Experimental vaccination of rats with Dermatophilus congolensis zoospores.

The number of zoospores recoverable from the skin of rats five days after challenge with Dermatophilus congolensis, was reduced if the rats had been injected intradermally with zoospores of this bacterium two weeks previously. The difference between zoospore recovery in vaccinated and control rats was increased when the challenge was applied to scarified skin. Assays involving a 24-hour delay between scarification and challenge gave the greatest difference in zoospore recovery. In rats which had been vaccinated 12 weeks before challenge protection was reduced.