To study the possibility of cross-species transmission of CWD, two species of nonhuman primates, squirrel monkeys and cynomologus macaques, were infected orally or intracerebrally with brain material derived from CWD affected deer or elk. At the conclusion of FY09 twelve of thirteen intracerebrally infected squirrel monkeys had developed clinical neurological signs and were confirmed by biochemical and pathological testing of brain to have a prion disease. Six orally infected squirrel monkeys have also developed disease, five remain asymptomatic. To this point no cynomologus macaques have developed any signs of disease regardless of inoculation route (all macaques were inoculated >6 years ago). Observations on the remaining monkeys will continue. During FY08 four additional cynomologus macaques and squirrel monkeys were inoculated with brain homogenates derived from a CWD infected squirrel monkey to evaluate the ability of CWD to adapt to a nonhuman primate host. In addition we are evaluating blood from infected squirrel monkeys for the presence of prion infectivity. None of these monkeys have shown any signs of disease at the close of FY09. Animal bioassays (transgenic mice) were used to measure infectivity levels of tissues from CWD-infected squirrel monkeys and the CWD-infected cervid tissues used to infect the monkeys. This portion of the project has been completed.