Martin Groschup

Infectivity of Scrapie Prion Protein (PrPSc) Following In vitro Digestion with Bovine Gastrointestinal Microbiota

The influence of a complex microflora residing in the gastrointestinal tract of cattle on the prion protein plays a crucial role with respect to early pathogenesis and the potential infectivity of faeces resulting in contamination of the environment. It is unknown whether infectious prion proteins, considered to be very stable, are inactivated by microbial processes in the gastrointestinal tract of animals during digestion. In our previous study it was shown that the scrapie‐associated prion protein was degraded by ruminal and colonic microbiota of cattle, as indicated by a loss of anti‐prion antibody 3F4 immunoreactivity in Western blot. Subsequently, in this study hamster bioassays with the pre‐treated samples were performed. Although the PrPSc signal was reduced up to immunochemically undetectable levels within 40u2003h of pre‐treatment, significant residual prion infectivity was retained after degradation of infected hamster brain through the gastrointestinal microflora of cattle. The data presented here show that the loss of anti‐prion antibody 3F4 immunoreactivity is obviously not correlated with a biological inactivation of PrPSc. These results highlight the deficiency of using Western blot in transmissible spongiform encephalopathies inactivation assessment studies and, additionally, point to the possibility of environmental contamination with faeces containing PrPSc following an oral ingestion of prions.

Cellular prion protein in the bovine mammary gland is selectively expressed in active lactocytes

The cellular prion protein (PrPc) is a highly conserved glycoprotein with a still enigmatic physiological function. It is mainly expressed in the central nervous system but accumulating data suggest that PrPc is also found in a broad spectrum of non-neuronal tissue. Here we investigated the cell-type-related PrPc expression in the bovine mammary gland by using immunohistochemistry (IHC), ELISA, Western blot, and real-time RT-PCR. Specific immunostaining of serial sections revealed that PrPc is selectively localized in mammary gland epithelial cells. Particularly strong expression was found at the basolateral surface of those cells showing active secretion. Results obtained by RT-PCR and ELISA complemented IHC findings. No correlation was found between the level of PrPc expression and other parameters such as age of the animals under study or stage of lactation.

Stability of Bovine Spongiform Encephalopathy Prions: Absence of Prion Protein Degradation by Bovine Gut Microbiota

Bovine spongiform encephalopathy (BSE) is transmitted by the oral route. However, the impacts of anaerobic fermentation processes in cattle on the stability of BSE‐associated prion protein (PrPSc) are still unresolved. In this study, experiments were designed to assess the ability of complex ruminal and colonic contents of bovines to degrade BSE‐derived PrPSc. No significant decrease in PrPSc levels in BSE brain homogenates was detected by Western blotting after up to 66u2003h of co‐incubation with intestinal fluids. These results indicate that BSE‐associated PrPSc survive gastrointestinal digestion processes in cattle and might be excreted via faeces.