Detection of virus-like particles in the liver of black and white ruffed lemurs with hepatitis.

Two young black and white ruffed lemurs (Varecia variegata variegata) died at the San Diego Zoo (San Diego, California, USA) with extensive liver lesions suggestive of acute viral infection. Immunoassays performed to detect hepatitis B virus (HBV) markers were negative. Polymerase chain reaction (PCR) primers overlapping the HBV core gene produced an amplicon of approximately 411 base pairs (bp) from serum DNA of a HBV-positive western lowland gorilla (Gorilla gorilla gorilla) but not from serum DNA of either lemur. Cesium chloride gradient fractions of liver homogenates from both lemurs contained a peak protein fraction with a density of 1.18 g/cm3. Electron microscopic analysis of fraction contents, concentrated by ultracentrifulgation, revealed numerous pleomorphic, spherical particles varying in diameter from 16-25 nm. In one of the lemurs, this peak fraction also contained a double-shelled virus-like particle 47-50 nm in diameter. The size, morphology, and density of these particles suggest they are members of the Hepadnaviridae, a group of hepatotropic DNA-genome viruses for which HBV is the prototype.

Coccidioidomycosis in Przewalski's horses (Equus przewalskii).

Coccidioidomycosis is a rare, often subclinical infection in domestic animals caused by the fungus Coccidioides immitis. Because of an apparent high incidence of coccidioidomycosis in Przewalski's horses (Equus przewalskii) housed at a single facility, necropsy records and biomaterials from animals that died between 1984 and 2000 were reviewed (n = 30, 15 males, 15 females). Coccidioidomycosis was the leading cause of death (33%) in this population with lesions in the lungs and tracheobronchial lymph nodes of all animals and variable involvement of the skeletal muscle, heart, kidney, liver, skin, brain, spinal cord, spleen, as well as other regional lymph nodes. At the time of death, affected horses tended to be younger than unaffected animals, were from multiple lineages, and males were over represented. During the same time period, no other exotic equids (n = 76) housed at the same facility were diagnosed with coccidioidomycosis, suggesting that environmental factors are not the sole cause of the high incidence in E. przewalskii. Numbers of the lymphocyte subsets (CD3, CD4, CD5, CD8, CD21+ cells) quantified by flow cytometry were similar between Przewalski's horses and domestic horses (Equus caballus). Although responses of lymphocyte blastogenesis assays were similar between Przewalski's (n = 5) and domestic horses (n = 5) in response to the T cell mitogen concanavalin A, lymphocytes from two of the Przewalski's horses failed to proliferate in response to Coccidioides. One of these horses had systemic disease and the second developed coccidioidomycosis 2 yr later. These results suggest that the immune system of some Przewalski's horses fails to respond appropriately to Coccidioides.