Intestinal immunity following a single intraperitoneal immunisation in lambs

Area of Science:

• Veterinary Immunology
• Gastrointestinal Immunology
• Vaccinology

Background:

• Intestinal immunity is crucial for protecting livestock against enteric pathogens.
• Immunization strategies targeting mucosal immunity require further investigation in young animals.
• Ovalbumin and Salmonella typhimurium are common models for studying immune responses.

Purpose of the Study:

• To investigate the development of intestinal antibody-producing cells after intraperitoneal ovalbumin immunization in lambs.
• To evaluate the protective efficacy of early-life intraperitoneal Salmonella typhimurium vaccination against postweaning challenge.
• To determine the role of specific immunoglobulin A (IgA) in intestinal secretions in conferring protection.

Main Methods:

• Young lambs received a single intraperitoneal injection of ovalbumin in oil adjuvant.
• Lambs were immunized intraperitoneally with a Salmonella typhimurium vaccine during the suckling period.
• Immune responses were assessed by identifying antibody-containing cells in the intestinal lamina propria and quantifying specific IgA in intestinal secretions.

Main Results:

• Intraperitoneal ovalbumin immunization led to the presence of antibody-containing cells, predominantly of IgA specificity, in the intestinal lamina propria.
• Intraperitoneal vaccination with Salmonella typhimurium during suckling provided protection against subsequent challenge with live organisms.
• The observed protection was correlated with the presence of specific IgA antibodies in intestinal secretions.

Conclusions:

• Intraperitoneal immunization can effectively stimulate intestinal IgA production in young lambs.
• Early-life intraperitoneal vaccination against Salmonella typhimurium induces protective mucosal immunity.
• Specific IgA in intestinal secretions plays a significant role in mediating protection against enteric bacterial challenges.