Oncornavirus: isolation from a squirrel monkey (Saimiri sciureus) lung culture.

An oncornavirus isolated from a squirrel monkey (Saimiri sciureus) lung culture has a density of 1.16 to 1.17 grams per milliliter, contains 70S RNA, and has an RNA-directed DNA polymerase that prefers Mg2+ over Mn2+ in an assay in which polyribocytidylate - oligodeoxyguanylate (12-18) is used as a synthetic template. Morphologically, the virus resembles Mason-Pfizer monkey virus but is antigenically distinct from this virus. The virus grows in cells of human, chimpanzee, rhesus monkey, canine, and mink origin, but not cells of squirrel monkey origin. On the basis of its properties, the newly isolated virus can be classified as a retravirus.

Observations of apparent C-type particles in baboon (Papio cynocephalus) placentas.

Ultrastructural investigations have revealed the presence of apparent endogenously derived C-type particles in the placental villi of each of 13 baboons studied. Both budding and mature forms were observed in the syncytiotrophoblast of these animals at various stages of pregnancy.

Retinal tumor induced in the baboon by human adenovirus 12.

Three of 21 newborn baboons injected intraocularly with human adenovirus type 12 developed an intravitreal mass 12 to 36 months later. Two of the masses were indistinguishable from human retinoblastoma, a retinal tumor that afflicts children. To our knowledge this is the first time a retinoblastoma-like tumor has been induced experimentally by adenovirus type 12 in a nonhuman primate.

Comparison of Mason-Pfizer monkey virus and squirrel monkey (Saimiri sciureus) retrovirus by immunoelectron microscopy.

Comparison of Mason-Pfizer monkey virus and squirrel monkey retrovirus (both candidate type D oncornaviruses) by immunoelectron microscopy revealed that these two viruses do not share common surface antigens.

C-type viruses in chimpanzee (Pan sp.) placentas.

C-type virus particles were observed by electron microscopy in placentas from 7 of 9 chimpanzees (Pan sp.). These viruses were morphologically similar to those observed in placentas of other primates.

Induction of retrovirus particles in human testicular tumor (Tera-1) cell cultures: an electron microscopic study.

The Tera-1 and Tera-2 cell lines, established from germ-cell tumors of the human testis, were examined by electron microscopy for particles with the morphology of retroviruses. Extracellular and budding particles were observed at low frequencies only in cultures of Tera-1 cells that had been treated with 5-iodo-2'-deoxyuridine and dexamethasone. No particles were detected in untreated cultures of Tera-1 cells or in any preparations of Tera-2 cells.

Squirrel monkey retrovirus and Herpesvirus saimiri: observation in the same cell following isolation.

Electron microscopic examination of mink lung cells previously cultured with a squirrel monkey (Saimiri sciureus) throat swab suspension revealed the presence of squirrel monkey retrovirus (SMRV) and Herpesvirus saimiri (HVS) coexisting within the same cells in culture. HVS was identified by serum neutralization, and the retrovirus isolate was identified as SMRV by a morphologic examination, microimmunodiffusion analysis, and demonstration of an Mg2+ preference for the RNA-directed DNA polymerase.

A x C rat prostate adenocarcinoma: initial characterization of testosterone regulation of hormone receptors of cultured cancer cells and derived tumors.

A x C rat prostate cancer cells were established in continuous culture. The polygonal epithelial cells had granular cytoplasm and well-defined cell margins, contained round to oval nuclei with prominent nucleoli, and were tumorigenic when inoculated into A x C male rats. The tumors produced by the injected prostate cancer cells grew as well-vascularized, solid, cribriform adenocarcinomas. The rat prostate cancer cells and derived tumors contained cytoplasmic and nuclear androgen receptors and prolactin receptors. Androgen regulation of prolactin receptor content and androgen receptor distribution in A x C rat prostate cancer cells were comparable to those of the normal ventral prostate gland. These studies suggest that the A x C rat prostate cancer cells and tumors may represent a unique model for studies of hormonal regulation of prostate cancer cell behavior.

Oncorna-like viruses in baboon prostate tissue.

Oncorna-like virus particles were observed in prostate tissue of 2 of 11 baboons inoculated 3 years previously with a chemical carcinogen. There were no indications, however, of any relationship between the carcinogen and the development of virus particles. Biopsy specimens from the animals showed no evidence of neoplasia, and electron microscopic examination suggested that this virus should be categorized as a B-type oncornavirus.

Autogenous humoral immunity to baboon xenotropic endogenous type C virus.

A radioimmune precipitation assay was used to evaluate the humoral immune response of baboons (Papio cynocephalus) to their endogenous, xenotropic, type C (M7) virus. Using 125I or [3H]leucine-labeled intact virus preparation, we demonstrated that baboons possess naturally occurring virus-binding antibodies to this virus. Antibody appeared directed against envelope and not internal viral proteins. Immunoglobulins responsible for virus-binding were predominant in the IgG and IgA serum fractions, whereas IgM participated to a minor degree. The biologic activities of these immunoglobulins were investigated by means of a focus reduction assay for virus neutralization with a murine sarcoma virus (M7) pseudotype. We determined that, despite the presence of considerable virus binding, none of the normal baboon sera tested possessed neutralizing activity for M7 virus.

Oncornavirus-like particles in baboon type C virus-infected chimpanzee lung cells (SFRE:CL-1).

Intracytoplasmic type A particles were observed in a fetal chimpanzee lung culture (SFRE:CL-1) inoculated with type C virus-containing supernatants from a coculture of baboon placenta and SFRE:CL-1 cells. Budding, immature, and mature type C particles were also noted. In thin section, spike-like structures were rarely detected on budding intracytoplasmic type A particles but were occasionally observed on some immature and mature virus particles. Unlike mouse mammary tumor virus or Mason-Pfizer monkey virus, infected SFRE:CL-1 cells contained no eccentric or rodshaped nucleoids.

Oncornavirus-like particles in squirrel monkey (Saimiri sciureus) placenta and placenta culture.

Oncornavirus-like particles similar in morphology to type D particles were observed in 1 of 2 squirrel monkey (Saimiri sciureus) placentas. Intracytoplasmic type A particles, immature virus particles, and mature viruses with eccentric or occasionally centric nucleoids were associated with placental syncytiotrophoblasts. A spike layer typical of type B viruses was not detected in viral envelopes. Onvornaviruses, identical to those previously isolated from squirrel monkey tissues and similar to Mason-Pfizer monkey virus, were seen in cultures derived from the virus-positive squirrel monkey placenta cocultivated with a mink lung culture. The major morphologic difference between the in vivo and the in vitro squirrel monkey virus was in the nucleoid position of mature virus particles.

Vertical transmission of C-type viruses: their presence in baboon follicular oocytes and tubal ova.

C-type viruses were found in baboon follicular oocytes and tubal ova adjacent to the plasma membrane in the perivitelline space or along the inner margin of the zona pellucida. Their presence support the concept of vertical transmission of C-type viruses.

Infection and disease induced in chimpanzees with 6/94, a parainfluenza type 1 virus isolated from human multiple sclerosis brain.

A parainfluenza type 1 virus (6/94) recovered from brain cell cultures of two patients with multiple sclerosis (MS) was inoculated into newborn chimpanzees by the intranasal (IN) or intracerebral (IC) routes. Four of the five animals receiving the virus IN developed clinical signs ranging from mild fever, with or without rhinorrhea, to severe respiratory disease. Two of the chimpanzees died as a result of pneumonia. Virus could be recovered from respiratory tracts for as long as 9 days after exposure and was followed by development of specific neutralizing antibody to the 6/94 virus but not to the HA2 strain of parainfluenza type 1. Brain examination showed astrocytosis, especially of posterior fossa structures, activation of microgliacytes and, in one animal, round cell infiltration of leptomeninges. Of thse three animals receiving virus IC, two developed recurrent seizures beginning 14 months after inoculation. One of these was sacrificed at 23 months of age after progressive neurologic disease, with electroencephalographic abnormalities, developed. The third animal died at 3 months of age of intercurrent pneumonia. No virus was recovered from these animals, although all showed antibody conversion to 6/94 but not HA2 virus. A variety of pathologic lesions were seen in the brains of both animals coming to necropsy particularly in the sacrificed chimpanzee. These included subacute encephalitis, extensive cortical and subcortical degeneration, vascular sclerosis, white matter gliosis and axonal dystrophy.

Chemical inhibition of foamyvirus in primary baboon (Papio cynocephalus) kidney cells.

This report describes the conditions for the use of aluminum chloride (AlCl3) in growth and maintenance media for the suppression or inhibition of simian foamyviruses (SFV) in primary baboon kidney (BAK) and rabbit kidney (RK) cell cultures. When RK cells were planted in medium containing AlCl3, infected with SFV, and passaged, the growth of SFV was suppressed or inhibited by the presence of AlCl3. With this method, BAK cells yielded higher viral titers after infection with various viruses, thus making these cells more suitable for virological applications.

The collection of blood on filter paper and its use in the dot-immunobinding assay (DIA) for detection of antibody.

The ability to collect whole blood directly onto filter paper pre-cut to the size used in the dot-immunobinding assay (DIA) is a practical adjunct to this procedure. Its applicability for field studies is suggested.

Surface ultrastructure of preimplantation baboon embryos.

Scanning and transmission electron microscopy were used to study baboon preimplantation embryos 3 to 5 days E.F.A. (estimated fertilization age), ranging from about 16 to more than 60 cells. The peripheral blastomers were covered with microvilli scattered on the convex outer surface and along the borders of the intercellular furrows. In younger morulae, some longer microvilli may bridge over the furrow separating contiguous blastomeres. A few blastomeres showed poorly developed microvilli. Blastomeres of smaller diameter than the others may arise from more recent cleavage. Cell junctions as well as small intercellular spaces were noted at the apposition of the blastomere plasma membranes whereas surface intercellular ridges were not observed.

Ultrastructure of cleavage stages and preimplantation embryos of the baboon.

The baboon preimplantation stages were examined using light and electron microscopy. Six cases were studied at 2, 3, 4, 5, 7 and 8 days estimated fertilization age. The first 3 specimens were composed of 2, 8 and 24 blastomeres respectively. At 5 days, 30 to 40 cells were counted and more than 60 cells in later stages. Primitive "trophoblast cells" differentiate at 7 days and a crescentic blastocoele appears at 8 days. Shedding of the zona pellucida is not observed in the 7 and 8 day specimens. The preimplantation period is longer in the baboon than in man. C-type viruses are observed in the zona pellucida, in the perivitelline and interblastomeric spaces. Microvilli and caveolae cover ther periphery of the baboon conceptus. As in many other mammals, transformation of the mitochondria, changes in the ribosomes distribution, multivesicular bodies, myelin figures, nucleoli and intranuclear clusters of granules are described in the baboon. Cytoplasmic fibrous strands are not present as in the mouse. Experiments on the influence of hormones and drugs on ultrastructural changes would help to evaluate the importance of biohazards during the early development of primates.

A fatal epizootic of undetermined etiology in new world monkeys.

A peracute epizootic disease, strikingly characterized by profuse terminal hemorrhaging from the lungs, caused the deaths of 104 squirrel monkeys and 3 capuchin monkeys over a 22-month period. The case fatality rate was 100%. The pulmonary hemorrhaging was often accompanied by pulmonary edema and congestion, interstitial pneumonia, and hydrothorax. Additional histologic lesions included interstitial nephritis, hepatitis and hepatic necrosis, adrenalitis and adrenal necrosis, myocarditis, splenic atrophy or hypoplasia, pancreatitis and pancreatic necrosis, sialoadenitis, and encephalitis. Macaques maintained under identical conditions were clinically unaffected by the epizootic. There was an incidental relationship with contamination of feed, water, and housing facilities by excrement from feral Norway rats and cockroaches. Due to the association of the disease outbreak with abundant rodent and cockroach populations, and because the histologic features of the disease were suggestive of a viral etiology, encephalomyocarditis virus infection was implicated. However, histopathologic examinations of tissues from 68 monkeys; electron-microscopic studies on five monkeys; bacteriologic culturing; virus isolation attempts from 10 monkeys, rats, and cockroaches; and experimental inoculation studies in mice and squirrel monkeys all failed to reveal the causative agent, to provide a definitive diagnosis, or to reproduce the disease.