Protection Against Necrotic Enteritis in Broiler Chickens by Regulated Delayed Lysis Salmonella Vaccines.

Abstract

Necrotic enteritis (NE), caused by Gram-positive Clostridium perfringens type A strains, has gained more attention in the broiler industry due to governmental restrictions affecting the use of growth-promoting antibiotics in feed. To date, there is only one commercial NE vaccine available, based on the C. perfringens alpha toxin. However, recent work has suggested that the NetB toxin, not alpha toxin, is the most critical virulence factor for causing NE. These findings notwithstanding, it is clear from prior research that immune responses against both toxins can provide some protection against NE. In this study, we delivered a carboxyl-terminal fragment of alpha toxin and a GST-NetB fusion protein using a novel attenuated Salmonella vaccine strain designed to lyse after 6-10 rounds of replication in the chicken host. We immunized birds with vaccine strains producing each protein individually, a mixture of the two strains, or with a single vaccine strain that produced both proteins. Immunization with strains producing either of the single proteins was not protective, but immunization with a mixture of the two or with a single strain producing both proteins resulted in protective immunity. The vaccine strain synthesizing both PlcC and GST-NetB was able to elicit strong production of intestinal IgA, IgY, and IgM antibodies and significantly protect broilers against C. perfringens challenge against both mild and severe challenges. Although not part of our experimental plan, the broiler chicks we obtained for these studies were apparently contaminated during transit from the hatchery with group D Salmonella. Despite this drawback, the vaccines worked well, indicating applicability to real-world conditions.

• Authors: Yanlong Jiang, Hua Mo, Crystal Willingham, Shifeng Wang, Jie-Yeun Park, Wei Kong, Kenneth L Roland, Roy Curtiss 3rd
• Journal: Avian diseases (Avian Dis) Vol. 59 Issue 4 Pg. 475-85 (Dec 2015) ISSN: 0005-2086 [Print] United States
• PMID: 26629620 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• Bacterial Proteins
• Bacterial Toxins
• Calcium-Binding Proteins
• Enterotoxins
• NetB protein, Clostridium perfringens
• Salmonella Vaccines
• Vaccines, Attenuated
• Vaccines, Synthetic
• Type C Phospholipases
• alpha toxin, Clostridium perfringens
• beta-Lactamases

Topics

• Amino Acid Sequence
• Animals
• Bacterial Proteins (chemistry, genetics, metabolism)
• Bacterial Toxins (genetics, immunology)
• Base Sequence
• Calcium-Binding Proteins (genetics, immunology)
• Chickens
• Clostridium Infections (immunology, microbiology, prevention & control, veterinary)
• Clostridium perfringens (genetics, immunology)
• Enteritis (immunology, microbiology, prevention & control, veterinary)
• Enterotoxins (genetics, immunology)
• Poultry Diseases (immunology, microbiology, prevention & control)
• Salmonella Vaccines (genetics, immunology, therapeutic use)
• Salmonella typhimurium (genetics, immunology)
• Type C Phospholipases (genetics, immunology)
• Vaccines, Attenuated (genetics, immunology, therapeutic use)
• Vaccines, Synthetic (genetics, immunology, therapeutic use)
• beta-Lactamases (chemistry, genetics, metabolism)