Date of this Version
Frontiers in Cellular and Infection Microbiology Volume 5 | Article 2 1-2
M. avium subspecies paratuberculosis, hereafter referred to as MAP, is a significant veterinary pathogen that causes Johne’s disease in ruminants, including cattle, sheep, and goats. This chronic intestinal disease is distributed worldwide and exacts a heavy eco- nomic toll on animal producers. For example, the dairy industry incurs substantial economic losses due to reduced milk production, premature culling, and reduced slaughter value (Raizman et al., 2009). It takes years for clinical signs to appear in animals after initial infection. The bacterium is shed in high numbers in the feces during this clinical phase of disease. Transmission is by ingestion of the bacterium while grazing on pastures contaminated by this shedding process. Milk, passed from the infected dam to the daughter, has also been shown as a transmission route (Stabel, 2008). To best combat this chronic infection, vaccination has the promise to reduce economic losses and control Johne’s disease. In the conception of this eBook for Frontiers in Cellular and Infection Microbiology, we solicited communications describing technologies and approaches to immunize animals against Johne’s disease.
Among the first large-scale vaccine trials for Johne’s disease began in the early 1990s using killed whole cells in oil injected into cattle (Kormendy, 1994; Wentink et al., 1994). Those trials showed vaccination was useful to reduce shedding of the bacteria in the feces, thus potentially reducing cow-to-calf transmission, but was ineffective at preventing infection. Since that time, experiments have evaluated extracts of the bacteria and live cells in all hosts including sheep, goats, deer, and cattle. Furthermore, the strain of MAP used has varied greatly in those studies. Then in 2007, an effort was made to standardize the challenge models used to test new vaccines for combating Johne’s disease (Hines et al., 2007). The parameters outlined for the goat model in that article were used to test the best available live attenuated candidates (Hines et al., 2014) as described in this eBook compilation.