Time course of hepatitis A viremia and viral load in the blood of human hepatitis A patients

The hepatitis A virus (HAV) is the most common etiological cause of acute hepatitis infections in humans in industrialized countries. Investigations into the viral load during HAV viremia, however, are rare. Therefore, correlation studies between viral load, biochemical, and specific serological markers have been undertaken. The group of sera comprised a series of multiple consecutive blood samples drawn from 11 patients at different times after onset of the disease. During the period up to 70 days after the onset of icterus, the individual range was at 1 x 10(3) to 3 x 10(4) HAV genome equivalents/ml. From day 75 until 120 after onset of the disease, the levels traced were at 10(3). In one case, it was possible to trace 1.25 x 10(4) genome equivalents/ml up to 180 days after onset of icterus and in two cases even up to 408 and 490 days viral load levels of 5 x 10(3) and 4 x 10(4) were detected, respectively. The same sera were used to measure IgM class antibodies to hepatitis A virus and the total anti-HAV. The results demonstrate that a direct correlation to peak levels of viral load exists with peak serum transaminase levels, but neither with peak anti-HAV IgM levels nor with total anti-HAV. Decreasing amounts of anti-HAV IgM tend to occur with decreasing amounts of HAV genome equivalents; and, vice versa, increasing amounts of total anti-HAV are accompanied by decreasing amounts of HAV genome equivalents. The longest duration of viremia was found in patients infected with HAV genotype IA.     

Hepatitis B viremia is associated with increased risk of hepatocellular carcinoma in chronic carriers

The role of quantitative viral load in development of hepatocellular carcinoma (HCC) among chronic hepatitis B virus (HBV) carriers was evaluated using real-time PCR (TaqMan PCR), a highly sensitive method for quantitative detection of HBV DNA. Serum samples collected at study entry from HCC cases and matched controls were chosen separately from ongoing prospective cohort studies in Senegal, West Africa, and Haimen City, China. For 14 HCC cases and 28 controls from Senegal, the relative risk (RR, 95% CI) of HCC was 15.6 (2.0-124.3) for those positive by the TaqMan PCR assay. Average length of follow-up (study entry to death from HCC) among cases was 2.8 (+/-1.6) years. The paired median difference between cases and controls was 3.8 x 10(4) virions/ml, with cases higher (P = 0.09). In order to clarify the relationship with lower-titer viremia, we selected 55 cases and 55 matched controls from the Chinese cohort all negative for serum HBV DNA by conventional dot blot hybridization. In this group, the RR associated with HBV DNA positivity by TaqMan PCR was 3.1 (1.1-9.2), with an average duration of follow-up of 3.3 (+/-2.1) years. The median difference in quantitative viremia between cases and controls was 6.0 x 10(4) virions/ml, with cases higher (P < 0.0001). Increased risk appeared to be confined to subjects with viral loads >2.3 x 10(4) virions/ml. In conclusion, HBV viremia, except perhaps at extremely low levels, is associated with increased risk for HCC in prospective studies of chronic carriers in two disparate populations.     

Acute viral hepatitis types E,A, and B singly and in combination in acute liver failure in children in North India

The aetiological agents responsible for, and the outcome of, acute liver failure were investigated prospectively in 44 children (29 males, 15 females) attending a tertiary health care facility in India. The children were between the ages of 2 months and 13 years. Studies for viral infections and other etiologies could be carried out in 40 patients. Specific aetiological labels were possible in 35 (87.5%) patients. Thirty (75%) had evidence of acute viral hepatitis. Acute hepatitis E virus (HEV) infection was found in a total of 18 children, with hepatitis A (HAV) in 16, hepatitis B in 5, and C in 1. Seven had isolated infection with hepatitis E, five with A, and four with B. Nine had both E and A infection. Superinfection of HEV was observed in a child with Indian childhood cirrhosis (ICC). Acute HEV infection was confirmed by immunoblot assay in all the patients and in eight of these, HEV-RNA was also detected in the serum. HAV was involved in 37.5% of cases with isolated infection in 10% (4 of 40). The aetiological factors associated with acute liver failure, apart from HAV and HEV, were other hepatotropic viruses (22.5%), Wilson's disease (5%), ICC (5%), and hepatotoxic drugs (7.5%). In five patients, no serological evidence of acute viral hepatitis could be found, neither did the metabolic screen yield any result. It was observed that enterically transmitted hepatitis viruses (HAV and HEV) were associated with 60% of acute hepatic failure in children. Mixed infection of HAV and HEV formed the single largest aetiological subgroup. In developing countries, where hepatitis A and E infections are endemic, severe complications can arise in the case of mixed infection. This may contribute to most of the mortality from acute liver failure during childhood. © 1996 Wiley-Liss, Inc.     

Distinct changing profiles of hepatitis A and E virus infection among patients with acute hepatitis, patients on maintenance hemodialysis and healthy individuals in Japan

To compare the epidemiologic profiles of hepatitis A virus (HAV) and hepatitis E virus (HEV) infections in Japan, the prevalence of clinical or subclinical HAV and HEV infections was investigated serologically and molecularly among 128 consecutive patients (age, mean +/- standard deviation, 37.5 +/- 14.7 years) who contracted acute hepatitis between 1989 and 2005 in a city hospital, and among 416 hemodialysis patients (60.1 +/- 12.6 years) and 266 medical staff members (34.6 +/- 11.4 years) at the same hospital, using stored periodic serum samples collected since the start of hemodialysis or employment, respectively. Between 1989 and 1995, among 93 patients with acute hepatitis, 51 (54.8%) were diagnosed with hepatitis A and only one patient with hepatitis E. Between 1996 and 2005, however, among 35 patients, only 3 (8.6%) were diagnosed with hepatitis A and 2 (5.7%) with hepatitis E. Although subclinical HEV infection was recognized in four hemodialysis patients (one each in 1979, 1980, 1988, and 2003) and two medical staff members (1978 and 2003) in previous studies, none of the 191 hemodialysis patients who had been negative for anti-HAV at the start of hemodialysis contracted HAV infection during the observation period of 7.6 +/- 6.4 years. Only one (0.4%) of the 246 medical staff members who had been negative for anti-HAV at the start of employment acquired hepatitis A during the observation period of 7.9 +/- 8.0 years: none had subclinical HAV infection. Clinical or subclinical HEV infection has occurred rarely during the last three decades, while HAV infection has markedly decreased at least since 1996.     

Quantitation of viral load in neonatal herpes simplex virus infection and comparison between type 1 and type 2

Neonatal herpes simplex virus (HSV) infection is a severe disease with high mortality and morbidity in spite of the development of effective anti-viral therapies. The viral load in neonatal herpes simplex virus (HSV) infection was measured retrospectively in 37 patients. HSV DNA copy numbers in serum and cerebrospinal fluid (CSF) were quantified using a real-time PCR assay. Patients with disseminated infection had a higher viral load in their sera. whereas patients with central nervous system (CNS) infection exhibited a higher viral load in the CSF. The viral load was significantly higher in the serum of patients who died later. Interestingly, patients with HSV type-2 infection exhibited more CNS involvement and neurological impairment, together with a high viral load in the CSF, than did HSV type-1 patients. These results suggest that quantitation of HSV viral load may be useful for assessing the prognosis, and may provide additional information for the management of neonatal HSV infection.     

Antibodies to Hepatitis A Virus in Immune Serum Globulin

Two hundred one immune serum globulin (ISG) lots manufactured in the US between 1967 and 1977 were tested for antibodies to the hepatitis A virus (anti-HAV) by a competitive-inhibition radioimmunoassay (RIA); a lesser number were also tested by immune adherence hemagglutination (IAHA). The percentage of ISG lots that contained anti-HAV with a titer of 1:100 or greater by RIA was 50% for those manufactured in 1967, 69% for those manufactured in 1972, and 100% for those manufactured in 1977. The percentage of lots with anti-HAV titers equal to or greater than 1:500 by RIA was 7% in 1967, 18% in 1972, and 70% in 1977. Only ten lots of ISG (5%) had anti-HAV titers of 1:1,000 or greater by RIA; seven of these were manufactured in 1977. Both the mean titer of anti-HAV in ISG lots and the percentage of lots containing significant titers of this antibody appear to have increased in the US over the past ten years. This may reflect the increased use of source plasma from paid plasmapheresis donors in the US during this period. The lower titers of anti-HAV in the older lots of ISG studied were shown not to be due to fragmentation of antibody molecules during storage.     

Chronic hepatitis C infection: influence of the viral load, genotypes, and GBV-C/HGV coinfection on the severity of the disease in a Brazilian population

The distributions of the different genotypes of the hepatitis C virus (HCV) and GBV-C virus (GBV-C/HGV) vary geographically and information worldwide is still incomplete. In particular, there are few data on the distribution of genotypes (and their relationship to the severity of liver disease) in South America. Findings are described in 114 consecutive patients from Northeast Brazil (median age 52 years, range 18-72 years) who had abnormal levels of serum aminotransferases and seropositivity for HCV RNA. The patients were recruited from an outpatient clinic between November 1997 and April 1998. Quantitative HCV RNA and GBV-C/HGV RNA estimations were carried out by double-nested polymerase chain reaction (PCR) using primers from the 5'-untranslated regions (UTRs) of the genomes. HCV genotypes were determined by restriction fragment length polymorphism (RFLP) analysis with 5'-UTR primers and by PCR with type-specific 5'-UTR primers. GBV-C/HGV-RNA genotypes were determined by RFLP with specific 5'-UTR primers and phylogenetic trees were constructed using the Neighbour-Joining and Drawtree programs. Histological features were graded and staged according to international criteria. Of the 114 patients, 35 (30.7%) patients had cirrhosis and 22 (27.8%) had mild, 51 (64.6%) had moderate, and 6 (7.6%) had severe chronic hepatitis. Median HCV viral load was 10(6) genome equivalents per millilitre (range 10(4)-10(9)/ml). Frequencies of genotypes were 5.3% type 1a, 44.7% type 1b, 3.5% type 2, 41.2% type 3, and 5.3% mixed types. GBV-C/HGV-RNA was detected in the sera of 12 (10.5%) patients and was distributed among three phylogenetic groups. There were no significant differences between patients with the predominant HCV genotypes (1b and 3) with respect to gender, age group, viral load, severity of liver disease, or coinfection with GBV-C/HGV.     

Determination of HPV type 16 and 18 viral load in cervical smears of women referred to colposcopy

It has been recognized that human papillomavirus infection is the major causal factor for high-grade cervical lesions. The aim of the study was to evaluate the relationship between HPV 16 and 18 viral loads and cervical status in different age strata. A duplex real time PCR method was devised to determine HPV 16 and 18 viral load per million of human cells using an in house plasmidic construct as a standard of quantification. The 151 cervical scrapes were collected before colposcopic examination from either abnormal cervico-vaginal smear (group 1, 97 patients) or from post treatment clinical follow-up (group 2, 54 patients). In women aged 30-40, the HPV16 viral loads were significantly higher in high-grade squamous intraepithelial lesion than in low-grade squamous intraepithelial lesion in both groups and HPV18 in group 1. In women aged 20-30 of group 1, high HPV viral load was associated in few cases with high-grade squamous intraepithelial lesion or low-grade squamous intraepithelial lesion, and surprisingly in some patients with normal cervix. HPV 16 and 18 viral loads are related to the severity of cervical lesion, and may be useful in the clinical management of cervical lesions. A specific follow-up may be useful for those with high viral load despite normal cervix.     

Clinical and virological characteristics associated with severe acute hepatitis B

To identify early predictors of a severe or fulminant course in patients with acute viral hepatitis B (AVH-B). One hundred and thirty-eight patients with symptomatic acute hepatitis B observed from 1999 to 2012 were enrolled. For each patient, the demographics, risk factors for the acquisition of hepatitis B virus (HBV) infection, clinical, biochemical and virological data (HBV DNA, HBV DNA sequences) were recorded and analysed. The HBV mutants in the polymerase region were sought in 110 (87%) patients by direct sequencing, and the rtM204V/I mutations also by an allele-specific PCR. AVH-B was severe in 13 (9.4%) of the 138 patients enrolled, fulminant in 6 (4.3%) and with a normal clinical course in 119. The 19 patients with severe or fulminant AVH-B more frequently than the 119 with a normal course stated intravenous drug use (63.2% versus 36.1%, p 0.04) and were HBV-DNA negative (31.6% versus 11.8%, p 0.03) and anti-hepatitis C virus (HCV) positive (57.9% versus 19.3%, p 0.0008); the prevalences of different HBV genotypes and of the rtM204V/I mutant were similar in these three forms of AVH-B. A multivariate logistic regression analysis identified a pre-existing HCV chronic infection as the only factor independently associated with a severe or fulminant clinical course of AVH-B (OR 4.89, 95% CI 1.5–15.94, p 0.01). A pre-existing HCV chronic infection was identified as the only factor independently associated with a severe clinical presentation of acute hepatitis B, an association most probably due to the combination of the liver lesions caused by acute hepatitis B and the pre-existing histological abnormalities related to HCV chronic infection.     

Serum Epstein-Barr virus DNA load in primary Epstein-Barr virus infection

Specific viral laboratory diagnosis of primary Epstein-Barr Virus (EBV) infection is usually based on antibody-detection assays. During acute, lytic phase of infection, viral DNA can also be detected in serum. In the present study, the diagnostic utility of EBV DNA detection and quantitation in serum in primary EBV infection was investigated. The level of EBV DNA in the serum of 98 immunocompetent patients aged 1-47 years with symptomatic, antibody-confirmed EBV primary infection was assessed using a quantitative real-time PCR assay. The association between viral load and time after onset of disease, age and clinical and laboratory data was investigated. Quantitative PCR detected EBV DNA in 93 of 98 samples (94.9%), and the measured viral loads ranged from 3.8 x 10(1) to 6.6 x 10(4) copies/ml. EBV DNA detection exhibited a sensitivity of 94.9% and a specificity of 97.4% for primary EBV infection. EBV DNA was always detectable until day 12 after onset of symptoms, whereas no further positive PCR results were found after a period of 22 days after onset of disease. Detection of EBV DNA also showed a clearer association with the clinical manifestation of disease than the presence of EBV specific VCA IgG antibodies of low avidity. EBV DNA load was found to correlate inversely with the time after onset of disease (P < 0.001), and higher viral load levels were detected in younger (P = 0.009) and in hospitalized patients (P = 0.038). The results indicate that real-time PCR is a reliable tool for diagnosis of primary EBV infection early in the course of disease. In addition, EBV DNA detection may serve as a useful diagnostic supplement in serologically indeterminate EBV infections.     

Algorithm based on CMV kinetics DNA viral load for preemptive therapy initiation after hematopoietic cell transplantation

Preemptive therapy in hematopoietic cell transplantation is initiated by a diagnostic technique at first detection of cytomegalovirus (CMV). The aim of this study was to use the viral dynamics of CMV DNA viral to start preemptive therapy, and to prospectively compare the CMV viral load kinetics to pp65 antigenemia. Two hundred sixty-three blood samples were collected prospectively from 93 patients. All clinical decisions regarding use of preemptive therapy were based on CMV antigenemia. Based on the positivity of the antigen assay and clinical CMV outcome in allotransplant patients, an optimal threshold of 3.05 log 10 (1,130 copies/ml) was found to discriminate patients who required preemptive therapy and those who did not (sensitivity, 71%; specificity, 65%). A DNAemia level increase of 2.24 log 10 (174 copies/ml) per day was the optimal threshold to discriminate between patients who required preemptive therapy and those who did not (sensitivity, 93%; specificity, 43%). Sensitivity of PCR assay was 92.4% compared with 39% for the antigen assay (P < 0.001). A standardized real-time PCR assay is more appropriate than the antigen assay for detecting CMV. It allowed earlier diagnosis of active CMV infection and monitoring of the response to anti-CMV treatment.     

Hepatitis A virus genotype and its correlation with the clinical outcome of acute hepatitis A in Korea: 2006-2008

Korea has recently experienced a nationwide outbreak of hepatitis A. This study aimed to investigate hepatitis A virus (HAV) genotypes and to compare clinical features between patients infected with HAV genotype IA and those with genotype IIIA. From September 2006 to August 2008, 595 patients with symptomatic hepatitis A were enrolled prospectively in four hospitals in Korea. Among them, 556 patients participated in this study by providing serum or stool samples for genotypic analysis. HAV RNA was detected in 499 patients (89.7%). Major genotypes included IA (n = 244, 48.9%) and IIIA (n = 244, 48.9%), and the remaining genotype was IB (n = 11, 2.2%). From September 2006 to August 2007, the distribution of genotypes IA and IIIA were 64.6% and 35.6%, respectively, which changed to 42.3% and 54.6%, respectively, from September 2007 to August 2008, indicating change of circulating HAV genotypes in the study period from IA to IIIA. Major patterns of amino acid substitution in the VP3/VP1 junction region were observed at position 512 (P → L) in genotype IA and at 520 (R → K) in genotype IIIA. Patients with genotype IIIA infection showed significantly higher aminotransferase levels, prothrombin time, and leukocyte count, with more severe symptoms than those with genotype IA at the time of admission. These results suggest the occurrence of a change of circulating HAV genotypes in recent community‐wide outbreaks of hepatitis A in Korea, and genotype IIIA infection, compared with genotype IA infection, might show more severe clinical manifestations. J. Med. Virol. 83:2073–2081, 2011. © 2011 Wiley Periodicals, Inc.     

Hepatitis B virus markers, alpha-fetoprotein and survival in fulminant viral hepatitis

The serological markers of hepatitis B virus and serum alpha-fetoprotein (AFP) levels have been studied in 28 consecutive cases of fulminant hepatitis, correlating the data with survival. On admission, 20 patients were found to be positive for HBsAg and eight for anti-HBs. All anti-HBs-positive cases showed high titers of anti-HBc, and six patients were positive for specific anti-HBc-IgM. DNA polymerase activity was detected in serum of 11 HBsAg-positive (55%) and four anti-HBs-positive (50%) patients. HBeAg was detected in six (21.4%) subjects (five HBsAg-positive and one anti-HBs-positive), whereas anti-HBe was present in nine (32.1%) subjects (six HBsAg-positive and three anti-HBs-positive). AFP levels greater than 60 ng/ml were found in sera of 14 patients (50%). No significant difference was evidenced in the survival rate between HBsAg-positive and anti-HBs-positive and between HBeAg-positive and HBe Ag-negative patients. However, a statistically significant difference (P less than 0.05) in the survival rate was found in patients positive and negative for DNA polymerase activity and in those with AFP levels higher and lower than 60 ng/ml (P less than 0.005). Pathogenetic and prognostic significance of these findings are discussed.     

Kinetics of HBV DNA and HBsAg in acute hepatitis B patients with and without coinfection by other hepatitis viruses

The kinetics of hepatitis B virus (HBV) and its surface antigen (HBsAg) during acute hepatitis has not yet been studied accurately in a representative number of patients. The influence of coinfecting hepatitis viruses during the acute phase of infection is not known. Three to four serum samples from 21 patients with acute HBV monoinfection and 27 with coinfection were taken at intervals of 6-10 days and analyzed for the number of HBV genome equivalents (ge) by real time polymerase chain reaction (PCR) and for HBsAg quantity using Laurell electrophoresis. Log HBV ge/ml decreased during the follow-up from 6.8 +/- 1.1 to 5.1 +/- 1.0 to 4.2 +/- 0.8 to 3.3 +/- 1.1 (mean +/- SD). The half-life times of HBV ge increased from 1.6 days at the beginning to 4 days at the end. HBsAg decreased much slower: from 38 to 23 to 12 to 3.8 microg/ml. Half-life time was around 8 days at the beginning and 5.7 days at the end, but 11 patients showed a rapid elimination of HBsAg and HBV DNA. Hepatitis C virus (HCV) coinfection did not change the kinetics of HBV ge and HBsAg significantly. A moderate but significant suppression of HBV ge levels was observed in hepatitis D virus (HDV) coinfected patients. HBsAg levels were, however, enhanced in this cohort. In conclusion, the data suggest that expression and elimination of HBV is in most patients with acute hepatitis B not altered by coinfecting hepatitis viruses. The initial decrease of HBV ge and HBsAg in serum appears to be caused by decay or non-specific removal in the absence of replacement.     

Advanced histology and impaired liver regeneration are associated with disease severity in acute-onset autoimmune hepatitis

Fujiwara K, Nakano M, Yasui S, Okitsu K, Yonemitsu Y & Yokosuka O
(2011) Histopathology 58 , 693–704
Advanced histology and impaired liver regeneration are associated with disease severity in acute‐onset autoimmune hepatitis Aims: Some cases of acute‐onset autoimmune hepatitis (AIH) develop into severe or fulminant forms showing massive/submassive hepatic necrosis, and have a poor prognosis. The pathological features of acute‐onset AIH remain uncertain. Ductular (intermediate) hepatocytes after massive/submassive necrosis may serve as hepatic progenitor cells, and could be seen as cytokeratin 7 (CK7)‐positive hepatocytes in immunohistochemistry. Therefore, the aim was to examine histological features to obtain a better evaluation of acute‐onset AIH. Methods: The histological features of 27 clinically acute‐onset AIH patients were examined by immunohistochemistry using CK7. Results: On staining for CK7, intermediate hepatocytes were less commonly present (P < 0.001) and ductular reactions were more commonly present (P < 0.001) in severe/fulminant patients than in non‐severe ones. In severe and fulminant patients, intermediate hepatocytes and intralobular progenitor cells were more commonly present (P < 0.005 and P < 0.05, respectively) and ductular reactions were less commonly present (P = 0.007) in recovered patients than in dead ones. Severe patients had more clinically and histologically advanced disease. Conclusions: Immunohistochemical evalution using CK7 might be a useful tool for evaluating liver regeneration, and intermediate hepatocytes and progenitor cells might play an important role in liver regeneration after massive and submassive necrosis in acute‐onset AIH.     

Hepatitis virus infection in an isolated canadian inuit (Eskimo) population

The epidemiology of Hepatitis A virus (HAV) and hepatitis B virus (HBV) infection was studied in a northern Canadian Inuit (Eskimo) settlement. Sera from 720 of the 850 inhabitants of Baker Lake, Canada, were tested for markers of HAV and HBV infection. Anti-HAV was present in 71% of the residents and its prevalence increased with age. Serologic evidence of HBV infections was found in 27% of residents. The prevalence increased with age, being uncommon under the age of 20 (6%)and almost universal over the age of 60 (93%). Among the 29 hepatitis B surface antigen (HBsAg) carriers identified, all were adults, all had low levels of HBsAg, and all were negative for hepatitis B e antigen (HBeAg) and DNA polymerase but positive for antibody to HBeAg. These data demonstrate a high prevalence of HAV and HBV infection in this population. Further, they suggest that a dramatic decrease in the transmission of HRV infection has occurred over the past 20–30 years.     

Comparison of real-time fluorescent RT-PCR and conventional RT-PCR for the detection of hepatitis E virus genotypes prevalent in China

To compare the specificity and sensitivity of a real-time fluorescent RT-PCR assay with conventional RT-PCR, sera from 110 healthy blood donors, 120 patients with a clinical diagnosis of chronic hepatitis B, and 416 patients with non-A-C acute hepatitis, as well as serial dilutions of HEV genotypes 1 and 4, were tested with both assays. All samples from healthy blood donors and patients with chronic hepatitis B were negative by both assays. Real-time RT-PCR could detect the same final dilution of genotype 1 as conventional RT-PCR but could detect a 10-fold lower concentration of genotype 4 than conventional RT-PCR. Of 416 samples from patients with a clinical diagnosis of non-A-C acute hepatitis, 127 (30.5%) and 83 (20.0%) were positive for HEV by real-time and conventional RT-PCR, respectively. The concordance of real-time and conventional RT-PCR was 80.8%. Furthermore, 96 and 57 of 171 samples were positive for anti-HEV IgM by real-time and conventional RT-PCR, respectively, and 31 and 26 of 245 samples negative for anti-HEV IgM, were positive by real-time and conventional RT-PCR, respectively. All amplicons positive by conventional RT-PCR were sequenced. Of 83 isolates, 7 and 76 belonged to genotypes 1 and 4, respectively. Thus, both assays have a high specificity, but the real-time RT-PCR assay is more sensitive than conventional RT-PCR. Furthermore, HEV genotype 4 is responsible for most sporadic cases of hepatitis E in the north of China.     

Incidence of hepatitis A virus (HAV) infection in rural Liberia

To provide background for future hepatitis A vaccine trials, sera were collected from 0- to 4-year-old Liberian infants and their mothers on two occasions an average of 14.75 months apart and tested for antibody to hepatitis A virus (anti-HAV). The prevalence of anti-HAV rose from 2.5% in infants 0-6 months of age to 70% in children 3-4 years of age and did not differ between male and female infants. The annual incidence of new infections was slightly lower in the first year of life (35%) than in the subsequent 3 years, when it averaged 45%. The presence of HBV infection did not affect the incidence of HAV seroconversion. No clinical hepatitis was recognized in the subjects who seroconverted. Dual hepatitis A and B virus infection were observed; these were all clinically inapparent. The extraordinary incidence of HAV infection documented in the present study offers an opportunity for vaccine efficacy trials requiring minimal numbers of subjects.     

Lack of complement-dependent cytolytic antibodies in hepatitis A virus infection

Sera collected from patients with acute hepatitis A virus (HAV) infection and convalescent sera were examined for cytolytic activity against HAV-infected human-embryo lung fibroblasts (HAV carrier fibroblasts). Using the 51chromium release assay, no complement dependent antibody mediated cytolytic activity against HAV carrier cells could be detected. In control experiments with identical cell strains, anti-herpes simplex virus (HSV) positive sera and complement caused specific lysis of HSV type 1 infected target cells. The data presented here do not support the hypothesis that in the possible immunopathogenesis of HAV infection, complement-dependent cytolytic antibodies play an essential role.