hmw1555-914, hmw2553-916, and hia585-705 as subunit vaccine candidates of nontypeable haemophilus influenzae induce specific antibody responses with bactericidal activity in balb/c

Background: nontypeable haemophilus influenzae (nthi) is responsible for diseases such as otitis media, sinusitis, bronchitis, and pneumonia. unlike h. influenzae serotype b (hib), there is no vaccine against diseases induced by nthi. high molecular weight1 (hmw1), high molecular weight 2 (hmw2), and h. influenzae type a (hia) proteins are critical protein adhesions of nthi with the potentiality to provide the protection. objectives: the current study aimed at investigating the potential of recombinant hmw1555-914, hmw2553-916, and hia585-705 proteins as subunit vaccines to induce immune responses after active immunization in bagg albino (inbred research mouse strain) or balb/c mice. methods: hmw1555-914, hmw2553-916, and hia585-705 amplified by polymerase chain reaction (pcr) were cloned into pet28a. sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) and th ewestern blotting analysis were carried out to investigate the characteristics of proteins. proteins were purified by ni-nitrilotriacetic acid (ni-nta) as a gel matrix. mice (balb/c) were immunized subcutaneously with hmw1555-914, hmw2553-916, and hia585-705 proteins, alone or in binary and ternary combinations. eventually, specific antibody responses were evaluated by the enzyme-linked immunosorbent assay (elisa) and serum bactericidal assay (sba). results: antibody responses significantly increased in balb/cimmunized by ternary combination compared with the control group. igg1/igg2a ratio indicated that proteins directed immune responses toward t-helper 2. antisera produced against purified proteins in ternary combination showed the highest bactericidal activity against nthi strains with the titer of 1:32. conclusions: the obtained results suggested that hmw1555-914, hmw2553-916, and hia585-705 adhesins were the potential subunit vaccine candidates of nthi and after further investigation could be considered for protection against nthi infections.