• Vaccine Name: Nontypeable H. influenzae Hap Protein Vaccine
• Target Pathogen: Haemophilus influenzae
• Target Disease: Meningitis
• Vaccine Ontology ID: VO_0000432
• Type: Subunit vaccine
• Antigen: Recombinant proteins corresponding to the C-terminal region of HapS from H. influenzae strains N187, P860295, and TN106.
• hap gene engineering:
  • Type: recombinant
  • Description:
  • Detailed Gene Information: Click Here.
• hap gene engineering:
  • Type: recombinant
  • Description:
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000143
  • Description: CT-E29H (a mutant cholera toxin)
• Preparation: Recombinant proteins corresponding to the C-terminal region of HapS from H. influenzae strains N187, P860295, and TN106 were used. To prepare the protein antigens for vaccination, 15 µg of rCBD was diluted in Dulbecco's PBS (D-PBS) to a final volume of 20 to 40 µl with or without 0.1 µg of CT-E29H (a mutant cholera toxin) as an adjuvant (Liu et al., 2004).
• Description: Nontypeable Haemophilus influenzae (NTHi), a nonencapsulated gram-negative bacterium, is the cause of a number of human respiratory tract diseases, such as otitis media, sinusitis, bronchitis, and pneumonia. Hap adhesin, promotes bacterial interaction with human respiratory epithelial cells and extracellular matrix proteins as well as mediates bacterial aggregation and microcolony formation. Hap belongs to the autotransporter family of proteins common among gram-negative pathogens . It is synthesized as a 155-kDa precursor protein, which consists of an N-terminal 25-amino-acid signal peptide, an internal 110-kDa passenger domain called HapS, and a C-terminal 45-kDa outer membrane domain called Hapß. Domain in Hap responsible for promoting adherence to epithelial cells resides in the C-terminal 311 amino acids the (cell binding domain [CBD]) of HapS (Liu et al., 2004).

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: Groups of 10 female, 6-week-old BALB/c mice were immunized intranasally with protein antigens as described previously at weeks 0, 1, 3, and 5. To prepare the protein antigens for vaccination, 15 µg of rCBD was diluted in Dulbecco's PBS (D-PBS) to a final volume of 20 to 40 µl with or without 0.1 µg of CT-E29H (a mutant cholera toxin) as an adjuvant . Control mice received D-PBS alone or D-PBS with 0.1 µg of CT-E29H. Sera collected at weeks 0, 3, 5, and 8 were pooled for analysis. Prior to immunization, mice were anesthetized with a mixture of ketamine (80 mg per kg of body weight) and xylazine (7 mg per kg of body weight), a dosage that maintains a state of anesthesia for 15 to 20 min. Vaccines were delivered by pipette in a volume of 20 µl per nostril. The pipette was positioned so that the tip touched the opening of the nostril, allowing the liquid to be drawn into the nasopharynx with breathing. Immediately following immunization, mice were placed in a supine position for 3 to 5 min (Liu et al., 2004).
• Challenge Protocol: Three weeks after the final immunization, mice were challenged intranasally with approximately 10^6 CFU of strain TN106.P2 . Three days after challenge, mice were sacrificed and the nasal tissue was harvested, weighed, homogenized, and plated on BHI-XV plates containing 100 µg of streptomycin/ml. The plates were incubated overnight, and the colonies were counted (Liu et al., 2004).
• Efficacy: Antisera against the recombinant proteins from all three strains not only recognized native HapS purified from strain P860295 but also inhibited H. influenzae Hap-mediated adherence to Chang epithelial cells. Furthermore, when mice immunized intranasally with recombinant protein plus mutant cholera toxin CT-E29H were challenged with strain TN106, they were protected against nasopharyngeal colonization (Liu et al., 2004).