Brain and buffy coat transmission of bovine spongiform encephalopathy to the primate Microcebus murinus.

Abstract

More than 100 cases of variant CJD resulting from infections with bovine spongiform encephalopathy (BSE) have accumulated in the United Kingdom since 1995. Concern about the possibility of secondary transmissions via blood and blood components donated by infected individuals has prompted a variety of international donor deferral policies that will continue until laboratory and epidemiologic evidence provides a consensus about potential risk. BSE was passaged through macaque monkeys and then adapted to the prosimian microcebe (Microcebus murinus). Brain homogenate and buffy coat from an affected microcebe were separately inoculated intracerebrally into three healthy microcebes (two animals received brain and one received buffy coat). All three inoculated microcebes became ill after incubation periods of 16 to 18 months. Clinical, histopathologic, and immunocytologic features were similar in each of the recipients. Buffy coat from a symptomatic microcebe infected 17 months earlier with BSE contained the infectious agent. This observation represents the first documented transmission of BSE from the blood of an experimentally infected primate, which in view of rodent buffy coat infectivity precedents and the known host range of BSE is neither unexpected nor cause for alarm.