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.

Heat inactivation of hepatitis A virus in dairy foods

Experiments were performed to determine the thermal resistance of hepatitis A virus (HAV) in three types of dairy products containing increased amounts of fat content (skim milk, homogenized milk; 3.5% MFG, and table cream; 18% MFG). HAV-inoculated dairy products were introduced into custom-made U-shaped microcapillary tubes that in turn were simultaneously immersed in a waterbath, using custom-made floating boats and a carrying platform. Following exposure to the desired time and temperature combinations, the contents of each of the tubes was retrieved and was tested by plaque assay to determine the reduction in virus titer. Our data indicated that < 0.5 min at 85 degrees C was sufficient to cause a 5-log reduction in HAV titer in all three dairy products, whereas at 80 degrees C, < or = 0.68 min (for skim and homogenized milk), and 1.24 min (for cream) were needed to cause a similar log reduction. Using a nonlinear two-phase negative exponential model (two-compartment model) to analyze the data, it was found that at temperatures of 65, 67, 69, 71, and 75 degrees C, significantly (P < 0.05) higher exposure times were needed to achieve a 1-log reduction in virus titer in cream, as compared to skim and homogenized milk. For example, at 71 degrees C, a significantly (P < 0.05) higher exposure time of 0.52 min (for cream) was needed as compared to < or = 0.18 min (for skim and homogenized milk) to achieve a 1-log reduction in virus titer. A similar trend of inactivation was observed at 73 and 75 degrees C where significantly (P < 0.05) higher exposure times of 0.29 to 0.36 min for cream were needed to cause a 1-log reduction in HAV in cream, as compared to < or = 0.17 min for skim and homogenized milk. This study has provided information on the heat resistance of HAV in skim milk, homogenized milk, and table cream and demonstrated that an increase in fat content appears to play a protective role and contributes to the heat stability of HAV.

Worldwide experience with the CR326F-derived inactivated hepatitis A virus vaccine in pediatric and adult populations: an overview

The worldwide experience to date with VAQTA, a highly purified formalin-inactivated hepatitis A vaccine containing alum-adjuvant, is reviewed. No serious adverse experience related to vaccination has been reported. The vaccine has proven highly immunogenic, with seroconversion detectable after a single dose in 90-99% of children 2-16 years old, and of adults under 77 kg (170 lb) body weight. There is a trend toward lower one-dose seroconversion rates with increasing age and with weight > 77 kg. Early seroconversion in the latter groups may require two 25-unit doses given 2, 4 or 8 weeks apart, or a higher priming dose. Seroconversion induced by this vaccine has been shown to signify protection from clinical hepatitis A disease. The few vaccines whose titers have waned to borderline levels responded anamnestically to a booster, suggesting that the vaccine induces an immune memory response and should provide long-term protection.

Unusual viral causes of transverse myelitis: hepatitis A virus and cytomegalovirus

Twenty to 40% of cases of acute transverse myelitis are attributed to viral infections, although the specific viral etiology is only rarely identified. We studied two patients with transverse myelitis in association with acute hepatitis A virus (HAV) infection and acute primary cytomegalovirus (CMV) infection. This is the first well-documented report of an association between HAV infection and transverse myelitis, and only the fourth documented case of transverse myelitis in association with CMV infection in an immunocompetent adult. Both viruses should be considered as rare causes of transverse myelitis in immunologically normal adults.

Two years' investigation of epidemic hepatitis E virus transmission in West Kalimantan (Borneo), Indonesia

Two years' follow-up investigation of a hepatitis E virus (HEV) outbreak in West Kalimantan, Indonesia in 1991 was carried out to investigate the epidemiology of epidemic HEV transmission and the persistence of the immunoglobulin G (IgG) antibody response. Sixty cases identified as anti-HEV IgG positive during the outbreak in 1991 were matched with 67 controls and examined, together with 318 members of their families. Overall, the prevalence of anti-HEV IgG among the 445 subjects (representing 127 households) was 59%. There was no significant difference in anti-HEV prevalence between cases (72%) and controls (61%). Loss of detectable anti-HEV IgG after 2 years was demonstrated in 17 of 60 subjects (28%) who were originally positive for anti-HEV in 1991. The mean number of anti-HEV positive subjects per household was 2.04. Cross-sectional prevalence of anti-HEV IgG increased significantly with age (P = 0.01). When communities were grouped into areas of low (< 40%), medium (40-59%) and high (> or = 60%) anti-HEV prevalence, use of river water for drinking and cooking (P < 0.001), personal washing (P < 0.0001), and human excreta disposal (P < 0.001) were associated with high prevalence communities. Conversely, boiling drinking water was negatively associated with increased prevalence (P = 0.02). Subnormal rainfall during the month (August) leading up to the 1991 outbreak (19 cm compared to the monthly mean of 209 cm in 1985-1993) may have contributed to favourable epidemic conditions.

Viral hepatitis and primates: historical and molecular analysis of human and nonhuman primate hepatitis A, B, and the GB-related viruses

The hepatitis viruses have long been assumed to be highly host-specific, with infection of other nonhuman primates occurring due to inoculation with, or exposure to, human viruses. This paradigm has slowly changed over the last 10 years, as mounting data has revealed nonhuman primate equivalents of hepatitis A virus, hepatitis B virus, and the hepatitis C-related viruses GBV-C and GBV-A. This review summarizes the historical and molecular information for each of these groups and highlights the impact of these nonhuman primate hepatitis viruses on our understanding of the evolution of each of these viruses.

An outbreak of intrafamiliar hepatitis A associated with clam consumption: epidemic transmission to a school community

An outbreak of hepatitis A is described involving thirteen cases in a town in central-northern Italy. The consumption of infected clams, caught in a polluted coastal area of the Adriatic Sea, caused hepatitis A in all five members of a family consisting of mother, father and children, two of whom attended primary school. The epidemic subsequently spread to the primary school with a secondary attack rate of 7.9%, 0 for female pupils and 18.9% for males. The epidemiological and environmental investigations showed that the critical exposure took place in the boys' toilet in the primary school (OR: 32.79, 95% CI: 6.83-157.45). To prevent the spreading of contagion, extra disinfection was carried out in the whole school and health education campaigns were mounted. The good basic hygienic conditions of the homes, together with the cooperation of school staff in surveillance and providing information, allowed the epidemic to be controlled.

Lymph node enlargement as a sign of acute hepatitis A in children

Abdominal ultrasound was performed in 58 children presenting with proven acute hepatitis A and in 63 controls of the same age. There are well-known echographic signs of hepatitis (liver enlargement, gallbladder wall thickening, periportal hyperechogenicity) but they were not constantly found. We describe in all the hepatitis cases an enlargement of lymph nodes located in the hepatic hilum, pancreatic area and small omentum: they appeared hyperechogenic at the centre with hypoechogenic outer layer. Such enlarged lymph nodes were not observed in the controls.

Exposure to hepatitis A virus among blood donors, injecting drug users and prison entrants in Victoria

To assess prevalence of exposure to hepatitis A virus (HAV) among injecting drug users (IDUs) and prison entrants in Victoria, and to compare this with prevalence of HAV among a reference population of blood donors, sera stored from two previous studies and from randomly selected blood donors were tested for total antibody to HAV. The first study was a longitudinal study of field-recruited IDUs from 1990 to 1992 and the second was a study of all prison entrants in 1991-92 (both studies were carried out in Victoria); blood donors were from the Australian Red Cross Blood Bank Victoria in 1995. Forty-five per cent of 2175 prison entrants and 51% of 293 IDUs were seropositive for HAV, compared with 30% of 2995 blood donors. When standardized for age against the blood donors, HAV seropositivity in IDUs was 44% and in prison entrants 60%. The strongest association of HAV seropositivity among the IDUs on multivariate analysis was a history of imprisonment. There are high rates of exposure to HAV among prison entrants, whether with a history of IDU or not, and among IDUs who have a prison history. The role of sharing contaminated injecting equipment in transmission of HAV seems to be less important than institutionalization per se. With adequate resourcing, both populations are appropriate targets for HAV vaccination, especially in a context of continuing decline of transmission of HAV in the general community.

Hepatitis B and A virus antibodies in alcoholic steatosis and cirrhosis

Sera from 74 alcoholics with cirrhosis and 63 alcoholics with steatosis were tested for antibody to hepatitis B surface antigen, to hepatitis B core antigen, and to hepatitis A virus by radioimmunoassay or enzyme-linked immunosorbent assay. No significant difference between the two groups of alcoholics could be found concerning the prevalence of these antibodies. The total group of patients had antibody to hepatitis B surface antigen or hepatitis B core antigen, or both, significantly (p less than 0.001) more often (26%) than sex- and age-matched controls (4%). No significant difference was found between patients and controls concerning the prevalence of antibody to hepatitis A virus (46% v 40%). In patients with cirrhosis, no correlation between wedged hepatic vein pressure or wedged-to-free hepatic vein pressure and any of the viral antibodies could be established. The present results suggest that hepatitis B virus does not play a major role in the progression of alcoholic liver disease, but longitudinal studies are needed to solve this problem. The reason for the increased prevalence of antibodies to hepatitis B virus in these patients is unknown.

Cost of an outbreak of hepatitis A in Puglia, Italy

In total, 5889 cases of hepatitis A virus infection were reported during an outbreak in Puglia, a region of Southern Italy, in 1996. The primary cause of the outbreak was consumption of contaminated food (raw shellfish, vegetables, etc.), with a contributory risk factor of person-to-person transmission. A detailed questionnaire was completed by 250 randomly selected patients to obtain information sufficient to calculate the direct and indirect costs of the outbreak for the individual patient, the National Health Service (NHS) and society as a whole. A conversion rate of $US1 = 1530 Italian lire (L) has been used throughout the study since this was the average exchange rate in 1996. For the individual patient with hepatitis A virus infection, the mean cost was L1.013 million ($US662), which was equivalent to 6.6% of the mean annual income of the employed patients. The total cost of the outbreak to the NHS was L23.98 billion ($US15.67 million), which was equivalent to 0.4% of the total public health expenditure in the region in 1996. The total cost of the outbreak to society (individual patient, NHS and third parties combined) was L37.406 billion ($US24.45 million), corresponding to 0.04% of the gross domestic product of the entire region in 1996, with a mean cost per patient of L6.35 million ($US4150) from a societal perspective. The majority of patients (86.3%) were 11 to 30 years of age, reflecting the increasing susceptibility of younger patients to hepatitis A virus infection in recent decades. These economic and demographic data provide important information for the evaluation of preventive strategies including public education, sanitation and immunisation, so as to optimise the use of local health resources.

Inducible nitric oxide synthase (iNOS) expression in liver and splenic T lymphocyte rise are associated with liver histological damage during experimental hepatitis A virus (HAV) infection in Callithrix jacchus

Callithrix jacchus is considered a reliable animal model for hepatitis A virus (HAV) infection. All three HAV orally inoculated marmosets developed hepatitis - the infection was monitored by continuous virus shedding, high levels of serum enzyme alanine aminotransferase, specific antibody and seroconversion 3-6 weeks after HAV inoculation. HAV antigen was detected in liver by immunofluorescence 4 days post inoculation (PI) and onwards. To gain insight into the biological role of inducible nitric oxide synthase (iNOS) during immune-related acute liver injury the enzyme was searched in frozen biopsies: immunofluorescent labeling was found in the cytoplasm of liver cells mainly Kupffer's cells and spleen macrophages (CD68+) starting 11 days PI with maximum intensity on the fifth to sixth week PI. Necroinflammatory liver lesions characteristic of viral hepatitis were also observed at 10 days PI with maximum severity at 4 to 6 weeks PI. Furthermore, T lymphocytes (CD2+) were raised at this time point. No difference was evident in the frequency of B lymphocytes (CD20+). Therefore, iNOS expression preceded necroinflammatory liver lesion and maximal immunofluorescence reaction was coincident with tissue injury, supporting the hypothesis that NO contributes to hepatic cytotoxic mechanism but also to virus clearance. The concomitant rise in T-lymphocyte population may suggest a role for these cells in this and/or other independent HAV-induced pathological changes.

Anatomy of a trial: a historical view of the Monroe inactivated hepatitis A protective efficacy trial

The performance of vaccine protective efficacy trials is often more complex than reports of final results suggest. The current article reviews the background, planning and preparations for the Monroe, NY, protective efficacy trial of a formalin-inactivated, alum-adjuvanted hepatitis A vaccine (VAQTA, manufactured by Merck Research Laboratories). The vaccine trial was carried out at Kiryas Joel, a Hasidic Jewish community which had experienced numerous annual outbreaks in a local environment with similarities to day-care centers. Careful communication, and cooperation of community leadership, a flexible technical resource team, and knowledge of an epidemic already ongoing in a sister community whose members were due to arrive for summer holidays, permitted rapid and efficient completion of the trial with a striking demonstration of protection after a single vaccine dose.

Studies of a myxovirus recovered from patients with infectious hepatitis

A virus has been isolated from the serum and urine of patients with infectious hepatitis. This virus is a member of the parinfluenza group. It is serologically distinct from the known members of the group, but apparently is antigenically related to the simian type-2 parainfluenza viruses. A causal relationship between WB virus and infectious hepatitis has not been established.

Evaluation and validation of virus removal by ultrafiltration during the production of diaspirin crosslinked haemoglobin (DCLHb)

Virus retention during ultrafiltration through A/G Technology filter cartridges was investigated to characterize the removal process and validate the degree of virus titre reduction during the filtration of red blood cell haemolysates performed as part of the production of diaspirin crosslinked haemoglobin (DCLHb). When viruses were suspended in phosphate buffered saline solution, retention was greater with larger sized viruses and smaller filter pore size. Virus titre was maintained at starting levels in the filter retentate circuit during the course of filtration, suggesting that the virus removal mechanism is predominantly size exclusion. Evaluation of specific processing variables indicated that the retention of phiX174 virus was increased in the presence of red blood cell haemolysate or at high membrane crossflow rates and transmembrane pressures, while the retention of EMC virus was less sensitive to variations in these parameters. Using these results to design a validation protocol, log reduction values of >7.9 were demonstrated for the retention of human immunodeficiency virus, pseudorabies virus and bovine viral diarrhoea viruses, 7.6 for hepatitis A virus, and 4.2 for porcine parvovirus. It was also shown that the retention of viruses was maintained during repetitive use of the same filter cartridge.

Nosocomial infection with hepatitis A

Nosocomial spread of hepatitis A is very uncommon but may occur under unusual circumstances, as shown by the incident described here and by the few other published reports. In this incident it is concluded that the patient, who was the index case, was excreting hepatitis A virus in the faeces 16 days before jaundice developed and 17 days before alanine aminotransferase (ALT) values reached a peak.