Abstract
AbstractExtraintestinal pathogenicE. coli(ExPEC) is the primary Gram-negative bacterial pathogen, and the leading cause of life-threatening sepsis and urinary tract infections (UTI) in adults. The emergence and increasing prevalence of multidrug-resistance (MDR) ExPEC strains have led to considerable treatment failures, increased hospitalization rates, morbidity, and mortality. A prophylactic vaccine against ExPEC has the potential to reduce severe infection-related morbidity and mortality, helping to address the escalating antimicrobial resistance (AMR) crisis worldwide. The α-hemolysin (HlyA) is a critical, frequently detected secreted cytotoxic virulence factor in ExPEC, with HlyA-expressing ExPEC strains correlating with increased severity and infection dissemination in clinical levels. In this study, we assessed the protective efficacy of pro-HlyA (the inactive and immature precursor of HlyA) and Dual-Hit (a combination of pro-HlyA and SinH-3, the previously reported immunoglobulin-like domain-3 of the invasin-like autotransporter protein SinH), as ExPEC vaccine candidates. We demonstrated that immunizing mice with pro-HlyA or Dual-Hit significantly reduced bacterial burden and increased survival rates against pandemic ExPEC sequence type strains, ST73 (CFT073) and ST95 (UTI89), in the model of bacteremia and mortality. Both pro-HlyA or Dual-Hit immunizations also provided significant protection against UTI89 colonization in the bladder in the murine UTI model. Furthermore, vaccination with Dual-Hit provided enduring and robust protection against a mixture of ten typical high-virulent sequence types of ExPEC strains, resulting in a promising broad-spectrum vaccine candidate. These findings suggest that pro-HlyA and Dual-Hit might serve as highly effective vaccine targets and highlight the potential of these vaccine candidates for further development and evaluation.
Publisher
Cold Spring Harbor Laboratory