Molecular typing of enteroviruses: comparing 5'UTR, VP1 and whole genome sequencing methods

Enteroviruses (EV) commonly cause hand, foot and mouth disease (HFMD), and can also cause potentially fatal neurological and systemic complications. In our laboratory, sequencing 5' untranslated region (UTR) of the viral genome has been the routine method of genotyping EVs. During a recent localised outbreak of aseptic meningitis, sequencing the 5'UTR identified the causative virus as EV-A71, which did not fit with the clinical syndrome or illness severity. When genotyped using a different target gene, VP1, the result was different. This led us to evaluate the accuracy of the two different target genome regions and compare them against whole genome sequencing (WGS). We aimed to optimise the algorithm for detection and characterisation of EVs in the diagnostic laboratory. We hypothesised that VP1 and WGS genotyping would provide different results than 5'UTR in a subset of samples. Clinical samples from around New South Wales which were positive for EV by commercial polymerase chain reaction (PCR) assays were genotyped by targeting three different viral genome regions: the 5'UTR, VP1 and WGS. Sequencing was performed by Sanger and next generation sequencing. The subtyping results were compared. Of the 74/118 (63%) samples that were successfully typed using both the 5'UTR and the VP1 method, the EV typing result was identical for 46/74 (62%) samples compared to WGS as the gold standard. The same EV group but different EV types were found in 22/74 (30%) samples, and 6/74 (8%) samples belonged to different EV groups depending on typing method used. Genotyping with WGS and VP1 is more accurate than 5'UTR. Genotyping by the 5'UTR method is very sensitive, but less specific.

Clinical Characteristics and Outcomes of COVID-19 in a low-prevalence, well-resourced setting, Sydney, Australia

Background

The Northern Sydney Local Health District was one of the first health regions to be affected by COVID‐19 in Australia.

Aims

To describe the clinical characteristics, risk factors and outcomes in our low‐prevalence Australian population.

Methods

This is a retrospective analysis of 517 laboratory‐confirmed COVID‐19 cases between January and June 2020. Patient information was collected as part of routine care within the COVID‐19 Virtual Hospital system. Outcomes examined were death, recovery at 30 days and intensive care unit (ICU) admission.

Results

The case fatality rate was 1.8%. Multivariate analysis showed factors independently associated with death, composite outcome of death/ICU admission or incomplete recovery at 30 days were age >80 years and presence of two or more comorbidities. Most cases acquired COVID‐19 through international (50.9%) or cruise ship travel (9.1%). Healthcare workers comprised 12.8% of the cohort and represented a disproportionately high percentage of the ‘unknown’ source group (27.6%). The median incubation period was 5 days (interquartile range 3–8); one patient had an incubation period of 15 days. Hospitalisation was required in 11.8%, ICU admission in 2.1% and ventilation in 1.4%. A Radiographic Assessment of Lung Oedema score on chest X‐ray of >10 was independently associated with death.

Conclusions

In this low prevalence, well resourced Australian setting, we report an overall low mortality. Factors associated with adverse patient outcomes on multivariate analysis were age greater than 80 and the presence of two or more comorbidities. These data can assist in early risk stratification of COVID‐19 patients, and in surge capacity planning for hospitals.

Next generation sequencing of human enterovirus strains from an outbreak of enterovirus A71 shows applicability to outbreak investigations

BACKGROUND

The most recent documented Australian outbreak of enterovirus A71 (EV-A71) occurred in Sydney from 2012 to 2013. Over a four-month period more than 100 children presented to four paediatric hospitals with encephalitic presentations including fever and myoclonic jerks. The heterogeneous presentations included typical encephalomyelitis, and cardiopulmonary complications.

OBJECTIVES

To characterise the genomes of enterovirus strains circulating during the 2013 Sydney EV-A71 outbreak and determine their phylogeny, phylogeography and association between genome and clinical phenotype.

STUDY DESIGN

We performed an analysis of enterovirus (EV) positive specimens from children presenting to hospitals in the greater Sydney region of Australia during the 2013 outbreak. We amplified near full-length genomes of EV, and used next generation sequencing technology to sequence the virus. We used phylogenetic/phylogeographic analysis to characterize the outbreak viruses.

RESULTS

We amplified and sequenced 23/63 (37 %) genomes, and identified the majority (61 %) as EV-A71. The EV-A71 sequences showed high level sequence homology to C4a genogroups of EV-A71 circulating in China and Vietnam during 2012-13. Phylogenetic analysis showed EV-A71 strains associated with more severe symptoms, including encephalitis or cardiopulmonary failure, grouped together more closely than those from patients with hand, foot and mouth disease. Amongst the non-EV-A71 sequences were five other EV subtypes (representing enterovirus subtypes A and B), reflecting the diversity of EV co-circulation within the community.

CONCLUSIONS

This is the first Australian study investigating the near full-length genome of EV strains identified during a known outbreak of EV-A71. EV-A71 sequences were very similar to strains circulating in Asia during the same time period. Whole genome sequencing offers additional information over routine diagnostic testing such as characterisation of emerging recombinant strains and inform vaccine design.

CCL19 is constitutively expressed in the CNS, up-regulated in neuroinflammation, active and also inactive multiple sclerosis lesions

CCL19 and CCL21 bind to CCR7, which is crucial for both inducing an immune response and establishing immunological tolerance. We report that in the normal human brain CCL19, but not CCL21, is transcribed, and detectable as a protein in tissue lysates and in cerebrospinal fluid. In both active and inactive multiple sclerosis (MS) lesions CCL19 transcripts were elevated. In cerebrospinal fluid from MS and OIND patients CCL19 protein was increased. In relapsing-remitting and secondary progressive MS patients CCL19 correlated with intrathecal IgG production. This study suggests that CCL19 plays a role in both the physiological immunosurveillance of the healthy CNS and the pathological maintenance of immune cells in the CNS of MS patients.

Peroxiredoxin V in multiple sclerosis lesions: predominant expression by astrocytes

Oxidative stress is implicated in the pathogenesis of multiple sclerosis (MS). Defence against oxidative damage is mediated by antioxidants. Peroxiredoxin V (PRDX V) is an intracellular anti-oxidant enzyme with peroxynitrite reductase activity. It is increased during inflammation, when free radical production intensifies, and is protective in an animal model of brain injury. However, little is known about PRDX V expression in the human brain. We investigated PRDX V expression in white matter from normal human brain (n = 5) and MS patients (n = 18), using immunohistochemistry and immunoblotting. A global increase in PRDX V was evident in MS normal-appearing white matter (NAWM) but the most striking increase was in astrocytes in MS lesions. PRDX V- positive hypertrophic reactive astrocytes were seen in acute lesions where inflammation was present. Yet surprisingly, in chronic lesions (CL), where inflammation has abated and a glial scar formed, there was strong PRDX V staining of post-reactive, scar astrocytes. Furthermore, immunoblotting analysis of tissue from two MS cases confirmed a substantial increase in PRDX V expression in CL compared with NAWM from the same individual. This might indicate ongoing oxidative stress despite the absence of histologically defined inflammation. Further investigations of this phenomenon will be of interest for therapeutic targeting.

Phenotypic and transcriptional characterization of the meningococcal PhoPQ system, a magnesium-sensing two-component regulatory system that controls genes involved in remodeling the meningococcal cell surface

We previously identified and characterized a two-component regulatory system in the meningococcus with homology to the phoP-phoQ system in salmonella and showed that allele replacement of the NMB0595 regulator gene led to loss of virulence, sensitivity to antimicrobial peptides, perturbed protein expression, and magnesium-sensitive growth. On the basis of these findings we proposed that the system should be designated the meningococcal PhoPQ system. Here we further characterized the NMB0595 mutant and demonstrated that it had increased membrane permeability and was unable to form colonies on solid media with low magnesium concentrations, features that are consistent with disruption of PhoPQ-mediated modifications to the lipooligosaccharide structure. We examined the transcriptional profiles of wild-type and NMB0595 mutant strains and found that magnesium-regulated changes in gene expression are completely abrogated in the mutant, indicating that, similar to the salmonella PhoPQ system, the meningococcal PhoPQ system is regulated by magnesium. Transcriptional profiling of the mutant indicated that, also similar to the salmonella PhoPQ system, the meningococcal system is involved in control of virulence and remodeling of the bacterial cell surface in response to the host environment. The results are consistent with the hypothesis that the PhoP homologue plays a role in the meningococcus similar to the role played by PhoP in salmonella. Elucidating the role that the PhoPQ system and PhoPQ-regulated genes play in the response of the meningococcus to the host environment may provide new insights into the pathogenic process.

High field MRI correlates of myelin content and axonal density in multiple sclerosis--a post-mortem study of the spinal cord

Different MRI techniques are used to investigate multiple sclerosis (MS) in vivo. The pathological specificity of these techniques is poorly understood, in particular their relationship to demyelination and axonal loss. The aim of this study was to evaluate the pathological substrate of high field MRI in post-mortem (PM) spinal cord (SC) of patients with MS. MRI was performed in PMSCs of four MS patients and a healthy subject on a 7 Tesla machine. Quantitative MRI maps (PD; T2; T1; magnetization transfer ratio, MTR; diffusion weighted imaging) were obtained. After scanning, the myelin content and the axonal density of the specimens were evaluated neuropathologically using quantitative techniques. Myelin content and axonal density correlated strongly with MTR, T1, PD, and diffusion anisotropy, but only moderately with T2 and weakly with the apparent diffusion coefficient. Quantitative MR measures provide a promising tool to evaluate components of MS pathology that are clinically meaningful. Further studies are warranted to investigate the potential of new quantitative MR measures to enable a distinction between axonal loss and demyelination and between demyelinated and remyelinated lesions.

Infection with an avirulent phoP mutant of Neisseria meningitidis confers broad cross-reactive immunity

Successful vaccines against serogroup A and C meningococcal strains have been developed, but current serogroup B vaccines provide protection against only a limited range of strains. The ideal meningococcal vaccine would provide cross-reactive immunity against the variety of strains that may be encountered in any community, but it is unclear whether the meningococcus possesses immune targets that have the necessary level of cross-reactivity. We have generated a phoP mutant of the meningococcus by allele exchange. PhoP is a component of a two-component regulatory system which in other bacteria is an important regulator of virulence gene expression. Inactivation of the PhoP-PhoQ system in Salmonella leads to avirulence, and phoP mutants have been shown to confer protection against virulent challenge. These mutants have been examined as potential live attenuated vaccines. We here show that a phoP mutant of the meningococcus is avirulent in a mouse model of infection. Moreover, infection of mice with the phoP mutant stimulated a bactericidal immune response that not only killed the infecting strain but also showed cross-reactive bactericidal activity against a range of strains with different serogroup, serotype, and serosubtyping antigens. Sera from the mutant-infected mice contained immunoglobulin G that bound to the surface of a range of meningococcal strains and mediated opsonophagocytosis of meningococci by human phagocytic cells. The meningococcal phoP mutant is thus a candidate live, attenuated vaccine strain and may also be used to identify cross-reactive protective antigens in the meningococcus.

Astrocyte characterization in the multiple sclerosis glial scar

Dense astrocytic scarring in chronic multiple sclerosis (MS) plaques produces an inhibitory environment which can impede tissue repair. Animal studies have shown that the antigenic phenotype of the most abundant cell type in the brain, the astrocyte, varies depending on astrocyte type and location. To identify the phenotype of scar astrocytes (SAs) in chronic lesions, markers of reactive astrocytes characterized in animal studies were investigated. To date these are the only established markers. Cerebral subventricular deep white matter from normal control, MS normal appearing white matter and lesions (acute, subacute and chronic) were examined by immunohistochemistry and immunoblotting. The antigenic profile of SAs revealed significant modification of astrocyte protein expression in chronic MS lesions. SAs express nestin, embryonic neural cell adhesion molecule, fibroblast growth factor receptor 4, epidermal growth factor receptor, nerve growth factor and a subpopulation of SAs also express basic fibroblast growth factor. These are in addition to the expected markers glial fibrillary acidic protein, vimentin, and the tenascins C and R. Therefore, an SA antigenic phenotype has now been defined. This knowledge may allow the development of therapeutic strategies that prevent scar formation and promote tissue repair.

Plasminogen activators in multiple sclerosis lesions: implications for the inflammatory response and axonal damage

Components of the plasminogen activator (PA) and matrix metalloprotease (MMP) cascade have been characterized in multiple sclerosis lesions by immunohistochemistry, enzyme-linked immunosorbent assay and enzyme activity assays in order to establish a functional role for the enzyme sequence in lesion development. Highly significant quantitative increases in urokinase PA (uPA), urokinase receptor (uPAR) and plasminogen activator inhibitor-1 were detected in acute multiple sclerosis lesions (P < 0.0001) and in uPAR in normal-appearing white matter (P < 0.0001) compared with control tissue. All three proteins were immunolocalized to mononuclear cells in perivascular cuffs and to macrophages in the lesion parenchyma. MMP-9 and the tissue inhibitor of metalloprotease-1 also increased during lesion development but the enzyme was present largely in the inactive pro-form. In contrast to uPA, the concentration and activity of tissue PA (tPA), the most abundant plasminogen activator in normal control brain, were reduced in multiple sclerosis specimens. In acute lesions tPA co-localized with fibrin(ogen) on large diameter axons also stained with SMI-32, an immunohistochemical marker of axonal damage. The uPA-uPAR complex, concentrated on inflammatory cells in the perivascular zone of the evolving lesion, may facilitate cellular infiltration into the CNS which is amplified by MMP- mediated degradation of blood vessel matrix. tPA localization on injured axons may be a marker of axonal damage or represent a protective mechanism aimed at removal of fibrin deposits and restoration of axonal function.

Generation and characterization of a PhoP homologue mutant of Neisseria meningitidis

Two-component regulatory systems are important regulators of virulence genes in a number of bacteria. Genes encoding a two-component regulator system, with homology to the phoP/phoQ system in salmonella, were identified in the meningococcal genome. Allele replacement was used to generate a meningococcal knock-out mutant of the regulator component of this system, and its phenotype was examined. The mutant displayed many differences in protein profiles compared with wild type, consistent with it being a gene-regulatory mutation. Many of the growth characteristics of the mutant were similar to those of phoP mutants of salmonella: it was unable to grow at low concentrations of magnesium and was sensitive to defensins and other environmental stresses. Magnesium-regulated differences in protein expression were abrogated in the mutant, indicating that the meningococcal PhoP/PhoQ system may, as in salmonella, respond to changes in environmental magnesium levels. These results are consistent with the PhoP homologue playing a similar role in the meningococcus to PhoP in salmonella and suggest that it may similarly be involved in the regulation of virulence genes in response to environmental stimuli in the meningococcus. In support of this conclusion, we found the mutant grew was unable to grow in mouse serum and was attenuated in its ability to traverse through a layer of human epithelial cells. Identification of those genes regulated by the meningococcal PhoP may provide a route towards the identification of virulence genes in the meningococcus.

The peripheral benzodiazepine binding site in the brain in multiple sclerosis: quantitative in vivo imaging of microglia as a measure of disease activity

This study identifies by microautoradiography activated microglia/macrophages as the main cell type expressing the peripheral benzodiazepine binding site (PBBS) at sites of active CNS pathology. Quantitative measurements of PBBS expression in vivo obtained by PET and [(11)C](R)-PK11195 are shown to correspond to animal experimental and human post-mortem data on the distribution pattern of activated microglia in inflammatory brain disease. Film autoradiography with [(3)H](R)-PK11195, a specific ligand for the PBBS, showed minimal binding in normal control CNS, whereas maximal binding to mononuclear cells was found in multiple sclerosis plaques. However, there was also significantly increased [(3)H](R)-PK11195 binding on activated microglia outside the histopathologically defined borders of multiple sclerosis plaques and in areas, such as the cerebral central grey matter, that are not normally reported as sites of pathology in multiple sclerosis. A similar pattern of [(3)H](R)-PK11195 binding in areas containing activated microglia was seen in the CNS of animals with experimental allergic encephalomyelitis (EAE). In areas without identifiable focal pathology, immunocytochemical staining combined with high-resolution emulsion autoradiography demonstrated that the cellular source of [(3)H](R)-PK11195 binding is activated microglia, which frequently retains a ramified morphology. Furthermore, in vitro radioligand binding studies confirmed that microglial activation leads to a rise in the number of PBBS and not a change in binding affinity. Quantitative [(11)C](R)-PK11195 PET in multiple sclerosis patients demonstrated increased PBBS expression in areas of focal pathology identified by T(1)- and T(2)-weighted MRI and, importantly, also in normal-appearing anatomical structures, including cerebral central grey matter. The additional binding frequently delineated neuronal projection areas, such as the lateral geniculate bodies in patients with a history of optic neuritis. In summary, [(11)C](R)-PK11195 PET provides a cellular marker of disease activity in vivo in the human brain.

Sensory neuron-specific sodium channel SNS is abnormally expressed in the brains of mice with experimental allergic encephalomyelitis and humans with multiple sclerosis

Clinical abnormalities in multiple sclerosis (MS) have classically been considered to be caused by demyelination and/or axonal degeneration; the possibility of molecular changes in neurons, such as the deployment of abnormal repertoires of ion channels that would alter neuronal electrogenic properties, has not been considered. Sensory Neuron-Specific sodium channel SNS displays a depolarized voltage dependence, slower activation and inactivation kinetics, and more rapid recovery from inactivation than classical "fast" sodium channels. SNS is selectively expressed in spinal sensory and trigeminal ganglion neurons within the peripheral nervous system and is not expressed within the normal brain. Here we show that sodium channel SNS mRNA and protein, which are not present within the cerebellum of control mice, are expressed within cerebellar Purkinje cells in a mouse model of MS, chronic relapsing experimental allergic encephalomyelitis. We also demonstrate SNS mRNA and protein expression within Purkinje cells from tissue obtained postmortem from patients with MS, but not in control subjects with no neurological disease. These results demonstrate a change in sodium channel expression in neurons within the brain in an animal model of MS and in humans with MS and suggest that abnormal patterns of neuronal ion channel expression may contribute to clinical abnormalities such as ataxia in these disorders.

Neuroinvasion by human respiratory coronaviruses

Human coronaviruses (HCoV) cause common colds but can also infect neural cell cultures. To provide definitive experimental evidence for the neurotropism and neuroinvasion of HCoV and its possible association with multiple sclerosis (MS), we have performed an extensive search and characterization of HCoV RNA in a large panel of human brain autopsy samples. Very stringent reverse transcription-PCR with two primer pairs for both viral strains (229E and OC43), combined with Southern hybridization, was performed on samples from 90 coded donors with various neurological diseases (39 with MS and 26 with other neurological diseases) or normal controls (25 patients). We report that 44% (40 of 90) of donors were positive for 229E and that 23% (21 of 90) were positive for OC43. A statistically significant higher prevalence of OC43 in MS patients (35.9%; 14 of 39) than in controls (13.7%; 7 of 51) was observed. Sequencing of nucleocapsid protein (N) gene amplicons revealed point mutations in OC43, some consistently found in three MS patient brains and one normal control but never observed in laboratory viruses. In situ hybridization confirmed the presence of viral RNA in brain parenchyma, outside blood vessels. The presence of HCoV in human brains is consistent with neuroinvasion by these respiratory pathogens. Further studies are needed to distinguish between opportunistic and disease-associated viral presence in human brains.

Expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in multiple sclerosis central nervous system tissue

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) characterised by perivascular inflammatory cell infiltrates and plaques of demyelination. Chemokines have been shown to play an important role in the activation and directional migration of cells to sites of CNS inflammation. The action of chemokines requires the expression of their complementary chemokine receptors by their target cells. We have examined the expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in post-mortem MS CNS tissue using single- and double-labelling immunocytochemistry techniques. Low levels of CCR2, CCR3 and CCR5 were expressed by microglial cells throughout control CNS tissue. In chronic active MS lesions CCR2, CCR3 and CCR5 were associated with foamy macrophages and activated microglia. CCR2 and CCR5 were also present on large numbers of infiltrating lymphocytes. A smaller number of CCR3-positive lymphocytes were present, but we also noted CCR3 and CCR5 on astrocytes in five of the 14 cases of MS investigated, particularly associated with processes around vessels and at the glia limitans. Ligands for CCR2 and CCR3 include MCP-1 and MCP-3 which were co-localised around vessels with the infiltrating leukocytes, but were also present in unaffected areas of cortex. The elevated expression of CCR2, CCR3 and CCR5 in the CNS in MS suggests these beta-chemokine receptors and their ligands play a role in the pathogenesis of MS.

Differential expression of NK T cell V alpha 24J alpha Q invariant TCR chain in the lesions of multiple sclerosis and chronic inflammatory demyelinating polyneuropathy

Human V alpha 24+ NK T cells are a unique subset of lymphocytes expressing the V alpha 24J alpha Q invariant TCR chain. Because they can rapidly produce large amounts of regulatory cytokines, a reduction of NK T cells may lead to the development of certain autoimmune diseases. Using a single-strand conformation polymorphism method, we demonstrate that a great reduction of V alpha 24J alpha Q NK T cells in the peripheral blood is an immunological hallmark of multiple sclerosis, whereas it is not appreciable in other autoimmune/inflammatory diseases such as chronic inflammatory demyelinating polyneuropathy. The chronic inflammatory demyelinating polyneuropathy lesions were often found to be infiltrated with V alpha 24J alpha Q NK T cells, but multiple sclerosis lesions only rarely expressed the V alpha 24J alpha Q TCR. It is therefore possible that the extent of NK T cell alteration may be a critical factor which would define the clinical and pathological features of autoimmune disease. Although the mechanism underlying the NK T cell deletion remains largely unclear, a remarkable contrast between the CNS and peripheral nervous system diseases allows us to speculate a role of tissue-specific elements such as the level of CD1d expression or differences in the CD1d-bound glycolipid.

Presentation of alpha B-crystallin to T cells in active multiple sclerosis lesions: an early event following inflammatory demyelination

In the development of multiple sclerosis (MS), (re)activation of infiltrating T cells by myelin-derived Ags is considered to be a crucial step. Previously, alpha B-crystallin has been shown to be an important myelin Ag to human T cells. Since alpha B-crystallin is an intracellular heat shock protein, the question arises at what stage, if any, during lesional development in MS this Ag becomes available for CD4+ T cells. In 3 of 10 active MS lesions, alpha B-crystallin could be detected inside phagocytic vesicles of perivascular macrophages, colocalizing with myelin basic protein and myelin oligodendrocyte glycoprotein (MOG). Although the detectability of MOG in phagosomes is considered as a marker for very recent demyelination, MOG was detected in more macrophages and in more lesions than alpha B-crystallin. The disappearance of alpha B-crystallin from macrophages even before MOG was confirmed by in vitro studies; within 6 h after myelin-uptake alpha B-crystallin disappears from the phagosomes. Alpha B-crystallin-containing macrophages colocalized with infiltrating T cells and they were characterized by expression of MHC class II, CD40, and CD80. To examine functional presentation of myelin Ags to T cells, purified macrophages were pulsed in vitro with whole myelin membranes. These macrophages activated both myelin-primed and alpha B-crystallin-primed T cells in terms of proliferation and IFN-gamma secretion. In addition, alpha B-crystallin-pulsed macrophages activated myelin-primed T cells to the same extent as myelin-pulsed macrophages, whereas myelin basic protein-pulsed macrophages triggered no response at all. These data indicate that, in active MS lesions, alpha B-crystallin is available for functional presentation to T cells early during inflammatory demyelination.

Expression of the interferon-gamma-inducible chemokines IP-10 and Mig and their receptor, CXCR3, in multiple sclerosis lesions

The recruitment of leucocytes to sites of inflammation is an important feature of multiple sclerosis (MS) pathology. Chemokines are involved in the activation and specific directional migration of monocytes and T-lymphocytes to sites of inflammation. Using immunocytochemistry, the expression of the alpha-chemokines, interferon (IFN)-gamma-inducible protein-10 (IP-10) and monokine induced by IFN-gamma (Mig), and their receptor CXCR3 have been examined in post-mortem central nervous system (CNS) tissue from MS cases at different stages of lesion development. In actively demyelinating lesions both IP-10 and Mig protein were predominantly expressed by macrophages within the plaque and by reactive astrocytes in the surrounding parenchyma. CXCR3 was expressed by T cells and by astrocytes within the plaque. Interferon-gamma may stimulate glial cells to express IP-10 and Mig, which continue the local inflammatory response by selectively recruiting activated T-lymphocytes into the CNS.

Subunit composition of Kv1 channels in human CNS

The alpha subunits of Shaker-related K+ channels (Kv1.X) show characteristic distributions in mammalian brain and restricted coassembly. Despite the functional importance of these voltage-sensitive K+ channels and involvement in a number of diseases, little progress has been achieved in deciphering the subunit composition of the (alpha)4(beta)4 oligomers occurring in human CNS. Thus, the association of alpha and beta subunits was investigated in cerebral grey and white matter and spinal cord from autopsy samples. Immunoblotting established the presence of Kv1.1, 1.2, and 1.4 in all the tissues, with varying abundance. Sequential immunoprecipitations identified the subunits coassembled. A putative tetramer of Kv1.3/1.4/1.1/1.2 was found in grey matter. Both cerebral white matter and spinal cord contained the heterooligomers Kv1.1/1.4 and Kv1.1/1.2, similar to grey matter, but both lacked Kv1.3 and the Kv1.4/1.2 combination. An apparent Kv1.4 homooligomer was detected in all the samples, whereas only the brain tissue possessed a putative Kv1.2 homomer. In grey matter, Kvbeta2.1 was coassociated with the Kv1.1/1.2 combination and Kv1.2 homooligomer. In white matter, Kvbeta2.1 was associated with Kv1.2 only, whereas Kvbeta1.1 coprecipitated with all the alpha subunits present. This represents the first description of Kv1 subunit complexes in the human CNS and demonstrates regional variations, indicative of functional specialisation.

Insulin-like growth factors and binding proteins in multiple sclerosis plaques

Insulin-like growth factors (IGFs) play an important role in development and myelination in the central nervous system (CNS) as well as in the proliferation and differentiation of cells of the immune system. To assess the influence of this growth factor family on demyelination and repair in multiple sclerosis (MS), the expression of IGF-I, IGF-II, insulin, IGF binding proteins (IGFBP) 1-3 and IGF-I receptor (IGF-IR) in CNS tissue from MS and normal control cases was studied by immunocytochemistry. In active MS lesions, the expression of IGF-I, insulin and IGFBP1 was detected in hypertrophic astrocytes while that of IGF-II and IGFBP2 and 3 was confined to foamy macrophages within lesions and activated microglia in adjacent white matter. IGF-IR, the major IGF receptor, was immunolocalized in macrophages and an astrocyte subpopulation in plaques. Oligodendrocytes in normal-appearing white matter expressed only IGFBP1, not IGFs or IGF-IR. As the remyelinating capacity of oligodendrocytes could be impaired owing to the absence of IGF-IR, the prevailing role of IGFs in inflammatory demyelination may be to promote phagocytosis of myelin and astrogliosis.

Tenascin-R and C in multiple sclerosis lesions: relevance to extracellular matrix remodelling

In the present study the distribution of the inhibitory extracellular molecules tenascin-R (TN-R) and tenascin- C (TN-C) was examined by immunocytochemistry during evolution of the multiple sclerosis (MS) lesion, in which astrogliosis is a prominent feature. Sections were cut from five control cases and from 22 blocks containing lesions representing different pathological stages in 18 cases of secondary progressive MS. Widespread expression of TN-R was found in the normal human central nervous system (CNS), while that of TN-C was in general restricted to white matter. In acute MS plaques however, there was a similar striking loss of both TN-R and TN-C up to the edge of the lesion, where the macrophage density is greatest, extending into the apparently normal white matter. In subacute lesions a TN-C and/or TN-R-immunopositive reactive astrocyte subpopulation was prominent, reflecting synthesis of extracellular matrix molecules. Both tenascins were expressed throughout chronic MS plaques at levels similar to those seen in adjacent white matter. The loss of TN-R and TN-C in acute plaques is indicative of enzyme-mediated breakdown of the matrix which may be a marker of blood-brain barrier breakdown and leucocyte extravasation. Subsequent production of tenascins by reactive astrocytes may result in glial scar formation impeding remyelination and axonal repair in MS lesions.

Oligodendrocyte progenitors are present in the normal adult human CNS and in the lesions of multiple sclerosis

In multiple sclerosis, partial remyelination is conspicuous in many lesions, but widespread and lasting myelin repair ultimately fails as disability and handicap accumulate. Thus far, the precise identity of the cell responsible for limited spontaneous myelin repair has remained obscure. In the rodent, the proliferative oligodendrocyte progenitor is the most efficient remyelinating cell; this has now been identified in cultures prepared from normal human brain, but has proved difficult to demonstrate in situ. We adapted techniques using antibodies against the human platelet-derived growth factor-alpha receptor to identify oligodendrocyte progenitors in human tissue sections. Small numbers of oligodendrocyte progenitors were found in normal adult human white matter. Progenitors were also demonstrable in acute and chronic lesions from patients dying with multiple sclerosis, but with no evidence of any marked reactive increase in cell numbers. Understanding the biology of the remyelinating cell, and in particular the reason for its apparent failure to repopulate demyelinated lesions, is important for the development of remyelination treatments.

Expression of monocyte chemoattractant protein-1 and other beta-chemokines by resident glia and inflammatory cells in multiple sclerosis lesions

Beta-chemokines induce the directional migration of monocytes and T lymphocytes and are thus associated with chronic inflammation. Using immunocytochemistry and in situ hybridisation (ISH) techniques, we have examined the expression of the beta-chemokines monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES (regulated upon activation, normal T cell expressed and secreted) in post-mortem human brain from multiple sclerosis (MS) cases, at different stages of lesion development. In actively demyelinating MS plaques RANTES expression was restricted to the blood vessel endothelium, perivascular cells and surrounding astrocytes, suggesting a role in the recruitment of inflammatory cells from the circulation. MCP-1 was expressed by astrocytes and macrophages within acute MS lesions, but was restricted to reactive astrocytes in the parenchyma surrounding the lesion. MIP-1alpha was expressed by astrocytes and macrophages within the plaque, while MIP-1beta was expressed by macrophages and microglia within the lesion, and by microglia in surrounding white matter. Glial cells may be stimulated to produce chemokines and continue the local inflammatory response by forming chemotactic gradients to attract T cells and mononuclear phagocytes from the circulation and surrounding tissue.

Transcription factor NF-kappaB and inhibitor I kappaBalpha are localized in macrophages in active multiple sclerosis lesions

NF-kappaB is a transcription factor family which on translocation to the nucleus regulates gene expression during cell activation. As such, NF-kappaB may play a role in the microglial response to myelin damage in multiple sclerosis (MS) lesions. Here the cellular localization of NF-kappaB and expression of the inhibitory I kappaBalpha were examined by immunocytochemistry on central nervous system (CNS) tissue from MS and control cases. In normal control white matter, the active form of the NF-kappaB subunit RelA (p65) was localized in microglial nuclei, while the c-Rel and p50 subunits and the inhibitory I kappaBalpha were restricted to the cytoplasm. In contrast, in actively demyelinating plaques, the RelA, c-Rel, and p50 subunits of NF-kappaB and I kappaBalpha were all present in macrophage nuclei in both parenchymal and perivascular areas. RelA was also found in the nuclei of a subset of hypertrophic astrocytes. Only c-Rel had a nuclear localization in lymphocytes in perivascular inflammatory cuffs. Our results suggest that constitutive activation of the RelA subunit in the nuclei of resting microglia may facilitate a rapid response to pathological stimuli in the CNS. Activation of the inducible NF-kappaB pool in macrophages in MS lesions could amplify the inflammatory reaction through upregulation of NF-kappaB-controlled adhesion molecules and cytokines.

PCR-single-stranded confirmational polymorphism analysis for non-culture-based subtyping of meningococcal strains in clinical specimens

Subspecific typing of clinical meningococcal strains is important in the investigation of outbreaks and for disease surveillance. Serogrouping, typing, and subtyping of strains currently require isolation of a meningococcus from one or more clinical specimens. However, the increasing widespread practice of preadmission administration of parenteral antibiotics has resulted in a decrease in the frequency of positive cultures obtained from blood and cerebrospinal fluid. Confirmation of meningococcal disease can be obtained by meningococcus-specific PCR from both cerebrospinal fluid (H. Ni et al., Lancet 340:1432-1434, 1992) and peripheral blood (J. Newcombe et al., J. Clin. Microbiol. 34:1637-1640, 1996) specimens. However, current PCR protocols do not yield epidemiologically useful typing information. We report here the use of PCR-single-stranded confirmational polymorphism (PCR-SSCP) analysis to amplify and type meningococcal DNA present in clinical specimens. PCR-SSCP analysis with the VR1 region of the Neisseria meningitidis porA gene as the target produced unique banding patterns for each serosubtype. Direct PCR-SSCP of clinical specimens can therefore provide typing data that can be used to investigate the epidemiology of clusters of cases and outbreaks and for disease surveillance in situations in which culture of patient specimens proves negative.

The expression of tissue-type plasminogen activator, matrix metalloproteases and endogenous inhibitors in the central nervous system in multiple sclerosis: comparison of stages in lesion evolution

The expression of tissue-type plasminogen activator (t-PA) and a number of metalloproteases as well as plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metalloproteases-1 (TIMP-1) was analyzed in the central nervous system (CNS) of normal control and multiple sclerosis (MS) cases by immunohistopathology. The expression of t-PA was detectable only in the blood vessel matrix in control white matter, but positive infiltrating mononuclear cells were also observed in MS white matter and primary lesions. In active plaques this pattern converted to strong positivity of foamy macrophages in areas of demyelination, declining in chronic lesions. In general PAI-1 expression paralleled that of t-PA. Gelatinase A and B were detected predominantly in astrocytes and microglia throughout normal control white matter, with additional positive mononuclear cells in perivascular cuffs in MS white matter. In the demyelinating lesion there is widespread prominent expression of gelatinase B in reactive astrocytes and macrophages, which persists in astrocytes in the chronic lesion. TIMP-1 was also present in the vessel matrix and in lesional macrophages. These observations on the coexpression of enzymes and inhibitors of the matrix degrading cascade in CNS tissue pinpoint t-PA, a rate-limiting enzyme, and gelatinase B as therapeutic targets in MS.

PCR of peripheral blood for diagnosis of meningococcal disease

Meningococcal disease is normally suspected on clinical grounds and is confirmed by isolation of Neisseria meningitidis bacteria from blood or cerebrospinal fluid or, more recently, by serology or PCR of cerebrospinal fluid. Achieving confirmation of a clinical diagnosis of meningococcal disease has become more difficult in the last few years. The pre-hospitalization administration of parenteral benzylpenicillin normally renders blood cultures sterile, and lumbar puncture is undertaken less frequently, especially in young children. We evaluated PCR for the detection of meningococcal DNA in 80 blood samples taken from patients with known or suspected meningococcal disease or from patients with other diagnoses (negative controls). Both the sensitivity and the specificity of the test were 100% for patients with confirmed cases of meningococcal disease when the blood buffy coat was used (83 to 100% sensitivity and 87 to 100% specificity with 95% confidence limits). Positive PCR results could be obtained from both blood buffy coat and serum samples. Sensitivity was unaffected by prior antibiotic treatment. PCR is a rapid, sensitive test that may be used to confirm a diagnosis of meningococcal disease by using peripheral blood samples. Introduction of this test into clinical laboratories may in some cases obviate the need for lumbar puncture to be performed on patients with suspected meningococcal disease. Our results demonstrate that a substantial number of cases of meningococcal disease are not confirmed by conventional techniques and remain undiagnosed. If the PCR test described here was widely applied, the number of cases of meningococcal disease ascertained might rise by as much as 60% greater than that recognized at present. It is likely that we are in a prevaccination era for meningococcal disease. Better case ascertainment is urgently required to assess the need for vaccines, to determine their costs and benefits, and to monitor their efficacies.

Microglia-derived macrophages in early multiple sclerosis plaques

One of the characteristics of ongoing demyelination in multiple sclerosis (MS) is the accumulation of lipid-laden macrophages in active lesions. Little is known about the source of these macrophages in the early stages of plaque evolution as microglial-derived and haematogenous macrophages share morphological characteristics and most cell surface antigens. A key issue in understanding the pathogenesis of MS is the reliable identification of phagocytes capable of degrading myelin and presenting autoantigen to T cells at the onset of demyelination. Using a combination of histochemistry and immunocytochemistry, an average of 60% of EBM11+ phagocytes (EMBII is a pan-macrophage marker) in early active MS plaques, defined as lesions with myelin-containing phagocytes but no obvious parenchymal myelin loss around these cells, were judged to originate from microglia as they exhibited nucleoside diphosphatase activity, a microglial marker. Only 4-15% of EBM11+ phagocytes in these lesions exhibited non-specific esterase activity, an enzyme marker for monocytes and macrophages. In contrast, 30-80% of EBM11+ phagocytes in more advanced active plaques with partial or complete myelin loss in the parenchyma were non-specific esterase+. Lysosomal enzyme acid phosphatase activity was strongly exhibited by 90% of phagocytes in all active plaques and there was a significant correlation between numbers of acid phosphatase+ cells and oil red O+ foamy macrophages. The results indicate that microglia are the main population of phagocytes in the early stages of demyelination and may play an important role in the pathogenesis of MS.

Expression of costimulatory molecules B7-1 (CD80), B7-2 (CD86), and interleukin 12 cytokine in multiple sclerosis lesions

Resting autoreactive T cells are present in the circulation of normal individuals without pathologic consequences. In autoimmune animal models, stimulation of these self-reactive T cells in the presence of costimulatory molecules B7-1 results in T cell-mediated autoimmune disease, whereas B7-2 stimulation generates regulatory autoreactive T cells that abrogate disease severity. Thus, reactivation in the brain of myelin-autoreactive T cells by antigen with costimulatory molecules may be a critical event in the pathophysiology of multiple sclerosis (MS), a putative autoimmune disease of central nervous system (CNS) myelin. We investigated the expression of cytokines and costimulatory molecules in a panel of 41 histologically characterized CNS specimens from 15 MS and 10 control cases using semiquantitative reverse transcriptase-polymerase chain reaction and immunocytochemistry. In four cases, vascular CNS infarcts with inflammation were compared with MS plaques from the same brain. We observed increased expression of B7-1 and interleukin (IL) 12p40 in acute MS plaques, particularly from early disease cases but not in inflammatory infarcts. B7-1 staining was localized predominantly to the lymphocytes in perivenular inflammatory cuffs but not the parenchyma. In contrast, B7-2 was expressed predominantly on macrophages both in MS lesions of varied time duration and in inflammatory infarcts. These findings indicate that an early event in the initiation of MS involves upregulation of B7-1 and IL-12, resulting in conditions that maximally stimulate T cell activation and induction of T helper 1-type immune responses.

Amyloid precursor protein (APP) expression in multiple sclerosis lesions

The amyloid precursor protein (APP) is rapidly induced in reactive glial cells in response to several pathological stimuli including inflammation. In the present study, observations previously made in animal models of autoimmune central nervous system inflammation have been extended to the analysis of multiple sclerosis (MS) lesions. A total of thirty fresh-frozen tissue blocks from six histopathologically normal control and six MS cases have been examined immunocytochemically with monoclonal antibodies directed against either C- or N-terminal epitopes of APP. Histopathological evaluation of disease progression was based on hematoxylin-eosin and oil red O staining and immunocytochemistry for T cells, macrophages/microglia, astrocytes, and oligodendrocytes. In control cases, APP immunoreactivity was generally low and confined to blood vessel walls, oligodendrocytes in white, and neurons in grey matter. In actively demyelinating plaques, however, levels of APP immunoreactivity were high, localised on T lymphocytes, foamy macrophages, activated microglia, and reactive astrocytes including astrocytic processes. In more chronic lesions, levels of APP immunoreactivity were generally lower than in acute lesions, mainly found on reactive astrocytes, their processes and a few macrophages/microglia depending on the stage of plaque development. In addition, a few 14E-positive oligodendrocytes and, moreover, numerous axons exhibited APP immunoreactivity, which was particularly pronounced with anti-C-terminal antibodies. These results demonstrate that APP is induced on reactive glial cells but also on T lymphocytes during demyelination. The extent of APP expression appears to be correlated to histopathological lesion development and thus suggests that APP detection serves as a sensitive marker for disease progression in MS.

Use of rubella virus E1 fusion proteins for detection of rubella virus antibodies

Two glutathione S-transferase fusion proteins containing 44 (p1503) and 75 (p1509) amino acid residues of the rubella virus E1 glycoprotein were expressed in Escherichia coli with the aim of producing a recombinant rubella virus antigen for use in serological assays. p1503 contained three neutralizing and hemagglutinating epitopes (G. M. Terry, L. M. Ho-Terry, P. Londesborough, and K. R. Rees, Arch. Virol. 98:189-197, 1988); p1509 contained the putative neutralization domain described by Mitchell et al. (L. A. Mitchell, T. Zhang, M. Ho, D. Decarie, A. Tingle, M. Zrein, and M. Lacroix, J. Clin. Microbiol. 30:1841-1847, 1992) in addition to the three epitopes present in p1503. Both fusion proteins were soluble and affinity purified on glutathione-Sepharose 4B. In Western blots (immunoblots), p1503 and p1509 reacted with human sera containing rubella virus-specific immunoglobulin G. When used as antigens in indirect enzyme immunoassays to detect rubella virus-specific immunoglobulin G, p1503 correctly identified the rubella virus antibody status of 43 (76.8%) and p1509 correctly identified that of 48 (85.7%) of 56 serum samples received for routine rubella virus antibody screening. The results obtained with p1509 compare well with those obtained with a latex agglutination assay.

High resolution proton NMR spectroscopy of multiple sclerosis lesions

Tissue from postmortem multiple sclerosis and normal control brains was extracted with perchloric acid and analysed using proton NMR spectroscopy. The content of N-acetyl-derived groups (the sum of N-acetyl-aspartate, acetate, and N-acetylaspartylglutamate) was decreased in multiple sclerosis plaques compared with normal control white matter (mean, 4.36 vs. 6.64 mumol/g wet weight). In normal appearing white matter adjacent to plaques a corresponding decrease was seen, with no change in white matter distant from plaques. A decrease in the content of total creatine was observed in multiple sclerosis plaques in comparison with normal control white matter (mean, 4.64 vs. 6.56 mumol/g wet weight), which correlated strongly with the decrease in N-acetyl-derived groups. No changes in other metabolites such as total choline or myo-inositol were seen. The decreases in content of N-acetyl-derived groups are in agreement with observations from in vivo proton NMR spectroscopy in multiple sclerosis patients. The decrease in total creatine is in contrast to most of the observations made in vivo where total creatine is assumed to be unchanged and metabolite levels are often expressed as a total creatine ratio. The use of a total creatine ratio in vivo could lead to an underestimation of reductions in N-acetylaspartate and an apparent increase in other metabolites in the multiple sclerosis lesion.

Recombinant rubella E1 fusion proteins for antibody screening and diagnosis

BACKGROUND

Until rubella is eradicated there will be a continuing need for rubella antibody surveillance. Antigen production using recombinant DNA technology may be a viable alternative to traditional techniques of producing antigens for enzyme immunoassays (EIAs).

OBJECTIVES

To investigate the potential of bacterial fusion proteins containing rubella E1 protein sequences for use in EIAs to detect rubella antibodies.

STUDY DESIGN

Purified bacterial fusion proteins containing rubella E1 sequences to be used as antigens in EIAs and compared to 'traditional' assays using virus derived antigens for rubella antibody screening.

RESULTS

cDNA clones coding for the complete rubella E1 protein sequence and subfragments of E1 were modified for expression as carboxy terminal fusions with either beta-galactosidase or glutathione-S-transferase. beta-galactosidase fusions with the complete E1 coding sequence or amino acids 201 to 307, which contain known epitopes, resulted in the production of predominantly insoluble fusion proteins unsuitable for use in EIA. Nine glutathione-S-transferase-E1 fusion proteins were produced with individual fusion proteins exhibiting varying properties with regard to the levels of protein produced, apparent stability, solubility and the potential for affinity purification using glutathione agarose. Reduction of the E1 component to only 44 amino acids containing three B-cell epitopes (Terry et al., 1988) produced an abundant soluble GST-E1 fusion protein (3.5 mug/ml), which could be affinity purified using glutathione agarose. This fusion protein has been successfully used in EIA to detect rubella antibodies.

CONCLUSIONS

We have shown that GST-E1 fusions have potential as antigens in tests for rubella antibodies.

Low density lipoprotein uptake by macrophages in multiple sclerosis plaques: implications for pathogenesis

Low density lipoprotein (LDL), the major carrier of plasma cholesterol, may enter the parenchyma of early multiple sclerosis (MS) lesions as a result of blood-brain barrier damage. We have used antibodies against LDL and epitopes found in LDL oxidized by two peroxidative end-products, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), to immunocytochemically stain MS plaques at different stages of pathology. Native LDL, epitopes of MDA-LDL, peptides of myelin basic protein and neutral lipid oil red O (ORO) staining were found to be co-localized within foamy macrophages in early and actively demyelinating MS plaques. Thus cholesterol esters, which are seen as Maltese crosses under polarized light in a proportion of foamy macrophages, appear to be derived from both LDL and myelin. ORO-negative astrocytes were strongly stained with the antibodies against 4-HNE-LDL and MDA-LDL, suggesting uptake of oxidatively modified protein products alone. Our findings suggest that a large proportion of the plasma LDL which enters the parenchyma of MS plaques is oxidatively modified in the lesion. Lipid peroxidation and oxidized LDL uptake by activated microglia and infiltrating macrophages in the early stages of MS plaque development may play important roles in demyelination.

Characterization and distribution of phagocytic macrophages in multiple sclerosis plaques

Populations of phagocytic cells in multiple sclerosis (MS) plaques were examined by quantitative immunocytochemical analysis of macrophage markers and myelin degradation products in serial cryostat sections from 10 cases of MS. Around lesions with ongoing demyelination expression of the Class II antigen HLA-DQ appeared to be a marker of microglial activation. Alpha 1-antichymotrypsin+ monocytes and myelin-laden macrophages expressing the later differentiation markers Ber-MAC3 and RFD7 were predominantly perivascular in location. On the basis of the distribution of oil red O (ORO)+ phagocytes and myelin loss, plaques were divided into groups representing different stages in lesion development. In early lesions (group 1), there was no apparent myelin loss around ORO+ macrophages although these cells contained material stained with antibodies against myelin basic protein (MBP) epitopes and neoepitopes. However, patchy myelin loss was detectable around the phagocytic macrophages uniformly distributed throughout group 2 plaques. ORO+ macrophages containing MBP peptides were confined to the hypercellular border of group 4 lesions, in which the demyelinating process may be recurrent.

Monoclonal antibody 14E recognizes an antigen common to human oligodendrocytes, Schwann cells, Bergmann glia, and a subpopulation of reactive glia

The monoclonal antibody 14E immunocytochemically stains the nuclear membrane of oligodendrocytes but not myelin in tissue sections of adult normal human white matter. The nuclear membranes of Schwann cells in human peripheral nerve and cerebellar Bergmann glia were also visualized with this antibody. In actively demyelinating multiple sclerosis plaques the 14E antibody stained increased numbers of oligodendrocytes and the nuclei, perikarya and cell processes of hypertrophic glia, which were often multinucleate. Scattered small groups of these hypertrophic glia were present in areas of dense astrogliosis in acute plaques. The 14E-positive hypertrophic cells could be either a subpopulation of reactive astrocytes or bipotential glial precursors.

Lipocortins (annexins) 1, 2, 4 and 5 are increased in the central nervous system in multiple sclerosis

Western blotting and densitometry have been used to investigate the lipocortin content of post-mortem central nervous system (CNS) tissue samples from multiple sclerosis (MS) patients and normal controls. Lipocortins 1, 2, 4 and 5 were all detected in normal control grey and white matter. In white matter samples from MS patients these lipocortins were found to be significantly increased, a further elevation in lipocortin content was observed in MS plaque tissue. The implications of these findings with respect to the role of these proteins in inflammatory CNS disease and a possible mechanism of steroid action in the therapy of MS are discussed.

Gamma delta T-cell receptor repertoire in acute multiple sclerosis lesions

Gamma delta T cells are a distinct lymphocyte population that can exhibit reactivity with heat shock proteins over-expressed at inflammatory sites. As gamma delta T cells may be involved in the central nervous system (CNS) inflammatory process in multiple sclerosis (MS), we examined T-cell populations in MS plaque tissue by quantitative immunohistochemistry and sequence analysis of T-cell antigen receptor (TCR) delta chains. Gamma delta T cells that express the variable (V) gene segments V delta 1, V delta 2, and V gamma 2 (V gamma 9) were found to accumulate in acute, demyelinating MS plaques and appeared to have undergone clonal expansion, most likely because of recognition of a specific CNS ligand. Further, 60-kDa and 90-kDa heat shock proteins (hsp60 and hsp90), which may be target antigens for autoreactive gamma delta T cells, were found to be expressed in normal CNS tissue and overexpressed in acute MS plaques. In acute plaques, hsp60 was found in foamy macrophages, while hsp90 was detected in reactive astrocytes. These results provide evidence for a role of gamma delta T cells in active stages of MS.