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Lack of cross-species transmission of porcine endogenous retrovirus infection to nonhuman primate recipients of porcine cells, tissues, or organs.

BACKGROUND: Nonhuman primates (NHPs) have been widely used in different porcine xenograft procedures inevitably resulting in exposure to porcine endogenous retrovirus (PERV). Surveillance for PERV infection in these NHPs may provide information on the risks of cross-species transmission of PERV, particularly for recipients of vascularized organ xenografts for whom data from human clinical trials is unavailable. METHODS: We tested 21 Old World and 2 New World primates exposed to a variety of porcine xenografts for evidence of PERV infection. These NHPs included six baboon recipients of pig hearts, six bonnet macaque recipients of transgenic pig skin grafts, and nine rhesus macaque and two capuchin recipients of encapsulated pig islet cells. Serologic screening for PERV antibody was done by a validated Western blot assay, and molecular detection of PERV sequences in peripheral blood mononuclear cells (PBMCs) and plasma was performed using sensitive polymerase chain reaction and reverse transcriptase-polymerase chain reaction assays, respectively. Spleen and lymph node tissues available from six bonnet macaques and three rhesus macaques were also tested for PERV sequences. RESULTS: All plasma samples were negative for PERV RNA suggesting the absence of viremia in these xenografted animals. Similarly, PERV sequences were not detectable in any PBMC and tissue samples, arguing for the lack of latent infection of these compartments. In addition, all plasma samples were negative for PERV antibodies. CONCLUSION: These data suggest the absence of PERV infection in all 23 NHPs despite exposure to vascularized porcine organs or tissue xenografts and the use of immunosuppressive therapies in some animals. These findings suggest that PERV is not easily transmitted to these NHP species through these types of xenografts.

Animals↗

Inhibition of hypercholesterolemia-induced atherosclerosis in the nonhuman primate by probucol. II. Cellular composition and proliferation.

In nonhuman primates (Macaca nemestrina) treated with the antioxidant probucol during diet-induced hypercholesterolemia, intimal lesion area in the thoracic aorta was decreased, with increased resistance of plasma LDL to oxidation. The cellular and molecular changes associated with the decrease in lesion size in the probucol-treated hypercholesterolemic animals are quantitatively evaluated in this study. Lesions from the probucol-treated animals appear less mature and have altered lipid distribution. Abundant lipid-laden smooth muscle cells are found in the intima and media of the probucol-treated animals, with fewer medial lipid-laden macrophages, compared with lesions at similar sites in the control hypercholesterolemic animals. In both the control and probucol-treated animals, macrophages are the predominant cells in most lesions, but the ratio of macrophages to smooth muscle cells is decreased in the lower thoracic and upper abdominal aortic sites in the probucol-treated animals. Lesions at all aortic sites in the probucol-treated animals have a 35% to 80% reduction in the percentage of cells in cell cycle traverse, as indicated by immunostaining for proliferating cell nuclear antigen (% PCNA-positive). In both groups, macrophages and smooth muscle cells are PCNA-positive, but the majority (> 60%) are macrophages. No difference in % PCNA-positive cells is seen in the iliac arteries, where the most advanced lesions were present at the time probucol administration was initiated. Limited Northern analysis of growth-regulatory molecules possibly involved in the cellular changes associated with lesions shows a 30% to 50% decrease in mRNA levels of platelet-derived growth factor (PDGF) B-chain, PDGF beta-receptor, colony-stimulating factor type 1, and monocyte chemotactic protein 1. Thus, a potential role for an antioxidant such as probucol in the treatment of atherosclerosis may be to alter the early inflammatory fibroproliferative processes of the disease. Whether these effects are directly related to the antioxidant properties or some other activity of probucol is not yet known.

Animals↗

Frequency of feeding enrichment and response of laboratory nonhuman primates to unfamiliar people.

Although environmental enhancement plans for nonhuman primates vary between facilities, feeding enrichment represents a component of most programs. As part of a facility's feeding enrichment program, offering hand-fed food items by trained staff provides an opportunity for positive human interaction. We hypothesized that increased implementation of such enrichment would be associated with increased likelihood of a monkey accepting a hand-fed treat from a stranger. Several species of monkeys were tested at the Tulane National Primate Research Center. In 2002 and 2005, we recorded the number of caged monkeys that accepted a treat tablet from an unfamiliar person within 10 s. We compared the frequency of caretaker-implemented feeding enrichment documented for each animal room during the month proceeding data collection with the proportion of animals within the room that accepted the treat from the stranger. In 2002, 29.8% of the 500 subjects accepted the treat from the unfamiliar person. The proportion of animals that accepted the treat was significantly correlated with the number of days during which feeding enrichment had been implemented. In 2005, feeding enrichment frequency had increased by 76%, and 53.4% of the 676 subjects accepted the treat. These findings suggest that this simple form of enrichment may improve monkeys' responses to unfamiliar people, and that it holds promise as a method for mediating the stress imposed by human activity in animal rooms. In addition, a stranger's treat-feeding attempts may be a useful indicator of an institution's implementation of their environmental enrichment program.

Animal Welfare↗

Characterization of plasma low density lipoproteins on nonhuman primates fed dietary cholesterol.

LDL from animals of three nonhuman primate species, Macaca mulatta, Macaca fascicularis, and Cercopithecus aethiops, were studied. A standard preparation of 125I-LDL was added to isolated lipoprotein mixtures just prior to separation of plasma lipoproteins by agarose gel chromatography. A relative size index, rI, was determined by dividing the elution volume of the iodinated LDL by the elution volume of the sample LDL, both volumes being determined simultaneously during chromatographic elution. Comparison of rI with molecular weights measured by flotation equilibrium analysis in the analytical ultracentrifuge showed a linear relationship across a molecular weight range of 2.5-8.0 X 10(6), r = 0.985. A regression equation describing this relationship was used to calculate molecular weights of LDL from a group of M. fascicularis that were fed cholesterol-containing diets. In these animals, plasma cholesterol concentration ranged from 100 to over 700 mg/dl and was highly correlated with LDL molecular weight and with the micromolar concentration of the LDL. Using multiple regression analyses, the two variables of plasma LDL could be shown to account for 94% of the variation in plasma cholesterol concentration in the M. fascicularis of this study. Micromolar concentration and molecular weight of LDL were not correlated with each other, suggesting that in M. fascicularis at least two independent types of controls are operative in the response of plasma LDL to dietary cholesterol. The increase in LDL molecular weight was associated with a large increase in cholesteryl ester content and concomitant smaller increases in protein, phospholipid, and free cholesterol. As molecular weight increased, these components appeared to be added to the LDL particles together as discrete increments of fixed composition. The data are consistent with a spherical model of LDL structure with a core of cholesteryl ester and triglyceride and a 21.3 A-thick coat of phospholipid, free cholesterol, and protein.

Animals↗

Hepatitis A and B: serologic survey of human and nonhuman primate sera.

Sera of humans and seven species of nonhuman primates were tested by radioimmunoassay and enzyme immunoassay for the presence of hepatitis A antibody, hepatitis B surface antigen and antibody to hepatitis B surface antigen. The outcome of testing a total of 276 serum or plasma specimens was as follows: with the exception of squirrel monkeys (0%) and cotton-top marmosets (0%), a considerable percentage of all other species tested had detectable antibodies to hepatitis A virus: humans 45.9%, chimpanzees 36.6%, baboons 38.2%, vervets 57.9%, cebus monkeys 40.0% and common marmosets 50.0%. Only one human and two chimpanzees were carriers of hepatitis B surface antigen. Antibodies to hepatitis B surface antigen were detected in human (11.3%), chimpanzees (29.9%), baboons (36.2%) and squirrel monkeys (5%). Chimpanzees showed an increasing prevalence of antibodies to hepatitis A virus and hepatitis B surface antigen with age.

Animals↗

Prevalence of herpes B virus antibody in nonhuman primates reared at the National University of Japan.

A serological investigation by means of an enzyme immuno assay test for herpes B virus (cercopithecine herpesvirus 1) was performed on 961 sera of healthy nonhuman primates reared in laboratory animal facilities which belong to the Association of Laboratory Animal Facilities of the National University of Japan. An antibody prevalence of 40% (384/ 961) was demonstrated. The antibody titer was shown to be higher among macaques (60% of cynomolgus monkeys, 53% of rhesus monkeys, and 34% of Japanese monkeys) than among non-macaque species (21%). These data indicate that nonhuman primates reared in animal facilities may present an occupational health problem and a potential zoonotic biohazard as demonstrated in limited cases in the United States.

Animals↗

Melatonin promotes sleep in three species of diurnal nonhuman primates.

Nocturnal melatonin secretion is concurrent with consolidated sleep episodes in diurnal mammals and physiological melatonin levels can promote sleep onset in humans and in pigtail macaques. In order to further investigate the effects of melatonin treatment on sleep parameters in diurnal nonhuman primates, three macaque species have been studied: Macaca nemestrina, Macaca fascicularis, and Macaca mulatta. Sleep was assessed using continuous actigraphic recording of motor activity in animals maintained under 12:12-h light/dark cycle. Oral doses of melatonin (5-320 microg/kg) were administered 2 h before lights-off time, with 5- and 10-microg/kg doses resulting in physiological circulating melatonin levels (31-95 pg/ml). The effects of melatonin administration were similar in three species studied and included significantly earlier sleep onset time and longer sleep period time, with no difference in time of awakening, following administration of both physiological (5-10 microg/kg) and pharmacological (20-320 microg/kg) doses. While low melatonin doses (5-20 microg/kg) did not significantly affect nighttime sleep efficiency, higher pharmacological doses reduced sleep efficiency and increased sleep fragmentation at night, and reduced spontaneous daytime locomotor activity. Daily administration of a 5-microg/kg dose for 4 weeks or gradually escalating melatonin doses (5-320 microg/kg over a 3-week period) did not result in the development of tolerance or sensitization to the effect of melatonin on sleep initiation or sleep period. These data affirm that sleep-promoting effects of melatonin observed in humans are also typical for diurnal primates. They also suggest that physiological and pharmacological melatonin levels might produce different effects on sleep efficiency and that nonhuman primates can serve as adequate animal model for studying the mechanisms of melatonin's action on sleep and performance.

Animals↗

Tacrolimus, a potential neuroprotective agent, ameliorates ischemic brain damage and neurologic deficits after focal cerebral ischemia in nonhuman primates.

Tacrolimus (FK506), an immunosuppressive drug, is known to have potent neuroprotective activity and attenuate cerebral infarction in experimental models of stroke. Here we assess the neuroprotective efficacy of tacrolimus in a nonhuman primate model of stroke, photochemically induced thrombotic occlusion of the middle cerebral artery (MCA) in cynomolgus monkeys. In the first experiment, tacrolimus (0.01, 0.032, or 0.1 mg/kg) was intravenously administered immediately after MCA occlusion, and neurologic deficits and cerebral infarction volumes were assessed 24 hours after the ischemic insult. Tacrolimus dose-dependently reduced neurologic deficits and infarction volume in the cerebral cortex, with statistically significant amelioration of neurologic deficits at 0.032 and 0.1 mg/kg and significant reduction of infarction at 0.1 mg/kg. In the second experiment, the long-term efficacy of tacrolimus on neurologic deficits and cerebral infarction was assessed. Vehicle-treated monkeys exhibited persistent and severe deficits in motor and sensory function for up to 28 days. A single intravenous bolus injection of tacrolimus (0.1 or 0.2 mg/kg) produced long-lasting amelioration of neurologic deficits and significant reduction of infarction volume. In conclusion, we have provided compelling evidence that a single dose of tacrolimus not only reduces brain infarction but also ameliorates long-term neurologic deficits in a nonhuman primate model of stroke, strengthening the view that tacrolimus might be beneficial in treating stroke patients.

Animals↗

Endothelin and ET(A) receptors in long-term arterial pressure homeostasis in conscious nonhuman primates.

This study was designed to quantify the long-term contribution of endogenous endothelin-1 (ET-1) and ET(A) receptors to the regulation of arterial pressure under normal conditions in nonhuman primates. Therefore, mean arterial pressure (MAP) and heart rate were measured 24 h/day with the use of telemetry techniques in conscious cynomolgus monkeys under control conditions, during administration of an ET(A) selective receptor antagonist (ABT-627; 5 mg/kg, 2 times a day by mouth, 4 days), and a 6-day posttreatment period. Systemic ET(A) blockade reduced MAP (24 h) from 89 +/- 3 to 82 +/- 2 and 79 +/- 2 mmHg on days 1 and 4, respectively. Subsequently, MAP remained suppressed for 3 days posttreatment. Heart rate increased from 111 +/- 5 to 122 +/- 4 and 128 +/- 6 beats/min on days 1 and 4 of ABT-627, respectively, and remained above control for 3 days posttreatment. Plasma ET-1 concentration increased from 1.0 +/- 0.3 to 1.9 +/- 0.4 pg/ml in response to ABT-627 (day 4) but decreased to control values 4 days posttreatment. These data demonstrate a physiologically important role for endogenous ET-1 and ET(A) receptors in the long-term regulation of arterial pressure and plasma ET-1 levels in the conscious nonhuman primate.

Animals↗

Compared with cyclosporine, ISATX247 significantly prolongs renal-allograft survival in a nonhuman primate model.

BACKGROUND: ISATX247 is a novel calcineurin inhibitor that has shown more potency than cyclosporine in vitro. This is the first study to compare the survival times of renal allografts in nonhuman primates treated with either ISATX247 or cyclosporine. METHODS: Adult, male cynomolgus monkeys were divided into blood-group compatible and mixed-lymphocyte, stimulation-mismatched, donor-recipient pairs. Heterotopic renal transplantation and bilateral native nephrectomies were performed. The monkeys were placed into either an ISATX247 or cyclosporine treatment group. Both groups were dosed twice daily to maintain a 12-hour drug-trough level of 150 ng/mL. Whole-blood concentrations of ISATX247 and cyclosporine, complete blood counts, and serum chemistry profiles were performed three times a week. Euthanasia was performed if the serum creatinine concentration became 7 or more mg/dL or a serious complication developed. RESULTS: The group receiving ISATX247 (n=8) survived significantly (P=0.0036) longer than the group receiving cyclosporine (n=7). The mean trough blood concentration of ISATX247 was 120 +/- 32 ng/mL and cyclosporine was 189 +/- 130 ng/mL. The average area under the curve 0-12 for ISATX247 was 6045 +/- 1679 ng/mL/hr and for cyclosporine was 4919 +/- 823 ng/mL/hr. The average calcineurin inhibition at trough blood concentrations was 80 +/- 11% for ISATX247 and 48 +/- 12% for cyclosporine. CONCLUSIONS: Allografts in monkeys treated with ISATX247 survived significantly longer than those treated with cyclosporine. On the basis of survival times and degree of calcineurin inhibition, ISATX247 is a more potent immunosuppressive agent than cyclosporine in this nonhuman primate model of renal-allograft transplantation.

Animals↗

Complement components C3, C4, and Bf in six nonhuman primate species.

The extent of cross reactivity between antisera to human complement proteins [the third (C3) and fourth (C4) components and factor B (Bf)] and these proteins in the sera of six species of nonhuman primates was examined. Strong cross reactivity was found with these antisera and the specific complement proteins from rhesus monkeys, stumptailed macaques, cynomolgus macaques, patas monkeys, African green monkeys, and squirrel monkeys. Although molecular differences were apparent as indicated by differences in antigenic determinants and electrophoretic mobility, the antisera developed against human C3, C4, and Bf could be used to identify and to characterize these proteins in the nonhuman primate species examined.

Animals↗

US policy for disease control among imported nonhuman primates.

In 1990, in response to the occurrence of Ebola virus (subsequently identified as subtype Reston) infection among cynomolgus monkeys imported from the Philippines, the United States implemented strict disease control measures for handling nonhuman primates during transit and quarantine and initiated importer facility compliance inspections. Disease control measures emphasized protection of workers from exposure, use of containment facilities and procedures, measures to prevent spread of infection among animals, and laboratory testing of animals that die or become ill during quarantine. From 1991-1995, no outbreaks of filovirus infection occurred, and only one other disease outbreak (caused by Mycobacterium species) was recognized. In April 1996, Ebola virus (subtype Reston) infection was identified in another group of cynomolgus monkeys imported from the Philippines. The disease control measures implemented since the first Ebola virus (subtype Reston) outbreak appeared to work well. Currently, the 27 registered importer facilities import approximately 8500 nonhuman primates annually, and mortality rates are <1.0%. Importer facilities receive regular inspections, and compliance with disease control measures and disease reporting is excellent.

Animals↗

Long-term parenteral nutrition in unrestrained nonhuman primates: an experimental model.

A freely mobile jacket and tether system was developed for the investigation of total parenteral nutrition (TPN)-induced metabolic bone disease and complications of prolonged TPN in 12 Macaca fascicularis nonhuman primates. The animals received TPN for 49 +/- 7 d (means +/- SEM), providing 82 +/- 2 kcal.kg-1.d-1. Serum glucose increased from 3.6 +/- 0.2 mmol/L at baseline to 8.3 +/- 1.9 mmol/L (p less than 0.01) during TPN, and serum albumin decreased from 38 +/- 1 g/L at baseline to 29 +/- 1 g/L (p less than 0.001) during 2.75% amino acid TPN and 30 +/- 2 g/L (p less than 0.01) during 5% amino acid TPN infusion. No significant changes were seen in serum prealbumin, total protein, bilirubin, alanine aminotransferase, and 5'-nucleotidase during TPN infusion. Major complications included catheter sepsis, hyperglycemia, diarrhea, and premature death in six animals. Thus, metabolic complications of prolonged TPN support may be investigated in a freely mobile nonhuman primate.

Animals↗

Intramuscular administration of recombinant adeno-associated virus 2 alpha-1 antitrypsin (rAAV-SERPINA1) vectors in a nonhuman primate model: safety and immunologic aspects.

We performed a series of studies in baboons to evaluate the safety of intramuscular administration of rAAV vector expressing the alpha-1 antitrypsin (AAT) gene (SERPINA1) in a nonhuman primate model. Initial experiments performed with an rAAV vector expressing the human SERPINA1 gene (at doses of up to 5 x 10(12) vector genomes/kg) resulted in the generation of anti-human AAT antibodies, which correlated with a loss of detectable transgene expression. Subsequent studies made use of the baboon SERPINA1 gene tagged with a short (10-amino-acid) c-myc tag. When animals were sacrificed, 4 months after vector injection, transduced myofibers showed efficient transgene expression without detectable humoral immune responses. Mild inflammation was observed in and near the sites of injection in some vector- and saline-injected animals, but serum creatine kinase (CK) values were normal in nearly every case. Real-time PCR was also performed 4 months after injection on gonadal tissue to evaluate the risk of germline transmission. No vector sequences were detected in the gonadal tissues from these animals. These studies indicate that the risks of immune reaction and germline transmission after intramuscular injection of rAAV-SERPINA1 in nonhuman primates are relatively low within the range of vector doses studied.

Animals↗

Generation of protective immunity by inactivated recombinant staphylococcal enterotoxin B vaccine in nonhuman primates and identification of correlates of immunity.

At this time there are no vaccines or therapeutics to protect against staphylococcal enterotoxin B (SEB) exposure. Here, we report vaccine efficacy of an attenuated SEB in a nonhuman primate model following lethal aerosol challenge and identify several biomarkers of protective immunity. Initial in vitro results indicated that the mutation of key amino acid residues in the major histocompatibility complex (MHC) class II binding sites of SEB produced a nontoxic form of SEB, which had little to no detectable binding to MHC class II molecules, and lacked T-cell stimulatory activities. When examined in a mouse model, we found that the attenuated SEB retained antigenic structures and elicited protective immune responses against wild-type SEB challenge. Subsequently, a vaccine regimen against SEB in a nonhuman primate model was partially optimized, and investigations of immune biomarkers as indicators of protection were performed. SEB-naïve rhesus monkeys were vaccinated two or three times with 5 or 20 microg of the attenuated SEB and challenged by aerosol with wild-type SEB toxin. Unlike exposure to the native toxin, the vaccine did not trigger the release of inflammatory cytokines (TNF alpha, IL6, or IFN gamma). All rhesus monkeys that developed anti-SEB serum titers > or = 10(4) and elicited high levels of neutralizing antibody survived the aerosol challenge. These findings suggest that the attenuated SEB is fully protective against aerosolized toxin when administered to unprimed subjects. Moreover, experiments presented in this study identified various biomarkers that showed substantial promise as correlates of immunity and surrogate endpoints for assessing in vivo biological responses in primates, and possibly in humans, to vaccines against SEs.

Animals↗

Combined ADP and thromboxane A2 antagonism prevents cyclic flow variations in stenosed and endothelium-injured arteries in nonhuman primates.

BACKGROUND: This study was designed to test the hypothesis that clopidogrel, a potent inhibitor of platelet aggregation, can eliminate cyclic flow variations in stenosed and endothelium-injured coronary and femoral arteries in nonhuman primates. METHODS AND RESULTS: We studied five anesthetized, open-chest baboons. Blood flow velocity in the coronary and femoral arteries was monitored by pulsed Doppler flow probes placed around the arteries. Cyclic flow variations were established by mechanically injuring the endothelium of the arteries and by narrowing the arteries with external constrictors. Clopidogrel (10 to 20 mg/kg i.v. bolus plus 2.5 mg.kg-1 x h-1 continuous infusion) was administered 60 minutes after cyclic flow variations were established. Clopidogrel abolished cyclic flow variations in the coronary and femoral arteries of all five baboons (frequency of cyclic flow variations, 0/h versus 14/h at baseline, P < .001). Then epinephrine was infused (maximum average dose, 2.2 micrograms.kg-1 x min-1 i.v.). Epinephrine did not restore cyclic flow variations in the coronary or femoral arteries of any baboon. Before treatment with clopidogrel, ADP, collagen, and U46619, a thromboxane A2 mimetic, induced dose-dependent platelet aggregation in vitro. Serotonin, however, did not induce platelet aggregation in vitro. Clopidogrel given in vivo completely inhibited ADP-induced platelet aggregation and significantly diminished collagen- and U46619-induced platelet aggregation in vitro. CONCLUSIONS: Clopidogrel eliminates cyclic flow variations in stenosed and endothelium-injured coronary and femoral arteries of nonhuman primates at least in part by antagonizing the platelet proaggregatory effects of ADP and thromboxane A2.

Adenosine Diphosphate↗

Metabolism of the serum amyloid A proteins (SSA) in high-density lipoproteins and chylomicrons of nonhuman primates (vervet monkey).

Serum amyloid protein (SAA) has been reported to be an apoprotein of high-density lipoprotein (HDL), but little is known concerning its metabolism. In this study, apoSAA was induced in nonhuman primate plasma HDL and thoracic duct lymph chylomicra by overnight chair restraint of the animals. There was a 3-6-fold increase in plasma HDL apoSAA in chair-restrained animals when compared with caged (control) animals. Lymph chylomicrons of chaired animals also contained significant amounts (approximately 20% of total protein) of apoSAA. For study of the metabolism of HDL apoSAA, animals were given injections of 131I-labeled lymph chylomicrons and autologous 125I-HDL. HDL were isolated from the plasma of recipient animals between 1 minute and 5 days after injection, and the specific activity of the apoSAA was determined. The turnover of apoSAA from plasma was biphasic, the initial phase having a t1/2 (0.39-0.48 days) similar regardless of the source (chylomicrons versus HDL) of the injected dose. The second phase of the turnover was significantly faster (t1/2 = 2.5 days) for apoSAA of 125I-HDL origin than that of 131I-chylomicron origin (t1/2 = 4.3 days). This difference also was suggested by the fractional catabolic rates (FCR) of 125I-HDL and 131I-chylomicron apoSAA (1.02 versus 0.74 d-1, respectively). From these studies it was concluded that 1) apoSAA can be rapidly induced in plasma HDL and lymph chylomicrons of nonhuman primates by chair restraint; 2) HDL apoSAA is catabolized more rapidly than HDL apoA-I and apoA-II; 3) and the catabolic rate of HDL apoSAA may be determined, in part, by its lipoprotein origin (chylomicrons versus HDL).

Amino Acid Sequence↗