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Background: Combination vaccines protecting against diphtheria, tetanus, pertussis, poliomyelitis, and Haemophilus influenzae type b reduce injection burden and improve compliance. While widely used globally, no domestically produced pentavalent vaccine is currently licensed in China. Recent updates to China’s immunization schedule—including earlier initiation and an added booster for pertussis—highlight the need for compatible combination vaccines. This study evaluated the immunogenicity and feasibility of a novel DTacP-sIPV/Hib candidate vaccine in preclinical models. Methods: The vaccine was assessed in NIH mice and Wistar rats. Two Hib dosages were tested in mice alongside a DTacP-wIPV/Hib vaccine (Pentaxim^®). In rats, two sIPV formulations (Formulations A and B) were administered using different intervals (1-month vs. 2-month) and injection methods (mixed vs. separate). Antibody titers were measured by ELISA and poliovirus neutralization assays. Results: The candidate vaccine elicited robust immune responses in both models. In mice, after three doses, the high-dose Hib group achieved >90% seroconversion for pertactin antigen, whereas the low-dose group reached 100% for all antigens. In rats, antibody responses after three doses were comparable to those induced by Pentaxim^®, with no significant differences between immunization schedules or administration routes. Compared with Formulation A (containing a higher type I sIPV antigen content), Formulation B exhibited reduced type I poliovirus neutralization after the first dose (p < 0.05) and delayed seroconversion, while responses to other antigens remained similar. Conclusion: The candidate DTacP-sIPV/Hib vaccine showed robust immunogenicity and flexibility across schedules and administration methods. A formulation including DT 12.5 Lf, TT 3.5 Lf, PT 25 μg, FHA 25 μg, PRN 8 μg, PRP 10 μg, and sIPV I/II/III at 30/32/45 DU is proposed for further development. Full article

The research and development of a pertussis-combined vaccine using a novel inactivated poliovirus vaccine made from the Sabin strain (sIPV) is of great significance in the polio eradication project and to address the recent resurge in pertussis. In the present study, we compared the immunogenicity and efficacy of a candidate DTacP-sIPV with those of a commercial DTacP-wIPV/Hib, DTaP/Hib, pertussis vaccine, and aluminum hydroxide adjuvant control in the rhesus macaque model with a 0-, 1-, and 2-month immunization schedule. At day 28 after the third dose, rhesus macaques were challenged with aerosol pertussis and the antibody and cellular response together with pertussis clinical symptoms were determined. The production of anti-PT, anti-PRN, anti-FHA, anti-DT, anti-TT, and polio type I, II, III antibodies was induced by the candidate DTacP-sIPV, which was as potent as commercial vaccines. In comparison with the control group that showed typical pertussis symptoms of humans after the aerosol challenge, the DTacP-sIPV group did not exhibit obvious clinical pertussis symptoms and had higher neutralization titers of anti-PT, anti-PRN, and anti-FHA. In conclusion, the DTacP-sIPV vaccine was able to induce immunity in rhesus macaques to prevent pertussis infections after immunization. The developed vaccine was as efficient as other commercial vaccines. Full article