Immunity and Protection Provided by Live Modified Vaccines Against Paratyphoid Salmonella in Poultry—An Applied Perspective

Non-Antibiotics Strategies to Control Salmonella Infection in Poultry

“…The poultry industry usually implements strategies of surveillance and biosecurity at international, national, and farm levels to prevent Salmonella spread [ 119 , 120 , 121 , 122 ]. Among the health management protocols, vaccination represents the most efficient and cost-effective method to reduce the impact of clinical disease, maintain herd immunity, decrease the shedding and reduce both horizontal and vertical transmission of Salmonella in poultry flocks [ 19 , 123 , 124 , 125 , 126 ]. Additionally, poultry vaccination provides safer food products for consumers reducing the likelihood of food poisoning in humans [ 30 , 125 , 127 , 128 ].…”

“…Live Salmonella vaccines are given frequently to layer flocks and are based on a live attenuated variant of the pathogen, which presents an intrinsic balance between immunogenicity and reactogenicity [ 128 , 136 , 137 ]. Live-attenuated vaccines are administered parenterally or orally and have the ability to colonize the chicken’s gut, so they mimic the natural infection and stimulate cell-mediated, humoral, and mucosal immune responses [ 11 , 19 , 138 , 139 ]. The chicken intestinal innate immune system possesses several elements, including epithelial cells, monocytes, macrophages, dendritic cells, natural killer cells, neutrophils, cytokines, antimicrobial peptides, and nitric oxide, which limits the proliferation of pathogenic invading bacteria [ 140 , 141 ].…”

“…Through gut colonization capacity, Salmonella live vaccines have been used immediately after hatching when young poultry are immunologically immature. This promotes competitive exclusion; that is to say, some heterologous strains from Salmonella are no longer capable of colonizing the gastrointestinal tract, which results in an effective vaccination strategy [ 19 , 130 , 139 , 142 ].…”

“…Among these strategies is the addition of probiotics [ 11 ], prebiotics [ 12 ], postbiotics, such as some bacteriocins [ 13 ], and other compounds such as phytobiotics [ 14 ] throughout the diet, which also promote food efficiency, acting as growth promoters. On the other hand, bacteriophages [ 15 , 16 ], in ovo applications [ 17 , 18 ], and vaccines [ 19 , 20 , 21 ] are viable and technological non-feeding-based strategies extensively proved and implemented to reduce or control Salmonella infection in poultry. Currently, -omic technologies can be used as complementary tools in poultry to obtain information that can result in the formulation of therapeutic strategies and for detecting patterns of resistance to antibiotics, reducing the presence of Salmonella and production costs [ 22 ].…”

Intra-cluster correlations for ceca Salmonella prevalence and enumeration from 40 experimental floor pen trials in broiler chickens using a seeder bird challenge model

“…In recent years, however, there has been increasing recognition that Salmonella prevalences and loads on the farm are positively associated with those at slaughter ( Berghaus et al, 2013 ). Consequently, there is a desire to identify on-farm interventions such as vaccination that can effectively reduce Salmonella in the farm environment ( Hofacre et al, 2021 ). Evaluating potential interventions in a commercial poultry farm environment is challenging because the scale of production is large, management is clustered at the level of the farm and house, and natural exposures to pathogens such as Salmonella are intermittent.…”