Vertical transmission of hepatitis C virus

New insights into hepatitis C virus infection of hemodialysis patients: the implications

The authors compared the diagnostic performance of a second-generation recombinant immunoblot assay (RIBA) (RIBA HCV 2.0 SIA) and the recently introduced third-generation RIBA (RIBA HCV 3.0 SIA) with that of hepatitis C virus (HCV) RNA by the polymerase chain reaction (PCR) in 55 patients on chronic hemodialysis. Compared with HCV RNA by PCR, RIBA 3.0 increased the sensitivity of HCV detection to 72% as compared with 56% of RIBA 2.0. Both assays underestimated the prevalence of HCV infection as determined by PCR. However, RIBA HCV 3.0 outperformed RIBA HCV 2.0, detecting all of the RIBA 2.0-positive patients plus an additional eight (8 of 22 RIBA 2.0 negative; confidence interval [CI] = [17.2%, 59.3%]). Forty-three of 51 patients with positive RIBA 3.0 or positive HCV RNA by PCR underwent a liver biopsy. Thirty (70%) had chronic hepatitis (three with cirrhosis), 10 (23%) had nonspecific changes, and three (7%) had normal liver histology. Thirty of 37 patients (81%) with hepatitis C viremia and positive anti-HCV had chronic hepatitis, whereas none of the viremic patients with negative anti-HCV had chronic hepatitis. Among the reactive antigens on RIBA 3.0, c33c was found to be most predictive of chronic hepatitis (P = 0.0002). Detection of HCV RNA continues to be the method of choice in the early phase of HCV infection. In places where a validated HCV RNA assay is not available, RIBA HCV 3.0 (soon to be commercially available) is a better alternative. Early detection of HCV infection and the implementation of an isolation strategy might be important in preventing the spread of HCV infection among hemodialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Mother-to-infant transmission of hepatitis C virus

Anti-hepatitis C virus (HCV) antibodies and HCV-RNA were measured in the sera of 22 anti-HCV positive, HIV-1 negative mothers and their infants. ELISA and RIBA II were used for anti-HCV determination. HCV-RNA was measured by a nested polymerase chain reaction. HCV-RNA was found in 12 of 22 mothers. All 22 children were followed for 12 months. All were anti-HCV positive by the fourth month; 18 became anti-HCV negative between the 8th and 12th month. HCV-RNA was detected in 5 of 22 infants in the fourth month. They remained HCV-RNA positive. All children born to HCV-RNA negative mothers were HCV-RNA negative while 5 of 12 babies born to HCV-RNA positive mothers were infected. All five infected babies were born to mothers infected through transfusions or drug use. ALT levels in mothers seemed to have no effect on mother-to-infant transmission. Hence evidence for perinatal transmission of HCV from HCV-RNA positive mothers was demonstrated in the present study.

Mother-to-infant transmission of hepatitis C virus. Lombardy Study Group on Vertical HCV Transmission

To assess the risk of mother-to-infant transmission of hepatitis C virus (HCV), we followed up 116 babies of anti-HCV positive mothers, of whom 22 were coinfected with HIV and 94 had HCV alone. None of the babies whose mothers had HCV alone acquired HCV, while 8 babies (36%; p < 0.001) of mothers co-infected with HIV acquired HCV (5 babies) or HCV and HIV (3). There was no association between any specific maternal HCV genotype and enhanced risk of neonatal infection. HCV-RNA levels were significantly higher (p < 0.05) in mothers with HIV coinfection than in those with HCV alone. These data indicate that maternal HIV status correlates with enhanced level of viraemia which favours neonatal infection.

Current status of the molecular genetics of hepatitis C virus and its utilization in the diagnosis of infection

BACKGROUND

Since the discovery of hepatitis C virus (HCV) as a major cause of non-A non-B hepatitis, advances have been made in our understanding of the molecular biology of HCV and its relatedness to the flaviviruses and pestiviruses. The use of molecular techniques to construct an antibody assay has enabled the accumulation of information concerning the natural history and pathogenesis of HCV infection.

OBJECTIVES

The objective was to review the literature to March 1994 on the structure, function and genetics of HCV and to correlate these findings with approaches to diagnosis that have contributed to our understanding of HCV infections.

STUDY DESIGN

We reviewed the virological and medical literature from 1988 to March of 1994 with a focus on the stated objectives.

RESULTS

Although the structure of HCV has been well-defined, our knowledge of the function of all the genes of HCV is incomplete. Structural core and envelope proteins as well as enzymes have been described. The 5' end of the polypeptide is most conserved. Genotyping of isolates varies according to the part of the gene examined. Several genotypes exist and tend to predominate in global populations. Antibodies to the various proteins can be measured by EIA assays and positive specimens often require confirmatory testing. Uniquely sensitive nucleic acid detection systems for RNA amplified by PCR have enabled a better understanding of the natural history, epidemiology and responses to treatment.

CONCLUSIONS

Well-designed studies for the detection of nucleic acid, antibodies and antigens using a variety of viral gene products will provide even more information about HCV infections and help lead to treatment and prevention.

Molecular detection of hepatitis C virus: impact of detection methodology on clinical and laboratory correlations

The clinical manifestations of hepatitis C virus (HCV) infection are generally indistinguishable from other causes of viral hepatitis. HCV infections are usually anicteric, asymptomatic, and rarely cause acute fulminant liver failure. Serological testing for HCV in conjunction with epidemiological studies have verified that HCV was the major cause of parenterally transmitted non-A, non-B hepatitis (NANBH). With the widespread introduction of serological screening of blood products for HCV antibody, the risk of transfusion-associated HCV infection has been dramatically reduced (to < 3 cases per 10,000 units transfused). Despite the virtual elimination of transfusion-associated infections, the diagnosis of HCV remains important because > 50% of infections are sporadic in origin, 50 to 70% of infected individuals develop chronic hepatitis, and these individuals are at risk of developing cirrhosis (> 20%) as well as hepatocellular carcinoma. Although currently available anti-HCV immunoassays function well as blood-donor screening assays, they are poor at detecting acute infection because of the prolonged lag time between infection and detection of seroconversion (approximately 10 to 26 weeks for second-generation immunoassays). In contrast, polymerase chain reaction (PCR)-based detection of HCV RNA in serum can detect infection in as little as 1 to 2 weeks after exposure. This review focuses on the impact of modern serologic and nucleic acid-based HCV detection methodology on the clinical understanding of HCV infection, its associated illnesses, and its transmissability. Quantitative and reproducible nucleic acid-based detection assays will be required to provide additional insights into the clinical spectrum of HCV infections as well as to assess the efficacy of antiviral agents.

Transmission of hepatitis C virus from mothers to infants: its frequency and risk factors revisited

A total of 16,714 pregnant Japanese women were tested for antibodies against hepatitis C virus (HCV), and 163 (0.98%) were positive. None of these were infected with human immunodeficiency virus-1 (HIV-1). We conducted a prospective study to discover the rate of HCV infection in babies born to mothers who were HCV RNA-positive but had no evidence for hepatitis (so called "asymptomatic carriers"), and only 2 (2.3%) of 87 such babies became infected during follow-up. This rate was considerably lower than those from other reports which included mothers with clinically overt chronic hepatitis C. We conducted another study to follow babies born to mothers with chronic hepatitis C, and found two babies infected. All of the four infected babies were born to mothers who had HCV RNA in their circulations around delivery at high titers (greater than 5.0 x 10(6) Eq/ml by branched DNA assay). This confirmed the previous finding that virus load was an important risk factor. In addition, we found three families where mother-to-infant HCV transmission was suspected in a retrospective study by indexing HCV-infected pediatric patients. Throughout the seven families, siblings of infected babies were free from HCV infection, suggesting that maternal infection of HCV owes much to chance. Breast milk feeding was not regarded as a risk factor. We also assessed the prevalence of anti-HCV antibody among 6-year old children, and only 10 of 10,446 (0.1%) were positive, suggesting low frequency of HCV infection during the period from birth to this age.

Hepatitis C: progress and problems

The hepatitis C virus (HCV), a single-stranded RNA virus, is the major cause of posttransfusion hepatitis. HCV isolates differ in nucleotide and amino acid sequences. Nucleotide changes are concentrated in hypervariable regions and may be related to immune selection. In most immunocompetent persons, HCV infection is diagnosed serologically, using antigens from conserved regions. Amplification of RNA may be necessary to detect infection in immunosuppressed patients. Transmission by known parenteral routes is frequent; other means of spread are less common and may represent inapparent, percutaneous dissemination. Infection can lead to classical acute hepatitis, but most infected persons have no history of acute disease. Once infected, most individuals apparently remain carriers of the virus, with varying degrees of hepatocyte damage and fibrosis ensuing. Chronic hepatitis may lead to cirrhosis and hepatocellular carcinoma. However, disease progression varies widely, from less than 2 years to cirrhosis in some patients to more than 30 years with only chronic hepatitis in others. Determinants important in deciding outcome are unknown. Alpha interferon, which results in sustained remission in selected patients, is the only available therapy. Long-term benefits from such therapy have not been demonstrated. Prevention of HCV infection by vaccination is likely to be challenging if ongoing viral mutation results in escape from neutralization and clearance.

Viral hepatitis in children with renal disease

Specific and sensitive diagnostic tests are now available to identify type A, B, C, D and E hepatitis. Hepatitis A and E which cause only acute, very rarely fulminant, hepatitis are spread largely by the faecal-oral route, having a brief viraemic phase. Hepatitis B, C and D which are transmitted parenterally and via secretions are often associated with chronic viraemia. Patients with chronic renal disease are at particular risk. Impaired immunity due to disease or drugs increases the propensity to develop a chronic carrier state which may progress to cirrhosis and hepatocellular carcinoma. Limited reports indicate that hepatitis C infection may cause cirrhosis more rapidly than hepatitis B. The emergence of mutants to both hepatitis B and C is a cause for concern. Treatment with interferon is of limited efficacy. Screening of blood products for viral markers and prudent handling of potentially infected materials to avoid contamination of damaged skin or mucous membrane are the best strategies to prevent infection. Hepatitis B vaccination of all newborns, young adolescents and those at risk is the most effective means of reducing the carrier frequency.

Improvement of hepatitis C virus RNA polymerase chain reaction through a multicentre quality control study. French Study Group for the Standardization of Hepatitis C Virus PCR

Nine French laboratories, using the polymerase chain reaction (PCR) for detection of hepatitis C virus (HCV) RNA, initiated a quality control study to assess and to improve the specificity and sensitivity of their procedures. The study was carried out in three rounds, based on coded panels consisting of anti-HCV positive and anti-HCV negative samples. For the first panel, each laboratory followed its own protocol: 100% sensitivity was observed in two laboratories, 100% specificity in seven. For the second panel, all laboratories were required to use both their own procedure and a consensus procedure established from those laboratories which provided the best results on the first panel. With their own procedure, 100% sensitivity was observed in five laboratories and 100% specificity in all. With the common procedure, 100% sensitivity was observed in all but one, and 100% specificity in all. The third panel included three positive samples with four successive dilutions. For two samples, 8/8 laboratories had positive signals until the 1/100 dilution and discrepant results beyond this dilution; for the third sample, the signals were more discrepant. These results indicate that optimization and standardization of PCR may help laboratories to improve their procedure.

Coinfection of hepatitis C virus in patients with chronic hepatitis B infection

Enzyme-linked immunosorbent assays for detecting antibodies against hepatitis C virus and the polymerase chain reaction were tested in 82 chronic hepatitis B surface antigen carriers for their accuracy in diagnosing patients coinfected with hepatitis B and C viruses. To clarify the role of each virus in chronic hepatitis, serologic assays against hepatitis B virus were also tested. Thirteen (14.9%), 14 (17.1%) and 15 (18.3%) patients were anti-HCV positive using C100 (HCV1), JCC, and a second generation test (HCV2), respectively. HCV RNA was detected by polymerase chain reaction in 9 of 18 anti-HCV-positive cases. Although HCV1 assays were not sufficient, either the JCC or HCV2 assay detected all polymerase chain reaction-positive cases. Fifteen of 18 specimens that were positive in at least one of the three ELISA were seronegative for the hepatitis B e antigen. As judged by HBV DNA polymerase activity, titers of hepatitis B surface antigen and immunoglobulin A antibody against hepatitis B core antigen (IgA anti-HBc), activity of hepatitis B virus replication and immune response against hepatitis B virus in patients with coinfection was decreased to the level of hepatitis B virus asymptomatic carriers. These results show that hepatitis C virus appears to be the primary cause of active hepatitis in most patients with hepatitis B and hepatitis C virus coinfection.

Seroepidemiology of hepatitis C virus infection in hemodialysis patients and the general population in Fukuoka and Okinawa, Japan

In 1992, a seroepidemiologic study was carried out among hemodialysis patients and the general population in Fukuoka and Okinawa, Japan to determine the presence of hepatitis C virus (HCV) infection and HCV viremia. The markers used were antibody to HCV, determined by second-generation assay (anti-HCV), and HCV RNA, determined by the polymerase chain reaction. The prevalence of anti-HCV in Fukuoka was 3.3%, 73 per 2237 persons, significantly (P < 0.001) higher than the 0.4%, 5 per 1295, in Okinawa. The prevalence of anti-HCV in hemodialysis patients in Fukuoka was 51.9% (161 of 310 patients), significantly (P < 0.001) higher than the 9.1% (13 of 143 patients) in Okinawa. The ratio of HCV RNA-positive to anti-HCV-positive persons was significantly higher in hemodialysis patients (147/174, 84.5%) than in the general population (49/78, 62.8%) (P < 0.001). Elimination of HCV among hemodialysis patients appears to be difficult, as such patients have lower immune responses than the general population. In Fukuoka, but not in Okinawa, blood used for transfusion was supplied by paid donors at commercial blood banks from 1953 to 1969. This may explain why HCV infection is endemic in Fukuoka and not in Okinawa. Differences between the prevalence of anti-HCV in the hemodialysis patients in Fukuoka and Okinawa reflect differences in the prevalence in the general population in these two areas of Japan.

Prevalence of hepatitis C virus infection in the household contacts of patients with HCV-related chronic liver disease

It is still controversial whether the familial environment plays a role in the diffusion of HCV infection. The aim of this study was to evaluate the prevalence of anti-HCV positivity in the household contacts of patients with HCV-related chronic hepatitis. Nearly all the household contacts of 113 subjects with anti-HCV+ chronic hepatitis (100/113 spouses and 260/290 children) were investigated. Anti-HCV was determined by means of ELISA II and was confirmed by RIBA II. Anti-HCV positivity was found in 27% of the spouses and in 1.9% of the children. Prevalence of anti-HCV positivity in spouses correlated positively with the duration of the marital status. Seventeen/32 (53.1%) of anti-HCV-positive subjects were found to have chronic hepatitis. This study indicates that intrafamilial diffusion of HCV infection is mostly accounted for by horizontal, in particular spouse to spouse, transmission and that spouse to spouse transmission of HCV infection correlates positively with the duration of marital status.

Temporal profile of hepatitis C virus antibody and genome in infants born to mothers infected with hepatitis C virus but without human immunodeficiency virus coinfection

To investigate mother-to-infant transmission of hepatitis C virus, serial follow-up of anti-HCV and hepatitis C virus RNA was undertaken in 11 infants born to hepatitis C virus-infected mothers who had been screened from 11,688 pregnant women. None of the hepatitis C virus-infected mothers was infected by human immunodeficiency virus. Anti-HCV was checked by the second-generation enzyme immunoassay kit, and hepatitis C virus RNA was examined by reverse transcriptase-nested polymerase chain reaction. Hepatitis C virus RNA was found in more than two serum samples in two of these 11 infants; those two infants were regarded as hepatitis C virus-infected. One of the two had hepatitis C virus RNA at the age of 1, 3, and 6 months, but not later. The course of hepatitis C virus RNA and anti-HCV in this baby may reflect fluctuating viral replication in chronic infectious disease or viral clearance in acute infection. The other infant had hepatitis C virus RNA detectable at the age of 3 months and at 15, 18 and 24 months. In the other nine non-hepatitis C virus-infected infants, maternally acquired anti-HCV gradually disappeared by the age of 6 months. The liver function profile fell to the normal range in all the infants, including the two hepatitis C virus-infected infants. This may indicate the subclinical nature of hepatitis C virus infection in infancy. Seven fathers and four siblings of these 11 infants were checked for anti-HCV and liver function tests; none had evidence of hepatitis C virus infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Rolling review--the pathogenesis, diagnosis and management of viral hepatitis

Five major hepatotrophic viruses have been identified. The pathogenesis, diagnosis and treatment of chronic viral hepatitis continues to be intensely researched. Experimental evidence suggests that HLA restricted virus-specific T cells play a role in hepatocellular injury in type A hepatitis. The absence of chronic infection indicates the effectiveness of the host immune response to hepatitis A virus (HAV). It is postulated that HAV may rarely trigger an autoimmune chronic hepatitis. Active prophylaxis of hepatitis A is possible. The elimination of hepatitis B is dependent on the recognition of viral determinants in association with HLA proteins on infected hepatocytes by cytotoxic T cells. The specific epitopes recognized by B and T cells are being mapped. Polymerase chain reaction (PCR) amplification and sequencing of genomic DNA in patients with chronic hepatitis B has indicated that nucleotide substitutions in the genome are not uncommon. Their pathogenicity is being explored. Antiviral therapy for hepatitis B remains difficult. Interferon is effective in a proportion of patients. Thymosin may prove to be more effective immunomodulatory therapy. New nucleoside analogues suppress HBV replication, but the safety of these drugs has been questioned after the appearance of severe liver toxicity with fialuridine. The data that hepatitis D virus is pathogenic has recently been challenged with the observation that HDV re-occurs in transplanted liver after engrafting, but without signs of HBV recurrence or evidence of liver damage. Treatment of hepatitis D virus remains difficult. Several isolates of hepatitis C virus have been cloned, and the sequence divergence of these isolates indicates that there are several major genotypes and component subtypes of this polymorphic virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Transmission of hepatitis C virus from mothers to infants. The Vertical Transmission of Hepatitis C Virus Collaborative Study Group

BACKGROUND

Although there are case reports of vertical transmission of hepatitis C virus (HCV), it remains uncertain to what extent infected mothers transmit this virus to their infants.

METHODS

We investigated the transmission of HCV from infected mothers to their babies by analyzing HCV RNA in the blood. Three independent studies were performed. First, 7698 parturient women were tested for anti-HCV antibodies; 53 were positive. Their 54 infants (including one set of twins) were followed prospectively for at least six months and tested for HCV disease were prospectively studied. Third, the families of three HCV-infected infants were examined retrospectively.

RESULTS

Of the 53 antibody-positive mothers, 31 were also positive for serum HCV RNA: Three of the 54 babies born to these mothers (5.6 percent) became positive for HCV RNA during the follow-up period. None of the babies of the 22 women who were antibody-positive but HCV RNA-negative became positive for HCV RNA: In the second study, HCV RNA was detected in one of the six infants of infected mothers. In the third study, HCV RNA was detected in the mothers of the three HCV-infected infants. In each of the seven infected infants we studied, the genomic sequence of HCV was almost identical to that from the mother. These seven mothers had significantly higher titers of HCV RNA than did the mothers of infants with no evidence of infection (mean [+/- SD], 10(6.4 +/- 0.5) vs. 10(4.4 +/- 1.5) per milliliter; P < 0.001).

CONCLUSIONS

HCV is vertically transmitted from mother to infant, and the risk of transmission is correlated with the titer of HCV RNA in the mother.

Hepatitis C virus infection in pregnant women: detection by different anti-HCV immunoassays and serum HCV-RNA

To assess the seroepidemiology of hepatitis C virus (HCV) infection in pregnant women and explore the correlation between different anti-HCV immunoassays, we investigated 2 independent groups in Taipei: 1,687 pregnant women without screening for serum alanine aminotransferase (ALT) (group A) and 260 pregnant women with elevated ALT activity (> 45 IU/l) screened from 15,978 cases (group B). In group A, 11 women (0.65%) were found to be anti-HCV-positive by first-generation tests and 21 (1.24%) by second-generation tests, while 7 (2.69%) and 15 (5.77%) of the group B subjects were positive, respectively. The results of the second-generation assays, based either on recombinant proteins or synthetic peptides, were identical. Among the 36 second-generation anti-HCV-positive cases, 18 (86%) of the 21 cases in group A and 13 (87%) of the 15 cases in group B contained serum HCV-RNA by RT-PCR. We conclude that the prevalence of anti-HCV in pregnant Taiwanese women is 1.24%, and the prevalence is 5.77% among those with an elevated ALT level. HCV-RNA is present in 86% of the cases positive for anti-HCV. The discrepancy between positive anti-HCV and negative HCV-RNA in some pregnant women suggests that anti-HCV positivity in such cases may merely represent a past HCV infection or a fluctuating viremia.

Intrafamilial transmission of hepatitis C virus: the important role of inapparent transmission

To evaluate the intrafamilial transmission of hepatitis C virus (HCV) 104 index patients with type C chronic liver disease and their 307 family contacts were interviewed. After a questionnaire on the risk factors of parenteral exposure, blood samples were obtained and tested for liver biochemistry and anti-HCV antibody by enzyme-linked immunosorbent assay (Abbott II). Overall, 52 family contacts (17%) were positive for anti-HCV, indicating a higher anti-HCV prevalence among family contacts than among the general population in Taiwan. The anti-HCV prevalences in parents, spouses, children, and other contacts of the patients were 54% (14/26), 28% (25/91), 6.9% (10/143), and 6.4% (3/47), respectively. The contacts of index patients had increasingly greater risk of HCV infection when they became older and had lived longer with index patients. All family contacts were divided into two groups categorized by whether the index patients had or did not have a history of parenteral exposure. Among 126 family contacts of the 42 patients without parenteral exposure, blood transfusion and surgery were the factors significantly associated with HCV infection in these family contacts (odds ratio = 7.26, 95% confidence interval = 2.32-32.67; odds ratio = 3.95, 95% CI = 1.29-12.11, respectively). Risk factors were not significantly associated with HCV infection among 181 family contacts of the 62 index patients with parenteral exposure. It is concluded that the index patients without parenteral exposure appeared to have acquired the disease from HCV-infected family members with risk factors. Most of the index patients had a history of parenteral exposure and in turn served as the source of the disease for family members.

[Hepatitis C]

Hepatitis C virus (HCV), identified in 1989, is the main agent of Non-A, Non-B hepatitis. The number of HCV carriers in France is estimated between 500,000 and 2 millions. The main risk factors for HCV infection are blood products transfusion and i.v. drug abuse. Cirrhosis occurs in 30% of cases with a delay ranging from 10 to 30 years, and hepatocellular carcinoma in 2.5% of cases. Interferon is, for instance, the only effective therapy in patients with chronic hepatitis C; however, prolonged response (in terms of transaminase normalization) after stopping treatment occurs only in 20% of patients.

Prevalence of hepatitis C virus infection in asymptomatic anti-HIV1 negative pregnant women and their children

The prevalence of hepatitis C virus (HCV) infection was studied prospectively in pregnant women in France and their children by detection of anti-HCV with second-generation ELISA (ELISA2). In ELISA2-positive women, anti-HCV was detected with second- and third-generation RIBA (RIBA2 and RIBA3) and serum HCV RNA was detected with PCR. Among 670 women, anti-HIV1-negative, 26 (3.9%) were positive with ELISA2. RIBA2 was positive in 13 and HCV RNA was found in 10. Ten ELISA2-positive women had a further evaluation with assessment of HCV infection in their children. Among the 10 children born to the index pregnancy, only one was positive with ELISA2 and RIBA2 but negative with RIBA3 and PCR; the nine other children were ELISA2, RIBA2, RIBA3, and PCR negative. All 26 siblings (2-16 years old), of whom 14 were born to PCR-positive mothers, were ELISA2 and RIBA2 negative. We conclude that among anti-HIV1-negative pregnant women with normal serum ALT levels, the prevalence of HCV infection is relatively high but the risk for mother-to-infant transmission of HCV seems to be low.

Detection of viremia by a one step polymerase chain reaction method in hepatitis C virus infection

A simple, sensitive, and specific one step polymerase chain reaction (PCR) method for the detection of hepatitis C virus (HCV) RNA in infected patients' serum or plasma samples is described. We performed the one step PCR amplification in combination with the initial step of reverse transcription by using oligonucleotide primers derived from the conserved 5'-untranslated region (5'-UTR) of the HCV genome. By utilizing this strategy, there was no need for nested or second stage PCR amplification. The PCR products (cDNAs) were easily visualized by agarose gel electrophoresis and ethidium bromide staining. Furthermore, the PCR products were characterized by Southern blot hybridization and DNA sequencing. We then used the one step PCR amplification method to detect the presence of HCV RNA in several infected patients' samples with acute and chronic infections. There was a 100% concordance between the results of PCR and second generation recombinant immunoblot assay (RIBA II). In addition, this method was found to be useful in determining viremia in HCV infected patients with indeterminate RIBA II results. The 5'-UTR of the HCV genome, being the most conserved region among different viral isolates, could be amplified by PCR for the detection of HCV RNA, as shown here, as well as serving as a potential target for antiviral agents.

Importance of the polymerase chain reaction in the study of hepatitis C virus infection

Recently, the principal etiological agent of parenterally transmitted non-A, non-B hepatitis was molecularly cloned from the plasma of an experimentally infected chimpanzee and has been named hepatitis C virus. Determination of the complete nucleotide sequence of the hepatitis C virus genome was a crucial step in preparing the way for future study of this medically important human pathogen. Due to the very low concentration of virus in serum, amplification of viral RNA sequences by reverse transcription and polymerase chain reaction is the only practical method currently available for demonstrating viremia in patients with hepatitis C virus infection. This review examines the pivotal role of the polymerase chain reaction in understanding the biology of hepatitis C virus.

Prevalence of hepatitis C virus in family members of patients with hepatitis C

To investigate the prevalence of hepatitis C virus in the family members of patients with hepatitis C, we examined antibody to hepatitis C virus with a second-generation enzyme-linked immunosorbent assay and viral RNA with a combined assay of reverse transcription and polymerase chain reaction in sera. Among 219 (75 spouses, 110 children, and 34 others), 26 (12%) were antibody positive. The positive rate of antibody to hepatitis C virus was significantly higher than that of the control group (2.0%) and of volunteer blood donors in our district (1.5%), and it increased with age. In particular, the positive rate of antibody to hepatitis C virus among spouses was high (24%). Among family members with elevated ALT, 59% were antibody positive, which was significantly higher than that of the control group (11%). Of the 26 who were antibody positive, 21 (81%) had viral RNA, whereas of the 70 who were antibody negative, only one (1.4%) had viral RNA. These data suggest that hepatitis C virus was transmitted by the infrafamilial route during long duration of contact with patients or sexual transmission. In family members, hepatitis C viral infection is the main cause of liver disorder, and many who were antibody-positive with a second-generation enzyme-linked immunosorbent assay had viremia in the sera.

Diagnosis and treatment of the major hepatotropic viruses

The hepatotropic viruses currently include hepatitis A, B, C, D, and E, and are associated with a spectrum of acute and chronic liver disease syndromes. The epidemiology and natural history of each are discussed, with emphasis on uncommon or newly recognized clinical presentations. The serodiagnosis of hepatitis A, B, and D is well established; the serodiagnosis of hepatitis C and E continues to evolve as serologic and virologic assays become refined. Hepatitis A and E only cause acute liver injury; current medical approaches therefore focus on vaccination strategies. Hepatitis B, C, and D can cause both acute and chronic liver injury. Sequelae of chronic liver disease, including portal hypertension and hepatocellular carcinoma, are not uncommon. Medical therapy of resulting chronic liver disease currently consists of interferon, though other anti-viral strategies are being explored. Advanced chronic liver disease due to hepatitis B, C, or D can be treated by orthotopic liver transplantation, but viral recurrence is near uniform and can be problematic. Further study of the hepatotropic viruses at the molecular biologic, epidemiologic, and clinical levels will continue to provide greater insight into the diagnosis and management of their associated clinical syndromes.

Demonstration of hepatitis C virus genome in saliva and urine of patients with type C hepatitis: usefulness of the single round polymerase chain reaction method for detection of the HCV genome

The possible transmission routes of hepatitis C virus (HCV) in patients without overt parenteral exposure (sporadic or community acquired form) were examined. Saliva and urine specimens obtained from type C hepatitis patients, whose sera were positive for the HCV genome, were examined by reverse transcription and polymerase chain reaction (RT-PCR). By analyzing the factors that influenced the detection of the HCV genome by PCR, we developed a single round method which enabled semiquantitative detection with higher sensitivity than that obtained with nested PCR. Single round PCR revealed that 34.8% (8 of 23) of saliva and 56.5% (13 of 23) of urine specimens from patients with type C hepatitis contained the HCV genome. The amounts of HCV genome in saliva and urine specimens correlated with those in serum. The relative amounts of HCV genome in serum, saliva, and urine from a chronic type C hepatitis patient were determined by comparing the reciprocal of the smallest volume of the specimens in which the PCR products were visualized in agarose gels (PCR units/ml), and the values were 1 x 10(5), 5 x 10(1), and 3 x 10(1) PCR units/ml for serum, saliva, and urine specimens, respectively.

Studies on transmission of hepatitis C virus from mother-to-child in the perinatal period

To elucidate whether breast milk, vaginal discharge and contamination with maternal blood at birth are possible routes of mother-to-child transmission of hepatitis C virus (HCV), we examined HCV RNA in the cord and peripheral blood of infants, and in the blood, vaginal discharge, and breast milk of anti-HCV seropositive mothers. From July 1991 to July 1992, we studied 20 healthy pregnant women, who were seropositive with the Ortho anti-HCV EIA, and their infants. Using a sensitive nested polymerase chain reaction (nested PCR), we investigated the presence or absence of hepatitis C virus in the above-mentioned specimens. Moderate elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was observed in only one woman in the first and third trimesters. The nested PCR and subsequent Southern hybridization detected 0.5-5.5 copies of HCV c-DNA. HCV RNA was detected in 17/20 blood samples (85%), 7/14 vaginal discharge samples (50%) and 4/10 cord blood samples (40%). However, no HCV RNA was identified in the peripheral blood of infants or breast milk. The mother-to-child transmission of HCV at delivery or via breast milk does not appear to contribute much to maintaining the global HCV reservoir.

Hepatitis C virus in pregnancy: seroprevalence and risk factors for infection

OBJECTIVES

Our purpose was to define the prevalence of antibodies to hepatitis C virus among inner-city prenatal patients. We also sought to examine both the reliability of traditional hepatitis risk factors to predict evidence of infection among these women and the incidence of coinfection in this population with other blood-borne and sexually transmissible agents.

STUDY DESIGN

An anonymous serosurvey was performed to define and compare anti-hepatitis C virus prevalences among women registering for prenatal care at both an inner-city, university hospital-based clinic and an academic private practice based at the same institution.

RESULTS

Anti-hepatitis C virus antibodies were detected in 4.3% of 599 pregnant women screened. In comparison, 0.8% had positive antibody tests for human T-lymphotropic virus and 0.5% were positive for antibodies to human immunodeficiency virus. Evidence of chronic hepatitis B infection was seen in 0.8%. The relative risk of other coexisting infections was significantly higher among women with anti-hepatitis C virus antibodies than among those who were antibody negative. Substance abuse was the most commonly identified risk factor for anti-hepatitis C virus-positive status, although risk factor-targeted screening would have failed to detect half of the anti-hepatitis C virus-positive women in this study.

CONCLUSIONS

Hepatitis C virus infection among inner-city pregnant women, with its potential for maternal-fetal transmission, represents a public health issue of sufficient magnitude to warrant more extensive study. More information is needed, given this documented reservoir of maternal seropositivity, regarding the vertical transmissibility of the virus and the effects of coinfections on neonatal disease.

Comparison of three different immunoassays and PCR for the detection of hepatitis C virus infection in pregnant women in Taiwan

To compare different hepatitis C virus (HCV) immunoassays and HCV-RNA in pregnant women, we investigated two independent groups: 1,687 cases without screening for serum alanine aminotransferase (ALT) (group A) and 333 cases with elevated ALT (> 45 IU/l) (group B), after screening 21,459 pregnant women. In group A, 11 (0.65%) and 21 (1.24%) were anti-HCV-positive by first- and second-generation tests, respectively, while in group B 8 (2.40%) and 19 (5.71%) were positive, respectively. The results revealed by second-generation assays based on either recombinant protein or synthetic peptides were identical, as were the anti-HCV titers in group B. Among 40 second-generation anti-HCV-positive cases, 18 (86%) of 21 in group A and 17 (89%) of the 19 in group B contained serum HCV-RNA by RT-PCR. Thus the prevalence of anti-HCV in Taiwanese pregnant women is 1.24% versus 5.71% in those with elevated ALT level.

A unique, predominant hepatitis C virus variant found in an infant born to a mother with multiple variants

To demonstrate vertical transmission of hepatitis C virus (HCV) from an HCV-infected, non-human immunodeficiency virus type 1-infected mother to her infant and to assess the distribution of viral species in the mother and infant, the hypervariable region of the gene encoding the putative envelope glycoprotein E2 (E2HV) was sequenced in three mothers and one mother-infant pair. The data indicate that (i) quasi-species distributions of HCV E2HV variants were found in all four mothers, (ii) a single predominant HCV E2HV variant was found in the infant of a mother shown to have nine predominant E2HV variants, and (iii) the infant's E2HV variant was highly related to, but not identical with, the nine variants identified in the mother at the time of birth. These findings indicate that HCV is transmitted from mother to infant and raise the possibility that the transmission occurs in utero.

Low prevalence of hepatitis C virus infection among dentists in Taiwan

To evaluate whether hepatitis C virus (HCV) infection is an occupational hazard in the dental environment, serum samples collected in 1990-1991 from 461 dentists were tested for the antibody to HCV (anti-HCV) with first- and second-generation HCV enzyme-linked immunoassays (EIAs). Five of the 363 (1.38%) serum samples were reactive by the first-generation (C100-3) HCV EIA. Of the same 363 samples and the other 98 samples, 3 (0.65%) were reactive by the second-generation test. Of the 5 first-generation EIA reactive samples, only the 2 samples showing an absorbance of greater than 2.0 were also reactive to the second-generation EIA. The other 3 low-absorbance samples became negative and were regarded as false positives. Among the 358 samples negative by the first-generation EIA, 1 was reacted by the second-generation EIA. Those samples positive by the first- and/or second-generation HCV EIA were analyzed further by cDNA/polymerase chain reaction (PCR) to detect the presence of HCV RNA. Only 1 of the 5 first-generation EIA reactive samples was positive by PCR, but 2 of the 3 second-generation EIA reactive samples were PCR positive. These results are comparable to the anti-HCV prevalence of healthy blood donors (0.95% by C100-3 assay) and pregnant women (0.63% by recombinant immunoblot assay). We conclude that the prevalence of HCV infection among dentists in Taiwan is low, and there is no increased risk of HCV infection through the practice of dentistry, at least in our area.

Prevalence of hepatitis C virus related to liver diseases in Korea

The authors investigated the epidemiology of hepatitis C virus (HCV) related to liver diseases in Korea. Anti-HCV was studied by EIA in sera from patients with chronic liver diseases (CLD), individuals at high risk, healthy individuals, and family members of patients with CLD. We also evaluated the efficacy of a new anti-HCV assay kit, HCD EIA, consisting of 3 recombinant peptides derived from CORE, NS3 and NS5 regions of the HCV genome, for screening HCV infection. The prevalence of anti-HCV in HCD EIA was 15.4% of 1055 cases studied, while that in the anti-C100-3 EIA was 11.1%. The incidence of anti-HCV in HCD EIA was 5.9% of 17 cases with acute hepatitis, 18.1% of 293 cases with chronic hepatitis, 24.1% of 79 cases with liver cirrhosis, 28.0% of 100 cases with hepatocellular carcinoma, 19.8% of 81 cases maintained with hemodialysis, 31.3% of 16 cases with blood dyscrasias, 4.4% of 114 cases with fatty liver, 1% of 100 healthy persons, 1.3% of 150 blood donors, and 6.2% of 97 family members from 26 patients with type C CLD. Familial HCV clustering was detected in 3 (11.5%) of 26 patients with anti-HCV(+) CLD. The prevalence of anti-HCV in 190 HBsAg positive CLD was 8.4%. The relative proportions of positive anti-HCV, HBsAg, both positive 17.4%, 40.7%, and 3.7%, respectively, while 38.2% of the cases were negative for both anti-HCV and HBsAg. The prevalence of anti-HCV among CLD increased significantly in relation to age (p < 0.05), and it became higher than that of HBsAg after age 60.(ABSTRACT TRUNCATED AT 250 WORDS)

Dizygotic twins discordant for HIV and hepatitis C virus

Twin girls were born at 37 weeks' gestation to a mother infected by HIV and hepatitis C virus. Twin 1 had symptomatic HIV infection by 9 months but was negative for hepatitis C virus antibody and RNA. Twin 2 became HIV antibody negative by 15 months but was positive for antihepatitis C virus and RNA.

Reliability of polymerase chain reaction for detection of hepatitis C virus

The polymerase chain reaction (PCR) is used to detect hepatitis C virus (HCV) RNA, and the results of this assay may have a bearing on management of patients. We tested 31 laboratories for performance of HCV PCR with a coded panel that comprised 4 HCV-positive plasma samples, 6 HCV-negative samples, and two dilution series of HCV-positive plasma. 15 (48%) laboratories had faultless results with both dilution series, and 16 (52%) laboratories reported erroneous results with one or both series. 10 (32%) laboratories had faultless results when testing undiluted plasma samples, 11 (35%) produced a false-negative result with a weak-positive sample, and 10 (32%) produced false negative and/or false positive results. Only 5 (16%) laboratories performed faultlessly with the entire panel of samples. Reports of presence of HCV should be interpreted with care until reliable HCV-RNA detection becomes widely available.

Chronic non-A, non-B hepatitis: role of hepatitis C virus

Thirty three consecutive children with chronic non-A, non-B hepatitis (NANBH) were studied during a four year period to evaluate clinical and histological features and the role of hepatitis C virus (HCV). All patients were asymptomatic. Thirteen (39%) of them were anti-HCV positive. A history of parenteral exposure was significantly more frequent among anti-HCV positive (69%) than anti-HCV negative patients (15%). Aminotransferase serum values were not statistically different between anti-HCV positive and anti-HCV negative patients. Unlike adults, cirrhosis was never found in the children studied. Our results suggest that chronic NANBH is, during childhood, an asymptomatic disease and that the prevalence of HCV infection is lower than in adults. As the majority of the children with chronic NANBH showed no evidence of HCV infection, it seems unwarranted to identify NANBH with HCV infection in children. The lack of cirrhosis in paediatric patients is probably related to a shorter duration of liver disease.

Polymerase chain reaction and transfusion microbiology

Polymerase chain reaction (PCR) involves alternate denaturing and re-annealing of DNA in test samples in the presence of appropriate oligonucleotide primers complementary to opposite strands of the target DNA together with a heat-stable DNA polymerase, Mg2+ and the four nucleotide triphosphates. DNA target segments can be 'amplified' ten-millionfold by 25-35 such cycles. Even greater amplification (approximately 10(12)-fold) with enhanced specificity can be obtained by a second set of amplification cycles using a further pair of 'nested' primers sited within the DNA sequence defined by the original primers. PCR can be applied to the study of the whole range of transfusion-transmitted infections, both plasma and cell associated; RNA viruses can be analyzed if a DNA copy is made from the viral RNA by treatment with reverse transcriptase. In a transfusion context, the retroviruses (HIV-1, HIV-2, HTLV-I, HTLV-II), HCV and HBV have been the viruses most intensively subjected to PCR analysis. The advantages of PCR in this context include its ability to detect virus during the 'window period' or seronegative stages of infections and its value as a marker for viraemia and for the detection of viruses in products made from large pools of plasma. True immunity may also be differentiated from persistent infection in the presence of antibody. Similarly, PCR can overcome problems of diagnosis of acute infection caused by the presence of passively transferred antibody. Detailed strain differentiation is also possible by PCR, in conjunction with sequencing or with the aid of restriction endonucleases.(ABSTRACT TRUNCATED AT 250 WORDS)

Standardization of in vitro synthesis and detection of HIV-1-specific antibodies

Optimal conditions for in vitro anti-human immunodeficiency virus type 1 (HIV-1) antibody (Ab) synthesis and detection were re-appraised. Western blot (WB) and radioimmunoassay (RIA) could detect about 1 and 10 ng, respectively, of HIV-1-specific Ab (HIV-Ab), while the sensitivity of an enzyme-linked immunosorbent assay (ELISA) was much lower. Optimal HIV-Ab recovery was obtained by culturing 2.5 x 10(6) peripheral blood mononuclear cells (PBMC)/ml from seropositive subjects for 16 days in the absence of mitogens; at higher cell concentrations, background levels were unacceptably high. The background of non-de novo synthesized HIV-Ab was due to insufficient PBMC washing and/or cytophilic immunoglobulin (Ig); a particular washing procedure, as well as 24 h peripheral blood mononuclear cells (PBMC) pre-culture, might help in limiting this phenomenon. However, results should be compared with those obtained in cultures containing puromycin especially in infants, where a higher CD16 antigen expression in lymphocytes is likely responsible for increased amounts of cytophilic Ig released in culture supernatants, compared to adults.

Is HCV transmitted by the vertical/perinatal route?

Hepatitis type C is the major aetiological cause of both parenterally transmitted and cryptogenic, sporadic or community acquired nonAnonB hepatitis. The lack of known parenteral risk factors in a consistent number of cases with nonAnonB hepatitis has stimulated the search of other possible modes of viral transmission. The aim of this report is to review the evidence both for and against vertical/perinatal transmission of HCV from anti-HCV positive mothers to infants.

Vertical transmission of hepatitis C virus (HCV) detected by HCV-RNA analysis

The rate of transmission of hepatitis C virus (HCV) from patients with chronic hepatitis C to their children was studied. Of the 64 children with a parent with chronic hepatitis C, two (3%) had abnormal alanine aminotransferase (ALT) activities, six (9%) had anti-HCV detected by c100 ELISA, seven (11%) had anti-HCV detected by ELISA-II, and 21 (33%) had HCV-RNA by polymerase chain reaction (PCR). Anti-HCV detected by ELISA-II disappeared within six months in all six infants. Of the five children whose mothers were given a blood transfusion after the child's first birthday, none had anti-HCV or HCV-RNA. In the five families whose elder or eldest offspring had HCV-RNA, all of the younger offspring had HCV-RNA. The vertical transmission rate of HCV was low if judged by the presence of anti-HCV or abnormal ALT values, but the rate was high (33%) if judged by the presence of HCV-RNA.

Polymerase chain reaction for the diagnosis of hepatitis B and C viral hepatitis

The detection of HBV, HCV, and HDV genomes through the use of the polymerase chain reaction (PCR) has made possible a new step in viral diagnosis. The main advantages of PCR are its extreme sensitivity and the possibility to develop rapid assays using non-radioactive probes. Several studies have now clearly shown its usefulness for the demonstration of viremias, the identification of seronegative viral carriers, and studies on mother-to-child transmission. Several limitations, however, still hamper the use of PCR and it should not yet be regarded as a routine test. The main developments to be expected in the near future deal with automatisation, prevention of contamination, and quantification.

The natural history of community-acquired hepatitis C in the United States. The Sentinel Counties Chronic non-A, non-B Hepatitis Study Team

BACKGROUND

Chronic liver disease develops in more than half of patients with post-transfusion hepatitis C, but little is known about the natural history of community-acquired hepatitis C.

METHODS

In 1985 and 1986 we identified adults with acute non-A, non-B hepatitis in four counties in the United States and followed them prospectively. We used three markers to detect hepatitis C virus (HCV) infection in stored samples of serum: antibody to HCV (anti-HCV) detected by second-generation serologic assays; HCV RNA detected by polymerase-chain-reaction assay; and antibody to HCV antigen (anti-HCVAg) detected by fluorescent-antibody-blocking assay.

RESULTS

Of 130 patients with non-A, non-B hepatitis, 106 (82 percent) had HCV infection, 93 were positive for anti-HCV, and 13 were positive only for HCV RNA or anti-HCVAg. Chronic hepatitis developed in 60 (62 percent) of 97 HCV-infected patients followed for 9 to 48 months, with no relation to the risk factors for infection. Ten of the 30 patients who had liver biopsies had chronic active hepatitis. In samples collected 42 to 48 months after the onset of hepatitis, HCV RNA was detected in 12 of 13 tested patients with chronic hepatitis and in all 15 tested patients with hepatitis that had resolved. Anti-HCV persisted in all but two of the initially positive patients, for a rate of antibody loss of 0.6 per 100 person-years.

CONCLUSIONS

Patients with community-acquired hepatitis C have a high rate of chronic hepatitis. HCV may be a major cause of chronic liver disease in the United States, and in most patients HCV infection seems to persist for at least several years, even in the absence of active liver disease.