Abstract: Virus-like particles were observed in the giant cells of a mammary adenoma of a snow leopard kept in captivity. Particles that measured 115 to 125 nm in diameter budded from the lamella of endoplasmic reticulum and were studded on their inner surfaces with dense granules (approximately 12 nm) that gave them their unique ultrastructural morphology. Such particles were not observed extracellularly. Type B or type C particles were not seen in the tumor tissue.

Abstract: Modified live feline panleukopenia virus (FPLV) vaccine protected dogs against canine parvovirus (CPV) infection. However, unlike the long- lived (greater than or equal to 20-month) immunity engendered by CPV infection, the response of dogs to living FPLV was variable. Doses of FPLV (snow leopard strain) in excess of 10(5.7) TCID50 were necessary for uniform immunization; smaller inocula resulted in decreased success rates. The duration of immunity, as measured by the persistence of hemagglutination-inhibiting antibody, was related to the magnitude of the initial response to vaccination; dogs with vigorous initial responses resisted oronasal CPV challenge exposure 6 months after vaccination, and hemagglutination-inhibiting antibodies persisted in such dogs for greater than 1 year. Limited replication of FPLV in dogs was demonstrated, but unlike CPV, the feline virus did not spread to contact dogs or cats. Adverse reactions were not associated with living FPLV vaccination, and FPLV did not interfere with simultaneous response to attenuated canine distemper virus.