Murine xenotropic type C viruses. IV. Replication and pathogenesis in ducks

1 Cancer Research Institute, Department of Medicine and 2 Animal Care Facility University of California, School of Medicine, San Francisco, California 94143, U.S.A. and 3 Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, U.K. The xenotropic (X-tropic) mouse type C virus (MuLV) and its pseudotype of murine sarcoma virus (MSV) were inoculated into several fertilized developing Pekin duck eggs. The development of the duck embryos was substantially reduced in those receiving the X-tropic viruses compared to eggs inoculated only with tissue culture medium. Infectious virus was isolated from some of the adult animals; in others, evidence for integrated virus sequences in the tissues was noted. No specific pathology was found in the ducks that received X-tropic MuLV alone, but one duck developed multiple fibrosarcomas when inoculated at birth with the X-tropic virus pseudotype of MSV. Two ducks receiving X-tropic MuLV had signs of haematopoietic disorders. In addition, more virus-inoculated animals had evidence of hepatitis and encephalitis than control ducks. Antibody production to X-tropic MuLV was present in several ducks inoculated with virus either in embryo or at birth. Absence of antiviral antibodies was noted in those animals whose tissues contained replicating virus. These studies confirm the observations with X-tropic virus in tissue culture. They demonstrate in vivo that avian species are susceptible to infection by the mouse X-tropic virus and that their fibroblasts can be transformed by the X-tropic MuLV pseudotype of MSV. Keywords: embryo development, fibrosarcoma, neurological symptoms, antiviral antibodies Present address: 1055 South Avenue, Madison, Georgia 30650, U.S.A. Received 16 November 1981; accepted 26 February 1982.