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GM2 gangliosidoses, including Tay–Sachs disease and Sandhoff disease, are lysosomal storage disorders caused by deficiencies in β-N-acetylhexosaminidase (Hex). Patients are afflicted primarily with progressive central nervous system (CNS) dysfunction. Studies in mice, cats, and sheep have indicated safety and widespread distribution of Hex in the CNS after intracranial vector infusion of AAVrh8 vectors encoding species-specific Hex α- or β-subunits at a 1:1 ratio. Here, a safety study was conducted in cynomolgus macaques (cm), modeling previous animal studies, with bilateral infusion in the thalamus as well as in left lateral ventricle of AAVrh8 vectors encoding cm Hex α- and β-subunits. Three doses (3.2 × 1012 vg [n = 3]; 3.2 × 1011 vg [n = 2]; or 1.1 × 1011 vg [n = 2]) were tested, with controls infused with vehicle (n = 1) or transgene empty AAVrh8 vector at the highest dose (n = 2). Most monkeys receiving AAVrh8-cmHexα/β developed dyskinesias, ataxia, and loss of dexterity, with higher dose animals eventually becoming apathetic. Time to onset of symptoms was dose dependent, with the highest-dose cohort producing symptoms within a month of infusion. One monkey in the lowest-dose cohort was behaviorally asymptomatic but had magnetic resonance imaging abnormalities in the thalami. Histopathology was similar in all monkeys injected with AAVrh8-cmHexα/β, showing severe white and gray matter necrosis along the injection track, reactive vasculature, and the presence of neurons with granular eosinophilic material. Lesions were minimal to absent in both control cohorts. Despite cellular loss, a dramatic increase in Hex activity was measured in the thalamus, and none of the animals presented with antibody titers against Hex. The high overexpression of Hex protein is likely to blame for this negative outcome, and this study demonstrates the variations in safety profiles of AAVrh8-Hexα/β intracranial injection among different species, despite encoding for self-proteins.

Background Simian immunodeficiency virus (SIV) infection and persistent CD8+ lymphocyte depletion rapidly leads to encephalitis and neuronal injury. The objective of this study is to confirm that CD8-depletion alone does not affect brain pathology in the absence of SIV infection.

Proton magnetic resonance spectroscopy has emerged as one of the most informative neuroimaging modalities for studying the effect of HIV infection in the brain, providing surrogate markers by which to assess disease progression and monitor treatment. Reductions in the level of N-Acetylaspartate and N-Acetylaspartate/creatine are established markers of neuronal injury or loss. However, the biochemical basis of altered creatine levels in neuroAIDS is not well understood. This study used a rapid progression macaque model of neuroAIDS to elucidate the changes in creatine. As the disease progressed, proton magnetic resonance spectroscopy revealed a decrease in N-Acetylaspartate, indicative of neuronal injury, and an increase in creatine yet to be elucidated. Subsequently, immunohistochemistry and stereology measures of decreased synaptophysin, microtubule-associated protein 2, and neuronal density confirmed neuronal injury. Furthermore, increases in ionized calcium binding adaptor molecule 1 and glial fibrillary acidic protein indicated microglial and astroglial activation, respectively. Given these data, elevated creatine may reflect enhanced high-energy phosphate turnover in highly metabolizing activated astrocytes and microglia. Magn Reson Med, 2011. © 2011 Wiley-Liss, Inc.

There is a critical need for animal models to study aspects type 2 diabetes mellitus pathogenesis and prevention. While the rhesus macaque is such an established model, the common marmoset has added benefits including reduced zoonotic risks, shorter life span, and a predisposition to birth twins demonstrating chimerism. The marmoset as a model organism for the study of metabolic syndrome has not been fully evaluated. Marmosets fed high-fat or glucose-enriched diets were followed longitudinally to observe effects on morphometric and metabolic measures. Effects on pancreatic histomorphometry and vascular pathology were examined terminally. The glucose–enriched diet group developed an obese phenotype and a prolonged hyperglycemic state evidenced by a rapid and persistent increase in mean glycosylated hemoglobin (HgbA1c) observed as early as week 16. In contrast, marmosets fed a high-fat diet did not maintain an obese phenotype and demonstrated a delayed increase in HgbA1c that did not reach statistical significance until week 40. Consumption of either diet resulted in profound pancreatic islet hyperplasia suggesting a compensation for increased insulin requirements. Although the high fat diet group developed atherosclerosis of increased severity, the presence of lesions correlated with glucose intolerance only in the glucose-enriched diet group. The altered timing of glucose dysregulation, differential contribution to obesity, and variation in vascular pathology suggests mechanisms of effect specific to dietary nutrient content. Feeding nutritionally modified diets to common marmosets recapitulates aspects of metabolic disease and represents a model that may prove instrumental to elucidating the contribution of nutrient excess to disease development.

The GM2 gangliosidoses are lysosomal storage disorders that encompass both Tay-Sachs and Sandhoff diseases. These diseases are associated with deficiencies in the lysosomal enzyme β-N-acetylhexosaminidase (HexA). These deficiencies result in accumulation of GM2 ganglioside (GM2) in the central nervous system leading to neuronal dysfunction and death. HexA is a heterodimer composed of α and β subunits encoded by HEXA and HEXB genes respectively. Gene therapy approaches using direct injection of AAV vectors into the brain of both small and large disease models (mice, cats, and sheep) have all been successful in treating CNS pathology as well as extending lifespan. These studies utilized two AAVrh8 vectors encoding species-specific alpha and beta subunits of HexA under a CBA promoter with a WPRE (CBA-HexA-WPRE). However, when preclinical safety studies were performed in cynomolgus macaques (cm) using the same strategy, severe neurotoxicity was observed for doses 0.1-3.2E12 vg, which are comparable to those tested in other species on a vg/kg brain weight basis. We hypothesized that the cause of unexpected toxicity was due to high expression of HexA. In order to reduce expression of HexA while maintaining our AAV dose (1.78E12-5.34E13 vg/kg brain weight), we generated a series of new vectors with different combinations of promoters and expression elements with a gradient of HexA expression levels. We tested 7 designs of AAVrh8 vectors encoding cm HexA subunits in athymic nude mice (3.3 E13 vg/kg brain weight). In mice injected with the original vector, AAVrh8-CBA-cmHexA-WPRE, we observed increased levels of reactive astrocytes (GFAP) and activated microglia (Iba1) at the injection site. We used this as a screen to test the other vectors for lower gliosis while expressing HexA activity above normal. Three vector designs emerged and were tested in cynomolgus macaques (n=2, 90 days) infused bilaterally into the thalamus and cerebral lateral ventricle at the intermediate dose (5.34 E12 vg/kg brain weight) as in the first study. The behavior of all monkeys remained normal throughout the study. An abnormal T2 weighted MRI signal was documented at day 90 post-injection in one injection site in a monkey in the cohort with the highest HexA activity (up to 88 fold over normal). This signal was absent in day 30 and 60 brain MRI. Neurohistopathological examination revealed considerable neurodegeneration at this site. The other two cohorts had minimal to no neurotoxicity associated with increased HexA expression (up to 9 fold). Two new AAV vectors have been identified for safe overexpression of HexA in the primate brain.

Diagnosis: Rat bite fever (RBF) due to Streptobacillus moniliformis. A Gram stain showed highly pleomorphic, gram-negative rods that were identified as S. moniliformis (figure l).The patient was given a regimen of penicillin (2 million U every 4 h intravenously). RBF has been associated with serious sequelae, such as endocarditis, hepatitis, meningitis, and nephritis. The patient did not meet Duke's criteria for diagnosis of endocarditis [1]. A transthoracic echocardiogram did not show vegetations. There was no evidence of involvement of other organs. Subsequent blood cultures showed no growth. The patient was treated with 7 days of intravenous penicillin, followed by 7 days of oral penicillin. She remained afebrile, no new skin eruptions appeared, and all residual lesions desquamated and healed. She did not return for her scheduled follow-up appointment. In a telephone interview that was conducted a week after she finished her course of penicillin, she stated that she had mild arthralgias but otherwise felt well, with no new skin eruptions. Six months after the initial presentation, the cryoglobulinemia had resolved, the antinuclear antibody titer had decreased to 1:40, and the patient remained symptom free. More than 2 million animal bites are reported each year in the United States, of which 1b% are attributable to rats [2]. t e ited States, of ic ~-1 are attributable to rats [2]. Although RBF is considered to be a rare illness, it is likely that it is underdiagnosed. S. moniliformis is found in the nasopharynx of most rats and is excreted in their urine. Nasopharyngeal carriage rates in healthy laboratory rats range from 10% to 100%; rates among wild rats have been estimated at 50%-100% [2]. The organism is usually transmitted by a bite or scratch from an infected animal, but it may also be acquired by simply handling the animal or from exposure to rat urine when handling cage materials [2]. On further questioning, the patient mentioned that she regularly cleaned the cages of all of her animals. She also informed us that she let her pet rats lick her teeth! RBF is characterized by the acute onset of shaking chills, fever, vomiting, and severe myalgias. After a few days, a maculopapular skin eruption appears, followed by arthralgias in up to 50% of cases. The eruption is usually seen on the extensor surface of the extremities and frequently involves the palms and soles. It can also be petechial, purpuric, or pustular and lasts for -3 weeks. Approximately 20% of the rashes undergo desquamation [3]. Usually the illness is self-limited. However, in a small number of untreated cases, serious sequelae, such as meningitis, endocarditis, hepatitis, nephritis, and brain or joint abscess may develop, with a mortality rate of 13% [4], increasing to 53% in cases with cardiac involvement [5]. Nineteen cases of S. moniliformis endocarditis have been reported; these cases occurred predominantly in patients with previously damaged heart valves [5, 6]. However, RBF is not a reportable disease, and the actual incidence of endocarditis associated with RBF is not known.

Background Marmosets are playing an increasingly large and important role in biomedical research. They share genetic, anatomical, and physiological similarities with humans and other primate model species, but their smaller sizes, reproductive efficiency, and amenability to genetic manipulation offer an added practicality. While their unique biology can be exploited to provide insights into disease and function, it is also important that researchers are aware of the differences that exist between marmosets and other species. The New World monkey family Callitrichidae, containing both marmoset and tamarin species, typically produces dizygotic twins that show chimerism in the blood and other cells from the hematopoietic lineage. Recently, a study extended these findings to identify chimerism in many tissues, including somatic tissues from other lineages and germ cells. This has raised the intriguing possibility that chimerism may play an increasingly pervasive role in marmoset biology, ranging from natural behavioral implications to increased variability and complexity in biomedical studies. Results Using a quantitative PCR based methodology, Y-chromosomes can be reliably detected in the females with male fraternal twins allowing for a relative quantification of chimerism levels between individuals and tissues. With this approach in common marmosets (Callithrix jacchus) and cotton-top tamarins (Saguinus oedipus), chimerism was detected across a broad array of tissues. Chimerism levels were significantly higher in tissues primarily derived from the hematopoietic lineage, while they were lower, though still detectable, in tissues with other origins. Interestingly, animals with a characteristic marmoset wasting disease show higher levels of chimerism in those tissues affected. Fibroblast cell lines from chimeric individuals, however, are not found to be chimeric themselves. Conclusion Taken together, the levels of chimerism in tissues of different origins coupled with other lines of evidence suggest that indeed only hematopoietic cell lineages are chimeric in callitrichids. The chimerism detected in other tissues is likely the result of blood or lymphocytic infiltration. Using molecular methods to detect chimerism in a tissue sample seems to have allowed a substantial increase in the ability to detect these minor cell populations.