Enhancement of the immune response by intradermal vaccination in cattle with enterotoxigenic Escherichia coli (ETEC) vaccine without adjuvant.

A comparison was made of the efficiency of intradermal and subcutaneous routes of vaccination in immunizing cattle with a killed vaccine of Escherichia coli K99+. In this study 135 heifers aged 8-18 months were included. The effect of the number of intradermal injection sites was examined, as well as the optimal time interval between the initial and booster intradermal vaccination. The intradermal route was found to be significantly superior to the subcutaneous route. The optimal time for intradermal booster was approximately 2 weeks. Increasing the number of intradermal injection sites up to 50 (using the same amount of antigen) did not result in an enhancement of the antibody level.