# Preclinical Study on Sabin Strain-Based DTaP-sIPV/Hib Pentavalent Vaccine: Evaluation of Repeated-Dose Toxicity and Immunogenicity

## TL;DR

A new five-in-one vaccine for children was tested in rats and showed good safety and strong immune responses.

## Contribution

The study introduces a Sabin strain-based pentavalent vaccine with improved biosafety and cost-effectiveness.

## Key findings

- The vaccine caused only reversible local swelling and no long-term organ damage.
- All rats developed immunity to bacterial components after the first dose.
- High and low doses produced similar antibody levels after three doses.

## Abstract

Background: Pertussis, diphtheria, tetanus, poliomyelitis, and Haemophilus influenzae type b (Hib) infections pose severe threats to children’s health globally. This study evaluated the safety and immunogenicity of a novel Sabin strain-based adsorbed pentavalent vaccine (DTacP-sIPV/Hib), which offers potential advantages in biosafety and cost-effectiveness compared to wild-type poliovirus-based vaccines. Methods: A repeated-dose toxicity study was conducted in 190 Sprague-Dawley rats, randomly divided into negative control, adjuvant control, low-dose, and high-dose groups. Animals received five intramuscular injections at 21-day intervals, followed by a 56-day recovery period. Parameters assessed included local reactions, body temperature, hematology, serum biochemistry, coagulation, histopathology, T-cell subsets, cytokine levels, and antigen-specific immunogenicity. Results: The primary adverse reaction was dose-dependent local muscle swelling, which was fully reversible within 3–21 days. Only transient body temperature fluctuations and adjuvant-related hematological/biochemical abnormalities were observed, all resolving after the recovery period. No vaccine-related damage occurred in hepatic/renal function or immune organs. Immunogenicity data showed 100% seroconversion for all bacterial components 21 days after the first dose. The high-dose group achieved 100% seropositivity for all poliovirus serotypes after the second dose, while the low-dose group reached the same after the third dose, with no significant difference in antibody levels between dose groups. Conclusions: The DTacP-sIPV/Hib vaccine exhibits a favorable safety profile and robust immunogenicity in rats, supporting its further clinical development. The use of Sabin strains reduces biosafety risks and manufacturing costs, making this vaccine a promising candidate for immunization programs, especially in resource-limited regions.