B-virus specific-pathogen-free breeding colonies of macaques (Macaca mulatta): retrospective study of seven years of testing.

Background and purpose: National Institutes of Health's Division of Comparative Medicine has sponsored a multi-institutional program for the establishment of specific-pathogen-free (SPF) macaque colonies. B virus (Herpesvirus simiae, Cercopithecine herpesvirus type 1) has been targeted in this surveillance. Participating institutions have established individual timetables for frequency of testing and types of monitoring and husbandry techniques, all with the common goal of producing pathogen-free monkeys for research. The greatest biosecurity threat to the program comes from failure to detect seronegative latent infections, either in first-year macaques or macaques introduced in subsequent years, although these are supposed to operate as closed colonies.

Methods: From January 1990 through December 1996, we screened macaques for B virus, using enzyme-linked immunoabsorbant assay (ELISA) and Western blot analysis.

Results: During the first year, 1,097 macaques from six colonies were tested, and 88.4% tested negative for B virus. During the seventh year, 1,843 were tested, of which 99.7% tested negative. Seropositive macaques were detected as late as the seventh year.

Conclusions: An aggressive program to establish an SPF colony of captive breeding macaques can be effective in reducing the risk of B-virus exposure.