Alterations in iron levels in Japanese encephalitis virus infection

Following Japanese encephalitis virus (JEV) infection in mice the serum iron concentration decreased; the decline started from day 3 and persisted up to day 9 postinfection. No significant difference was found in the total iron-binding capacity of serum in JEV-infected mice compared with that of controls. The hypoferraemia was associated with accumulation of iron in the spleen. Large amounts of stainable iron were demonstrated in splenic macrophages from day 5. This was accompanied by transient anaemia. Thus, the hypoferraemia, following intraperitoneal inoculation of JEV, was attributed to a block in the release of iron from the RES.

Meteorological factors involved in Japanese encephalitis virus infection in cattle

From 1982 to 1987 a total of 4,371 dairy cattle in Saitama Prefecture, were examined for levels of hemagglutination inhibition (HI) antibody to Japanese encephalitis virus (JEV) and the correlation with meteorological factors and an antibody positive rate was studied. Positivity rates of HI antibody from July to October each year (Yi) ranged from 58.8 to 88.0% with a considerable annual variation. Simple regression analysis of Yi with the comparative meteorological value (Xi) was determined from mean temperatures (Ti, j-1), rainfalls (Ri, j-1) for 10-day-periods each, and the number of days showing 25 degrees C or above (ti, j-1) from June to September, which yielded a correlation coefficient of 0.8147 (p less than 0.05) and an equation for estimated HI antibody positivity rate: Yi = -0.04Xi+79.9 (p less than 0.05). Multiple regression analysis with the power values of three meteorological parameters as independent variables and Yi as the dependent variable, showed a multiple correlation coefficient of 0.987 (p less than 0.05) and a multiple regression equation: Yi = -3991T1/13-0.0035R-12+1978t1/9+4187 (p less than 0.05), giving estimated positivity rates almost equal to the values from the observations. Therefore, a predictive equation was formulated reflecting positive and negative correlations of sero-positivity with the temperature and the precipitation, respectively.

Field trial of a Japanese encephalitis diagnostic kit

Serum and cerebrospinal fluid (CSF) obtained from patients in rural Thailand during an encephalitis epidemic were assayed with a Japanese encephalitis rapid diagnosis kit. Japanese encephalitis was diagnosed by detection of virus-specific IgM (JEV IgM) in CSF (1:10 dilution) or serum (1:100 dilution) with an antibody capture enzyme-linked immunosorbent assay. Specimens were assayed immediately on site at the provincial hospital and scored by visual examination within 4 h. Each specimen was retested carefully later to accurately determine its activity (units) at a single screening dilution; each was tested also at serial dilutions to determine its end-point titer. On-site kit results showed close agreement with subsequent laboratory results for detection and quantitation of JEV IgM and JEV IgG in either serum or CSF. Using the kit on site, admission CSF from 35 (73%) of 48 laboratory-proven JEV-infected patients were scored as definitely positive for JEV IgM, while all 17 CSF specimens from non-JEV infected patients were read as negative (sensitivity 73%, specificity 100%). A rapid and early diagnosis of acute Japanese encephalitis can be accomplished almost anywhere.

A clinical study of adult Japanese encephalitis in the Chonnam District, Korea, during summer of 1982--a difference between improved and expired cases

In the summer of 1982, we experienced a great number of patients with Japanese encephalitis compared with the previous years. We have studied 85 adult cases of Japanese encephalitis which were diagnosed clinically and/or serologically. A difference between improved and expired cases was also investigated. We found that deteriorated mental state, elevated SGOT (AST) level, lower hemagglutination-inhibition(H-I) titer, and a more acute onset of the illness were associated with higher mortality. The mortality rate in our cases was 35.3 percent.

Virus-specific antibody-producing cells in blood and cerebrospinal fluid in acute Japanese encephalitis

During an epidemic of Japanese encephalitis (JE) in northern Thailand, cerebrospinal fluid (CSF) leukocytes and blood leukocytes from 28 patients with suspected JE were tested for spontaneous in vitro synthesis of antibodies to JE virus (JEV). Sixteen patients were subsequently proven to be infected with JEV. Supernatant fluids of three-day cultures of unstimulated peripheral blood mononuclear leukocytes or unstimulated unfractionated CSF leukocytes were tested for JEV IgM and IgG antibodies with isotype-specific "antibody capture" radioimmunoassays. Blood-derived leukocytes from all sixteen JEV-infected patients and CSF-derived leukocytes from four JEV-infected patients synthesized JEV antibodies. Blood-derived and CSF-derived leukocytes from all 12 patients with central nervous system infections caused by agents other than JEV uniformly failed to synthesize JEV antibodies. Virus-specific antibody-producing cells can be detected in the blood and CSF early in the clinical course of acute JE.

Japanese encephalitis virus immunoglobulin M antibodies in porcine sera

A solid-phase enzyme-linked immunosorbent assay (ELISA) was developed for detection of porcine immunoglobulin (Ig)M antibodies to Japanese encephalitis virus (JEV). Antibodies in sera were captured onto the solid phase of Microtiter plates sensitized with mouse monoclonal antibodies to porcine mu heavy chain. Virus antigen binding to the lawn of IgM was quantitated by subsequent binding of peroxidase-labeled human hyperimmune anti-JEV IgG, which in the final step, catalyzed a substrate color change. In sucrose density-gradient fractionated sera from recently infected pigs, the peak of ELISA JEV IgM activity corresponded to the peak of 18-S, 2-mercaptoethanol-sensitive hemagglutination-inhibiting (HAI) antibody activity. Within 2 to 3 days, JEV-infected sentinel pigs developed high JEV IgM activity; this activity decreased within 2 weeks. Among specimens collected from 99 random swine at abattoirs in Thailand during a period of low JEV transmission, none of 25 JEV HAI-negative sera had JEV IgM activity, 7 of 74 JEV HAI-positive sera did have JEV IgM activity, and the remaining 67 sera had readily detectable JEV HAI antibodies, but lacked JEV IgM. The JEV IgM solid-phase ELISA was useful for rapidly diagnosing active or recent JEV infections in swine.

The effect of interferon-alpha A on two cases of Japanese encephalitis in Thailand

Two Japanese encephalitis cases with serious comatous symptoms were treated with the Human Recombinant Interferon-alpha A. The clinical responses to IFN were found to be satisfactory. The first case showed improvement on the 5th day of IFN treatment and the general condition slowly improved. The second case recovered from the comatous stage on the 6th day of IFN, followed by quick improvement of general symptoms in the 2nd week and complete recovery without any mental sequelae. Leukopenia and neutropenia occurred during the first week of administration of IFN, but were only temporary. Slight elevation of SGOT and SGPT was observed in the first case. No other side effects including general toxicity, neurotoxicity or allergy, or any abnormal hematological and blood chemistry changes were observed in these 2 cases. Two other JE cases (the 3rd and 4th consecutive JE cases) were not treated with IFN, but received the usual regimens of symptomatic and supportive drugs. Both patients died on the 7th-9th day of illness. This study suggests that the Human Recombinant Leukocyte A Interferon possibly is an effective and promising agent in the treatment of Japanese encephalitis in Thailand. More studies to treat JE cases with this IFN are being performed in order to assess the efficacy, tolerance and safety of rIFN-alpha A on Japanese encephalitis in Thailand.

The use of the single radial haemolysis technique in the serological diagnosis of dengue and Japanese encephalitis virus infections

The single radial haemolysis test for the serological diagnosis of suspected dengue and Japanese encephalitis virus infections uses crude virus antigens with a haemagglutinin titre of 1:320 or 1:640. The results, which may be read 3 hours after the addition of a patient's serum, showed a general agreement between this test and haemagglutination-inhibition tests in the number of case diagnoses that were confirmed. The antibody responses of individual patients shown by the two tests, however, were different, which suggests that the two tests may not be measuring the same antibody. The single radial haemolysis test can distinguish between dengue and Japanese encephalitis viruses using specific mouse hyperimmune sera. Tests on a limited number of sera from Japanese encephalitis patients also showed no cross-reactions with dengue virus antigens in those cases having a low-titred but significant fourfold antibody rise to Japanese encephalitis antigen.

Mononuclear cells in Japanese encephalitis virus infection: changes in cells counts and specific fluorescence

Progressive reduction in blood cell counts was observed in mice inoculated intracerebrally (ic) with Japanese encephalitis (JE) virus. No changes were observed in the blood cell counts of mice inoculated intraperitoneally (ip). Reduction in cell counts after a transient rise was noticed in lymph nodes of mice inoculated by either route but the cell counts returned to normal in lymph nodes of ip inoculated mice by the 8th day post inoculation (p.i.). JE virus antigen was demonstrated by immunofluorescence in mononuclear cells from the blood, spleen and lymph nodes starting from the 3rd and 4th day p.i. in mice inoculated ic and ip, respectively. The number of fluorescent cells increased as the infection progressed. The number of fluorescent spleen cells uas higher in ip than in ic inoculated mice. Live virus could only occasionally be demonstrated in the cells.

Hematogenous cells in experimental Japanese encephalitis

Four adult mice were injected with 3H-thymidine repeatedly so that in their brains only circulating blood cells were labelled with 3H-thymidine. They then received an intracerebral injection of Japanese encephalitis virus, were sacrified on the 3rd, 4th and 5th day after inoculation: the brains were examined by light and electron microscopic autoradiography. Inflammatory cells appearing in the brain parenchyma and perivascularly in the acute stage of the experimental Japanese encephalitis are derived from circulating mononuclear leukocytes. They assume the shape of "rod cells" and are the main constituents of the "glial nodule" in the brain parenchyma. Their fine structural characteristics are discussed.

Dual infections of mice: visceral larva migrans and sublethal infection with Japanese encephalitis virus

Experiments in 3 weeks old albino mice with Toxocara canis and sublethal infection with JE virus established a marked synergestic effect in dually infected mice. The results are discussed to indicate the possible role of visceral larva migrans in creating exploxive outbreaks of "acute encephalopathy syndrome" in individuals having simultaneous infection with a virus (es) which, alone, might produce only mild illness. The nature of the possible mechanisms involved yet remains to be understood.

Studies on Japanese B encephalitis virus vaccines from tissue culture. XI. Immune mechanism and evaluation of the mouse challenge potency test

A study was carried out to evaluate the reliability of and to determine the mechanism involved in an antigen extinction mouse intraperitoneal (ip) challenge test for potency of a cell culture vaccine for Japanese B encephalitis, a modification of a test originated by Sabin for a mouse brain vaccine. Some comparisons were made with the official Japanese test using an intracerebral (ic) challenge after a more prolonged immunization procedure. The Japanese method of using a lyophilized reference vaccine with each test was also employed. It was found that the ip and the ic test appeared to show similar relative differences between lots. The ip test was more quickly and readily performed, gave reasonably consistent results on repetition, and, when used with a suitable reference vaccine, gave promise of being an entirely suitable and reliable test. Immunization by the intramuscular route rather than by the regular ip route appeared to offer no advantage and was less consistent in responses shown. Neutralizing antibody responses of the mice in the standard procedure were very quick to appear, about 4 days after the first dose of vaccine and had a peak titer about the seventh day, the time of challenge. This titer fell quickly unless challenge occurred. The antibody was heat stable, but it was readily inactivated by 2-mercaptoethanol (2-ME). Not until the 11th or 15th day did a small amount of immunoglobulin G appear. Challenge on day 7 significantly increased titers, but this antibody was also mostly inactivated by 2-ME. Interferon did not appear to play any significant role in the protection shown by the mice.