B-cell responses to myelin basic protein and its epitopes in autoimmune encephalomyelitis induced by Semple rabies vaccine

Determinants of health seeking behaviour following rabies exposure in Ethiopia

The objective of this study was to identify factors that determine medical treatment seeking behaviour following potential rabies exposure after being bitten by a suspected dog and the likelihood of compliance to receive sufficient doses of post-exposure prophylaxis after the visit to a health centre visit. A detailed survey based on case investigation was conducted on suspected rabid dog bite cases in three areas of Ethiopia. Two multivariable logistic regression models were created with a set of putative variables to explain treatment seeking and compliance outcomes. Based on the registered bite cases at each health centre and the set of unregistered bite cases derived by contact tracing, 655 bite victim cases were identified to have occurred between September 2013 and August 2014. Of these evaluated bite incidences, 465 cases were considered to have been caused by a potentially rabid dog. About 77% of these suspected rabid dog bite victims visited a health centre, while 57% received sufficient doses of PEP. The overall likelihood of seeking medical services following rabies exposure was higher for people bitten by dogs of unknown ownership, where the bite was severe, being bitten on the leg, spend of more than 100 USD per month and where the victim lived close to the nearest health centre, while the likelihood of receiving sufficient doses of PEP was sensitive to monthly spending and distance to health centre. However, the evaluated factors did only explain a part of the variation among the three districts. The district in which victims lived appeared to have a relevant influence on the likelihood of seeking medical treatment but did not improve the prediction on the likelihood of treatment compliance. Given the insights obtained from this study, improvements in the rural districts with regard to accessibility of post-exposure prophylaxis delivering health centres in shorter distance could improve health seeking behaviour. In addition, in rural districts, majority of exposed persons who seek medical treatment tend to comply with treatment regimen, indicating that the promotion of medical treatment through awareness creation campaigns could be beneficial.

Estimating the burden of rabies in Ethiopia by tracing dog bite victims

In developing countries where financial resources are limited and numerous interests compete, there is a need for quantitative data on the public health burden and costs of diseases to support intervention prioritization. This study aimed at estimating the health burden and post-exposure treatment (PET) costs of canine rabies in Ethiopia by an investigation of exposed human cases. Data on registered animal bite victims during the period of one year were collected from health centers in three districts, i.e. Bishoftu, Lemuna-bilbilo and Yabelo, to account for variation in urban highland and lowland areas. This data collection was followed by an extensive case search for unregistered victims in the same districts as the registered cases. Victims were visited and questioned on their use of PET, incurred treatment costs and the behavioral manifestations of the animal that had bitten them. Based on the collected data PET costs were evaluated by financial accounting and the health burden was estimated in Disability-Adjusted Life Years (DALYs). In total 655 animal bite cases were traced of which 96.5% was caused by dog bites. 73.6% of the biting dogs were suspected to be potentially rabid dog. Annual suspected rabid dog exposures were estimated per evaluated urban, rural highland and rural lowland district at, respectively, 135, 101 and 86 bites, which led, respectively, to about 1, 4 and 3 deaths per 100,000 population. In the same district order average costs per completed PET equaled to 23, 31 and 40 USD, which was significantly higher in rural districts. Extrapolation of the district results to the national level indicated an annual estimate of approximately 3,000 human deaths resulting in about 194,000 DALYs per year and 97,000 exposed persons requiring on average 2 million USD treatment costs per year countrywide. These estimations of the burden of rabies to the Ethiopian society provide decision makers insights into the potential benefits of implementing effective interventions.

High-Density Peptide Microarray Analysis of IgG Autoantibody Reactivities in Serum and Cerebrospinal Fluid of Multiple Sclerosis Patients

Intrathecal immunoglobulin G (IgG) synthesis and oligoclonal IgG bands in cerebrospinal fluid (CSF) are hallmarks of multiple sclerosis (MS), but the antigen specificities remain enigmatic. Our study is the first investigating the autoantibody repertoire in paired serum and CSF samples from patients with relapsing-remitting MS (RRMS), primary progressive MS (PPMS), and other neurological diseases by the use of high-density peptide microarrays. Protein sequences of 45 presumed MS autoantigens (e.g.MOG, MBP, and MAG) were represented on the microarrays by overlapping 15mer peptides. IgG reactivities were screened against a total of 3991 peptides, including also selected viral epitopes. The measured antibody reactivities were highly individual but correlated for matched serum and CSF samples. We found 54 peptides to be recognized significantly more often by serum or CSF antibodies from MS patients compared with controls (pvalues <0.05). The results for RRMS and PPMS clearly overlapped. However, PPMS patients presented a broader peptide-antibody signature. The highest signals were detected for a peptide mapping to a region of the Epstein-Barr virus protein EBNA1 (amino acids 392-411), which is homologous to the N-terminal part of human crystallin alpha-B. Our data confirmed several known MS-associated antigens and epitopes, and they delivered additional potential linear epitopes, which await further validation. The peripheral and intrathecal humoral immune response in MS is polyspecific and includes antibodies that are also found in serum of patients with other diseases. Further studies are required to assess the pathogenic relevance of autoreactive and anti-EBNA1 antibodies as well as their combinatorial value as biomarkers for MS.

[Acute disseminated encephalomyelitis after rabies vaccination: a case report]

Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disease of the central nervous system. It is a disease whose incidence is not precisely known. The presumed mechanism is demyelination of the immune-mediated central nervous system. There is no pathognomonic clinical presentation in ADEM. The combination of multifocal neurological disorders arising in the aftermath of an infection or vaccination should alert the clinician. We report a case of ADEM in an 8-year-old child occurring after antirabies vaccination. The diagnosis was made by nuclear magnetic resonance imaging (bilateral and multifocal lesions in the subcortical occipitoparietal and frontal left anterior white matter with involvement of U fibers) and a history of antirabies vaccination. The clinical course was marked by the appearance of motor and visual effects.

Autoantibodies to myelin basic protein (MBP) in healthy individuals and in patients with multiple sclerosis: a role in regulating cytokine responses to MBP

Anti-myelin basic protein (-MBP) autoantibodies have generally been considered to be absent from sera from healthy individuals, but to be detectable in sera from some patients with multiple sclerosis (MS). However, their pathogenic role is uncertain. We demonstrate the presence of MBP-reactive autoantibodies in sera from 17 healthy individuals and 17 MS patients. The addition of MBP to the sera caused a dose-dependent deposition of MBP and co-deposition of immunoglobulin M (IgM) and fragments of complement component 3 (C3) on allogeneic monocytes. Calcium chelation abrogated the immunoglobulin deposition, indicating that formation of complement-activating immune complexes played a role in the binding process. Furthermore, MBP elicited tumour necrosis factor (TNF)-alpha and interleukin (IL)-10 production by normal mononuclear cells in the presence of serum from both patients and controls. Mononuclear cells from MS patients responded to MBP with the production of interferon (IFN)-gamma, IL-4 and IL-5, in addition to TNF-alpha and IL-10. The production of IFN-gamma and IL-5 was increased when MS serum was added rather than normal serum. Denaturation of MBP strongly inhibited MBP deposition and the MBP-induced IgM deposition and cytokine production, indicating that these events were facilitated by autoantibodies recognizing conformational epitopes on MBP. We infer that MBP-elicited TNF-alpha and IL-10 responses are promoted to equal extents by naturally occurring MBP autoantibodies and autoantibodies contained in MS sera. However, the latter seem to be more efficient in facilitating the production of IFN-gamma and IL-5.

Myelin basic protein-reactive autoantibodies in the serum and cerebrospinal fluid of multiple sclerosis patients are characterized by low-affinity interactions

The presence of autoantibodies to the immunodominant antigen, myelin basic protein (MBP), in the serum and cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) has been poorly characterized. Many studies report detectable levels of autoantibodies to myelin basic protein though other studies, using similar techniques, report their absence. We compared a solution-phase assay that has detected clinically relevant autoantibodies in diabetes and other autoimmune diseases to solid phase assays similar to those used in previous reports. The solution-phase assay consistently measured autoantibodies to MBP in serum from human subjects with Semple rabies vaccine (SRV)-induced demyelinating disease and from MBP-immunized animals. A solid phase assay detected MBP autoantibodies in the serum of a fraction of patients with MS. Autoantibodies capable of binding to MBP in the solution-phase were not detected in the CSF or serum of patients with MS. Additional solution-phase measurements revealed that anti-MBP antibodies from individuals with SRV-induced demyelinating disease demonstrated a binding affinity profile consistent with that of polyclonal antibodies with a range of affinities from low to high. In contrast, antibodies to MBP in the serum of MS patients detected by ELISA did not bind soluble MBP in the same assay. These results indicate that the humoral response in patients with MS does not include moderate- or high-affinity autoantibodies to MBP.

Transient virus infection and multiple sclerosis

Multiple sclerosis (MS) is a chronic, demyelinating disease of the CNS in which autoimmunity to myelin plays a role in pathogenesis. The epidemiology of MS indicates that it may be triggered by a virus infection before the age of adolescence, but attempts to associate a specific virus with MS have produced equivocal results. Many studies of the aetiology of MS have postulated that a persistent virus infection is involved, but transient virus infection may provide a plausible alternative mechanism that could explain many of the inconsistencies in MS research. The most studied animal model of MS is chronic relapsing experimental autoimmune encephalomyelitis (CREAE), which is induced in susceptible animals following injection of myelin components. While CREAE cannot provide information on the initiating factor for MS, it may mimic disease processes occurring after an initial trigger that may involve transient virus infection. The disease process may comprise separate triggering and relapse phases. The triggering phase may involve sensitisation to myelin antigens as a result of damage to oligodendrocytes or molecular mimicry. The relapse phase could be similar to CREAE, or alternatively relapses may be induced by further transient virus infections which may not involve infection of the CNS, but which may involve the recrudescence of anti-myelin autoimmunity. Although current vaccines have a high degree of biosafety, it is suggested that the measles-mumps-rubella vaccine in particular could be modified to obviate any possibility of triggering anti-myelin autoimmunity.