Detection of immunoglobulin M antibodies to hepatitis A virus by enzyme-linked immunosorbent assay

Serological and immunohistochemical studies on porcine-serum-induced hepatic fibrosis in rats

We previously reported that the strain difference in the development of porcine-serum (PS)-induced rat hepatic fibrosis was closely related to the difference in the mode of MHC class-II-related genes expression. This study was carried out to clarify the serological and immunohistochemical changes in this hepatic fibrosis model. Six-week-old male Brown Norway (BN) and Wistar rats were injected with 0.5 ml of sterile PS twice a week for up to 8 weeks. The serum levels of PS-specific IgG1, IgG2a, and IgM were elevated more prominently in BN rats than Wistar rats. In the liver, significant increases in the numbers of PS-, OX-6 (RT1.B)-, CD4-, CD8, ED1-, and ED2-positive cells occurred earlier in BN rats than Wistar rats. At 8 weeks, deposition of PS and immunoglobulins was observed in hepatic fibrous septa and renal glomerular mesangium, and IgG1- and IgG2a-positive cells were found in the white pulp of the spleen. The present results suggest that humoral immunity probably regulated by MHC class II molecules and inflammatory cells may be involved in PS-induced hepatic fibrosis in rats.

Natural history and etiology of liver disease in patients with previous community-acquired acute non-A, non-B hepatitis. A follow-up study of 178 Danish patients consecutively enrolled in The Copenhagen Hepatitis Acuta Programme in the period 1969-1987

BACKGROUND/AIMS

Consecutive patients originally diagnosed with acute non-A, non-B hepatitis were followed up to assess the long-term morbidity and mortality and to re-evaluate the etiology in surviving patients.

METHODS

Follow-up was performed in 178 patients with acute non-A, non-B hepatitis enrolled in the Copenhagen Hepatitis Acuta Programme in the period 1969-1987. Mortality and morbidity were assessed using: i) death certificates and ii) diagnoses at discharge following all somatic admissions. All patients who were alive were offered a re-examination encompassing clinical, biochemical and virological evaluation.

RESULTS

After a median of 23 years, 71 (40%) had died and seven (4%) were untraceable. Overall mortality and mortality due to cirrhosis and accidents, mainly intoxication with drugs, were significantly higher compared to those of an age- and sex-matched Danish population. Chronic hepatitis had been diagnosed in 19 (11%) and cirrhosis in 16 (9%). Of 100 patients who were alive, 57 accepted a re-examination. Anti-HCV was detected in 24 (42%) and 19 (33%) were HCV-RNA positive. Of the viremic patients, 11 (58%) had elevated P-ALT, but only three (16%) had already been diagnosed with HCV infection. A history of intravenous drug use was tantamount to anti-HCV positivity.

CONCLUSIONS

Danish patients with community-acquired acute non-A, non-B hepatitis had an increased mortality due to liver cirrhosis during the first years after the acute infection. Alcohol was the etiological agent in several cases, but HCV infection may also have been present. However, the long-term HCV-related morbidity and mortality were low.

Parameters affecting the adsorption of ligands to polyvinyl chloride plates in enzyme immunoassays

In the present work, we studied the efficacy of three blocking agents (HSA, BSA and OVA) in the inhibition of non-specific binding to PVC plates. According to the inhibition data, 1% OVA was the most effective blocking agent. On the other hand, the presence of detergents in all of the blocking solutions drastically decreased the percent inhibition of the non-specific binding. Furthermore, the effect of ligand concentration on adsorption and the kinetics of ligand adsorption to PVC plates were also investigated. Ligand adsorption is a linear function of input up to a limit (around 8.70 ng/mm2) where saturation is reached. The rate of adsorption of pure human IgG to PVC plates was proportionally increased with the temperature, as shown by proportional rate constants almost 2 times faster at 37 degrees C than at 4 degrees C. These results have practical implications for investigators using PVC for immunoassays and should be taken into consideration when designing such assays.

Antibody to the hepatitis C virus in acute hepatitis and chronic liver diseases in Japan

In a 6-month follow-up study of acute hepatitis in Japan, 31 out of 41 (75.6%) cases of post-transfusion non-A and non-B hepatitis (NANB-PTH) and 14 out of 40 (35.0%) cases of sporadic non-A non-B hepatitis (NANB-SPO) were found to be positive for antibody to the hepatitis C virus (HCVAb). After 12 months of follow-up, 30 cases (81.1%) became chronic among 37 HCVAb positive acute NANB hepatitis cases. This figure shows a significantly higher rate of chronicity as compared with HCVAb negative acute NANB hepatitis. The prevalences of HCVAb in hepatitis B surface antigen (HBsAg) negative cases of chronic hepatitis and liver cirrhosis were 76.3% (200/262) and 66.7% (106/159), respectively, which were significantly different from the values of 5.1% (13/255) and 10.6% (13/123) observed in HBsAg positive cases. Of chronic liver disease cases positive for HCVAb, 45.8% (152/332) had a history of blood transfusion, in contrast to the value of 3.7% (13/352) observed in HBsAg positive cases of chronic liver disease that were negative for HCVAb.

A clinical study of immunoglobulin class specific antibody response following hepatitis A

Anti-HAV activity was determined by radioimmunoassay for serum fractions of IgG, IgM, and IgA separated with sucrose gradient centrifugation and immunoglobulin absorption using class-specific anti-immunoglobulin. Anti-HAV following hepatitis A was detected initially in IgM and IgA within one week after onset, and also detected in IgG within the next one week. IgM anti-HAV activity reached its peak level at the 21st-30th day of illness with a mean titer of 16.4 by RIA, and then declined gradually, whereas serum IgM concentration increased and reached the peak earlier, and no correlation was seen between them. IgG anti-HAV activity increased rapidly and it exceeded a RIA titer of 80 in 80 days from onset in 12 of the 18 cases. According to the kinetics of IgM and IgG anti-HAV, four types of antibody response following the disease were observed. However, no correlation between antibody response patterns and clinical findings was seen, therefore less relationship of anti-HAV to the liver cell injury was indicated. Furthermore, it was suggested that some immunological mechanisms controlled the level of antigen-specific antibody activity, which maintained the high level of IgM antibody in case of poor response of IgG antibody.

Thyroid gland volume and thyroid function during and after acute hepatitis infection

Thyroid function, the occurrence of goiter, and ultrasonically determined thyroid gland volume were investigated in 23 consecutive nonalcoholic patients with acute viral hepatitis during and six months after recovery, and compared with data obtained from 23 matched controls. Seven patients had clinically detectable goiter during disease, but only one after recovery (P less than 0.05). Median thyroid volume was 28 mL (range 15 to 42 mL) compared with 18 mL (range 12 to 27 mL) after recovery (P less than 0.001), and 17 mL (range 11 to 24 mL) in the controls (P less than 0.001). During acute hepatitis, serum levels of thyroxine, thyroxine binding globulin, and free thyroxine index were significantly increased while triiodothyronine and thyrotropin levels were unaltered and triiodothyronine resin uptake and free triiodothyronine index levels were decreased. After recovery all thyroid variables were normalized. In conclusion, acute liver disease was associated with a marked increase in thyroid volume, but the study did not clarify the mechanism underlying thyroid enlargement.

Morphological studies on the mechanism of hepatocellular injury during acute phase of infection in marmosets inoculated with hepatitis A virus

The histological changes during the acute phase of infection in the livers of marmosets inoculated with hepatitis A virus were examined. The acute phase was divided into four stages according to the liver enzyme changes and serological markers for the viral infection (Stage I, II, III, IV). Round cell infiltration in the portal tracts was first recognized in Stage I. Localization of parenchymal changes was predominantly periportal in Stage I, II, and IV, whereas the lesion was diffuse in Stage III. Hepatitis A virus antigen (HAVA) was widely distributed but spotty and the largest amount of HAVA was found in Stage II by immunofluorescent and immunoperoxidase study. By electron microscopy the endoplasmic reticulum was altered in the liver cells and in some area there was interaction between the hepatocytes and lymphocytes. These findings suggest that hepatocellular damages seen in this model are the result of immune response rather than cytotoxic effect.

Detection of Ross River virus immunoglobulin M antibodies by enzyme-linked immunosorbent assay using antibody class capture and comparison with other methods

An enzyme-linked immunosorbent assay based on antibody class capture was developed for the detection of Ross River virus-specific immunoglobulin M antibodies (RRV IgM). The assay was specific, reproducible and precise. When compared with conventional tests for the detection of RRV IgM, such as hemagglutination inhibition following sucrose density gradient centrifugation and indirect enzyme-linked immunosorbent assay, the class capture assay was more sensitive. In 186 sera which were collected from 39 patients with RRV infection over a period of 1-4 yr from onset of initial symptoms, RRV IgM persisted for at least 1-2 yr. Sera were tested both at a single dilution from which the results were expressed as a binding index and in a dilution series in which they were expressed as an antibody titre. Binding index values gave better discrimination between sera collected during acute and later phases of the disease and may be of greater value than antibody titres in the diagnosis of RRV infection.

Enzyme immunoassay for detection of total and IgM-specific antibodies to hepatitis A virus and its clinical application

Antibody to hepatitis A virus (anti-HAV) and IgM class antibody to HAV (IgM anti-HAV) in sera from 73 patients with hepatitis A and from 550 normal subjects were measured by enzyme immunoassay (EIA) and the results were compared with those of radioimmunoassay (RIA). Since RIA has the disadvantage of requiring radioisotopes and special equipment, the clinical applicability of EIA and possible methodological problems were evaluated. The EIA for anti-HAV showed an excellent correlation with RIA, indicating its usefulness for the demonstration of the immune status in these subjects. Positive results of anti-HAV were obtained in the early stage after the onset of hepatitis A. However, pretreatment for inactivation of samples was required. False-positive reactions were found in sera to which sodium azide was added as preservative. In the measurement of IgM anti-HAV, a fundamental study revealed quite satisfactory results, correlation with the results of RIA was excellent. In patients with hepatitis A, the titers reached a peak in the second to third week, followed by a gradual decline. Changes to a negative reaction were never encountered within three months. We concluded that the EIA is an useful tool in the diagnosis of hepatitis A and can replace RIA.

Hepatitis virus non-A, non-B: the cause of a major public health problem in India

Serological studies of hepatitis viruses A and B were carried out on 362 patients with acute viral hepatitis, 130 with fulminant hepatitis, and 56 with subacute hepatitis, and on samples of serum from 230 subjects during epidemics of viral hepatitis. A diagnosis of non-A, non-B viral hepatitis was made when serological tests showed that anti-HAV IgM and anti-HBc IgM were absent. Hepatitis virus non-A, non-B was the causative agent responsible for 58% of cases with acute viral hepatitis, 58% with fulminant hepatitis, 87% with subacute hepatitis, and 66% with epidemic hepatitis. A considerable proportion of patients (6-32%) were infected with both hepatitis virus non-A, non-B and hepatitis virus B. Viral hepatitis non-A, non-B is probably transmitted by infection of drinking-water and is the principal cause of hepatitis in India.

A comparison of enzyme-immunoassay and radioimmunoassay for detection of hepatitis A virus and antibodies against hepatitis A virus

A direct comparison has been made of tracers labelled with an enzyme and with 125I in solid phase enzyme-immunoassay (EIA) and solid phase radioimmunoassay (RIA) for the detection of hepatitis A virus (HAV) antigen and antibodies to HAV. By comparing the binding capacity of peroxidase-labelled anti-HAV-IgG and anti-HAV-F(ab)2 fragments tracers, anti-HAV-IgG was found to have a higher binding capacity than anti-HAV-F(ab)2 fragments in both EIA and RIA. For EIA 16.25-fold more anti-HAV-IgG was needed for one test probe compared to RIA and 32.5-fold more anti-HAV-F(ab)2 fragments. For the detection of HAV antigen from stool preparations and IgG and IgM antibodies against HAV, there were only minor quantitative differences in titre. EIA was as sensitive as RIA.

Etiopathogenetic aspects of hepatitis A II. Specific and nonspecific humoral immune response during the course of infection

The anti-HAV humoral immune response in the IgM, IgA, and IgG classes was analyzed weekly in 35 patients with clinically overt hepatitis A during the time of their hospitalization and 2-3 years afterward. In parallel, the dynamics of total immunoglobulins and complement C3 component (C3) levels were determined. The results suggest that the appearance of class-specific anti-HAV is compatible with the course of primary humoral immune response, with IgM and IgA anti-HAV, providing immunity in the early and intermediate phases of the infection, and IgG anti-HAV, providing immunity in the later phase. The overall appearance of anti-HAV, total immunoglobulins, and C3, do not support the view that liver injury is mediated by the humoral immune mechanisms. Instead, the hepatocyte damage is probably caused by direct viral cytotoxicity. This hypothesis is supported by a case of hepatitis A in a patient under immunosuppressive treatment.

Etiological spectrum of viral hepatitis and prevalence of markers of hepatitis A and B virus infection in north India

The etiological spectrum of viral hepatitis and the prevalence of serological markers of hepatitis A and B virus infection in healthy persons in north India were studied. Hepatitis A virus was found to be the most common cause of acute hepatitis in children (67%). It was a less frequent cause of this disease in adults (14%). Hepatitis A virus was only rarely the cause of acute (12%) and subacute (4%) liver failure. It was recorded as the etiological agent in an epidemic among schoolchildren. Exposure to hepatitis A virus occurs in early childhood, and by the age of 10 years, 90% of healthy persons have serological evidence of hepatitis A virus infection.Hepatitis non-A non-B virus was the cause of acute hepatitis in 44% of adults and 24% of children with this disease. This virus was also the most important etiological agent in acute liver failure (55%) and subacute hepatic failure (51%). It was the cause of all the hepatitis epidemics in the general population.Only 9% of hepatitis cases in children were due to hepatitis B virus whereas 42% of cases in adults were attributable to this virus. Hepatitis B virus was the causative agent in 33% of cases of acute hepatic failure and 45% of cases of subacute hepatic failure. The carrier rate for hepatitis B virus was 5% and antibody to hepatitis B surface antigen was found in up to 38% of specific population groups.

Nonculture techniques using blood specimens for the diagnosis of infectious disease

Recent technological advances have increased the use of blood as a source for diagnosis of local and systemic infectious diseases. Traditionally, viable organisms may be cultured from the blood and others identified microscopically. The ability to detect microbial products by physicochemical, bioactivity, and antigenic techniques and the ability to detect specific immunoglobulin M (IgM) responses to infection improve our diagnostic capabilities but also present new problems in determining clinical relevance. The diagnostic use and reproducibility of new tests should be verified by comparative clinical field testing before implementation.

Increased occurrence of hepatitis A with cyclic outbreaks among drug addicts in a Swedish community

To determine the prevalence of antibodies to Hepatitis A virus (anti-HAV) among drug addicts, sera collected in a Swedish city during a ten-year period from 234 drug addicts with acute hepatitis B were tested for anti-HAV. The results were compared with the normal population, where only 3.8% of those born after 1950 were anti-HAV-positive. In individuals born between 1941 and 1965, 8.2% in the normal population and 30.2% of the drug addicts were anti-HAV-positive (p less than 0.001). The level of immunity to hepatitis A among drug addicts ranged from 7.7% to 60% during the ten-year period. Low levels of immunity were seen in the years preceeding outbreaks of hepatitis A among drug addicts. These outbreaks occurred in a cyclic pattern. Higher levels of immunity were seen after each outbreak.

Liver histopathology of the hepatitis A virus infection: a comparison with hepatitis type B and non-a, non-b

Liver biopsies from 86 patients with serologically established acute hepatitis A were evaluated for quantitative and qualitative light microscopic features together with biopsies from 78 patients with acute hepatitis type B and 76 patients with acute hepatitis type non-A, non-B. Hepatitis A was characterised by more pronounced portal inflammation than hepatitis non-A, non-B (p less than 0.01) but less conspicuous parenchymal changes (focal necrosis, Kupffer cell proliferation, acidophil bodies, ballooning) than found in hepatitis type B (p less than 0.01). Steatosis occurred in 10% of the hepatitis A biopsies compared with 26% (p less 0.01) and 6% (not significant) in the hepatitis non-A, non-B and B groups, respectively. A comparison between the histological findings in women and men revealed that iron deposits occurred in more than half of the men compared to less than 20% of the women (p less than 0.01) irrespective of hepatitis type. Histological and biochemical follow-up was available in 36 patients with hepatitis A. For the majority of these patients the bilirubin concentration reached normal values within one month of the initial biopsy. The activity of serum transaminases showed good correlation with the degree of histological resolution. Non-specific reactive hepatitis with slightly raised serum transaminases were often seen during recovery from hepatitis A. These patients may be misinterpreted as cases of acute non-A, non-B hepatitis.

The long-term prognosis of non-transfusion-associated non-A, non-B hepatitis. A clinical, epidemiological, and histological investigation

In a prospective study of the natural course of acute hepatitis, 157 of 1020 patients with biopsy-verified acute hepatitis could be classified as having hepatitis type non-A, non-B. We here report on the long-term prognosis for these 157 patients. The main type of exposure was drug addiction (40%), whereas 40% had no known hepatitis exposure. Only two patients had received blood products (blood transfusion and factor VIII). Follow-up liver biopsy (mean histological follow-up, 22 months) in 94 of the 157 patients showed chronic liver disease in 15-that is, cirrhosis in 6, suspicion of cirrhosis in 2, chronic aggressive hepatitis in 5, and chronic persistent hepatitis in 2. There was a striking predominance of elderly women with no known hepatitis exposure and with a high frequency of autoantibodies in serum among the patients with progression to chronicity, whereas chronic non-A, non-B hepatitis in drug addicts or after blood transfusions seems to be a limited problem. A comparison of histological features in the initial biopsies from patients with progression to chronicity or complete resolution showed piecemeal necrosis and abnormal bile duct epithelium to be of prognostic value.

Acute hepatitis A, B and non-A, non-B in a Swedish community studied over a ten-year period

985 episodes of hepatitis representing 98% of all acute hepatitis episodes found in a Swedish city during a 10-year period were analyzed for anti-hepatitis A IgM antibodies and hepatitis B surface antigen. Hepatitis A was diagnosed in 311 episodes (32%), hepatitis B in 494 (50%), simultaneous acute hepatitis A and B in 12 (1.2%), and 168 episodes (17%) were classified as hepatitis non-A, non-B. The majority of the hepatitis A cases were drug addicts (58%), and all were concentrated in 3 outbreaks of 1-2 years duration. 16% of all hepatitis A cases were probably imported. Hepatitis B cases decreased significantly (p less than 0.001) between the first and second half of the study period. 47% were drug addicts. Hepatitis non-A, non-B was also dominated by drug addicts (61%). Approximately 20% of the cases in all 3 types of hepatitis had no identifiable source.

Use of conventional and IgM-specific radioimmunoassays for anti-hepatitis A antibody in an outbreak of hepatitis A

During a common source outbreak of hepatitis A, we studied the characteristics and utility of commercially available radioimmunoassays for total and IgM-specific antibody to hepatitis A virus. IgM hepatitis A antibody was detectable in all serum specimens obtained up to 119 days following onset from the seven persons with hepatitis A, and as long as 347 days in one person. Acute infection could also be documented by a four-fold or greater increase in titers of hepatitis A antibody, although as long as nine weeks was required between the times acute and convalescent specimens were obtained. The radioimmunoassay for IgM-specific hepatitis A antibody had greater specificity (99 percent versus 84 percent) and a higher positive prediction value (88 percent versus 23 percent) for the diagnosis of acute hepatitis A than did the radioimmunoassy for hepatitis A antibody. Uses of the radioimmunoassay for IgM-specific hepatitis A antibody include rapid diagnosis of acute hepatitis A, differentiation between recent and past hepatitis A infection, and screening for recent hepatitis A infection in epidemiologic investigation.

Light microscopic morphology of acute hepatitis non-A, non-B. A comparison with hepatitis type A and B

Liver biopsies from a total of 240 patients with acute hepatitis A (86 patients), B (78 patients) and non-A, non-B (76 patients) were blindly evaluated for quantitative and qualitative light microscopic differences. No qualitative differences separate the three types of hepatitis, but the frequency and degree of some histological features seem to be characteristic of acute human non-A, non-B hepatitis. The degree of focal necrosis and portal inflammation was less pronounced in the non-A, non-B group as compared to the hepatitis A and B groups (P less than 0.01). Twenty-six percent of the non-A, non-B liver biopsies showed steatosis as compared with 10% and 6% in the hepatitis A and B groups, respectively (P less than 0.01). Bridging necrosis only occurred in liver biopsies from patients with non-A, non-B and B hepatitis. Abnormal bile ducts were detected in a total of five patients, three of whom were found in the non-A, non-B group. A comparison between histological findings in non-A, non-B patients with and without a possible intravenous exposure revealed that steatosis, cholestasis, large piecemeal necrosis and confluent necrosis occurred with the highest incidence in the patients without intravenous exposure, indicating that non-A, non-B hepatitis may be caused by more than one etiological agent.

Azathioprine versus prednisone in non-alcoholic chronic liver disease (CLD). Relation to a serological classification

One hundred and forty-eight patients with non-alcoholic cirrhosis or chronic aggressive hepatitis entered a prospective, unblinded, randomized trial on the effect of azathioprine versus prednisone. For all 148 patients, there were no differences in survival related to the two drugs. In 99 patients the disease was classified as autoimmune, in 23 as posthepatitic, and in 26 as cryptogenic. No significant differences were seen in survival between these three groups of patients and no differences in survival related to the two drugs were registered within any of the groups. The autoimmune group included the patients with the biochemically most active disease, and a statistically significant reduction in activity was obtained with prednisone as well as azathioprine. Most remarkably, the frequencies of the autoantibodies were reduced parallel to the biochemical improvement in these patients. Immunosuppressive treatment was found to be rather ineffective in posthepatic chronic liver disease of type B; however, no signs of activation of the hepatitis B virus were seen.

Mortality after acute hepatitis type A, B, and non-A non-B in 981 patients followed up for up to 10 years

During 0-10 years of follow-up of 981 patients who had had biopsy-verified and serologically classified acute hepatitis, 50 died, which is 35 more than expected according to Danish mortality statistics. Four out of 284 with hepatitis type A died (expected, 1.8), and none of the deaths were due to liver disease or showed liver affection at autopsy. Out of 555 patients with hepatitis type B, 33 died (expected, 8.8); 1 died of subacute liver atrophy, and autopsy revealed cirrhosis in 2 who died of other causes. In the group of 142 with hepatitis type non-A non-B, 13 died (expected, 4.5); 5 had cirrhosis at autopsy, but death was caused by the liver disease only in 2 cases. The three liver deaths occurred among non-addicts (no. = 618), of whom 28 died (expected, 13.2). The drug addicts had a very high mortality, mainly owing to poisoning. This study suggests that during the first 10 years after acute hepatitis the mortality is slightly increased by the disease when of type B or non-A, non-B.

Chronic persistent hepatitis: serological classification and meaning of the hepatitis B e system

In order to evaluate the prognostic implications of the hepatitis B e system in patients with chronic persistent hepatitis (CPH), 53 consecutive patients were studied. Fourteen of 16 patients with HBsAg and HBeAg were followed from 12 to 120 months (mean, 38 months). Eleven of the 14 patients were persistently HBeAg positive and five of these developed chronic active hepatitis (CAH) or cirrhosis. A further nine patients were HBsAg positive but HBeAg negative at time of CPH diagnosis (mean follow-up, 47 months). One of these nine patients developed CAH during follow-up. The remaining 28 patients were all HBsAg negative, and only 2 or the 28 patients progressed to CAH or cirrhosis during the time of follow-up (mean, 43 months). It is concluded that the persistence of HBeAg in patients with CPH indicates a serious prognosis with a frequent transition to CAH or cirrhosis.

Use of an enzyme-linked immunosorbent assay for screening hybridoma antibodies against hepatitis B surface antigen

An enzyme-linked immunosorbent assay (ELISA) was developed for screening production of monoclonal antibodies with specificity for HBsAg. Mouse hybridoma IgG were firstly extracted from assay medium with goat anti-mouse IgG adsorbed on polystyrene beads. The specific antibody was revealed by saturation with HBs antigen from human positive sera followed by reaction with specific sheep anti-HBs antibody conjugated with peroxidase. The sensitivity was of the order of 0.5-1 ng/ml specific antibody and specificity was satisfactory. The assay permits easy identification of determinant specificity on screening.

IgM antibody to the hepatitis B core antigen in acute hepatitis determined by SPRIA--diagnostic value

A solid phase radio-immunoassay (SPRIA) was developed for the detection of anti-HBc IgM. The assay proved sensitive and easy to perform and rheumatoid factor did not affect the test results. Anti-HBc IgM titres were followed in consecutive samples from 15 patients after uncomplicated acute hepatitis B. In the acute phase anti-HBc IgM titres ranged from 10(-5) to 10(-7) (mean 10(-6.4)). One year after onset of disease ten of the 15 had titres below 10(-4) and between two and three years after onset most patients had titres 10(-3). Anti-HBc IgM titres were determined in six episodes of acute hepatitis B, all HBsAg negative but anti-HBc positive in the first samples obtained (within 8 days) and developing anti-HBs during convalescence. Acute phase anti-HBc IgM titres in these patients ranged between 10(-5.5) and 10(-7) (mean 10(-6.5)) and were thus identical with HBsAg positive cases. When acute phase sera from 168 episodes of acute hepatitis primarily classified as non-A, non-B, were tested for anti-HBc IgM titres above 10(-5), sera from 13 episodes were positive and in seven of these hepatitis B diagnosis could be confirmed by rising anti-HBs titres in convalescence. Sera from four of the 13 patients contained HBeAg, which was thus demonstrated in the absence of HBsAg. The results show that testing for anti-HBc IgM is important for a true non-A, non-B diagnosis.

Viral hepatitis in Danish children. Disappearance of an infection from its previous reservoir

Two hundred and eighty-five healthy Danish children aged between 7 and 17 years were studied for hepatitis B antigen and antibodies to hepatitis A and B. A positive response to each of these infections was found in 0.7% of them. During a 5-year period 40 children were admitted to hospital with viral hepatitis, 30 of whom had hepatitis A. Eighty-three per cent of these cases of hepatitis A were secondary to adult cases, or had resulted from foreign travel. Hepatitis A is no longer endemic in Danish children, and morbidity from hepatitis B or non-A non-B is negligible.

The spread of hepatitis A virus in connection with hepatitis cases in children's communities

In order to investigate the characteristics of hepatitis A virus excretion, 372 children in semi-closed day-care centres were examined at the time of the seasonal increase in hepatitis incidence. Enzyme immunoassay and immune electron microscopy were used to detect virus in faeces. Ten communities were surveyed and, for the purposes of this paper, were divided into four groups on the basis of the observed pattern of virus excretion. The first group consisted of 4 communities with one hepatitis case in each; in this group, there was a relatively low rate of virus excretion throughout the study. The second group comprised 2 communities with one or two hepatitis cases; this group was characterized by an increase in the rate of virus excretion some time after isolation of the patient. In the communities of the third group, there were numerous hepatitis cases and a high rate of virus excretion during the first weeks of observation, followed by a significant decrease. There were no hepatitis cases in the fourth group, but some hepatitis A virus shedding was detected.The ratio of the number of cases to the number of virus carriers was 1:11.4 in the first two groups, and 1:3.4 in the third. Administration of normal serum immunoglobulin did not significantly affect the rate of HAV excretion. The cause of the differences in shedding of hepatitis A virus in the communities is unknown, but may possibly be related to the size of the immune section of the population.

Acute type B hepatitis among HBsAg negative patients detected by anti-HBc IgM

A consecutive group of 169 patients with acute hepatitis found negative for hepatitis B surface antigen (HBsAg) and negative for IgM antibody against hepatitis A (anti-HAV IgM) was studied for presence of IgM antibody against hepatitis B core antigen (anti-HBc IgM) by ELISA. Anti-HBc IgM was found in a total of 34 of 60 patients with detectable total anti-HBc. One hundred and nine patients had no detectable anti-HBc IgM and no total anti-HBc and were thus considered as having acute non-A, non-B hepatitis. Among the 34 patients with anti-HBc IgM in their first serum sample, 23 were anti-HBs negative and all had high and steadily decreasing ratio unit (RU) values for anti-HBc IgM (mean RU value 17.1). Twelve of the 23 patients showed seroconversion to anti-HBs during the follow-up, indicating an actual hepatitis B virus infection. Eleven of the 34 anti-HBc IgM positive patients had anti-HBs in their first serum sample. In this group, the RU values for anti-HBc IgM were high and steadily declining and the initial values were significantly lower (mean RU value 9.9) (p less than 0.05) than in the anti-HBs negative group. Evidence is provided that anti-HBc IgM in serum from patients with HBsAg negative hepatitis with or without anti-HBs indicates an actual hepatitis B virus infection. According to generally accepted criteria, the demonstration of anti-HBc IgM identified 20% of the 169 patients with acute non-A, non-B hepatitis as having an actual hepatitis B infection.

Hepatitis A virus: virologic, clinical, and epidemiologic studies

The last decade has borne witness to accelerated expansion of our understanding of hepatitis A virus. The agent of type A hepatitis is an RNA virus with a mean diameter of 27 nm. and biochemical-biophysical properties of an enterovirus. A variety of sensitive specific serologic techniques have been developed with which to identify hepatitis A virus and antibody, and both chimpanzees and marmosets have been studied extensively as experimental animal models. As a result of these studies, in vitro cultivation of hepatitis A virus has finally been accomplished, and a commercial radioimmunoassay for IgM antibody to hepatitis A virus has been developed for the rapid diagnosis of hepatitis A virus infection during acute illness. Clinically the illness caused by hepatitis A virus is relatively mild, often subclinical, and of limited duration and does not progress to chronic liver disease. This relative clinical benignity is reflected, according to preliminary histologic observations, in the sparing of the centrozonal area of the liver lobule. Rarely, however, hepatitis A virus can cause fulminant hepatitis. Type A hepatitis is transmitted almost exclusively by the fecal-oral route, and its spread is enhanced by epidemiologic settings favoring dissemination of enteric infections. Hepatitis A virus does not contribute to transfusion associated or other types of percutaneously transmitted hepatitis. Exposure to the virus increases as a function of age and decreasing socioeconomic class, but the incidence of hepatitis A virus infection in urbanized societies is decreasing. There is no evidence for the existence of chronic hepatitis A virus carriage; natural perpetuation of hepatitis A virus in urban communities appears to depend on a reservoir of nonepidemic, clinically inapparent cases. Until a vaccine, now being developed, becomes available, prevention of hepatitis A virus infection will continue to depend on maintenance of high standards of environmental and personal hygiene and on timely administration of immune serum globulin. Such prophylaxis may confer long lasting passive-active immunity but more frequently prevents infection entirely.

Enzyme immunoassays for measurement of cytomegalovirus immunoglobulin M antibody

The diagnosis of congenital cytomegalovirus (CMV) infection is often accomplished by the detection of circulating antibody directed against CMV. We devised a method for measuring CMV-specific immunoglobulin M (IgM) based on the isolation of IgM antibody by reaction with a solid phase coated with antihuman IgM. The determination of IgM antibody specific for CMV was accomplished by the subsequent addition of CMV or control antigen and enzyme-labeled CMV antibody (solid phase-IgM method). We compared the sensitivity and specificity of this method with those of a conventional form of solid-phase enzyme immunoassay in which CMV antigen is bound to the solid phase (solid phase-antigen method). Both assay systems were capable of detecting CMV-specific IgM antibody in the sera of 10 babies with documented CMV infection and in those of the mothers of 4 of these babies. The solid phase-IgM method yielded negative results in all 66 sera available from babies who did not have congenital CMV infection. On the other hand, the solid phase-antigen system yielded false-positive results in 12 (18%) of these sera. In addition, the solid phase-antigen system yielded false-positive results in 8 of 12 sera obtained from patients with demonstrable rheumatoid factor. However, the solid phase-IgM system yielded negative results for the rheumatoid sera, provided that appropriate control reactions were performed. The solid phase-IgM system is thus a specific and sensitive method for the determination of CMV IgM antibody.

Comparison of two different enzyme immunoassays for detection of immunoglobulin M antibodies against tick-borne encephalitis virus in serum and cerebrospinal fluid

Two enzyme immunoassays for the detection in immunoglobulin M (IgM) antibodies against tick-borne encephalitis virus were compared, employing a solid phase coated either with antigen or with mu-chain-specific antiserum to human IgM. The latter IgM-capturing assay system proved to be more sensitive, and its superiority was especially prominent when high titers of tick-borne encephalitis virus-specific IgG antibodies in addition to specific IgM antibodies were present in the sample. The application of this test is a valuable extension of the diagnostic tools for the rapid diagnosis of tick-borne encephalitis by IgM detection. Since specific IgG does not interfere, diagnosis can be readily established when patients have already developed high titers of IgG antibodies relatively late after the onset of the disease.

Presence and meaning of anti-HBc IgM as determined by ELISA in patients with acute type B hepatitis and healthy HBsAg carriers

To evaluate the clinical implication of IgM antibody against hepatitis B core antigen (anti-HBc IgM), a consecutive series of 87 patients with acute type B hepatitis and 16 healthy carriers of hepatitis B surface antigen (HBsAg) were studied by a newly developed reverse ELISA technique. Anti-HBc IgM was present for at least 2 months in 81 of the 82 patients with HBsAg at the time of admission. Seroconversion from HBsAg to anti-HBs was observed in 38 patients during the time of observation, and in all patients, anti-HBc IgM was present until clearance of HBsAg. Thirty-three of the 38 patients remained anti-HBc IgM positive, at least until the appearance of anti-HBs. Quantitation of anti-HBc IgM by ratio unit (RU) values revealed that 3 of 8 patients with RU values greater than or equal to 5 for more than 6 months subsequently developed chronic liver disease, as compared to 1 of 72 patients with anti-HBc IgM above this level for less than 6 months. Anti-HBc IgM was demonstrated in 3% of 5 patients with total anti-HBc titer above 1:100 despite the presence of anti-HBs. In these patients, anti-HBc IgM steadily decreased after the onset of illness indicating a recent acute hepatitis B infection. Anti-HBc IgM was present in 12 of 16 healthy HBsAg carriers (75%). However, these 12 carriers had RU values between 2.5 to 5.5, compared with RU values above 5 (mean RU value 11.3) at the onset of illness in 80 of 82 HBsAg-positive patients with acute hepatitis. Anti-HBc IgM seems to be a specific serological marker for recent or ongoing hepatitis B infection which may be useful in differentiation between hepatitis B infection with or without HbsAg and acute non-A, non-B hepatitis.

Enzyme-linked immunosorbent assay for detection of immunoglobulin M antibody to hepatitis B core antigen

An enzyme-linked immunosorbent assay for detection of specific immunoglobulin M (IgM) antibodies against the core antigen of the hepatitis B virus (anti-HBc IgM) is described. The interference of IgM rheumatoid factor was evaluated quantitatively. In the anti-HBc IgM test, the rheumatoid factor gave false-positive results when the concentration exceeded 20 IU/ml. The rheumatoid-positive sera were disclosed by a control and retested for anti-HBc IgM after absorption of rheumatoid factor with latex particles aggregated with human IgG. In five of seven selected patients with acute hepatitis B followed to biochemical and clinical recovery, anti-HBc IgM was present transiently until antibodies against hepatitis B surface antigen (anti-HBs) appeared. Two patients had persistent anti-HBc IgM during the follow-up period. Four patients with hepatitis B surface antigenemia and progression to chronic liver disease did not clear their anti-HBc IgM in the period of observation (11 to 24 months). Anti-HBc IgM could not be demonstrated in 223 of 225 Danish blood donors. The two donors found positive for anti-HBc IgM also had anti-HBs. Twenty patients with acute A or non-A non-B hepatitis were negative for anti-HBc IgM. The enzyme-linked immunosorbent assay for anti-HBc IgM described here has a high specificity and sensitivity. The diagnostic relevance needs further evaluation, including quantitation of anti-HBc IgM, but the results presented indicate that anti-HBc IgM may be helpful in differentiating between prior and recent or ongoing hepatitis B infection.

Viral hepatitis in southeast Asian refugees

Five hundred sixty-four Vietnam refugees were studied for past or present infection with hepatitis A and B virus (HAV and HBV) by sensitive serological assays for hepatitis B surface and e-antigen and antibodies to HBsAg, HBeAg, HBcAg, and HAV. Fifteen percent of the men and 6% of the women were HBsAg-positive. Of these 66% were also positive for HBeAg. Serum transaminase values did not effectively differentiate between the infectious HBeAg carriers and the less infectious anti-HBe carriers. The HBsAg carrier rate did not increase by age after infancy, and among children, carriers clustered around HBsAg carrier mothers only. In contrast, the distribution of antibodies to the three HBV-associated antigens suggested continuous exposure throughout childhood, and a 90% prevalence rate was found at the age of 20 years. Screening for HBeAg in this new population group is necessary if appropriate precautions are to be taken, and if medical management of these patients is to be optimal. The prevalence of antibody to hepatitis A increases with age to 90% at 15 years. Among anti-HAV-positive children and adults IgM- anti-HAV was found in 8% of the children and none of the adults, indicating that only a few children may be in an infectious stage at the time of study, and therefore no specific prophylactic precautions are necessary.

Serum antibodies to oral Bacteroides asaccharolyticus (Bacteroides gingivalis): relationship to age and periondontal disease

An enzyme-linked immunosorbent assay microplate method was used for measuring levels of antibody specific for the oral serotype of Bacteroides asaccharolyticus (Bacteroides gingivalis) in serum samples obtained from umbilical cords, infants, children, periodontally normal adults, and edentulous adults. Serum from patients with various periodontal diseases, including adult periodontitis, localized juvenile periodontitis, generalized juvenile periodontitis, post-localized juvenile periodontitis, and acute necrotizing ulcerative gingivitis, were also studied. A positive correlation between increase in age and increase in both prevalence and level of specific antibody in the G, A, and M classes of immunoglobulins was observed. This indicates that antibodies reactive with oral B. asaccharolyticus found in up to 84% of normal adults are natural antibodies, presumably with a protective role. Among the patient groups, those with adult periodontitis were found to have levels of immunoglobulin G antibodies to oral B. asaccharolyticus that were five times higher than the antibody levels found in control subjects. The levels of IgG antibodies to this organism in the other patient groups were comparable to the levels found in the control group. However, 50% of the individuals in the generalized juvenile periodontitis group had high levels of immunoglobulin G antibodies to B. asaccharolyticus, suggesting heterogeneity with respect to immune response in these patients. These results indicate that antibodies to oral B. asaccharolyticus (B. gingivalis) occur at low levels in most normal children and adults and that the rise in titer of the specific antibodies of each major class of immunoglobulins parallels the ontogenic change in serum levels of that isotype. In contrast, there is a marked increase in titer of immunoglobulin G antibodies to oral B. asaccharolyticus in the group of patients with adult periodontitis and in patients with the generalized form of juvenile periodontitis.

Hepatitis A virus infection: pathogenesis and serodiagnosis of acute disease

The early development of immune electron microscopic (IEM) methods for the detection of HAV in acute-phase stool suspensions and antibody to HAV (anti-HAV) in serum made it possible to serologically identify cases of hepatitis A using paired acute and convalescent phase sera. Introduction of less cumbersome and time-consuming serologic test methods, including complement fixation (CF) and immune adherence hemagglutination (IAHA), made it feasible to rapidly assay larger numbers of specimens for HAV or anti-HAV. Subsequent development of sensitive immunofluorescence (IF) assays, solid-phase radioimmunoassays (RIA), and enzyme immunoassays (EIA) for HAV and anti-HAV heralded intensive laboratory studies of the biophysical and biochemical properties of the virus as well as efforts to define the pathogenesis and clinical course of disease. Results of the latter studies showed that the bulk of HAV was usually excreted in stool before the onset of clinical symptoms. Other serologic studies demonstrated that all acutely ill patients had circulating anti-HAV IgM, while all convalescent patients were positive for anti-HAV IgG. The development of sensitive serologic tests (RIA and EIA) that could differentiate between anti-HAV IgM and IgG made it possible to serodiagnose an acute case of hepatitis A using a single-phase serum specimen.