Central Nervous System Of Monkeys Research Articles

Molecular-genetic characteristics of the tick-borne encephalitis virus pathogenicity of far eastern subtype

The aim of the work: Using the data of genome-wide sequencing of tick-borne encephalitis virus strains of the Far Eastern population, reveal the peculiarities of the moleculargenetic characteristics and their relationship with the pathogenicity of the agent. Materials and methods. A full-genomic characteristic of 63 TBEV strains isolated in the Far East and registered in GeneBank wos given. A pathohistological study of the central nervous system of monkeys infected with the highly virulent strains Sofjin and Khabarovsk-17 TBEV was conducted. Results. All strains are assigned to the Far Eastern subtype of TBEV and are located in three clusters, the territorial attachment of individual strains groups is noted. In the cluster of Sofjin-like strains, independent groups were identified, isolated in the territories of Primorsky Krai only, and separate groups – only in northern focal territories (Khabarovsk Krai). The cluster Senzhang-like strains are represented by strains of different clusters, isolated in China and throughout the Far East. The Oshima-like cluster of strains, except for strains from Japan, consists of strains isolated only in the south of the Far East (in Primorsky Krai). The incubation period of the disease in experimental animals was shorter when infected with the Sofjin strain (3–5 days) than when infected with the Khabarovsk-17 strain (7 days or more). The strain-specific differences in the severity of morphological changes in the central nervous system were revealed. For primorsky TBEV strains, a higher degree of neuroinvasiveness was characteristed with a more rapid development of severe manifestations of neuroinfection, compared to khabarovsky strains.Findings: 1) based on full-genome sequencing and phylogenetic analysis of 63 TBEV strains, three main clusters were distinguished: Sofjin-, Senzhang- and Oshima-like; 2) in these clusters, territorial attachment of TBEV strains groups with a certain molecular genetic characteristic was established; 3) in primorsky TBEV strains, genetically determined advantages in the degree of neuroinvasiveness have been revealed, which provide them with the ability to more quickly overcome the blood-brain barrier compared to khabarovsky strains.

Anatomical Organization of Urocortin 3-Synthesizing Neurons and Immunoreactive Terminals in the Central Nervous System of Non-Human Primates [Sapajus spp.

Urocortin 3 (UCN3) is a neuropeptide member of the corticotropin-releasing factor (CRF) peptide family that acts as a selective endogenous ligand for the CRF, subtype 2 (CRF2) receptor. Immunohistochemistry and in situ hybridization data from rodents revealed UCN3-containing neurons in discrete regions of the central nervous system (CNS), such as the medial preoptic nucleus, the rostral perifornical area (PFA), the medial nucleus of the amygdala and the superior paraolivary nucleus. UCN3-immunoreactive (UCN3-ir) terminals are distributed throughout regions that mostly overlap with regions of CRF2 messenger RNA (mRNA) expression. Currently, no similar mapping exists for non-human primates. To better understand the role of this neuropeptide, we aimed to study the UCN3 distribution in the brains of New World monkeys of the Sapajus genus. To this end, we analyzed the gene and peptide sequences in these animals and performed immunohistochemistry and in situ hybridization to identify UCN3 synthesis sites and to determine the distribution of UCN3-ir terminals. The sequencing of the Sapajus spp. UCN3-coding gene revealed 88% and 65% identity to the human and rat counterparts, respectively. Additionally, using a probe generated from monkey cDNA and an antiserum raised against human UCN3, we found that labeled cells are mainly located in the hypothalamic and limbic regions. UCN3-ir axons and terminals are primarily distributed in the ventromedial hypothalamic nucleus (VMH) and the lateral septal nucleus (LS). Our results demonstrate that UCN3-producing neurons in the CNS of monkeys are phylogenetically conserved compared to those of the rodent brain, that the distribution of fibers agrees with the distribution of CRF2 in other primates and that there is anatomical evidence for the participation of UCN3 in neuroendocrine control in primates.

Gene transfer to the rhesus monkey brain using SV40-derived vectors is durable and safe

Gene transfer to central nervous system (CNS) has been approached using various vectors. Recombinant SV40-derived vectors (rSV40s) transduce human neurons and microglia effectively in vitro and in rodent brains in vivo, so we tested rSV40s gene transfer to rhesus monkey CNS in vivo, to characterize the distribution, duration and safety of such gene delivery. We used rSV40s carrying HIV-1 RevM10 with a carboxyl-terminal AU1 epitope tag as a marker, and others with the antioxidant enzymes, Cu/Zn superoxide dismutase and glutathione peroxidase. Vectors were injected stereotaxically into the caudate nucleus. Transgene expression was studied at 1 and 6 months by immunostaining serial brain sections. After intraparenchymal administration, numerous transgene-expressing cells were seen, with a longitudinal extent of 20 mm. In neurons and, more rarely, microglial cells, transgene expression remained strong throughout the 6-month study period. Astrocytes and oligodendroglia were not transduced. No evidence of inflammation or tissue damage was observed. SV40-derived vectors may thus be useful for long-term gene expression in the monkey brain and, potentially, in the human brain.

High-throughput automated image analysis of neuroinflammation and neurodegeneration enables quantitative assessment of virus neurovirulence

Historically, the safety of live attenuated vaccine candidates against neurotropic viruses was assessed by semi-quantitative analysis of virus-induced histopathology in the central nervous system of monkeys. We have developed a high-throughput automated image analysis (AIA) for the quantitative assessment of virus-induced neuroinflammation and neurodegeneration. Evaluation of the results generated by AIA showed that quantitative estimates of lymphocytic infiltration, microglial activation, and neurodegeneration strongly and significantly correlated with results of traditional histopathological scoring. In addition, we show that AIA is a targeted, objective, accurate, and time-efficient approach that provides reliable differentiation of virus neurovirulence. As such, it may become a useful tool in establishing consistent analytical standards across research and development laboratories and regulatory agencies, and may improve the safety evaluation of live virus vaccines. The implementation of this high-throughput AIA will markedly advance many fields of research including virology, neuroinflammation, neuroscience, and vaccinology.

The neuronal-specific SGK1.1 kinase regulates δ-epithelial Na+ channel independently of PY motifs and couples it to phospholipase C signaling

The δ-subunit of the epithelial Na(+) channel (ENaC) is expressed in neurons of the human and monkey central nervous system and forms voltage-independent, amiloride-sensitive Na(+) channels when expressed in heterologous systems. It has been proposed that δ-ENaC could affect neuronal excitability and participate in the transduction of ischemic signals during hypoxia or inflammation. The regulation of δ-ENaC activity is poorly understood. ENaC channels in kidney epithelial cells are regulated by the serum- and glucocorticoid-induced kinase 1 (SGK1). Recently, a new isoform of this kinase (SGK1.1) has been described in the central nervous system. Here we show that δ-ENaC isoforms and SGK1.1 are coexpressed in pyramidal neurons of the human and monkey (Macaca fascicularis) cerebral cortex. Coexpression of δβγ-ENaC and SGK1.1 in Xenopus oocytes increases amiloride-sensitive current and channel plasma membrane abundance. The kinase also exerts its effect when δ-subunits are expressed alone, indicating that the process is not dependent on accessory subunits or the presence of PY motifs in the channel. Furthermore, SGK1.1 action depends on its enzymatic activity and binding to phosphatidylinositol(4,5)-bisphosphate. Physiological or pharmacological activation of phospholipase C abrogates SGK1.1 interaction with the plasma membrane and modulation of δ-ENaC. Our data support a physiological role for SGK1.1 in the regulation of δ-ENaC through a pathway that differs from the classical one and suggest that the kinase could serve as an integrator of different signaling pathways converging on the channel.

Safety evaluation of chimeric Langat/Dengue 4 flavivirus, a live vaccine candidate against tick‐borne encephalitis

The chimeric flavivirus LGT/DEN4 containing prM and E genes of naturally attenuated Langat virus with remaining sequence derived from low neuroinvasive Dengue 4 virus was previously produced and assessed as a candidate for live vaccine against tick-borne encephalitis (TBE) [Pletnev and Men (1998): Proc Natl Acad Sci USA 95:1746-1751; Pletnev et al. (2000): Virology 274:23-31; Pletnev et al. (2001): J Virol 75:8259-8267; Wright et al. (2008): Vaccine 26:882-890]. In this article we compared two animal species: mice and monkeys, in order to select most sensitive models for safety evaluation of new vaccine candidates against TBE. Direct neurovirulence in suckling mice, neuroinvasiveness upon peripheral inoculation, rate of virus multiplication and expansion in CNS and its ability to persist in the central nervous system (CNS) were studied in adult mice; virological and pathomorphological examination of the CNS and visceral organs after intrathalamic virus inoculation was selected as a safety neurovirulence test in monkeys. The chimera was substantially less virulent in both animal models compared to the Absettarov strain of TBE virus. LGT/DEN4 was highly attenuated in suckling and adult mice with no evidence of viral persistence in CNS. In contrast to the mouse model, the chimera was able to reproduce in the CNS of monkeys to moderate titers, caused pathomorphological lesions in two and even illness in one of four animals, and was registered in simian brain on the 30th day post-infection. The presented data show that tests in mice solely might not be a sufficient model for safety testing of chimeric viruses.

The effects of normal aging on myelinated nerve fibers in monkey central nervous system.

The effects of aging on myelinated nerve fibers of the central nervous system are complex. Many myelinated nerve fibers in white matter degenerate and are lost, leading to some disconnections between various parts of the central nervous system. Other myelinated nerve fibers are affected differently, because only their sheaths degenerate, leaving the axons intact. Such axons are remyelinated by a series of internodes that are much shorter than the original ones and are composed of thinner sheaths. Thus the myelin-forming cells of the central nervous system, the oligodendrocytes, remain active during aging. Indeed, not only do these neuroglial cell remyelinate axons, with age they also continue to add lamellae to the myelin sheaths of intact nerve fibers, so that sheaths become thicker. It is presumed that the degeneration of myelin sheaths is due to the degeneration of the parent oligodendrocyte, and that the production of increased numbers of internodes as a consequence of remyelination requires additional oligodendrocytes. Whether there is a turnover of oligodendrocytes during life has not been studied in primates, but it has been established that over the life span of the monkey, there is a substantial increase in the numbers of oligodendrocytes. While the loss of some myelinated nerve fibers leads to some disconnections, the degeneration of other myelin sheaths and the subsequent remyelination of axons by shorter internodes slow down the rate conduction along nerve fibers. These changes affect the integrity and timing in neuronal circuits, and there is evidence that they contribute to cognitive decline.

Method for the construction and use of carbon fiber multibarrel electrodes for deep brain recordings in the alert animal

Microiontophoresis of neuroactive substances during single unit recording in awake behaving animals can significantly advance our understanding of neural circuit function. Here, we present a detailed description of a method for constructing carbon fiber multibarrel electrodes suitable for delivering drugs while simultaneously recording single unit activity from deep structures, including brainstem nuclei and the cerebellum, in the awake behaving primate. We provide data that should aid in minimizing barrel resistance and the time required to fill long, thin multibarrel electrodes with solutions. We also show successful single unit recording from a variety of areas in the awake squirrel monkey central nervous system, including the vestibular nuclei, Interstitial Nucleus of Cajal, and the cerebellum. Our descriptions and data should be useful for investigators wishing to perform single unit recordings during microiontophoresis of neuroactive substances, particularly in deep structures of animals with chronically implanted recording chambers.

Comparative neuropathogenesis and neurovirulence of attenuated flaviviruses in non-human primates

Based on previous preclinical evaluation in mice and monkeys, the chimeric TBEV/DEN430 virus, carrying the prM and E protein genes from a highly virulent Far Eastern strain of tick-borne encephalitis virus (TBEV) on the backbone of a nonneuroinvasive dengue type 4 virus (DEN4), has been identified as a promising live attenuated virus vaccine candidate against disease caused by TBEV. However, prior to use of this vaccine candidate in humans, its neurovirulence in nonhuman primates needed to be evaluated. In the present study, we compared the neuropathogeneses of the chimeric TBEV/DEN430 virus; Langat virus (LGTV), a former live TBEV vaccine; and yellow fever 17D virus vaccine (YF 17D) in rhesus monkeys inoculated intracerebrally. TBEV/DEN430 and YF 17D demonstrated remarkably similar spatiotemporal profiles of virus replication and virus-associated histopathology in the central nervous system (CNS) that were high in cerebral hemispheres but progressively decreased toward the spinal cord. In contrast, the neurovirulence of LGTV exhibited the reverse profile, progressing from the site of inoculation toward the cerebellum and spinal cord. Analysis of the spatiotemporal distribution of viral antigens in the CNS of monkeys revealed a prominent neurotropism associated with all three attenuated viruses. Nevertheless, TBEV/DEN430 virus exhibited higher neurovirulence in monkeys than either LGTV or YF 17D, suggesting insufficient attenuation. These results provide insight into the neuropathogenesis associated with attenuated flaviviruses that may guide the design of safe vaccines.

Comparative Neuropathogenesis and Neurovirulence of Attenuated Flaviviruses in Nonhuman Primates

Based on previous preclinical evaluation in mice and monkeys, the chimeric TBEV/DEN4Delta30 virus, carrying the prM and E protein genes from a highly virulent Far Eastern strain of tick-borne encephalitis virus (TBEV) on the backbone of a nonneuroinvasive dengue type 4 virus (DEN4), has been identified as a promising live attenuated virus vaccine candidate against disease caused by TBEV. However, prior to use of this vaccine candidate in humans, its neurovirulence in nonhuman primates needed to be evaluated. In the present study, we compared the neuropathogeneses of the chimeric TBEV/DEN4Delta30 virus; Langat virus (LGTV), a former live TBEV vaccine; and yellow fever 17D virus vaccine (YF 17D) in rhesus monkeys inoculated intracerebrally. TBEV/DEN4Delta30 and YF 17D demonstrated remarkably similar spatiotemporal profiles of virus replication and virus-associated histopathology in the central nervous system (CNS) that were high in cerebral hemispheres but progressively decreased toward the spinal cord. In contrast, the neurovirulence of LGTV exhibited the reverse profile, progressing from the site of inoculation toward the cerebellum and spinal cord. Analysis of the spatiotemporal distribution of viral antigens in the CNS of monkeys revealed a prominent neurotropism associated with all three attenuated viruses. Nevertheless, TBEV/DEN4Delta30 virus exhibited higher neurovirulence in monkeys than either LGTV or YF 17D, suggesting insufficient attenuation. These results provide insight into the neuropathogenesis associated with attenuated flaviviruses that may guide the design of safe vaccines.

Prolonged Microgliosis in the Rhesus Monkey Central Nervous System after Traumatic Brain Injury

Impaired fine motor functions after traumatic brain injury (TBI) in humans and non-human primates often continue to improve months after injury. To initiate a series of studies in the primate model designed to investigate possible involvement of microglia/macrophage in the long-term recovery processes, changes in these cells were studied in the rhesus monkey central nervous system at 1, 6, and 12 months after a combined unilateral lesion of the arm area of the primary motor cortex and arm area of the lateral premotor cortex. Immunohistological studies showed profound CD68 immunoreactivity in the lesion area and the contralateral lateral corticospinal tract in the spinal cord at all time points, demonstrating that microglia/macrophage remain reactive at the sites of injury and axonal degeneration/survival for at least 12 months. We also observed marked increases in brain-derived neurotrophic factor (BDNF) and its receptor subtypes, TrkB[gp145] and TrkB[TK-], around the cortical lesion site after 6-month survival. Similar increases were also observed in the spinal cord, although it was less apparent for TrkB[gp145]. Double-labeling revealed that a subpopulation of CD68-immunoreacitve microglia/macrophage co-expressed BDNF in the cortex and spinal cord, and also TrkB[gp145] or TrkB[TK-] in the spinal cord. In contrast, cytokine expression of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) at these time intervals was less prominent, suggesting that immediate inflammatory responses had subsided. These results demonstrate that microglia/macrophage undergo prolonged activation after TBI in the non-human primate brain and express BDNF and its receptors, suggesting their tropic/trophic roles in the long-term recovery processes.

Distribution and pharmacological characterization of primate NK‐1 and NK‐3 tachykinin receptors in the central nervous system of the rhesus monkey

Much attention has focused on tachykinin receptors as therapeutic targets for neuropsychiatric disorders, although their expressional distributions in the primate central nervous system (CNS) remain unclear. We cloned the genes encoding the NK-1 and NK-3 tachykinin receptors (referred to as rmNK-1 and rmNK-3) from the rhesus monkey (Macaca mulatta) brain and examined their pharmacological profiles and regional distributions in the CNS. The deduced rmNK-1 amino-acid sequence differed by only two amino acids from the human NK-1 (hNK-1). The deduced rmNK-3 amino-acid sequence was two amino acids shorter than human NK-3 (hNK-3), with a seven-amino-acid difference in sequence. Ligand binding studies revealed that the affinity of rmNK-1 to substance P (SP) was comparable to that of hNK-1 in cell lines that expressed individual receptors stably. Nonpeptide antagonists had similar effects on the binding of rmNK-1 and hNK-1. Affinity of rmNK-3 for NKB was stronger than for SP and the IC50 value was comparable with that of hNK-3. Ca2+ imaging showed that activations of both rmNK-1 and rmNK-3 by specific ligands, SP and senktide, induced increased intracellular Ca2+ in cell lines that stably expressed individual primate tachykinin receptors. The amounts of rmNK-1 and rmNK-3 mRNAs were quantitatively determined in the monkey CNS. The expression of rmNK-1 was observed in all of the cortical and subcortical regions, including the hippocampus and the amygdala. The putamen contained the most NK-1 mRNA in the brain, with less rmNK-3 mRNA found in the cortex compared to rmNK-1 mRNA. In the monkey hippocampus and amygdala, rmNK-1 mRNA was present at markedly higher concentrations than rmNK-3 mRNA. The present results provide an insight into the distinct physiological nature and significance of the NK-1 and NK-3 tachykinin systems in the primate CNS. These findings are indispensable for establishing model systems in the search for a subtype-specific tachykinin receptor agonist and antagonist for the treatment of neuropsychiatric disorders.

Temperature-sensitive mutants of enterovirus 71 show attenuation in cynomolgus monkeys

Enterovirus 71 (EV71) is one of the major causative agents of hand, foot and mouth disease and is sometimes associated with serious neurological disorders. In this study, an attempt was made to identify molecular determinants of EV71 attenuation of neurovirulence in a monkey infection model. An infectious cDNA clone of the virulent strain of EV71 prototype BrCr was constructed; temperature-sensitive (ts) mutations of an attenuated strain of EV71 or of poliovirus (PV) Sabin vaccine strains were then introduced into the infectious clone. In vitro and in vivo phenotypes of the parental and mutant viruses were analysed in cultured cells and in cynomolgus monkeys, respectively. Mutations in 3D polymerase (3D(pol)) and in the 3' non-translated region (NTR), corresponding to ts determinants of Sabin 1, conferred distinct temperature sensitivity to EV71. An EV71 mutant [EV71(S1-3')] carrying mutations in the 5' NTR, 3D(pol) and in the 3' NTR showed attenuated neurovirulence, resulting in limited spread of virus in the central nervous system of monkeys. These results indicate that EV71 and PV1 share common genetic determinants of neurovirulence in monkeys, despite the distinct properties in their original pathogenesis.

Pre- and post-developmental neurogenesis in primates

The [ 3H]TdR or bromodeoxyuridine (BrdU) methods for marking DNA replication were used to determine time of origin of over 125 classes of neurons in the 34 structures of the macaque monkey central nervous system. The analysis revealed that each neuronal class is generated in a precisely defined developmental period, the duration of which did not depend on the size and final number of neurons in a given structure. An exception was the granule cell class of the olfactory bulb and dentate gyrus that continues genesis at a low rate even after sexual maturity. Thus, most neurons of the primate brain, including cerebral cortex last the entire life span and are normally not renewable. Overcoming resistance of the adult primate's brain to acquisition of functionally competent neurons as a form of therapy would benefit from insight into why neurogenesis normally ceases at a specific developmental period as well as why there are species-specific and regional differences in the capacity for neurogenesis.

Localization of nicotinic receptor subunit mRNAs in monkey brain by in situ hybridization.

Nicotinic receptors are implicated in memory, learning, locomotor activity, and addiction. Identification of the specific receptor subtypes that mediate these behaviors is essential for understanding their role in central nervous system (CNS) function. Although expression of nicotinic receptor transcript has been studied in rodent brain, their localization in the monkey CNS, which may be a better model for the human brain, is not yet known. We therefore investigated the distribution of alpha4, alpha6, alpha7, beta2, beta3, and beta4 receptors subunit mRNAs in the monkey brain by using in situ hybridization. alpha4 and alpha7 mRNAs were very widely expressed, with a substantial degree of overlap in their distribution, except for the reticular nucleus of the thalamus in which alpha7 mRNA was much more prominently expressed. beta2 and beta4 mRNA were also widely distributed, although beta4 was more prominently localized in thalamic nuclei than beta2. The distribution of alpha6 and beta3 mRNA was very distinct from that of the other transcripts, being restricted to catecholaminergic nuclei, the cerebellum, and a few other areas. Although there were similarities in distribution of the nicotinic receptor subunit mRNAs in monkey and rodent brain, there were prominent differences in areas such as the caudate, putamen, locus coeruleus, medial habenula, and cerebellum. In fact, the distribution of alpha4 and alpha7 mRNAs in the monkey caudate and putamen was more similar to that reported in the human than rodent brain. These findings have implications for the development of drug therapies for neurological disorders, such as Alzheimer's and Parkinson's disease, in which nicotinic receptors are decreased.

Cellular localization of brain-derived neurotrophic factor-like immunoreactivity in adult monkey brain

Immunohistochemical localization of brain-derived neurotrophic factor (BDNF) in the monkey brain was investigated using a polyclonal anti-BDNF antibody produced in our laboratory. The antibody recognized a single band in monkey brain homogenates, and the estimated molecular weight was approximately 14 kDa, which corresponds well to the molecular weight of BDNF monomer. BDNF-like immunoreactivity was observed in the somata and processes of discrete neuronal subpopulations in the monkey brain. BDNF-positive neurons were widely distributed in various structures of the brain, including the cerebral cortex, hippocampus, basal forebrain, basal ganglia, diencephalon, brainstem and cerebellum. In addition, immunopositive glial cells were found in some brain regions. These data suggest that BDNF may exist widely in the monkey brain, and may be concerned with various types of neurons in the monkey central nervous system.

Psychophysical study of noxious and innocuous cold discrimination in monkey.

Psychophysical evidence shows that humans are better able to distinguish differences in the intensity of cutaneous temperature in the cool range than in the noxious cold range. In order to compare these human perceptual findings with physiological data from non-human primates, we performed similar psychophysical experiments of cold perception in monkeys. Two adult male rhesus monkeys were trained to detect cooling shifts from baseline temperatures between 0 degrees and 22 degrees C applied to the face with a 1-cm2 contact thermode. Detection thresholds were determined using the method of constant stimuli for one monkey and an adaptive psychophysical algorithm which insured constant behavioral performance for the other monkey. Results showed that both monkeys detected significantly smaller temperature decreases from innocuous cool baselines (i.e., 22 degrees and 16 degrees C) than from noxious and near-noxious baselines (10 degrees, 6 degrees, 0 degrees C). Similarly, the latencies for detecting the cooling shifts were shorter and less variable in the innocuous cool range than in the noxious cold range. The observation of more precise discrimination of innocuous cool than noxious cold temperatures in monkeys is consistent with human psychophysical data. Thus, these data suggest that differential patterns of neuronal activity evoked by cool and noxious cold cutaneous stimuli, observed in peripheral afferents as well as in the central nervous system of monkey and cat, probably also exist in the human.

Change of expression of full-length and truncated TrkBs in the developing monkey central nervous system

We examined the expression of full-length TrkB (TrkB TK+) and truncated TrkB (TrkB TK−) in the central nervous system (CNS) of the macaque monkey ( Macaca fascicularis) using a western blot analysis. At the adult stage, the levels of TrkB TK+ in cerebral cortices were higher than those in other structures of CNS and the expressions of TrkB TK+ in the association cortices (except area PE) were relatively lower than those in the primary cortices. In contrast, TrkB TK− in the hippocampus and the cerebellum was significantly higher than in other structures. In various developing cerebral cortices, TrkB TK+ was detected at the same levels from embryonic day 120 (E120) to the adult period. In contrast, the expression of TrkB TK− increased remarkably after the newborn stage (NB), reached the maximum level at postnatal day 60 (P60) and maintained the same level into adulthood. The peaks of TrkB TK− in the association cortices were more delayed than in the primary cortices. The expression of TrkB TK− occurred at a time that correlates with the elimination of axons and the down-regulation of neuropeptides. The present study suggests that TrkB TK− plays an important role in the axonal remodelling and that it may act as a negative effector of TrkB TK+ in the primate CNS, reducing responsiveness to BDNF and/or NT-4/5.

Ciliary neurotrophic factor receptor alpha-immunoreactivity in the monkey central nervous system.

Ciliary neurotrophic factor (CNTF) sustains the viability and phenotypic expression of a variety of neuronal populations in the central nervous system. Cranial and spinal motor neurons are particularly sensitive to the trophic effects of CNTF, and clinical trials are underway testing the potential therapeutic value of this trophic factor in patients with amyotrophic lateral sclerosis. Yet, the distribution of the alpha subunit of the receptor for ciliary neurotrophic factor (CNTFR alpha), which is essential for the trophic effects of CNTF to occur, is unknown in any primate species. Towards this end, the present study used a polyclonal antibody directed against CNTFR alpha to evaluate the distribution of CNTFR alpha-immunoreactive (-ir) cells within the brain and spinal cord of Cebus apella monkeys. CNTFR alpha-ir was found exclusively within neurons. In the anterior horn of the spinal cord, virtually all motor neurons were darkly immunoreactive for CNTFR alpha. A similar pattern of CNTFR alpha-ir was seen within all cranial motor nuclei with general somatic efferent function (III, IV, motor V, VI, VII, and XII cranial nerves). CNTFR alpha-ir was also seen in other regions involved with motor function including the Purkinje cells of the cerebellum, the substantia nigra pars compacta, red nucleus, dorsal motor nucleus of X cranial nerve, and giant neurons of sensory motor neocortex. A few CNTFR alpha-ir neurons were seen within the globus pallidus with concomitant terminal-like staining within the subthalamic nucleus. Autonomic regions such as the mesencephalic nucleus of the trigeminal nerve and the interomedial lateral cell column of the thoracic spinal cord also contained CNTFR alpha-ir neurons. Finally, the hippocampus displayed dense CNTFR alpha-ir within the pyramidal cell layer of the hippocampal formation and the granule cell layer of the dentate gyrus. The dense expression of this CNTFR alpha protein within regions subserving motor, autonomic, and sensory functions suggests that CNTFR alpha supports many central nervous system regions with diverse functions.

Succession of Mutations in the Sabin Strain of Type 3 Poliovirus Replicating in the Central Nervous System of Monkeys

Sabin strains of oral poliovirus vaccine (OPV) undergo limited genetic changes during replication in cell cultures, the gastrointestinal tract of vaccinees, and the central nervous system of monkeys. Some of these changes are associated with loss of attenuation markers. Here we report the dynamics of mutant accumulation in the Sabin strain of poliovirus type 3 inoculated intraspinally into monkeys. Thr → Ile reversion in amino acid 6 of VP1 (2493 C → U) occurred within the first few days postinoculation (p.i.), but decreased on later days and completely disappeared by Day 17 p.i. 472 U → C reversion in the 5′-untranslated region appeared to accumulate slower and by Day 17 completely substituted for the vaccine-type nucleotide at this site. These results indicate that experimental infection of the central nervous system of monkeys consists of early and late phases in which a different genetic constitution of the virus is favored. In several isolates one additional neurovirulent revertant was found: a Phe → Ser at amino acid 91 of VP3 (2034 U → C). Since this mutation was never detected in vaccine lots and is strongly selected against in cell cultures at temperatures below 38.5°, it does not threaten the safety of OPV.