NR AWGA
AU Gregori,L.; Rohwer,R.G.
TI Infectivity in urine of hamsters infected with scrapie and implications on mechanisms of horizontal transmission
QU International Conference - Prion 2006: Strategies, advances and trends towards protection of society - 3.10.-6.10.2006, Torino, Italy, Lingotto Conference Centre - Oral sessions ORAL-32
PT Konferenz-Vortrag
AB
Horizontal transmission from animal to animal of transmissible spongiform encephalopathies (TSE) has been documented in the wild and in laboratory animals. The mechanism underlining these transmissions is not fully understood although several studies implicated environmental contamination. Urine and feces could be responsible for environmental contamination since they are excreted and due to the resistant nature of the TSE agent their infectivity could persist indefinitely. Previous studies have indicated that urine from TSE affected animals and humans is not infectious. However, those studies were conducted with a small number of animals and in some cases transmissions were attempted across the species barrier. We investigated urinary excretion as a potential source of secondary exposure in the environmental.
Urine from hamsters infected with the 263K strain of scrapie was collected using metabolic cages and titered by intracerebral inoculation in the same animal species with the limiting dilution method. Five-ml equivalents of urine (diluted 1:3) were inoculated. After 267 days post inoculation, 4 animals developed scrapie. Although the study is still on-going, the current data indicate that urine from infected hamsters contains low but measurable levels of infectivity (at least 0.8 + 0.4 infectious doses per ml). These results are in contrast with previously reported studies. We argue that similarly to blood infectivity, quantitation of infectivity in urine requires inoculation of a few milliliters of urine into the same animal species. Ten percent bladder and kidney tissue homogenates from infected hamsters were also titered using the end point titration method. At 253 days, the titers are 104.5 and 103.6 ID50/ml for bladder and kidney, respectively. Furthermore, in a look-back investigation of previous titrations conducted in our laboratory, we observed a pattern of clustering of positive cases consistent with infectivity been transmitted by secondary exposure in the cage environment. Our results highlight a new pathway of TSE infection in animals and may be in humans. This pathway involves the organs of the urinary system and directly affects the environment via urine infectivity excretion. Exposure to chronic low doses of infectivity in the environment may be responsible for TSE horizontal transmission.
AD Veterans Affairs Medical Center, Baltimore and University of Maryland at Baltimore. USA. E-mail: lgreg002@umaryland.edu
SP englisch
PO Italien