A report published in the Journal of Virology suggests that scrapie may be transmitted by prion excretion in milk that is ingested by naïve suckling lambs. The report also demonstrates that by causing inflammation, lentiviral infection increases prion shedding. These results help to explain sustained prion disease in flocks over generations and warns us about the dangers of administering pooled milk supplement to sheep populations (as if we didn’t already learn this lesson with BSE).
Another report studied a transgenic mouse system featuring a hamster PrP (HPrP) ORF controlled by the neuron-specific enolase promoter. Expression of HPrP only occurred in brain tissues. The transgenic mice were susceptible to hamster scrapie showing a longer incubation period than observed in normal hamsters. Non-transgenic mice were not susceptible to hamster scrapie. These results indicate that neuron-specific expression of the HPrP minigene will reliably induce susceptibility to hamster scrapie, overcoming the TSE species barrier.
Ligios C. et al. Sheep with scrapie and mastitis transmit infectious prions through the milk. J. Virol. 2001. 85(2):1136-9.
Race R.E. et al. Neuro-specific expression of a hamster prion protein minigene in transgenic mice induces susceptibility to haster scrapie agent. Neuron. 2011. 15(5):1183-91.