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

Spontaneous hepatocellular carcinoma in captive prosimians

Spontaneous hepatocellular carcinoma has been reported as a relatively common neoplasm in prosimians; however, the cause is unknown. To investigate possible pathogenic mechanisms, the authors performed a review of all adult animals from a captive prosimian population that had postmortem examinations over the past 10 years. They performed a detailed histologic evaluation of all suspected proliferative liver lesions and diagnosed hepatocellular carcinoma in 14 of 145 lemurs (9.7%). Affected animals ranged between the ages of 6 and 40 years old. The tumors had an unusually aggressive growth pattern for animal species; metastasis to the lungs or mediastinum was evident in 7 of 14 animals. Thirty-one animals-9 with hepatocellular carcinomas and 22 age-matched controls without hepatic neoplasia-were tested to evaluate the relationship between hepatic iron stores (as well as other trace metals) and the presence of hepatocellular carcinoma. There was no difference between the hepatic iron, copper, or molybdenum in lemurs with hepatocellular carcinoma and those without, suggesting that iron is not a key element in the pathogenesis of liver tumor formation. Analysis of 22 serum samples from animals with and without liver tumors indicated no evidence of active infection with a hepadnavirus, the virus family that includes hepatitis B virus. Hepatitis C virus and aflatoxin B1 were considered as potential causes and ruled out owing to lack of associated histopathologic lesions. In conclusion, hepatocellular neoplasia is relatively common in captive prosimians, although previously suspected etiologies seem unlikely.

Geographic and species association of hepatitis B virus genotypes in non-human primates

Infection with hepatitis B virus (HBV) has been detected in human populations throughout the world, as well as in a number of ape species (Pan troglodytes, Gorilla gorilla, gibbons [Nomascus and Hylobates species] and Pongo pygmaeus). To investigate the distribution of naturally occurring HBV infection in these species and other African Old World monkey species (Cercopithecidae), we screened 137 plasma samples from mainly wild caught animals by polymerase chain reaction (PCR) using several of highly conserved primers from the HB surface (HBs) gene, and for HBs antigen (HBsAg) by ELISA. None of the 93 Cercopithecidae screened (6 species) showed PCR or serology evidence for HBV infection; in contrast 2 from 8 chimpanzees and 5 from 22 gibbons were PCR-positive with each set of primers. Complete genome sequences from each of the positive apes were obtained and compared with all previously published complete and surface gene sequences. This extended phylogenetic analysis indicated that HBV variants from orangutans were interspersed by with HBV variants from southerly distributed gibbon species (H. agilis and H. moloch) occupying overlapping or adjacent habitat ranges with orangutans; in contrast, HBV variants from gibbon species in mainland Asia were phylogenetically distinct. A geographical rather than (sub)species association of HBV would account for the distribution of HBV variants in different subspecies of chimpanzees in Africa, and explain the inlier position of the previously described lowland gorilla sequence in the chimpanzee clade. These new findings have a number of implication for understanding the origins and epidemiology of HBV infection in non-human primates.

A primer of primate pathology: lesions and nonlesions

Nonhuman primates are important laboratory animals for biomedical, pharmacology, and toxicology research. To effectively use primates as models, their gross and histologic anatomy, physiology and natural history, as well as common health problems and the source from which the primate is obtained, must be known and understood by pathologists involved in study design and/or interpretation. The first very important lesson in the "primer" is: there is no such thing as a generic monkey. Brand names (ie, species and subspecies) are important. Several taxonomic groups of primates are used in research including: prosimians, such as galagos and lemurs; New World monkeys, particularily marmosets; Old World monkeys, especially macaques and baboons; and the chimpanzee, an African ape. Differences between taxa are exemplified by the glucocorticoid resistance of New World monkeys compared to Old World monkeys, which results in the requirement for Vitamin D3 and their high circulating levels of steroids such as cortisone and progesterone. Differences in ovarian histology between Old and New World monkeys probably relate to steroid receptor biology as well. There are also variations in disease manifestations, even among closely related primate species such as rhesus and cynomolgus macaques (cynos). For example type D retrovirus infection is accompanied by lymphomas in cynos, but not rhesus. The second important lesson in this "primer" is: "not test article related" does not always mean "normal." Lymphoid nodules in bone marrow or salivary gland, a common background finding in macaques, often signal the presence of type D retrovirus. Other histologic changes and normal anatomic variations may be confusing to individuals not routinely examining primate tissues. The objective of this paper is to familiarize pathologists with the use of primates in research as well as lesions and nonlesions (normal anatomy or physiology) of primates that may influence study design and confound interpretation.