tracheitis -a very common infection of cattle -, abortion, pustular vulvovaginitis, meningoencephalitis of calves, and conjunctivitis. The incidence of infection is high with viremia a common feature. It replicates in leukocytes and can stay there latently. It is never found free in the bloodstream. It replicates in bovine cells, but also in cell cultures from: elk, mule deer, sheep, L cells, chick embryo cells, pig, human (amnion (probably also a clon of HeLa cells (see chapter by Masters)), HeLa), and primary monkey kidney cells (Kniazeff, 1973) .