Seroepidemiological investigation of patients and family contacts in an epidemic of hepatitis A

Immunogenicity of an inactivated hepatitis A pediatric vaccine: three-year post-booster follow-up

The persistence of anti-hepatitis A virus antibody concentrations was followed over 3 years in 177 healthy children following primary and booster vaccination with an inactivated hepatitis A vaccine, Avaxim 80 pediatric. Seroconversion rates (post-immunization anti-HAV antibody concentration >or=20 mIU/mL) and geometric mean concentrations (GMC) were estimated for each of three age groups: 18 month--3 years, 4--8 years, and 9--15 years. Only subjects who were initially HAV-seronegative at inclusion (<20 mIU/mL) were analyzed. Follow-up visits at years 1, 2, and 3 involved 177, 149, and 135 children, respectively. A decline in GMCs of about 74% occurred during the first year, from 3,060 to 814 mIU/mL overall, but did not continue during years 2 and 3. All subjects remained seropositive (antibody concentration >or=20 mIU/mL), with overall GMCs of 814, 891, and 924 mIU/mL in years 1--3, respectively. The inactivated hepatitis A study-vaccine resulted in sustained seroprotective antibody concentrations in 100% of these children, without a significant decline in antibiotic concentrations over the 3 years following booster injection, thus demonstrating the long-term protection expected with this vaccine.

Safety, immunogenicity and antibody persistence of an inactivated hepatitis A vaccine in 4 to 15 year old children

Among 277 healthy Venezuelan children, aged between 4 and 15 years, who were screened for hepatitis A virus (HAV) antibodies, 118 seronegative children were enrolled in an open study. Each child received one dose of the Pasteur Mérieux Connaught inactivated hepatitis A vaccine (AVAXIM¿trade mark omitted¿, 160 antigen units), followed by a booster dose 24 weeks later. All seronegative subjects seroconverted 2 weeks after immunisation (antibody titres greater, similar20 mIU/ml), and antibody titres were still over greater, similar20 mIU/ml after 24 weeks, at the moment of the booster dose. The anti-HAV antibody geometric mean titre (GMT), as measured by a modified radio-immunoassay (HAVAB(R), Abbott Laboratories, North Chicago, IL, USA), was 73.7 mIU/ml, 2 weeks after the first dose. Four weeks after the booster, the GMT value reached 6999 mIU/ml, representing a 29.6-fold rise from pre-booster levels. One year after the booster dose, the GMT value was 1673 mIU/ml in the 92 subjects who provided blood samples at this time, all of whom were still seroconverted ( greater, similar20 mIU/ml). No serious adverse event related to the vaccination occurred during the study. No immediate systemic reaction occurred. Local reactions were reported by 9.3% of subjects who received the primary injection and 5.5% of those given the booster dose. The systemic reactions were mainly fever and myalgia reported over the 7 days following the injection by 3.4% of subjects after the first dose and 5.5% of subjects after the booster dose. A clinically significant elevation of serum transaminase from pre-immunisation levels was noted in one subject (AST level 2.2 times the upper normal limit) 2 weeks after the first injection, although this was not associated with any clinical signs of impaired liver function. This trial demonstrated that AVAXIM¿trade mark omitted¿ containing 160 antigen units is safe and highly immunogenic in healthy children aged between 4 and 15 years, and could be included in the childhood vaccination schedule to control infection in areas endemic for hepatitis A.

Comparison of two immunization schedules with an inactivated hepatitis A vaccine (AvaximTM)

BACKGROUND

Inactivated hepatitis A vaccines are licensed with a vaccination schedule based on two injections of vaccine given at least 6 months apart.

METHODS

Two vaccination schedules for the inactivated hepatitis A vaccine, AvaximTM (Pasteur Mérieux Connaught, Lyon, France), were compared in a monocentric, randomized, open trial. Two doses of the vaccine were given at intervals of either 6 months (0-6 month group) or 12 months (0-12 month group) to 96 adult volunteers. Anti-hepatitis A virus (HAV) antibody titers were determined in a blind fashion using the modified RIA (mRIA) HAVABtrade mark assay. After excluding subjects with positive preimmunization anti-HAV titers and those with protocol deviations, both groups were still comparable by sex ratio and mean age.

RESULTS

Four weeks (28 6 4 days) after the first dose, the seroconversion (SC) rate of initially HAV-seronegative subjects (antibody titer < 20 mIU/mL) was 100% in the 0-6 month group and 96. 9% in the 0-12 month group, with corresponding geometric mean titer (GMT) values (95% CI) of 369 mIU/mL (274-497 mIU/mL) and 445 mIU/mL (292-679 mIU/mL), respectively. After 6 months, SC was obtained in all subjects, and the corresponding GMT values were 349 mIU/mL and 359 mIU/mL in the 0-6 month group and the 0-12 month group, respectively. Four weeks after the booster dose given at 6 months, a 14.5-fold rise in GMT was observed. In the 0-12 month group, anti-HAV GMT values decreased by only 20% from 6 months to 12 months with a pre-booster GMT value of 286 mIU/mL at the 12-month evaluation. Four weeks after the booster given at 12 months, a 22. 5-fold rise in GMT was observed. Statistical analysis showed that the two vaccination schedules were comparable in their ability to boost antibody titers. Unsolicited reactions to vaccination were not different to those reported during earlier trials. Less than 12% of the vaccinees reported reactions after the first dose (11/93), or after the booster dose (11/92).

CONCLUSIONS

This trial demonstrated antibody persistence is excellent for at least 12 months after one dose of this vaccine, and that a booster may be given at any time between 6 and 12 months after primary immunization.

Does immunoglobulin interfere with the immunogenicity to Pasteur Mérieux inactivated hepatitis A vaccine?

BACKGROUND/AIMS

The aim of this study was to compare the immunogenicity of Pasteur Mérieux (P.M. s.v.) inactivated hepatitis A vaccine when given alone with its immunogenicity when given in combination with immunoglobulin.

METHODS

We enrolled 80 healthy volunteers who were seronegative for anti-HAV. Forty subjects (group A) were given two doses of vaccine at 0 and 6 months plus 4 ml of immunoglobulin given simultaneously with the first vaccine injection; and 40 subjects (group B) were given vaccine alone. The population characteristics (age, sex, height and weight) of the two groups were comparable.

RESULTS

Anti-HAV antibody was detectable at week 1 in 100% of group A and in 5.7% of group B, and in 100% of both groups at 4 and 8 weeks. Seroconversion rates (> or = 20 mIU/ml) were 97.4% in group A and 100% in group B at week 24 and were 100% in both groups 4 weeks after a booster injection at 6 months. The antibody response level was lower after concomitant administration of vaccine with immunoglobulin. The antibody geometric mean titer was higher at week 1 in subjects who had been given vaccine and immunoglobulin, but nearly 50% lower at week 4 and thereafter, indicating inhibition of the vaccine-induced immune response by immunoglobulin. At week 28, i.e. 4 weeks after the booster injection, geometric mean titers had increased about 13-15 times in both groups, reaching highly protective antibody levels (3351 mIU/ml in group A and 5843 mIU/ml in group B). No serious adverse effects were observed during the follow-up.

CONCLUSIONS

These data indicate that P.M. s.v. hepatitis A vaccine is highly immunogenic and safe, even when given simultaneously with immunoglobulin. Despite the interference of the immunoglobulin with the active immune response, individuals who were immunized passively plus actively also developed high titers of anti-HAV antibody. It is therefore reasonable to expect that this inhibition will not affect the overall protection conferred by the vaccine.

Immunogenicity and safety of a new inactivated hepatitis A vaccine in a comparative study

A multicentre, controlled, randomised, open, comparative trial including 839 healthy adult volunteers was carried out in order to compare the immunogenicity and reactogenicity of two vaccines against hepatitis A virus (HAV) during primary immunization and after booster injection. The first vaccine was produced by Pasteur Mérieux (PM), and the second vaccine by Smith-Kline Beecham (SKB). The vaccination schedule consisted of 2 doses (months 0, 6) for PM and 3 doses (months 0, 1, and 6) for SKB. Two weeks after the first dose, the seroconversion rates among initially HAV seronegative subjects (n = 608) were 93.4% and 76.1% for the PM and SKB vaccines, respectively, the corresponding geometric mean titres (GMTs) were 59.0 mIU/ml versus 30.8 mlU/ml (modified RIA HAVAB assay, Abbott Laboratories). Two months after the beginning of immunization (one dose versus two doses) the GMTs were 138.4 and 161.6 mlU/ml, respectively. At month 7, the seroconversion rates were 100% for both vaccines, and the GMTs were 4,189 and 3,163 mlU/ml, respectively. After the first dose of vaccine, 24.6% and 19.6% of the PM and SKB vaccines reported local reactions. The rates for systemic reactions were 27.2% and 25.0%, respectively. Lower rates for local and systemic reactions were seen after booster injections and statistical differences were not observed between the two vaccines. The study also demonstrated that vaccination was as well tolerated in subjects with anti-HAV antibodies as in HAV seronegative subjects. Logistic regression analysis revealed a significant vaccine effect on seroconversion rates only at week 2 (P < 10(-4). The same conclusions were drawn from the analysis of GMT by multivariate regression.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunogenicity trial of inactivated hepatitis A virus vaccine in human volunteers

An inactivated hepatitis A virus (HAV) vaccine was tested on a group of human adult volunteers. The vaccine was administered subcutaneously, and a control group received a placebo (aluminium hydroxide). The vaccine was found to be relatively well tolerated and non-reactogenic, and levels of anti-HAV were comparable to those in other studies.

Detection and characterization of subgenomic RNAs in hepatitis A virus particles

Defective viral particles containing deleted genomes were detected in harvests of cell cultures infected with various HAV isolates. The most prominent deletions were identified within the region of the genome coding for structural proteins. In this location three different deletions spanning nts 930-4380 (A), 1140-3820 (B), and 1370-3240 (C) were characterized. In addition to these internal deletions, various truncated RNAs were detected lacking either partially or completely the 3' terminal region which is supposed to code for viral replicase. RNA molecules with internal deletions as well as those with 3' terminal truncations could also be extracted directly from infected cells. During multiple consecutive passages of a given HAV strain, deletions A, B, and C accumulated and a quantitative increase of deleted RNAs occurred. Type and predominance of deletions varied with virus strains (CLF, GBM, MBB11/5, HM175, CR326, H141) and with the type of cells used for propagation (MRC-5, BGM, HELF, PLC/PRF/5). However, within the limits of the reliability of S1 analysis the endpoints of deletions A, B, and C were conserved. The mechanisms leading to formation of deletions remain unclear. Yet, some sequences flanking internal deletions showed homology with common splice signals and 3' terminal truncations proved to be confined to a distinct region within the genome.

Shifts in the rates and levels of antibody to hepatitis A virus associated with hepatitis A infection in children's communities

In order to investigate the shift in the rates and levels of antibody to hepatitis A virus, 567 children in 20 isolated groups of five day-care centers were observed over a period of 8 months during which the seasonal rise in hepatitis A morbidity occurs. Increases in the proportion of seropositive ranging from 5 to 37% were demonstrated in 6 groups, and were always associated with the occurrence of either overt or sub-clinical hepatitis A infection. High rates of seropositivity were also noted in the groups in which cases of hepatitis A had been registered prior to the period of observation. In some children with low and medium antibody levels, antibody titres showed further increases after reinfection. A substantial part of children retained low antibody titres during the entire period of observation, and eight previously sero-negative children developed low antibody levels after asymptomatic hepatitis A infections. In one group the spread of hepatitis A infection (clinical and asymptomatic) was prevented by the administration of commercially available immunoglobulin immediately after the discovery of an infected food handler. Passive antibodies were found in previously sero-negative children, and these antibodies dropped to undetectable levels two months after administration.

Evidence of hepatitis A infection in immature rhesus monkeys

Forty immature (less than 2 years old) rhesus monkeys (Macaca mulatta) with marked increases in aspartate and alanine aminotransferase activities were examined. Serological and histopathological evaluations were done to determine if affected animals were infected with hepatitis A virus. Although no clinical signs of illness were noted in any of the monkeys, an excellent correlation was found between the increased serum aminotransferase values and seropositivity with the acute phase (IgM) HAVAB-M antibody. Histopathological evaluations of livers of selected animals revealed hepatic lesions consistent with those in chimpanzees and marmosets infected with hepatitis A virus: generalized activation of sinusoidal lining cells, focal hepatocellular necrosis with occasional acidophilic bodies, and cuffs of mononuclear cells in the portal areas. Although no animals were seropositive for HAVAB upon receipt from the breeding colony, a total of ten of 18 animals for which serological data were available had seroconverted to HAVAB positivity during the 4-month observation period. These results are consistent with hepatitis A infection in immature rhesus monkeys and indicate the potential significance of serological testing in animals in which hepatic function is being evaluated.

Replicative events in hepatitis A virus-infected MRC-5 cells

Replication of hepatitis A virus (HAV) in MRC-5 cells was studied under one-step growth conditions. Viral replication neither interfered detectably with cellular DNA, RNA, and protein synthesis, nor could cytopathologic changes be recorded over a prolonged period of incubation. Synthesis of mature, infectious HAV particles could be detected as early as 2-4 days p.i. and occurred at a maximal rate around 8 days p.i., shortly before infectivity titers reached a plateau. Synthesis of total viral RNA, of positive-strand genomic RNA, of viral mRNA, as well as of negative-strand RNA followed the same pattern. By Day 14 p.i., when active HAV replication had developed into persistent infection, synthesis of viral RNA declined to background levels. The mechanism(s) guiding active HAV replication into a state of persistent infection could not be positively defined. Yet there exists the possibility that this is brought about by down regulation of viral RNA synthesis. Whether this is related to the appearance of a subgenomic viral RNA molecule about 2000 nucleotides in length and detected in association with ribosomes on Days 7 and 10 p.i. remains to be shown.

Antibody to hepatitis A virus after overt and asymptomatic hepatitis A infection

The titres of antibody to hepatitis A virus (anti-HAV) were found to fall rapidly during 3-4 years after hepatitis A and more slowly thereafter, though they never reached undetectable levels in at least 23 years. The levels of anti-HAV in convalescents after overt hepatitis A were found to be significantly much higher than in those who had anti-HAV as a result of asymptomatic infection.

Serological hepatitis A virus infections and ratio of clinical to serological infections in a controlled trial of pre-exposure prophylaxis with immune serum globulin

Seroconversion to hepatitis A virus was studied in a sub sample of 802 Israeli military recruits (611 men and 191 women) who were taking part in a randomised controlled trial of pre-exposure immune serum globulin (ISG) for the prevention of viral hepatitis. On intake into the service 35% of the men and 47% of the women were negative to hepatitis. A virus antibody (anti-HAV). After three years 7 of 71 men (9.9%) who had not received pre-exposure ISG had become positive to anti-HAV compared to 2 of 83 (2.4%) who had received it; the statistical significance of this difference was p = 0.052. At two years 2 of 30 women (6.7%) who had not received ISG had converted compared to 1 of 43 (2.3%) who had received ISG (p = 0.37). Pooling the sexes gave conversion rates of 8.9% in those not immunised and 2.4% in those immunised (p = 0.029). The sex adjusted odds ratio was 4.0 (95% confidence limits 1.3-19.0). The morbidity rates for clinical non B hepatitis over the three year period among 12 835 men were 7.2 per 1000 in those not immunised and 3.6 per 1000 in those immunised (p = 0.004). Point estimates of the ratio of clinical hepatitis to seroconversion in men ranged from 0.25 to 0.30. It is concluded that pre-exposure administration of ISG effectively prevented clinical expression of viral hepatitis, apparently reduced seroconversion, and did not induce passive-active immunisation.

Etiopathogenetic aspects of hepatitis A. I. Excretion of hepatitis A virus, biochemistry of liver function, and humoral immune response in patients with hepatitis A on admission to hospital

The excretion of hepatitis A virus (HAV) in stools from 30 patients with clinically overt hepatitis A infection on the day of their admission to the hospital was determined and compared with the dynamics and values of biochemical indices of hepatocyte injury as well as with the immune response to HAV. Virus was found in 16 out of 30 stools (53%) collected within 1 week after the appearance of clinical symptoms. In sera obtained on the day of hospitalization both IgM and IgA anti-HAV were detected in all of the 30 patients, while IgG anti-HAV were found in 20 (67%). There was a correlation between HAV excretion and increasing SGPT upon admission to hospital, while the level of SGPT or bilirubin as well as presence or absence of IgG anti-HAV did not correlate with excretion of HAV. HAV from stools was characterized morphologically and physicochemically. The majority of particles visualized by immune electron microscopy had electrondense appearance, while electron-lucid particles were only occasionally encountered. Isopycnic banding of HAV in CsCl revealed a broad range of densities with HAV activity. Rebanding of pooled fractions containing HAV revealed peak amounts of the virus in fractions with densities 1.32-1.33 gm/cm3.

Propagation and assay of hepatitis A virus in vitro

Ten strains of hepatitis A virus (HAV) originating from far distant geographical locations were adapted to growth in PLC/PRF/5 (human hepatoma derived and/or MRC-5 (human embryonic lung) cells. In the course of primary adaptation some of these strains exhibited a predilection for distinct cultural conditions such as type of host cell and temperature of incubation. With progressive passage, variant viruses with quite different requirements could be selected; yet, it proved impossible to isolate a virus which replicated equally well in both types of cells and at both 32 and 37 degrees C without at least one preceding passage under the new conditions. Analysis of the virus/cell relationship of well adapted HAV strains revealed that the replication cycle of HAV extends over about 24 h. Moreover, replication evidently passes from a state of active production of infectious virus to a phase during which hepatitis A antigen (HAAg) is synthesized and terminates in the state of persistent infection with markedly reduced synthetic activity. In all three phases replication of HAV is non-cytolytic and the vast majority of both infectious virus and of HAAg remains cell associated. The observations concerning the growth characteristics of HAV were used to develop two rapid in vitro assay systems for HAV infectivity (fluorescent focus assay and in situ RIA). Finally, the conditions for large scale production of infectious HAV and of HAAg in a cell factory system were analysed.

Hepatitis A-virus in cell culture. IV. Comparison of cell-culture-produced HAV with stool-derived HAV in diagnostic test systems

Hepatitis A-virus produced in Frhk-4/R cells is used and compared with stool-derived HAV as an antigen in diagnostic test systems. It is shown that the two antigens react identically in the anti-HAV test with anti-HAV-IgG positive human sera. In the anti-HAV-IgM test, too, stool-derived HAV and cell-culture-produced HAV react very similarly. The titres of anti-HAV-IgG and anti-HAV-IgM positive sera, obtained with stool and cell-culture HAV in quantitative antibody determinations, are shown to be identical. It is shown that the problem of HAV antigen production can now be solved by propagation of HAV with Frhk-4/R cells and that this antigen is very useful in diagnostic test systems.

Serodiagnosis of viral hepatitis A: rise in antibody titre and evaluation of three methods for detecting early and late antibodies

A serological investigation was made on patients with viral hepatitis A and individuals with a past history of this disease. Titration of antibody in sequential samples was found to be of no help in diagnosis. Separation of early (IgM) from late (IgG) antibodies by protein A or by 2-mercaptoethanol did not prove to be convenient for the serodiagnosis. A chromatographic separation of late and early antibody was found to be satisfactory, and equivalent to a radioimmunoassay for IgM-antibodies.

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.

Viral hepatitis: a four-year hospital and general-practice study in Sydney. 2. Transmission of viral hepatitis among residential contacts in Sydney

Clinical and serological study of household contacts of index patients suffering from acute viral hepatitis showed the high infectivity of hepatitis A viral (HAV) for susceptible contacts. The anti-HAV specific IgM developed in sera of 67% of susceptible children and 31% of susceptible adult contacts. Of 81 susceptible contacts whose sera became anti-HAV positive, 28.4% developed clinically overt hepatitis. Administration of human immunoglobulin reduced the rate of clinical expression of hepatitis A among susceptible contacts; it also appeared to reduce the actual infection rate. The infection rate among susceptible adult contacts of adult index cases suffering from hepatitis B was 24%. Of 25 susceptible contacts whose sera became HBV-marker positive, 24% developed clinical illness. Transmission occurred probably both by parenteral and non-parenteral means. It is currently not possible to determine susceptibility or seroconversion to hepatitis non-A non-B agents.

Excretion of hepatitis A virus in the stools of hospitalized hepatitis patients

A study was carried out to determine whether hepatitis A virus (HAV) can be detected in the stools of patients hospitalized for HAV infection. Acute phase samples of whole blood and stool, as well as completed questionnaires, were obtained from 31 patients hospitalized at any of 13 hospitals in the Phoenix metropolitan area. Blood specimens were tested for hepatitis B surface antigen (HBsAg), IgG antibody to HAV (IgG anti-HAV), and IgM antibody to HAV (IgM anti-HAV). Stools were tested for HAV by radioimmunoassay. Five patients (16.1%) had acute hepatitis B, five (16.1%) had acute non-A/non-B hepatitis, and 21 (67.7%) had acute hepatitis A. Of these 21 patients with acute hepatitis A, 11 (52.4%) were found to have HAV in their stools. These results confirm the potential for infectivity of stools of patients hospitalized for hepatitis A and emphasizes the need for caution when dealing with such stools.

[Hepatitis A antibody: placental transmission and disappearance in the first year of life (author's transl)]

Sera of 114 mothers and their newborn (cord blood) were tested for the presence of antibodies to hepatitis A virus (Anti-HAV) by a competitive solid phase radioimmunoassay. Antibodies were detectable in 80 pairs of sera but not in another 31 pairs. 3 newborns proved to be anti-HAV positive, while their mothers had not detectable antibodies. 72 infants could be followed up for about one year. The disappearance of antibodies occurred between the first and 14th month of life. 50% of the tested infants were still(Anti-HAV positive at the age of 7-8 months.

Characterization and classification of virus particles associated with hepatitis A. III. Structural proteins

Hepatitis A virus was purified from fecal samples collected at various times in the incubation period of patients with naturally acquired hepatitis A. The proteins of particles banding at around 1.34 g/ml in CsCl and sedimenting at about 160S were radioiodinated in vitro and separated by electrophoresis on polyacrylamide gels in the presence of 0.1% sodium dodecyl sulfate and 8 M urea. Under these conditions, the capsid proteins resolved into four polypeptides with molecular weights of approximately 31,000, 24,500, 21,000, and 9,000, respectively. A fifth protein of about 40,000 daltons in size and assumed to be equivalent to the precursor polypeptide VP0 of the picornaviruses was present in particles sedimenting at only 150 to 155S and banding at around 1.33 g/ml in CsCl. The physicochemical characteristics of these particles are consistent with those of the provirion structures of picornaviruses. In several of the fecal samples, these particles represented a considerable fraction of all particles present. The significance of this finding with respect to the antigenicity of hepatitis A antigen extracted from stool specimens is discussed.

Propagation of hepatitis A virus in human embryo fibroblasts

human diploid fibroblasts and human primary liver cell carcinoma cells (PLC/PRF/5) were infected with hepatitis A virus (HAV) adapted to growth in cell culture or derived directly from human stool. Viral antigen was expressed in PLC/PRF/5 cells 28 days after infection with cell culture-adapted HAV, and 50 days after infection with virus from human stool. In human fibroblasts the periods until first expression of viral antigen were 90 and 210 days, respectively. During further passages of HAV in fibroblasts the time of first appearance of antigen decreased to about 28 days. Biophysical properties of HAV extracted from infected fibroblasts were comparable to those of HAV derived directly from human stool. Immunofluorescence studies showed that the antigen was located exclusively within the cytoplasm of the infected fibroblasts. Kinetics of antigen production indicated that an equilibrium between virus multiplication and cell metabolism was reached in persistently infected fibroblasts.

Serodiagnosis of viral hepatitis A by a solid-phase radioimmunoassay specific for IgM antibodies

A solid-phase radioimmunoassay for detecting specific IgM antibodies to hepatitis A virus (HAV) was developed and characterized. The test utilized microtiter plates coated with anti-IgM to specifically absorb the IgM antibodies from the test serum. The anti-hepatitis A IgM antibodies are measured by the specific consecutive binding of hepatitis A antigen and radiolabelled anti-hepatitis A antibodies (anti-HA). In 6 chimpanzees infected with HAV, IgM anti-HA was detected from about the first date of elevated transaminases and was positive for about 3 months. The usefulness of the test was confirmed by testing acute phase sera of 30 patients from a common source outbreak of epidemic hepatitis, and negative sera from 2 control groups. A collection of serum specimens from 190 patients with sporadic HBsAg-negative hepatitis in Brazil was also tested and an etiologic association with HAV was confirmed in the majority of these cases.

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.

Epidemic and endemic hepatitis in India: evidence for a non-A, non-B hepatitis virus aetiology

69 serum pairs from two common-source water-borne outbreaks and one series of endemic cases of hepatitis in three parts of India were tested for hepatitis A and hepatitis B virus infections. None of the patients had evidence of HAV infection and only 10.1% had evidence of HBV infection. A large proportion of hepatitis in India seems to be caused by previously unrecognised agents.

Hepatitis A-virus in cell culture: I. propagation of different hepatitis A-virus isolates in a fetal rhesus monkey kidney cell line (Frhk-4)

A fetal rhesus monkey kidney cell line (Frhk-4) was infected with different hepatitis A-virus (HAV) isolates GBG, GBM, GJA. The time-dependent absorption of the HAV isolates of Fhrk-4 cells was measured. Replication of all three isolates in these cells could be demonstrated intracellularly 8--10 weeks after infection, and release of HAV into the supernatant some 10--15 weeks after infection could be shown. The specificity of the virus determination by RIA from supernatants of HAV-infected cells from passages 1, 2, and 3 in Frhk-4 cells was shown with sera that were collected from a chimpanzee infected with MS-1 both before infection as well as during convalescence. These results were subsequently compared with sera collected from human patients before the onset of hepatitis as well as during convalescence. With immunofluorescence microscopy a cytoplasmic fluorescence could be shown in HAV-infected Frhk-4 cells and finally the release of 27 nm HAV particles into the supernatant of HAV-infected Frhk-4 cells could be demonstrated by immune electron microscopy.

Serum immunoglobulin levels in hepatitis non-A, non-B: a comparison with hepatitis A and B

The serum levels of IgA, IgG and IgM were determined by the single radial immunodiffusion method in 86 patients with acute viral hepatitis serologically differentiated by radioimmunoassays. The levels of IgA and IgG were similar in patients with hepatitis A, B and non-A, non-B, while differences in IgM levels were observed between the three groups. The hepatitis non-A, non-B group had significantly lower levels of IgM than both the hepatitis A and hepatitis B group, a finding which may be diagnostically useful if hepatitis A serology fails.

Hepatitis A outbreak in a residential school

Outbreaks of hepatitis A occurred sequentially in two wards for children in a residential institution for the mentally retarded in Sydney. Twenty-six of 41 children were initially susceptible to hepatitis A. In the first ward affected, 11 of 13 susceptible children (85%), and in the second ward, four of 13 susceptibles (31%), were infected. Of the 15 showing serological evidence of infection, five (33%) were clinically jaundiced.

IgM responses to hepatitis-A virus and hepatitis-B core antigen in acute and chronic liver disease in Malawi; possible role of non-A, non-B, hepatitis

Of 33 patients with acute hepatitis in Malawi, 21 had infection by hepatitis-B virus (HBV), five by hepatitis-A virus (HAV) and seven, who had no markers of current HBV or HAV infections, were probably infected by the agent(s) of non-A, non-B, hepatitis. 87 of 88 sera from persons without liver disease contained antibody to HAV and 49 antibody to hepatitis-B surface antigen (anti-HBs) (six were positive for hepatitis-B surface antigen). The diagnosis of recent infection by HAV was made by detecting HAV-specific IGM in single serum samples and, although such tests showed that HAV caused acute hepatitis, its absence in patients with chronic liver disease suggests that, unlike HBV, infection by HAV does not play a role in chronic liver disease in Malawi. Anti-hepatis-B core antigen (anti-HBc)-specific IgM was detected in 19 of 21 patients with acute HBV infection, in three of five HbsAg-positive patients with cirrhosis, but in none of five HbsAg-positive patients with hepatoma.

Hepatitis A diagnosis in man: radioimmunoassay for hepatitis A antigen detection in faeces

A new radioimmunoassay (RIA) procedure using a double-sandwich technique was developed for the detection of hepatitis A antigen (HAV) in crude faecal extracts for patients involved in three outbreaks of type A hepatitis. Stools were obtained from 24 residents suffering from acute hepatitis A and from six children who remained asymptomatic throughout the epidemic. In addition, the HAV detection was performed in sera from 13 patients with hepatitis. HAV was detected in stools as early as five days before and as late as five days after the onset of jaundice. In this procedure, positive activity was only found in stools from patients with type A hepatitis, but not in negative controls. HAV was not detected in acute-phase sera. The double-sandwich RIA test used appears to be a reliable test for the large-scale screening of HAV in stool samples from patients suffering from type A hepatitis.

Comparison of solid phase test systems for demonstrating antibodies against hepatitis A virus (anti-Hav) of the IgM-class

Three methods were compared for determining anti-HAV of the IgM class. In the first method flat-bottomed microtiter plates coated consecutively with anti-HAV of the IgG class and HAAg were incubated with patient serum and, after washing, peroxidase conjugated anti-mu was added. After subsequent incubation with substrate the enzymatic reaction was stopped and the optical density was measured. In the second method the solid phase was coated first with antibodies to IgM and after incubation with patient serum and subsequent incubations with HAAg and 125I anti-HAV of the IgG class radioactivity was counted. These two methods were compared with reorienting sucrose gradient ultracentrifugation, an established method for demonstrating specific IgM antibodies. The persistence of IgM anti-HAV in 103 sera drawn at different times after onset of jaundice was evaluated. Sera drawn up to 30 days after onset of hepatitis A were IgM anti-HAV positive with both of the first two methods. Forty-one to 90 days after onset of illness IgM anti-HAV could be demonstrated with the first method in 47% of the patients, in 94% with the second method, and in 82% with gradient centrifugation. The second method was most sensitive and could be adjusted so that at a serum dilution of 1:10(4) anti-HAV IgM was detected only up to six months after infection. In contrast to the first method, nonspecific reactions caused by rheumatoid factor were not detected with the second method. During a one-year period about 15,000 sera of patients with clinical diagnoses of acute hepatitis were tested; the positive results correlated well with the clinical data, and there was no indication of nonspecific positive results.

Clinical, epidemiological and prognostic aspects of hepatitis "non-A, non-B"--a comparison with hepatitis A and B

Sera of 480 hospitalized hepatitis patients were tested for hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs) and to hepatitis B core antigen (anti-HBc), antibody to hepatitis A virus (anti-HAV) and anti-HAV of IgM-class. Serological markers indicating hepatitis A infection were found in 107 (22.3%) and markers indicating hepatitis B in 297 patients (61.9%), while 63 patients (13.1%) were classified as hepatitis type "non-A, non-B". The latter group mainly comprised drug addicts (50.8%), cases of post-transfusion hepatitis (11.1%) and patients without obvious hepatitis exposure (28.6%). In spite of these epidemiological similarities to hepatitis B, the maximum levels of serum alanine aminotransferase and bilirubin were comparable to those in patients with hepatitis A and significantly lower than in hepatitis B infection. Chronic hepatitis developed in 7.1% of the "non-A, non-B" patients, a figure close to that reported for hepatitis B.

Hepatitis A antibodies in Finland

Serum specimens from 191 Finnish adults were tested for antibodies to hepatitis A virus (anti-HAV). The frequency of anti-HAV increased from 8% in the age group of 20-29 years to 92% in those older than 60 years. The level of 50% was reached between 40 and 50 years.

Studies on antibody to hepatitis A virus in children and adults in London

366 specimens of serum from children and adults without liver disease were screened for antibody to hepatitis A virus (anti-HAV) by means of radioimmunoassay. 56% were born in London, 26% came to London from various parts of the United Kingdom and the remainder (18%) from various parts of the world. The prevalence of antibody was related to increasing age, ranging from 7% in children under ten years of age to 77% in adults aged 50 years or more. The prevalence of anti-HAV was significantly higher in females, in the lower socio-economic class and in those not indigenous to London. In comparison to other urban populations such as those of the United States and Western Europe, the prevalence of anti-HAV was similar in terms of the overall prevalence and age distribution. By contrast, these findings were entirely different from the countries of Eastern Europe and the Middle East where the overall prevalence was higher but the anti-HAV was equal in all ages. Thus, the findings presented indicate that hepatitis A virus infection is common in London and also shows a clear relationship to advancing age, lower socioeconomic class and the country of origin.

Propagation of human hepatitis A virus in a hepatoma cell line

Hepatitis A virus (HAV) was isolated directly from human feces and propagated serially in an HBsAg producing human hepatoma cell line. No cytopathic effect was observed in the tissue culture and no detectable amounts of HAV were present in the tissue culture supernatant fluid. However, increasing amounts of hepatitis A antigen (HAAg) were detected by radioimmunoassay in the cell extracts obtained by freezing and thawing of cells. Specificity of the HAAg determination was shown by neutralization with convalescent sera of marmosets experimentally infected with the MS-1 strain of hepatitis A and by the absence of this neutralization with preinoculation sera. HAAg was first detected after four weeks in the cell extract of infected cultures after inoculation of 10(2)--10(4) tissue culture infectious doses of HAV from second passage.

Progression of hepatitis non-A, non-B to chronic active hepatitis: a histological follow-up of two cases

Two patients with histologically verified acute hepatitis but without any serological evidence of hepatitis A or hepatitis B infection are described. In both cases the acute attack of hepatitis type 'non-A, non-B' progressed histologically and clinically to chronic active hepatitis within a two-year period. One of the patients died from liver insufficiency a year later, while the other is still alive after eight years of follow-up. The two cases illustrate that a progression of acute hepatitis 'non-A, non-B' to chronic liver disease may occur just as has been reported for hepatitis B infection.

Hepatitis types A, B, and non A--non B in childhood

199 children with acute hepatitis hospitalized between 1968 and 1978 were tested for serological markers of hepatitis A and B infection. In 24 out of 28 HBsAg-positive patients, hepatitis B infection was diagnosed because of the disappearance of the antigen during convalescence. The histories of the 171 HBsAg-negative children suggested acute hepatitis A infection in 69% of the patients. This diagnosis could be confirmed in 110 of the 116 tested cases (95%) by a more than fourfold increase in the anti-HAV titer or by detection of anti-HAV of the IgM class. In the 55 HBsAg-negative patients without epidemiological clues as to the type of hepatitis, 40 children exhibited anti-HAV which could be related to acute A infection in 21 out of 22 tested cases. At least 11 patients had to be classified as having nonn A--non B infection. The results indicate that a combination of evaluation of the patient's history and selected serological tests will permit a fast preliminary diagnosis. This is important in the clinical management of patients and protection of contacts with immunoglobulin.

Decrease in incidence of hepatitis A infections in Germany

The hypothesis of a decline in the incidence of hepatitis A infections in Germany in recent decades was confirmed by determining the prevalence of hepatitis A antibody (anti-HAV) in sera collected in 1965 and in 1975 under the same conditions in North Germany. The prevalence of anti-HAV correlated with the year of birth and was independent of the time of serum sampling. The force of infection fell from 0.04 in 1945 to 0.005 in 1965 as judged from a catalytic epidemic model with a sigmoidal decrease.

Tourist hepatitis, antibodies to hepatitis A virus and immune serum globulin prophylaxis

Immune serum globulin prophylaxis for foreign travellers should be reserved for those at high risk having no immunity against hepatitis A. In this study from Sweden the incidence of tourist hepatitis in different age groups was correlated to the prevalence of antibodies to hepatitis A virus (anti-HAV) in the population. 58% of individuals over 50 years had anti-HAV and travellers in these ages seldom experienced "tourist hepatitis". In younger age groups a low prevalence of anti-HAV (11%) was combined with a higher incidence of tourist hepatitis.

The epidemiological pattern of hepatitis A, B, and non-A, non-B in Sweden

In a clinical series of 148 patients with acute hepatitis, serological analysis of hepatitis A and hepatitis B markers revealed 16% of the cases as hepatitis type non-A, non-b. Hepatitis A was diagnosed in 27% of the patients with drug addicts as the predominating category, while serological evidence of hepatitis B infection was found in 57%, again with drug addicts in the majority. Drug addicts also predominated among the non-A, non-B cases, and possibly this category of patients is today the main reservoir not only of hepatitis B but also of hepatitis A and non-A, non-B.

Thermal treatment and infectivity of hepatitis A virus in human feces

The susceptibility of white-lipped marmoset monkeys (Saguinus sp) to human hepatitis A virus (HAV) provides a system for evaluation of thermal inactivation of HAV in feces and contaminated shellfish. Intramuscular or oral administration of HAV derived from feces of four patients with acute hepatitis A induced hepatitis in 28--100% of the inoculated marmosets. A 10% (w/v) fecal pool (GBG-BM) prepared from two patients (GBG and GBM) induced hepatitis in marmosets (2/4 with 1 ml; 2/2 with 3 ml) when given orally as a 1 : 3 dilution. A HAV-baby food raw oyster mixture fed to fasted marmosets induced hepatitis in 1/4 and seroconversion in 2/4 animals. Two groups of oysters were injected with HAV (concentrated 3 : 1 by centrifugation of the GBG-BM pool); one group was treated at 140 degrees F for 19 minutes and the other served as an untreated control. In animals fed the untreated inoculum, 4/6 developed hepatitis and 6/6 seroconverted, whereas of those fed the heat-treated inoculum 1/7 developed hepatitis and 2/7 seroconverted. These data suggest that pasteurization methods could be developed that would eliminate shellfish-associated hepatitis A and retain the palatability of the shellfish.