The effect of air on the potency of multi-use vials of Mycobacterium bovis purified protein derivative (bPPD)

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Sigafoose, Teresa Marie
Iowa State University; Digital Repository @ Iowa State University
Mycobacterium bovis; oxidation; potency; protein; purified protein derivative; stability
thesis / dissertation description
The effects of air on the potency of human tuberculin purified protein derivative (PPD) was studied 30 years ago and based on this information, recommendations as to the bottling and handling of multi-use vials were made to manufacturers and health care workers to reduce air exposure to the PPD . Until this current study, there has been no published work done to determine the effect of air on maintaining potency of bovine PPD (bPPD). Bovine PPD is used by the United States Department of Agriculture (USDA) Tuberculosis (TB) Eradication Program as an diagnostic test for bovine tuberculosis. Currently, guidelines issued by the USDA TB Eradication Program call for the disposal of multi-use vials of bPPD 2 weeks after the initial use.In this study, we utilized one lot of bPPD that was distributed to field personnel to test for bovine TB. Seven bottles of bPPD were exposed to air and held at 4°C storage conditions for varying time periods over the course of 6 months. One bottle of bPPD was never exposed to air and used as a negative control reference. Duplicates of each experimental PPD were utilized. At the end of 6 months, potency testing was performed in vivo in sensitized guinea pigs and experimentally infected cattle. The Bovigam® assay was used as an in vitro potency tool to measure gamma interferon production by lymphocytes upon stimulation utilizing bPPDs from each treatment group. Protein concentration remained the same in all bottles as well as the pH and no visual changes were apparent.We found that bPPD retained acceptable potency for up to 6 months after being exposed to air, stored at 4 °C, and in the original amber colored multi-use vials.