Filovirus clearance in non-human primates

There has been concern in the USA and Europe about filovirus outbreaks in recently imported monkeys, and possible transmission to human beings. Healthy monkeys have been found to have low-titre immunofluorescence antibody (IFA) to Asian filoviruses (Reston and Pennsylvania viruses) as well as to the African filoviruses that caused fulminating human outbreaks in the 1970s (Ebola [Zaire] and Sudan viruses). We have assessed whether such monkeys are a risk to man. We studied 42 non-human primates; 31 were experimentally infected with African and Asian filoviruses, 6 were infected during a documented Reston filovirus outbreak, and 5 had serological evidence suggestive of recent filovirus infection. During the first 15 days after infection, virus could be routinely recovered from serum or biopsy or necropsy tissue, and Asian filovirus RNA could be detected by polymerase chain reaction. 20 to 600 days after challenge, filovirus could no longer be recovered nor viral RNA detected in 141 serum, liver, spleen, or kidney specimens. Animals surviving filovirus infection develop high-titre, cross-reacting filovirus-specific antibody 14 to 21 days after infection, and this coincides with virus clearance. Healthy monkeys with low-titre filovirus antibody may be regarded as uninfected.