Experimental neonatal colibacillosis in cows: immunoglobin classes involved in protection

Area of Science:

• Veterinary immunology
• Bovine neonatology
• Microbial pathogenesis

Background:

• Neonatal colibacillosis, caused by Escherichia coli, is a significant disease in calves.
• Passive immunity transfer from dam to calf via colostrum is crucial for neonatal protection.
• Specific antibodies in colostrum play a vital role in protecting calves against enteric pathogens.

Purpose of the Study:

• To evaluate the efficacy of different vaccine preparations in inducing passive immunity in calves against E. coli.
• To investigate the correlation between colostral antibody levels and protection against neonatal colibacillosis.
• To identify key immunoglobulin types involved in passive immunity against E. coli in calves.

Main Methods:

• Pregnant cows were vaccinated with one of four preparations.
• Offspring were challenged orally with E. coli strain B-44.
• Colostral whey was analyzed for specific antibodies (IgG, IgA, IgM) against E. coli O and K antigens.
• Calf scours were clinically assessed using a semiquantitative scour index.

Main Results:

• All vaccinated and control dams had anti-O antibodies in colostral whey.
• A deficiency in IgA and IgM anti-K antibodies was observed in control dams.
• Lower calf scour indexes were inversely related to higher levels of IgA and IgM anti-K antibodies in the whey of vaccinated dams.

Conclusions:

• Colostral IgA and IgM anti-K antibodies are important for passive immunity in experimental bovine neonatal colibacillosis.
• Vaccination strategies can enhance protective antibody levels in colostrum.
• Targeting specific antibody responses may improve calf health and reduce disease incidence.