Paramyxovirus infection in caiman lizards (Draecena guianensis)

Three separate epidemics occurred in caiman lizards (Dracaena guianensis) t hat were imported into the USA from Peru in late 1998 and early 1999. Histo logic evaluation of tissues from necropsied lizards demonstrated a prolifer ative pneumonia. Electron microscopic examination of lung tissue revealed a virus that was consistent with members of the family Paramyxoviridae. Usin g a rabbit polyclonal antibody against an isolate of ophidian (snake) param yxovirus, an immunoperoxidase staining technique demonstrated immunoreactiv ity within pulmonary epithelial cells of I lizard. Homogenates. of lung, br ain, liver, or kidney from affected lizards were placed in flasks containin g monolayers of either terrapene heart cells or viper heart cells. Five to 10 days later, syncytial cells formed. When Vero cells were inoculated with supernatant of infected terrapene heart cells, similar syncytial. cells de veloped. Electron microscopic evaluation of infected terrapene heart cells revealed intracytoplasmic inclusions consisting of nucleocapsid strands. Us ing negative-staining electron microscopy, abundant filamentous nucleocapsi d material with a herringbone structure typical of the Paramyxoviridae was observed in culture medium of infected viper heart cells. Seven months foll owing the initial epizootic, blood samples were collected from surviving gr oup 1 lizards, and a hemagglutination inhibition assay was performed to det ermine presence of specific antibody against the caiman lizard isolate. Of the 17 lizards sampled, 7 had titers of less than or equal to1:20 and 10 ha d titers of >1:20 and less than or equal to1:80. This report is only the se cond of a paramyxovirus identified in a lizard and is the first to snow the relationship between histologic and ultrastructural findings and virus iso lation.