The results of this study have significant implications for both previous and future studies of prion-soil interactions as well as prion fate in the environment. Previous PrP adsorption studies have used a wide range of adsorption solutions, which may hinder comparison and Linolenic acid interpretation of results across studies. Given that solution chemistry has been shown to be an important variable in pure protein adsorption studies, caution is clearly warranted when interpreting or designing PrP-soil studies using pure recPrP or enriched PrPSc. However, our results suggest that although solution chemistry is an important consideration for prion adsorption, it may be less significant in short-term studies that use brain homogenate or excreta as a prion source. The present results are generally consistent with previous studies of long-term unbound and soil-associated PrP survival. Detectable BSE and scrapie PrPSc from brain homogenate was shown to survive 140 d incubation at 20uC in PBS and for 6 months at 16uC in water containing two mild detergents. Detectable amounts of soil-bound BSE and scrapie PrPSc were observed following 18 months incubation at 16uC. Additionally, the 263K agent remains infectious following burial of BH-soil mixtures for up to 3 years. It must be noted that the present study used HY TME hamster prions which, although used extensively for previous prion-soil experiments, are not naturally-occurring and may not accurately simulate CWD or scrapie fate in the environment. Moreover, our results do not consider prion infectivity, only PrPSc levels and replication efficiency. While PrPSc levels are not necessarily indicative of infectious titer, our previous studies using PMCA indicate a strong correlation between PMCA replication efficiency and infectious titer. The control of immune homeostasis at the maternal-placental interface involves several and redundant immunoregulatory circuits. From an immunological standpoint, pregnancy evolves 2-NP through different stages with predominant pro-inflammatory or anti-inflammatory profiles depending on the stage of gestation.