In vitro evaluation of the inhibitory potential of specific egg yolk antibodies induced by different antigens of Salmonella Typhimurium.

Abstract

Salmonella Typhimurium (S. Typhimurium) is one of the major causes of foodborne infections in humans, mainly transmitted through poultry products. Its remarkable ability to survive in various environments and resist antibiotic treatments poses a significant challenge to the poultry industry. With growing concerns over antibiotic resistance and its adverse effects on public health, egg yolk-specific antibodies (IgY) have gained increasing attention as a safe and effective alternative to antibiotics. This study aimed to compare the effects of two different S. Typhimurium antigens formalin-inactivated antigen (FIA) and ultrasonically prepared antigen (UIA) to induce IgY production in laying hens. Additionally, the study evaluated these antibodies' ability to inhibit bacterial growth, prevent adhesion to intestinal mucosa, and exert antibacterial effects. Twenty-four Lohmann LSL-Lite laying hens (37 weeks old) were randomly divided into three groups: the first group received FIA (1.5 &#xd7; 10&#x2078; CFU/mL), the second UIA (500 &#xb5;g/mL protein), and the third (control) received physiological saline. After a two-week acclimation, antigens were injected into four breast muscle sites using complete Freund's adjuvant (FCA), with booster doses at 14-day intervals using incomplete Freund's adjuvant (FIncA). Results demonstrated that immunization with both antigens significantly increased IgY production, peaking in week 10 for UIA (OD&#x2084;&#x2085;&#x2080;: 1.59) and FIA (OD&#x2084;&#x2085;&#x2080;: 1.35). From weeks 4 to 14, the UIA group maintained higher IgY levels than the FIA group (P< 0.0001). Moreover, IgY inhibited S. Typhimurium growth in a dose-dependent manner, with significantly greater inhibition observed in the UIA group compared to the FIA group during the logarithmic growth phase at 200 mg/mL, reducing bacterial counts to 5.02 and 5.76 LogCFU/mL, respectively. Adhesion to the intestinal mucosa was also inhibited, with the UIA group showing greater reduction (2.94 vs. 4.12 LogCFU/mL, P< 0.05). Cross-reactivity revealed effective inhibition of other Salmonella serovars, including S. Enteritidis and S. Infantis (P< 0.05). These findings highlight the potential of IgY as a safe and efficient antibiotic alternative in poultry production.