Development of AIDS in a chimpanzee infected with human immunodeficiency virus type 1.

The condition of a chimpanzee (C499) infected with three different isolates of human immunodeficiency virus type 1 (HIV-1) for over 10 years progressed to AIDS. Disease development in this animal was characterized by (i) a decline in CD4+ cells over the last 3 years; (ii) an increase in viral loads in plasma; (iii) the presence of a virus, termed HIV-1JC, which is cytopathic for chimpanzee peripheral blood mononuclear cells; and (iv) the presence of an opportunistic infection and blood dyscrasias. Genetic analysis of the V1-V2 region of the envelope gene of HIV-1JC showed that the virus present in C499 was significantly divergent from all inoculating viruses (> or = 16% divergent at the amino acid level) and was suggestive of a large quasispecies. Blood from C499 transfused into an uninfected chimpanzee (C455) induced a rapid and sustained CD4+-cell decline in the latter animal, concomitant with high plasma viral loads. These results show that HIV-1 can induce AIDS in chimpanzees and suggest that long-term passage of HIV-1 in chimpanzees can result in the development of a more pathogenic virus.

Time versus density enhancement of liver, spleen, and great vessels following rapid intravenous infusion of perflubron emulsion.

RATIONALE AND OBJECTIVES: We studied hepatosplenic enhancement in rhesus monkeys for 5 hr after rapid administration of perflubron (perfluorooctyl bromide [PFOB]) in an attempt to determine a clinically useful imaging window. METHODS: Five rhesus monkeys were examined using perflubron emulsion, 90% w/v perfluorochemical administered intravenously at a dose of 1.5 ml/kg and rate of 0.5 ml/sec. Helical computed tomography examination of the abdomen was obtained prior to the contrast bolus and 5 min, 30 min, 1, 2, 3, 4, and 5 hr postcontrast. Mean density of liver, spleen, and aorta was measured at each time interval. RESULTS: Significant aortic enhancement of 53 +/- 7 Hounsfield units (HU) (p < .0001) and liver enhancement of 19 +/- 4 H (p < .0004) occurred after 5 min and did not change significantly (p > .05) over 5 hr. Splenic enhancement of 35 +/- 9 HU was significant at 5 min (p < .0001) and continued to increase for 5 hr. CONCLUSION: Enhancement of the liver, blood vessels, and spleen is rapid and persists for at least 5 hr, which suggests a wider temporal window for hepatosplenic imaging with perflubron than is currently available with iodinated contrast agents.

Perfluoroctyl bromide as a blood pool contrast agent for computed tomographic angiography.

RATIONALE AND OBJECTIVES: We determined whether perfluoroctyl bromide (perflubron) could be used as a computed tomography (CT) angiographic agent by studying vessel visibility (celiac artery, superior mesenteric artery [SMA], and renal arteries) with spiral CT and three-dimensional (3D) reconstructions. METHODS: Five rhesus monkeys were examined with a perflubron emulsion (90% [w/v] perfluorochemical; administered intravenously at a dose of 1.5 ml/kg and at a rate of 0.5 ml/sec. Spiral CT was performed immediately and at 5 hr after injection. Three dimensional images of the aorta at the level of the celiac artery, SMA, and renal arteries were reconstructed and blindly rated 0-4 (0 = not seen; 4 = excellent visualization) by two observers. RESULTS: All the vessels had the best ratings immediately after injection: celiac artery, 2.8 +/- 0.42; SMA, 2.7 +/- 0.48; left renal artery, 2.1 +/- 0.99; and right renal artery, 1.2 +/- 1.03. The ratings after the 5-hr delay were as follows: celiac artery, 1.3 +/- 1.34; SMA, 1.5 +/- 1.08; left renal artery, 1.5 +/- 0.97; and right renal artery, 1.2 +/- 0.79. CONCLUSIONS: Spiral CT angiography with a perflubron emulsion successfully demonstrated all vessels immediately and at 5 hr after contrast agent infusion. Further refinements of the dose, rate, and reconstruction technique are expected to increase vessel visibility over this wide imaging window.

Effect of recombinant human interleukin-6 (rhIL-6) and rhIL-3 on hematopoietic regeneration as demonstrated in a nonhuman primate chemotherapy model.

Using a recently developed hepsulfam-induced pancytopenia model in rhesus macaques, we have studied the effects of recombinant human interleukin-6 (rhIL-6) and rhIL-3 on marrow regeneration. Control animals were given hepsulfam (1.5 g/m2 by a single 30-minute intravenous [i.v.] injection, n = 4), while study animals received hepsulfam followed by rhIL-6, rhIL-3, or a combination of rhIL-6 and rhIL-3 (n = 3 per study group). Each cytokine was administered by once-daily subcutaneous (SC) injection (15 micrograms/kg/d) for 3 weeks beginning the day after chemotherapy (days 2 through 22). Mean platelet counts in control animals were < 100,000/microL on days 15 through 24, with 50% of the counts < 50,000/microL and two of four animals requiring platelet transfusion. In the rhIL-6- and rhIL-6/rhIL-3-treated groups, the nadir mean platelet counts were 164,000 +/- 58,700/microL and 162,300 +/- 23,800/microL, respectively, and occurred on day 15. Platelet counts in the rhIL-3-treated group were similar to those in controls. Mean absolute neutrophil counts (ANCs) < 1,000/microL occurred on days 10 through 29 in control animals, days 8 through 15 in rhIL-6-treated animals, and days 6 through 8 and 13 in rhIL-6/rhIL-3-treated animals. The frequency of ANCs < 500/microL was significantly less in the rhIL-6- and rhIL-6/rhIL-3-treated groups versus control groups (2.7 +/- 0.6 and 2.0 +/- 1.0 vs 7.0 +/- 1.4 occurrences, respectively; P < .05). rhIL-3-treated animals had ANCs similar to those in controls; one animal died with septicemia on day 21. Monkeys receiving rhIL-6 were significantly more anemic during the cytokine administration period; however, the anemia resolved by day 24. Coadministration of rhIL-3 and rhIL-6 partially corrected the anemia. The data indicate that rhIL-6 prevents significant thrombocytopenia and shortens the neutropenic period in this chemotherapy model.

Peripheral blood stem cell acquisition by large-volume leukapheresis in growth factor-stimulated and unstimulated rhesus monkeys: development of an animal model.

Twelve (eight unstimulated [UNS], four growth factor-stimulated [ST]) anesthetized adult male rhesus monkeys underwent a single large-volume leukapheresis (> 3 blood volumes processed) in an attempt to define an animal model for use in future peripheral blood stem cell (PBSC) transplantation studies. The cell separator was primed with autologous blood and saline and set according to the manufacturer's mononuclear cell (MNC) protocol using the granulocyte separation and small volume collection chambers with additional modifications. Stimulated animals received 5 micrograms/kg recombinant human interleukin-3 (rhIL-3) on days -12 to -5, 5 micrograms/kg granulocyte-macrophage colony-stimulating factor (GM-CSF) on days -4 to -1, and large-volume leukapheresis on day 0. UNS animals did not receive growth factors. Vascular access was via a triple lumen intra-aortic catheter; blood pressure was monitored via the third lumen. Pre- and post-apheresis blood counts were determined and product hematocrit (Hct), MNC, colony-forming units-granulocyte/macrophage (CFU-GM), CD34+, and lymphocyte subsets were studied. During the 100-minute large-volume leukapheresis with mean flow rate 26.4 +/- 3.9 mL/min, the pre- and post-Hct were 36.6 +/- 2.6 and 32.3 +/- 7.0%, platelets 447 +/- 305 and 154 +/- 77 x 10(9)/L, and MNC 2.7 +/- 0.9 and 1.9 +/- 1.4 x 10(9)/L (all p < .05) in UNS animals. In ST animals, the pre- and post-Hct were 39.0 +/- 5.6 and 34.9 +/- 3.7%, platelets 507 +/- 100 and 150 +/- 9 x 10(9)/L (p < .05), and MNC 4.9 +/- 1.6 and 2.8 +/- 0.7 x 10(9)/L (p < .05). The product contained 98.5 +/- 1.4% MNC, 4.1 +/- 4.1% Hct, 1.9 +/- 0.6 x 10(9) MNC, 9.2 +/- 7.3 x 10(4) CFU-GM, and 3.5 +/- 2.1 x 10(6) CD34+ cells in UNS animals. In ST monkeys, the product contained 49.5 +/- 32% MNC, 6.4 +/- 4.4% Hct, 3.6 +/- 1.8 x 10(9) MNC, 49.3 +/- 39 x 10(4) CFU-GM, and 9.1 +/- 5.5 x 10(6) CD34+ cells. Greater than 75% of the product MNC were CD2+ T cells in ST and UNS animals. Large-volume leukapheresis in rhesus monkeys was tolerated well. Herein we characterize an animal model for large-volume leukapheresis in UNS monkeys that is similar to that of human PBSC leukapheresis. In ST animals there is more than a five-fold increase in CFU-GM collected and an increase in circulating CFU-GM/MNC.(ABSTRACT TRUNCATED AT 400 WORDS)

Prolonged CD4+ lymphocytopenia and thrombocytopenia in a chimpanzee persistently infected with human immunodeficiency virus type 1.

The immunologic and virologic status of a chimpanzee inoculated with multiple isolates of the human immunodeficiency virus type 1 (HIV-1) were assessed over 57 months to determine whether prolonged thrombocytopenia and CD4+ lymphocytopenia observed in the animal might be associated with long-term HIV infection. Although the chimpanzee showed no signs of disease, it lost both CD4+ (as low as 134 cells/microliter) and CD8+ lymphocytes approximately 30 months after initial infection, followed by thrombocytopenia that has persisted for greater than 2 years. Lymphopenia and thrombocytopenia were preceded by or coincided with the appearance of antibodies cross-reactive with histone H2B and decreased levels of complement component C4; an eightfold decrease in HIV-specific antibody titers; the inability of CD8+ lymphocytes to suppress virus replication; impaired proliferative responses to T cell mitogens; and the isolation of cell-free HIV from plasma. These data suggest that, given sufficient time, HIV-infected chimpanzees may develop disease.

HIV infection of chimpanzees as a model for testing chemotherapeutics.

Following inoculation of chimpanzees, the human immunodeficiency virus (HIV) establishes a long-term persistent infection characterized by seroconversion and the presence in peripheral blood cells of recoverable virus which can be quantitated. Because most HIV-infected chimpanzees have developed no signs of clinical diseases or hematologic abnormalities, their virologic, serologic and other immune responses can be compared with those of asymptomatic HIV-infected persons. This analysis might lead to the identification of factors important in preventing the development of disease. There are now approximately 100 HIV-infected chimpanzees in the United States, and many of these animals could be made available for testing chemotherapeutic agents for the ability to alter virus load or to enhance immune responses.

Superinfection of a chimpanzee with a second strain of human immunodeficiency virus.

Two chimpanzees, one (C-499) infected with the acquired immunodeficiency syndrome-associated retrovirus type 2 (ARV-2) strain of human immunodeficiency virus (HIV) and one (C-560) infected with the lymphadenopathy-associated virus type 1 (LAV-1) strain of HIV, were inoculated with approximately 10(4) tissue culture infective doses of the reciprocal strain. At the time of the second inoculation, both chimpanzees had high titers of HIV-specific antibodies, including antibodies that neutralized both virus strains. After inoculation of the second strain of HIV, the antibody titers in both chimpanzees increased 4- to 10-fold, and in one chimpanzee (C-499), the numbers of infectious peripheral blood mononuclear cells (PBMC) increased 1,000-fold to levels that are comparable with those observed after primary HIV infections. By restriction enzyme analysis of virus recovered from PBMC, both ARV-2 and LAV-1 were identified in C-499, thus demonstrating that superinfection had occurred.

Infection of chimpanzees with Nigerian I/CDC strain of Plasmodium ovale.

Seven splenectomized chimpanzees were infected with the Nigerian I/CDC strain of Plasmodium ovale. Two of the animals had no history of previous malarial infection whereas three had been infected with P. vivax, one with P. malariae, and one with P. vivax and P. malariae. The two animals with no previous malarial experience had maximum parasitemias of 88,700 and 127,000 per mm3 while the other animals had maximum parasitemias ranging from 10,100 to 60,600 per mm3. Anopheles freeborni, An. dirus, An. stephensi, and An. gambiae were readily infected via membrane feeding on heparinized blood obtained from these chimpanzees during the ascending phases of their primary attacks. The parasitemias in the chimpanzees with previous malarial experience were transient.

Effect of immunization with a vaccinia-HIV env recombinant on HIV infection of chimpanzees.

Acquired immunodeficiency syndrome (AIDS) is caused by human immunodeficiency virus (HIV) and is now recognized as a worldwide epidemic for which there is no cure or vaccine. Chimpanzees are the only other animals that can be infected by HIV, and therefore the chimpanzee-HIV model system is useful for testing potential HIV vaccines. However, with one exception, there have been no reports of clinical manifestations of AIDS in chimpanzees. We report here results of an HIV vaccine trial in which nine chimpanzees were first immunized with either a recombinant vaccinia virus expressing the envelope glycoproteins of HIV strain LAV-1 (v-env5) or a control recombinant vaccinia virus and were then challenged with a high or low dose of LAV-1. Although HIV-specific antibody and T-cell responses were elicited by immunization, virus was isolated from lymphocytes of all challenged chimpanzees, indicating that immunization did not prevent infection by HIV. Among the animals that received a higher dose of LAV-1, one of two control chimpanzees, but none of the four v-env5-immunized chimpanzees developed substantial and persistent lymphadenopathy.

Mycobacterium paratuberculosis infection in a colony of stumptail macaques (Macaca arctoides).

Mycobacterium paratuberculosis infection was documented in a colony of stumptail macaque monkeys (Macaca arctoides), with 29 (76%) of 38 monkeys infected and shedding organisms in feces. Thirteen deaths have occurred during the past five years. Animals without overt clinical disease were shedding as many as 2 X 10(6) colony-forming units of M. paratuberculosis/g of feces. Intestinal tissues from animals dying of this disease contained up to 10(8) colony-forming units of M. paratuberculosis/g of tissue. The clinical and pathological features of paratuberculosis in this species were comparable to those reported for paratuberculosis in ruminants and Mycobacterium avium infections in primates. By enzyme-linked immunosorbent assay, antibodies to M. paratuberculosis were found in 79%-84% of the animals. Antibodies could not be detected in six animals with clinical disease. These findings extend the natural host range of M. paratuberculosis to include nonhuman primates and add support to current suggestions that M. paratuberculosis may be pathogenic for humans.

Fluorine-NMR studies of chimpanzee hemoglobin.

It has been demonstrated that 4-fluorophenylalanine, a known inhibitor of protein synthesis, becomes incorporated into hemoglobin when present in the diet of a chimpanzee. 19F-NMR spectra of various forms of this protein show well-resolved lines, each line presumably corresponding to a unique phenylalanine/fluorophenylalanine position of the primary sequence. Fluorine chemical shifts and, by implication, tertiary structures vary with the oxidation state and ligand.

Isolation of a T-lymphotropic retrovirus from naturally infected sooty mangabey monkeys (Cercocebus atys).

Healthy mangabey monkeys in a colony at the Yerkes Regional Primate Research Center were found to be infected with a retrovirus related to human immunodeficiency virus (HIV). Virus was isolated from peripheral blood cells of 14 of 15 randomly selected mangabeys. All virus-positive animals had antibodies to the mangabey virus at the time of virus isolation and, in a retrospective study, 82% of mangabey serum samples obtained in 1981 had antibodies to the virus. The newly isolated retrovirus is (i) morphologically identical to HIV by electron microscopy; (ii) serologically related to the human virus by enzyme immunoassay, immunoblotting experiments, radioimmunoprecipitation, and neutralization; and (iii) cytopathic for human OKT4+ cells. The mangabey virus also shares these properties with the simian T-lymphotropic virus type III (STLV-III) recently isolated from diseased macaques and from healthy African green monkeys (STLV-IIIAGM). However, the mangabey virus, like STLV-IIIAGM, differs from both HIV and STLV-III in that it apparently does not cause clinical immunodeficiency or disease following natural infection of the host from which it was isolated. Comparison of the virus-host interactions of these isolates may be valuable in defining determinants of pathogenicity for cytopathic retroviruses.

Persistent infection of chimpanzees with human T-lymphotropic virus type III/lymphadenopathy-associated virus: a potential model for acquired immunodeficiency syndrome.

The lymphadenopathy-associated virus (LAV) prototype strain of human T-lymphotropic virus type III/LAV was transmitted to juvenile chimpanzees with no prior immunostimulation by (i) intravenous injection of autologous cells infected in vitro, (ii) intravenous injection of cell-free virus, and (iii) transfusion from a previously infected chimpanzee. All five animals that received more than one 50% tissue culture infective dose were persistently infected with LAV or chimpanzee-passaged LAV for up to 18 months. During this time they developed no illnesses, but they exhibited various degrees of inguinal and axillary lymphadenopathy and significant reductions in rates of weight gain. Detailed blood chemistry and hematologic evaluations revealed no consistent abnormalities, with the exception of immunoglobulin G (IgG) hypergammaglobulinemia, which became apparent in one animal 6 months postinfection and continued at more than 1 year postinfection. Transient depressions followed by increases in the numbers of T4 cells to levels greater than normal were observed in all animals after virus inoculation. However, the number of LAV-infected peripheral blood cells decreased with time after infection. Results of enzyme immunoassays showed that all infected animals seroconverted to IgG anti-LAV within 1 month postinfection and that antibody titers remained high throughout the period of observation. In contrast, only three of the five LAV-infected chimpanzees had detectable IgM antibody responses, and these preceded IgG-specific serum antibodies by 1 to 2 weeks. Virus morphologically and serologically identical to LAV was isolated from peripheral blood mononuclear cells of all infected animals at all times tested and from bone marrow cells taken from one animal 8 months after infection. One chimpanzee that was exposed to LAV only by sharing a cage with an infected chimpanzee developed lymphadenopathy and an IgM response to LAV, both of which were transient; however, no persistent IgG antibody response to LAV developed, and no virus was recovered from peripheral blood cells during a year of follow-up. Thus, LAV readily infected chimpanzees following intravenous inoculation and persisted for extended periods despite the presence of high titers of antiviral antibodies. However, the virus was not easily transmitted from infected to uninfected chimpanzees during daily cage contact.

Infection of mosquitoes with Plasmodium vivax from chimpanzees using membrane feeding.

Six splenectomized chimpanzees were infected with the Chesson or the North Korean strains of Plasmodium vivax. Heparinized blood taken from the animals was fed to approximately 45,000 mosquitoes using parafilm membranes. High-level mosquito infections were obtained with the blood from 4 animals. One animal infected mosquitoes only at a very low level. The other chimpanzee failed to produce a parasitemia high enough to warrant mosquito feeding.

Natural genital herpesvirus hominis infection in chimpanzees (Pan troglodytes and Pan paniscus).

Type 2 Herpesvirus hominis was isolated from pustulovesicular lesions on the external genitalia of two chimpanzees. Histopathologic examination of biopsy specimens from both animals revealed typical herpetic changes which included necrosis, superficial ulceration acute inflammatory cell infiltration, multinucleated syncytial giant cells, and intranuclear inclusions. Large numbers of herpes-type viruses were demonstrated by electron microscopy in biopsy specimens from both animals. Serologic studies also demonstrated infection of these animals with Herpesvirus hominis.

Treatment regimen for air sacculitis in the chimpanzee (Pan troglodytes).

Six champanzees (Pan troglodytes) developed air sacculitis. Except for air sac distension and malodorous breath, clinical signs were rare. A variety of organisms, mainly enteric, were isolated from the air sacs. Only one case was treated surgically. Other cases were treated by the conservative method of irrigation which worked well.

Correlation of serum testosterone levels with age in male chimpanzees.

Serum testosterone was measured in a group of male chimpanzees of varying ages by radioimmunoassay using a specific antiserum to testosterone-3-carboxym ethyloxime-bovine serum albumin. The juvenile age group, ranging from one through six years (n=26), had a mean serum testosterone value of 13ng/100ml (range 3.5-59ng/100ml). The adolescent age group, spanning years seven through ten (n=19), had a mean value of 178ng/100ml (range 14.6-238ng/100ml). The adult group, comprised of animals over eleven years of age (n=29), had a mean peripheral serum testosterone value of 397ng/100ml (range 92-680ng/100ml). These data suggest that serum testosterone levels may be useful in determing the age and sexual maturity of chimpanzees of unknown age.