Susceptibility of a fetal tongue cell line derived from bighorn sheep to five serotypes of bluetongue virus and its potential for the isolation of viruses.

A cell line (BHFTE) was derived from a tongue explant of a bighorn sheep fetus (Ovis canadensis nelsoni). The cells have been maintained through 23 serial passages, and the modal number of chromosomes was calculated to be 55. Monolayer cultures were shown to be susceptible to various viruses, including bluetongue virus (BTV). Of 5 BTV serotypes (2, 10, 11, 13, and 17) tested, each produced a cytopathic effect (CPE) on initial passage at 33 C. A field isolate (serotype 10) of BTV from a black-tailed deer (Odocoileus hemionus columbianus) in its second passage in Vero-M cells also produced CPE when inoculated into BHFTE cells. Antigens of BTV were demonstrated by direct immunofluorescence in the cytoplasm of BHFTE cells inoculated with homogenates of chicken embryos injected with clinical specimens from a domestic sheep and an Arabian oryx (Oryx gazella leucoryx). A suspension of BTV-infected gnats (Culicoides spp.) produced CPE and BTV-specific fluorescence on the first passage in cells inoculated with a suspension of blood from sheep experimentally infected with BTV. Additionally, selected bovine viruses induced CPE in the cells. The cell line, which is free of mycoplasma and bovine viral diarrhea virus contamination, may be useful in diagnostic medicine and research involving the ruminant species.

A rapid monoclonal immunofluorescence assay for Chlamydia psittaci in fecal smears from psittacine birds.

One hundred two fecal specimens from psittacine birds submitted to Veterinary Laboratory Services of the California Department of Food and Agriculture at Petaluma were screened for Chlamydia psittaci by a direct immunofluorescence assay using a fluorescein-labeled monoclonal antibody conjugate specific for Chlamydia sp. Results were compared with those obtained by isolation of chlamydia in cultures of McCoy mouse cells. The relative specificity of the direct fluorescent antibody test on fecal smears was 98.9% and the relative sensitivity was 62.5%. The results of this study suggested that the direct fluorescent antibody test was highly specific, and it proved to be a useful same-day antemortem diagnostic test for birds with symptomatic chlamydial infection. The use of centrifugation in the cell culture assay was found to significantly enhance the level of chlamydial infection in cell culture.

Ultrastructure of cellular changes in the replication of the alcelaphine herpesvirus-1 of malignant catarrhal fever.

Cell cultures inoculated with 5 different viral isolates from 4 species of ruminants with clinical signs of malignant catarrhal fever (from the San Diego Wild Animal Park) were examined by electron microscopy. Each had the morphology of a herpesvirus (118 to 220 nm) and was icosahedral, and the nucleocapsid matured in the nucleus of the infected cell. Envelopment of budding occurred with each viral isolate at the nuclear and the plasma membranes. The virions egressed from the cell by budding from the plasma membrane or through channels of the Golgi apparatus or the endoplasmic reticulum. A proposed scheme for the morphogenesis of the herpesvirus of malignant catarrhal fever is presented.

Characteristics of the herpesvirus of malignant catarrhal fever isolated from captive wildebeest calves.

A herpesvirus was isolated from buffy coat cells from a newborn wildebeest (Connochaetes gnou) and from tissues of a 12-day-old wildebeest during the 1982 calving season of a captive, inbred herd maintained in a zoologic collection. Both wildebeests were clinically healthy, and there was no herd record that malignant catarrhal fever (MCF) existed. Each viral isolate produced cytopathologic changes in bovine kidney cell cultures (intranuclear inclusions and massive syncytia). The viral-infected cell cultures contained antigens of MCF virus detected by immunofluorescence. The morphology of each viral isolate as determined by electron microscopy was that of a herpesvirus. Suspensions of 4 to 5 ml of disrupted cell culture material which contained virus from each wildebeest were inoculated (IV) into white-tailed deer (Odocoileus virginianus). Each deer became clinically ill within 28 days. Both deer had mucoid catarrh and a febrile response (40.5 to 41 C). Each also seroconverted to MCF virus. The histopathologic change in the tissues from the 2 inoculated deer was vasculitis. At 16 to 17 days after the deer were inoculated, a syncytial-forming virus was isolated from each deer from buffy coat cells fused with polyethylene glycol (1000) to bovine fetal kidney cells. The virus was identified as MCF virus by immunofluorescence and production of antibody to MCF virus. The presence of virus in the inbred wildebeest herd established this species as a reservoir or latent carrier of African MCF virus at the zoologic park.