Encephalitis Virus Immunoglobulin Research Articles

Poor performance of two rapid immunochromatographic assays for anti-Japanese encephalitis virus immunoglobulin M detection in cerebrospinal fluid and serum from patients with suspected Japanese encephalitis virus infection in Laos.

Background Japanese encephalitis virus (JEV) is a leading identified cause of encephalitis in Asia, often occurring in rural areas with poor access to laboratory diagnostics. We evaluated two rapid diagnostic tests (RDTs) for anti-JEV immunoglobulin M (IgM) detection.MethodsConsecutive cerebrospinal fluid and serum from 388 patients (704 samples) with suspected JEV infections admitted to six hospitals in Laos were tested with one of two SD-Bioline anti-JEV IgM RDTs and the World Health Organization standard anti-JEV IgM enzyme-linked immunosorbent assay (ELISA; Panbio Japanese Encephalitis–Dengue IgM Combo ELISA.Results and ConclusionsThe performance of both RDTs showed strikingly low sensitivity in comparison to anti-JEV IgM antibody capture ELISA (2.1–51.4%), suggesting low sensitivity of the RDTs. We highlight the fundamental prerequisite to validate RDTs prior to use to ensure that they meet standards for testing.

Japanese encephalitis virus infection in an endemic area: hospital based study 1998 to 2000

Gampaha Deputy Provincial Director of Health Services division reported a large number of Japanese encephalitis cases during 1996 to 1997. Notified cases included unconfirmed and confirmed cases. A study to determine the true disease burden was considered necessary. Proportion of undifferentiated fever cases due to Japanese encephalitis virus varies in different populations and the Sri Lankan situation is not known. The objectives were to determine the proportion of undifferentiated fever cases and encephalitis cases due to Japanese encephalitis virus; and the case fatality rate and frequency of neurological sequelae in Japanese encephalitis, in a tertiary care hospital in Gampaha. A cross-sectional descriptive study was carried out in the paediatric and medicine units of the North Colombo Teaching Hospital, Ragama during 1998 to 2000. Ninety three randomly selected patients with a diagnosis of undifferentiated fever from whom paired sera could be collected and 32 patients suspected of encephalitis, which were not overtly due to mumps, measles or chicken-pox were included. The Armed Forces Research Institute in Medical Sciences Enzyme linked immunosorbent assay for anti-Japanese encephalitis virus immunoglobulin M and G was used to confirm Japanese encephalitis virus infection. One of 93 (1.08%) undifferentiated fever cases was due to Japanese encephalitis virus infection. Eleven of 32 (34.38%) encephalitis cases had Japanese encephalitis virus infection and 3 (27.3%) had IgM antibodies to Japanese encephalitis virus in cerebrospinal fluid. Case fatality rate and sequelae at discharge were 11.1% each. Japanese encephalitis virus was an important cause of encephalitis in Gampaha during this period. DOI: http://dx.doi.org/10.4038/sljid.v2i1.3321 Sri Lankan Journal of Infectious Diseases Vol.2(1) 2012: 19-27

Toscana Virus Infection in American Traveler Returning from Sicily, 2009

Toscana Virus Infection in American Traveler Returning from Sicily, 2009

Validation of a Microsphere-Based Immunoassay for Detection of Anti-West Nile Virus and Anti-St. Louis Encephalitis Virus Immunoglobulin M Antibodies

A microsphere-based immunoassay (MIA) was previously developed that is capable of determining the presence of anti-West Nile (WN) virus or anti-St. Louis encephalitis (SLE) virus immunoglobulin M (IgM) antibodies in human serum or cerebrospinal fluid. The original data set on which the classification rules were based comprised 491 serum specimens obtained from the serum bank at the Division of Vector-Borne Infectious Diseases of the Centers for Disease Control and Prevention (DVBID). The classification rules were used to provide a result and to determine whether confirmatory testing was necessary for a given sample. A validation study was coordinated between the DVBID and five state health laboratories to determine (i) the reproducibility of the test between different laboratories, (ii) the correlation between the IgM-enzyme-linked immunosorbent assay (MAC-ELISA) and the MIA, and (iii) whether the initial nonspecific parameters could be refined to reduce the volume of confirmatory testing. Laboratorians were trained in the method, and reagents and data analysis software developed at the DVBID were shipped to each validating laboratory. Validating laboratories performed tests on approximately 200 samples obtained from their individual states, the collections of which comprised approximately equal numbers of WN virus-positive and -negative samples, as determined by MAC-ELISA. In addition, 377 samples submitted to the DVBID for arbovirus testing were analyzed using the MIA and MAC-ELISA at the DVBID only. For the specimens tested at both the state and the DVBID laboratories, a correlation of results indicated that the technology is readily transferable between laboratories. The detection of IgM antibodies to WN virus was more consistent than detection of IgM antibodies to SLE virus. Some changes were made to the analysis software that resulted in an improved accuracy of diagnosis.

Clinical Features in Children Hospitalized during the 2005 Epidemic of Japanese Encephalitis in Uttar Pradesh, India

Japanese encephalitis is a disease that affects the rural poor in Asia. In August-September 2005, a severe epidemic of Japanese encephalitis occurred in Uttar Pradesh, one of India's poorest states. Children admitted to the King George Medical University hospital (Lucknow, Uttar Pradesh, India) with acute febrile encephalopathy (defined as fever plus encephalopathy of <or=2 weeks' duration) from July to October 2005 underwent ELISA for Japanese encephalitis virus immunoglobulin M in cerebrospinal fluid or serum on hospital admission. Clinicolaboratory features of patients with positive test results were recorded.Results. Of the 223 children tested, 77 had positive results for Japanese encephalitis immunoglobulin M. Patients were from 18 districts of Uttar Pradesh. All but 1 were from rural areas, and none were <2 years of age. The prodromal period was very short (mean+/-standard deviation, 2.61+/-2.23 days). Convulsions were present in 76 patients (98.7%). The mean (+/- standard deviation) Glasgow Coma Scale score was 7.4+/-2.7. Generalized hypertonia was found in 39 patients (50.6%), and focal deficits were found in 35 patients (45.4%), including 19 cases of monoparesis and 16 cases of hemiparesis. Gastric hemorrhage was found in 42 patients (54.5%). Extrapyramidal features were found in 24 (31.1%), a hyperepneic breathing pattern was found in 20 (26%), and thrombocytopenia was found in 5 (15.6%) of 32 patients. The mean cerebrospinal fluid cell count was 48.3 cells/mm(3). The serum bilirubin level was normal in all patients, but the aspartate aminotransferase level was elevated in all 21 patients (100%) tested and the alanine aminotranferase level was elevated in 25 (47.2%) of 53 patients. In-hospital mortality was 34%. Clinical features of Japanese encephalitis were severe. Derangements in liver function and thrombocytopenia were found in a significant proportion of patients. These findings were not highlighted during earlier epidemics of the illness and could suggest a possible mutation of the virus towards other flaviviruses.

Duplex Microsphere-Based Immunoassay for Detection of Anti-West Nile Virus and Anti-St. Louis Encephalitis Virus Immunoglobulin M Antibodies

West Nile (WN) virus was introduced into the United States in 1999, when the first human cases of WN fever and encephalitis appeared in New York City. From there, the virus has spread throughout North America, in some areas cocirculating with the related flavivirus St. Louis encephalitis (SLE) virus. Public health laboratories currently use an immunoglobulin M (IgM) antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) as a primary test for human serodiagnosis, followed by a confirmatory plaque-reduction neutralization test (PRNT). The MAC-ELISAs take 2 days to perform; therefore there is a need for a more rapid test. This report describes a duplex microsphere-based immunoassay (MIA) that shortens the test processing time to about 4.5 h. The assay employs two sets of microspheres coupled to a single flavivirus group-reactive antibody, which are used to capture the WN and SLE viral antigens independently. Immunoglobulin G-depleted serum is concurrently assayed for IgM antibodies to each of the viral antigens. The results are standardized and classified by using quadratic discriminant analysis so that a single result, anti-WN IgM-positive, anti-SLE IgM-positive, negative, or nonspecific, can be determined. The duplex MIA results compared favorably to those of the plaque-reduction neutralization test and MAC-ELISA. The assay proved to be reproducible, produced accurate classifications as to the infecting virus, and was specific.

Pre- and postexposure protection by passive immunoglobulin but no enhancement of infection with a flavivirus in a mouse model.

Antibody-dependent enhancement of flavivirus infection, which except for dengue virus is without clear proof in vivo, is still under debate. Recently, postexposure immunoglobulin prophylaxis against tick-borne encephalitis virus, a flavivirus, was claimed to possibly have worsened the outcome of infection due to antibody-dependent enhancement. In the present study, antibody-dependent enhancement and pre- or postexposure protection by passive administration of tick-borne encephalitis virus immunoglobulin were evaluated in a mouse model. Preexposure treatment with homologous murine or heterologous human immunoglobulin provided complete protection against lethal challenge with tick-borne encephalitis virus. For postexposure treatment with antibody, the degree of protection correlated with the amount of immunoglobulin administered and was inversely related to the time interval between infection and treatment. Indications of enhancement of infection would have been increased lethality or reduced mean survival time, but neither was observed under the conditions used in our experiments despite the broad range of immunoglobulin and virus challenge doses applied. In contrast to these in vivo results, antibody-dependent enhancement of tick-borne encephalitis virus infection of murine peritoneal macrophages was readily demonstrable in vitro. Thus, antibody-dependent enhancement of viral infection in vitro does not necessarily predict enhancement in vivo.

Antibody capture immunoassay detection of japanese encephalitis virus immunoglobulin m and g antibodies in cerebrospinal fluid.

Immunoglobulin M (IgM) and IgG antibodies to Japanese encephalitis virus (JEV) were detected in acute-phase cerebrospinal fluid (CSF) specimens from patients with acute encephalitis by using a solid-phase radioimmunoassay of the antibody capture type. Of 12 patients with JEV infections subsequently proven by hemagglutination inhibition serology, 11 had JEV IgM antibodies, as measured by antibody capture radioimmunoassay, in the first CSF specimen (geometric mean titer, 1:2,500) compared with 0 of 8 patients with acute encephalitis proven not to be due to JEV. Specific IgM anti-JEV activity (units per microgram) was greater in CSF than in parallel serum specimens in all 11 positive cases by more than fourfold on the average (range, 1.4 to 13). Among seven patients with broadly reactive hemagglutination inhibition seroresponses typical of persons previously exposed to other flaviviruses, six had high levels of JEV IgG antibodies (as measured by antibody capture radioimmunoassay) in their acute-phase CSF (geometric mean titer, 1:26,000), whereas in five patients experiencing their first flavivirus infection, JEV IgG antibodies measured by antibody capture radio-immunoassay were either absent (one patient) or weakly reactive (four patients; geometric mean titer, 1:3,200). Specific IgG anti-JEV activity was greater in CSF than in parallel serum specimens in eight of the nine positive cases measured (range, 1.3- to 24-fold). The antibody capture solid-phase immunoassay approach is well suited for detecting specific antibody activity in CSF.

Detection of Japanese encephalitis virus immunoglobulin M antibodies in serum by antibody capture radioimmunoassay.

An assay for detecting human immunoglobulin M (IgM) antibodies to Japanese encephalitis (JE) virus was developed by using the antibody capture solid-phase radioimmunoassay approach (JE IgM ACRIAAA). Heavy-chain-specific goat antihuman IgM was first bound to the wells of a polyvinyl microtiter plate, and successive steps involved sequential binding of test sample IgM, acetone-extracted mouse brain JE antigen, and (125)I-labeled flavivirus hyperimmune human IgG. Among 20 patients hospitalized in Bangkok with clinical diagnoses of acute encephalitis, and with acute flavivirus infections proven by hemagglutination inhibition (HAI) serology, 16 had detectable (positive/negative [P/N] ratio, greater than 3.0) JE IgM ACRIA antibodies in the acute-phase serum specimen, and 19 had such antibodies in the convalescent-phase serum specimen. Convalescent patient sera regularly had higher P/N values than the corresponding acute-phase sera (mean +/- 1 standard deviation = 13.0 +/- 9.3 with acute-phase sera and 25.8 +/- 19.6 with convalescent-phase sera). JE virus-infected patients with HAI serological responses indicative of a primary flavivirus infection had higher JE IgM ACRI P/N responses than did those patients whose serological response indicated past exposure to other flaviviruses. None of 70 serum specimens from healthy Thai adults and children with serum JE HAI antibodies had detectable JE IgM ACRIA activity (P/N ratios all less than or equal to 3.0). Biological false-positives with low P/N ratios (range, 3 to 15) were found in sera from patients with acute or recent infections with flaviviruses other than JE virus but could be differentiated by the fact that these sera gave higher P/N ratios with homologous antigens than with JE virus. False-positive reactions with low P/N ratios (range, 3 to 6) due to serum rheumatoid factor activity were differentiated by testing with control antigen. The JE IgM ACRIA technique permits a rapid, accurate diagnosis of acute JE virus infections in both patients with and those without previous exposure to other flaviviruses.