the concentration of live bacteria (Sabirov et al., 2004).
• Efficacy: The protective effect of intranasal immunization was demonstrated by enhancement of sinus clearance of NTHi. Therefore, unilateral intranasal immunization has a capacity to induce protective immunity against NTHi in the bilateral maxillary sinuses. Systemic administration of the vaccine did not affect sinus clearance of NTHi (Sabirov et al., 2004).