Production and proteomic characterisation of purified protein derivative from Mycobacterium avium subsp. paratuberculosis

Using a standardised protocol, five in-house preparations of PPDj were prepared from cultures of Mycobacterium avium subsp. paratuberculosis (MAP). Compared to PPDs obtained from other institutes/laboratories, these preparations appeared to perform similarly well in the IFN-γ test. Although the broad proteomic composition of all PPDj preparations was remarkably similar, the absolute abundance of individual proteins varied markedly between preparations. All PPDj preparations contained common immunogenic proteins which were also observed in PPD preparations from Mycobacterium avium subsp. avium (PPDa) and Mycobacterium bovis (PPDb). Temporal difference in protein secretion of in vitro cultured MAP was observed between 20 and 34 weeks suggesting that the age of MAP culture used for PPDj preparations may markedly influence PPDj composition.This study describes a protocol for the production of PPDj and its subsequent proteomic characterisation. The broad proteomic composition of different preparations of PPDj was, for the most part, highly similar. Compositional differences between PPDj preparations were found to be a direct reflection of genetic differences between the MAP strain types used to produce these preparations and the age of MAP cultures they were derived from. A number of conserved immunogenic proteins, such as members of the cutinase-like protein family, were found to be more abundant in PPDj compared to PPDa and should be considered as possible diagnostic antigens for the future.Johne's disease (JD) is a significant animal health issue worldwide. JD is a chronic infectious enteritis of wild and domestic ruminants. Caused by the Gram positive, acid fast bacilli, Mycobacterium avium subsp. paratuberculosis (MAP), JD is responsible for significant financial losses to many livestock industries, most notably dairy and beef cattle production [1]. Asymptomatic subclinically infected animals pose a significant challenge for the control and management of JD. From th