Role of vaccines in Salmonella control — a review

Salmonella remains a persistent threat in broiler poultry production, posing significant public health and economic challenges due to its potential for foodborne transmission and clinical disease in poultry. Vaccination is a vital pre-harvest control strategy aimed at reducing colonization, shedding, and transmission of key Salmonella serovars, particularly Salmonella Enteritidis and Salmonella Typhimurium, as well as host-adapted serovars such as Salmonella Gallinarum, and Salmonella Pullorum. This review evaluates various vaccine platforms used in broiler production systems, including live attenuated, inactivated (killed), subunit, and ghost vaccines, based on their safety, immunogenicity, practicality, and application in commercial poultry production. Live attenuated vaccines, though effective in eliciting strong mucosal and systemic immunity, carry risks of persistence and reversion to virulence. Inactivated vaccines are safer and widely accepted but generally stimulate weaker immune responses and require multiple doses. Subunit vaccines, especially when delivered via nanoparticles or in-ovo methods, offer targeted protection with improved safety profiles compared to live attenuated or inactivated vaccines, although their immunogenicity remains a limiting factor. Ghost vaccines, composed of empty bacterial envelopes, represent an innovative platform that preserves antigenicity while eliminating infectivity, demonstrating promising cross-protective potential. Various studies and field applications underscore that while each vaccine type presents distinct advantages and limitations, their strategic deployment, often in combination and integration with biosecurity and surveillance measures, can significantly lower Salmonella burden in poultry. Ultimately, tailored vaccine use based on serovar prevalence, production scale, and host-specific responses offers a practical pathway toward safer poultry products and improved public health outcomes.