A Review on Escherichia coli Vaccine Development: Current Progress and Future Prospects

Abstract

Escherichia coli ( E. coli ) is a diverse bacterium commonly found in the intestinal tract of humans and animals. While many strains are harmless, pathogenic variants such as enterotoxigenic (ETEC), enterohemorrhagic (EHEC), and avian pathogenic (APEC) strains cause significant health problems in humans and livestock. In Pakistan, E. coli infections are especially problematic in the poultry and dairy industries, where they cause economic losses through mortality, decreased productivity, and increasing antibiotic resistance. The overuse of antibiotics has further intensified the problem, making vaccine development an important alternative preventive strategy. This review summarizes current approaches to E. coli vaccine development, including inactivated vaccines, attenuated vaccines, recombinant protein-based vaccines, DNA vaccines, and autogenous farm-specific vaccines. Each approach is considered in terms of its mechanism, potential advantages, limitations, and applicability to different E. coli pathotypes. Particular attention is given to antigenic diversity, mucosal immunity, antimicrobial resistance, and the need for vaccines adapted to strains circulating in Pakistan. The review also discusses recent international progress, research gaps, infrastructure limitations, and future priorities. Developing effective and locally relevant E. coli vaccines could reduce antibiotic reliance, improve animal and public health, strengthen farm biosecurity, and support microbiological research and vaccine innovation in Pakistan. The review emphasizes that vaccine performance varies with pathogen type, antigen selection, delivery route, and the ability to induce durable protective immunity.