Salmonella Infantis, a Potential Human Pathogen has an Association with Table Eggs

Chitosan-nanoparticle-based oral Salmonella enteritidis subunit vaccine elicits cross-protection against Salmonella typhimurium in broilers

Non-typhoidal Salmonella infection is a significant health and economic burden in poultry industry. Developing an oral vaccine to induce robust mucosal immunity in the intestines of birds, especially cross protection against different Salmonella serotypes is challenging. Therefore, a potent oral vaccine platform that can mitigate different serotypes of Salmonella is warranted for the poultry industry. We reported earlier that the Salmonella enteritidis (SE) immunogenic outer membrane proteins (OMPs) and flagellin (FLA) entrapped in mannose chitosan nanoparticles (OMPs-FLA-mCS NPs) administered prime-boost (d-3 and 3-wk later) by oral inoculation elicits mucosal immunity and reduces challenge SE colonization by over 1 log10 CFU in birds. In this study, we sought to evaluate whether the SE antigens containing OMPs-FLA-mCS NPs vaccine induces cross-protection against Salmonella typhimurium (ST) in broilers. Our data indicated that the OMPs-FLA-mCS NPs vaccine induced higher cross-protective antibody responses compared to commercial Poulvac ST vaccine (contains a modified-live ST bacterium). Particularly, OMPs-FLA-mCS-NP vaccine elicited OMPs and FLA antigens specific increased production of secretory IgA and IgY antibodies in samples collected at both post-vaccination and post-challenge timepoints compared to commercial vaccine group. Notably, the vaccine reduced the challenge ST bacterial load by 0.8 log10 CFU in the cecal content, which was comparable to the outcome of Poulvac ST vaccination. In conclusion, our data suggested that orally administered OMPs-FLA-mCS-NP SE vaccine elicited cross protective mucosal immune responses against ST colonization in broilers. Thus, this candidate vaccine could be a viable option replacing the existing both live and killed Salmonella vaccines for birds.

Salmonella Enteritidis ghost vaccine carrying the hemagglutinin globular head (HA1) domain from H1N1 virus protects against salmonellosis and influenza in chickens

This study evaluated the attenuated Salmonella Enteritidis (SE) ghost strain JOL2114 (Δlon ΔcpxR Δasd), which displays on the bacterial surface the H1N1 hemagglutinin globular head portion (HA1; amino acid residues 63-286) on the bacterial surface for protective efficacy against Salmonella and H1N1 challenge in the chicken model, as the birds are the predominant reservoirs for both diseases. The ghost system enhanced the lysis process by converging two lysis processes found in bacteriophages: bacteriophage PhiX174 lysis gene E and holin-endolysin genes found in bacteriophage λ, complemented with accessory lysis-related proteins Rz/Rz1. The present lysis machinery resulted in complete lysis of host-attenuated SE strains in about 24 hrs of incubation under a non-permissible temperature of 42 °C in the absence of L-arabinose, an antisense inducer that blocks lysis gene expression during the growth phase. SE ghost JOL2114 surface display of HA1 was confirmed by Western blot analysis resulting in an immune-reactive band of 31 kDa in size. Chicken immunization via intramuscular and oral routes yielded both SE and HA1 antigen-specific immune responses. Protective humoral and cell-mediated immune responses were effectively elicited against both Salmonella and influenza challenge. This efficient strategy of ghost generation employs a dual system of phage lysis for biological generation of SE ghosts that preserves the surface antigenic architecture, offering a rapid and effective way to generate vaccines that could be deployed in urgent circumstances to protect against both Salmonella and influenza infection.

Inactivation of bacteria on surfaces by sprayed slightly acidic hypochlorous acid water: in vitro experiments

The capacity of slightly acidic hypochlorous acid water (SAHW), in both liquid and spray form, to inactivate bacteria was evaluated as a potential candidate for biosecurity enhancement in poultry production. SAHW (containing 50 or 100 ppm chlorine, pH 6) was able to inactivate Escherichia coli and Salmonella Infantis in liquid to below detectable levels (≤2.6 log10 CFU/ml) within 5 sec of exposure. In addition, SAHW antibacterial capacity was evaluated by spraying it using a nebulizer into a box containing these bacteria, which were present on the surfaces of glass plates and rayon sheets. SAHW was able to inactivate both bacterial species on the glass plates (dry condition) and rayon sheets within 5 min spraying and 5 min contact times, with the exception of 50 ppm SAHW on the rayon sheets. Furthermore, a corrosivity test determined that SAHW does not corrode metallic objects, even at the longest exposure times (83 days). Our findings demonstrate that SAHW is a good candidate for biosecurity enhancement in the poultry industry. Spraying it on the surfaces of objects, eggshells, egg incubators and transport cages could reduce the chances of contamination and disease transmission. These results augment previous findings demonstrating the competence of SAHW as an anti-viral disinfectant.