Duration of viremia in hepatitis A virus infection

TIM-1, a novel allergy and asthma susceptibility gene

Atopic diseases, including asthma, allergic rhinitis, and atopic dermatitis, are caused by environmental factors in genetically predisposed individuals. Although the prevalence of these diseases has risen dramatically over the past two decades, it has been difficult to identify the underlying causes of these diseases due to the complex interplay between the genetic and environmental factors involved. Using a congenic mouse model of asthma, we simplified this complex trait and identified the novel T cell immunoglobulin domain, mucin-like domain (TIM) gene family, that encodes transmembrane proteins expressed by CD4 T cells. Recent studies demonstrate that the TIM family, particularly TIM-1, plays a critical role in immune responses that regulate the development of atopic diseases. In humans, certain polymorphic variants of TIM-1 are strongly associated with protection against atopy, and this association occurs only in individuals who have had past infection with hepatitis A virus (HAV). Since TIM-1 functions as the cellular receptor for HAV, activation of T cells through TIM-1 by HAV or by its natural ligand may affect T cell differentiation and the development of Th2-driven allergic inflammatory responses. Epidemiologically, HAV infection is associated with a reduced risk of developing atopy, and because the incidence of HAV infection has been significantly reduced in industrialized countries over the past 30 years, the discovery of a genetic interaction between HAV and TIM-1 provides the first molecular genetic evidence for the hygiene hypothesis.

HAV replication in acute hepatitis with typical and atypical clinical course

The correlation between the length of viremia as detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and the clinical course of hepatitis A virus (HAV) infection was studied. Sixty-six consecutive patients with acute hepatitis A who were admitted to hospital in two infectious disease units in southern Italy were enrolled: 57 had a self-limited course of the disease (typical course), 4 a prolonged course, and 5 relapsing hepatitis. Plasma HAV RNA was sought by RT-PCR, using primers made at 5'-NTR of HAV, designed to amplify a 273-bp fragment and detected by 2% agarose gel and by hybridization with a specific biotinylated probe. In four patients with prolonged acute hepatitis A, the plasma HAV RNA, which was positive on the day of admission to hospital, was found to be negative from day 62, 46, 84, and 105, respectively, after the onset of the symptoms. In patients with relapsing hepatitis, HAV viremia paralleled the clinical and biochemical course of disease. In all patients with a typical self-limiting course, clearance of plasma HAV RNA was observed within 20 days of the onset of symptoms. In most patients, plasma HAV viremia became undetectable before the normalization of serum aminotransferases, underlining the importance of the immune reaction in the pathogenesis of acute hepatitis A. The data also suggest that the detection of plasma HAV RNA after 20 days of illness may predict a prolonged course of the disease, but relapsing hepatitis remains unpredictable on the basis of plasma HAV determination.

Viral and clinical factors associated with the fulminant course of hepatitis A infection

Fulminant hepatitis is a severe complication of hepatitis A virus infection. Its mechanism is unknown. Liver transplantation can be necessary, but spontaneous recovery is frequent. There are no data on the level of viral replication according to the clinical form of hepatitis A. We reviewed the files of 50 patients with acute hepatitis A. Nineteen patients had fulminant hepatitis (defined by encephalopathy and factor V <50%), and, from them, 10 patients underwent transplantation. Hepatitis A virus (HAV) RNA was quantified by real-time PCR on sera obtained at admission. The genotype was determined by phylogenetic analysis of HAV RNA. HAV RNA was detected in serum by RT-PCR in 39 out of 50 patients. Encephalopathy and low factor V level were significantly related to female gender, HAV PCR negativity (9/19 vs. 5/31, respectively; P =.03), a low serum HAV RNA level (log, 3.6 +/- 0.6 vs. 4.4 +/- 0.9, respectively; P =.02), genotypes other than IA, and acetaminophen intake. In multivariate analysis, low or undetectable HAV viral load and a high bilirubin level were independently associated with both low factor V levels and fulminant hepatitis and also with death or transplantation. In conclusion, HAV-related liver failure is due to an excessive host response associated with a marked reduction in viral load. Serum HAV RNA assay could be of help in the management of severe hepatitis A.

Hepatitis A virus infection in hepatitis C Brazilian patients

OBJECTIVE

HAV infection in patients with pre-existing chronic liver disease has been associated with increased rate of fulminant hepatitis and mortality. The aim of this study was to investigate the presence of serological and molecular HAV markers in a population of HCV infected patients.

PATIENTS AND METHODS

The presence of total and IgM anti-HAV antibodies was investigated in 197 patients (mean age 44.8+/-12.5 years) referred to the Brazilian Reference Center for Viral Hepatitis and who tested positive for anti-HCV antibodies and HCV RNA. HAV RNA was investigated by reverse transcription-nested PCR in these patients.Results. One hundred seventy patients (86%) had total, but not IgM anti-HAV antibodies, being therefore, immune to hepatitis A, while 27 (14%) were not. A high proportion (6/27, 22%) of the susceptible patients presented markers of recent HAV infection: One patient was IgM anti-HAV positive, three were HAV RNA positive, and two presented both markers. By nucleotide sequencing, it was demonstrated that the HAV isolates infecting these patients belonged to subgenotypes 1A and 1B.

CONCLUSIONS

Superinfection with HAV was a common event in the group of HCV infected patients under study. Implementation of hepatitis A vaccination should be considered for this population.

Transmission of hepatitis A via WBC-reduced RBCs and FFP from a single donation

BACKGROUND

Currently, individuals donating whole blood and cellular components are not screened for hepatitis A (HA). However, transfusion-transmitted HA can occur, albeit very rarely. Although infection is typically mild and self-limited, it may be catastrophic in a small percentage of cases. Two cases of HA transmission from a single donation to two patients with subsequent variable morbidity are reported.

CASE REPORTS

A 50-year-old, asymptomatic, volunteer blood donor made a whole-blood donation. He was found to have HA 18 days later. When notified, the donor center initiated a recall of the components produced from the donated unit. However, the RBCs and FFP had already been transfused. Subsequently, both recipients developed HA as documented by IgM anti-HA serology. The RBC recipient was a 49-year-old woman, transfused after a hysterectomy, who was found to have HA at the time of unit recall (20 days after transfusion). Her condition required the use of medical disability leave. The FFP was infused to a 52-year-old female cardiac surgical patient. Her course was marked by multiple complications, including postoperative development of mild hepatic dysfunction. After testing negative for HA, hepatitis B, and hepatitis C (24 days after transfusion), she suffered a second bout of more severe hepatic dysfunction and was documented to have HA at Day 55 after transfusion. Evaluation of both recipients' close contacts revealed no evidence for exposure to HA by any route other than transfusion.

CONCLUSION

HA can be transmitted by transfusion of units obtained from asymptomatic, infectious donors. Two patients contracted HA from components obtained from a single whole-blood donation. The RBC recipient had a typical self-limited course of HA. The FFP recipient developed HA of relatively delayed onset. Both recovered from HA.

Risks associated with transfusion of cellular blood components in Canada

We provide a comprehensive review of risks associated with allogeneic red blood cell and platelet transfusions in Canada. The review focuses on clinically symptomatic noninfectious transfusion risks (acute and delayed hemolytic, febrile nonhemolytic [FNHTR], allergic, volume overload, transfusion-related acute lung injury, graft-versus-host disease, and posttransfusion purpura) and the risk of clinically significant disease from transfusion-transmitted infections. Data sources include information from Canadian Blood Services, Héma-Québec, Health Canada, and the Québec Hemovigilance System as well as published information from research studies and international hemovigilance systems. We estimate that in 2000 the aggregate risk of potentially severe reactions (excluding FNHTR and minor allergic reactions) was 43.2 per 100000 red cell units (95% confidence interval [CI]: 38.7-48.1), affecting 337 recipients, and 125.7 per 100000 platelet pools of 5 units (95% CI: 100.8-154.9), affecting 88 recipients. The most frequent potentially severe outcomes for red cell transfusion were hemolytic reactions and volume overload and for platelet transfusion were major allergic reactions and bacterial contamination. The current risk of human immunodeficiency virus and hepatitis C virus transmission is approximately 1 in 4 million and 1 in 3 million units, respectively. These estimates are useful for decisions concerning transfusion therapy, the informed consent process, and for evaluating efficacy of interventions to reduce risk.

Molecular characterization of hepatitis a virus isolates from a transcontinental shellfish-borne outbreak

One hundred eighty-four serologically confirmed cases of hepatitis A were reported in eastern Spain in 1999. A matched case-control study implicated imported coquina clams complying with European Union shellfish standards as the source of infection; this implication was confirmed by the detection by reverse transcription-PCR of hepatitis A virus (HAV) RNA in shellfish samples. In spite of the recognized low variability of HAV, genetic characterization of the complete capsid region of virus isolates from patient serum samples revealed the existence of both synonymous and nonsynonymous variants. Two antigenic variants were detected, one in a discontinuous epitope defined by monoclonal antibody K3-4C8 and a second in a linear VP1 epitope of the virus. In spite of these antigenic variants, all isolates were assigned to genotype IB, providing further evidence that the outbreak originated from a common source, although multiple strains were likely to be involved.

Genetic characterization of hepatitis A virus isolates from Buenos Aires, Argentina

The Hepatitis A virus (HAV) has been classified in seven different genotypes, which include human (I, II, III, and VII) and simian (IV, V, and VI) groups. The sequence analysis of HAV strains contributes to the molecular epidemiology of the virus. Although the infection with HAV is endemic in Argentina and vaccination is being implemented in this country, using both IA and IB strains, there are very few data on the genotypes of the circulating viruses. On the basis of the sequences of 20 isolates collected in Buenos Aires during a 2-year period (extended to 3 years by two additional specimens), we observed the presence of a single sub-genotype, IA, but with a high genetic diversity. We analyzed the VP1-2A junction and also the VP3-VP1 region. Most of the Argentine isolates grouped in at least two clusters. One of these was related to South American strains, thus suggesting a co-circulation of related isolates in neighbor countries. The other cluster was composed only of Argentine specimens. Other sequences were more scattered along the phylogenetic tree. However, we demonstrated that a consistent genetic relatedness of sequences could only be inferred on the basis of a more extensive sequencing of each isolate.

Prolonged hepatitis A infection in an HIV-1 seropositive patient

Hepatitis A virus (HAV) is a worldwide disease; in most cases, it causes an acute self-limited illness that does not lead to a chronic state. The course of HAV viremia in a homosexual male with human immunodeficiency virus type 1 (HIV-1) and the correlation between HIV and HAV viral load, alanine aminotranferase (ALT) level, and CD4(+) lymphocyte count were investigated during the course of the infection. HAV RNA was detected quantitatively up to 256 days after clinical onset. To our knowledge, this specific case is the first report of a prolonged infection with hepatitis A in a male with HIV-1. The ALT levels decreased gradually; however, 286 days after clinical onset of hepatitis, ALT levels were three times higher than normal values. HIV viral load was not affected by the infection with HAV and CD4(+) cell count was stable during the course of the co-infection. The duration and the high-titer viremia of hepatitis A virus in an immunodeficient patient constitute a serious risk of the spread of hepatitis A within this population. As inactivated HAV vaccine is safe in HIV-positive subjects, it would be wise to establish a strategy of preventive vaccination in this high-risk group.

Foodborne viruses

Foodborne and waterborne viral infections are increasingly recognized as causes of illness in humans. This increase is partly explained by changes in food processing and consumption patterns that lead to the worldwide availability of high-risk food. As a result, vast outbreaks may occur due to contamination of food by a single foodhandler or at a single source. Although there are numerous fecal-orally transmitted viruses, most reports of foodborne transmission describe infections with Norwalk-like caliciviruses (NLV) and hepatitis A virus (HAV), suggesting that these viruses are associated with the greatest risk of foodborne transmission. NLV and HAV can be transmitted from person to person, or indirectly via food, water, or fomites contaminated with virus-containing feces or vomit. People can be infected without showing symptoms. The high frequency of secondary cases of NLV illness and - to a lesser extent - of hepatitis A following a foodborne outbreak results in amplification of the problem. The burden of illness is highest in the elderly, and therefore is likely to increase due to the aging population. For HAV, the burden of illness may increase following hygienic control measures, due to a decreasing population of naturally immune individuals and a concurrent increase in the population at risk. Recent advances in the research of NLV and HAV have led to the development of molecular methods which can be used for molecular tracing of virus strains. These methods can be and have been used for the detection of common source outbreaks. While traditionally certain foods have been implicated in virus outbreaks, it is clear that almost any food item can be involved, provided it has been handled by an infected person. There are no established methods for detection of viruses in foods other than shellfish. Little information is available on disinfection and preventive measures specifically for these viruses. Studies addressing this issue are hampered by the lack of culture systems. As currently available routine monitoring systems exclusively focus on bacterial pathogens, efforts should be made to combine epidemiological and virological information for a combined laboratory-based rapid detection system for foodborne viruses. With better surveillance, including typing information, outbreaks of foodborne infections could be reported faster to prevent further spread.

Quantification and duration of viraemia during hepatitis A infection as determined by real-time RT-PCR

Human transmission studies and molecular techniques have provided evidence that transient viraemia occurs during infection with hepatitis A virus (HAV). However, the duration of its presence and levels during the phases of clinical disease and convalescence has not yet been well studied in human patients. Real-time RT-PCR techniques are increasingly used to quantify RNA viruses for diagnosis and/or research purposes. We have optimized a one-step RT-PCR that contains a dual-labelled fluorogenic probe to quantify the 5' noncoding region (5' NCR) of HAV. This method has a dynamic range (5-5 x 10(6) copies). The coefficient of regression of the standard curve was, on average 0.978. Intra-assay CVs% varied from 6.1% to 0.98%, and interassay CVs% from 6.46% to 2.1%. In the currently reported study 41 HAV IgM positive serum samples and 200 serum samples from healthy blood donors were tested by the quantitative RT-PCR method. The mean values on the first day of diagnosis found was 6.38 x 10(5) copies/mL. In a longitudinal study, viraemia persisted for an average of 60 days after clinical onset. These results show that viraemia in HAV infection lasts for many weeks.

Influence of human immunodeficiency virus type 1 infection on acute hepatitis A virus infection

To assess the possible influence of human immunodeficiency virus type 1 (HIV-1) infection on the clinical course of acute hepatitis A virus (HAV) infection, 15 HIV-1-infected homosexual men and 15 non-HIV-infected age-matched subjects were compared. HAV load was higher in HIV-1-infected than in non-HIV-infected patients (P<.001). Duration of viremia in HIV-1-infected patients (median, 53 days) was significantly (P<.05) longer than in non-HIV-infected patients (median, 22 days). HIV-1-infected patients had lower elevations in alanine aminotransferase levels than did non-HIV-infected patients (P<.01) but had higher elevations in alkaline phosphatase levels than did non-HIV-infected patients (P<.001). Some HIV-1-infected patients still had HAV viremia when clinical symptoms had disappeared and alanine aminotransferase levels had returned to normal (60-90 days after the onset of symptoms). HIV-1 infection was associated with prolongation of HAV viremia, which might cause a long-lasting outbreak of HAV infection in HIV-1-infected homosexual men.

Characterization of hepatitis A virus isolates from subgenotypes IA and IB in Rio de Janeiro, Brazil

Hepatitis A virus (HAV) isolates from around the world have been classified into seven genotypes (I-VII). Most human strains belong to genotype I, which has been divided into two subgenotypes, A and B. South America has provided a small number of strains studied at the genome level. In the present study, IgM anti-HAV antibodies were detected in 116 out of 250 (46%) serum samples collected from consecutive patients with acute hepatitis referred to the Brazilian Reference Center for Viral Hepatitis, Rio de Janeiro. Viral RNA were extracted from all 250 samples and submitted to a reverse transcription-polymerase chain reaction (RT-PCR) assay designed to amplify a genome segment in the VP1/2A junction region. HAV RNA was detected in 54/116 (47%) and 17/134 (13%) IgM anti-HAV-positive and -negative sera, respectively. In addition, HAV RNA was detected in 17/35 (49%) IgM anti-HAV-positive sera that had been collected at a day care center where cases of acute hepatitis were being observed for 3 months. Nucleotide sequences (168 bp) of PCR products were determined for 30 HAV isolates. Phylogenetic analysis showed that 21 belonged to subgenotype IB, while 9 were of subgenotype IA. Interestingly, a concomitant circulation of isolates from subgenotypes IA and IB was observed in the day care center.

Posttravel hepatitis A: probable acquisition from an asymptomatic adopted child

We report a case of acute hepatitis A in an adoptive parent that was probably acquired from a recently adopted child with asymptomatic, active infection. Prospective adoptive parents should be protected against hepatitis A because of potential exposure during travel and the risk of unrecognized active infection in adopted children.

Nucleic acid testing: update and applications

Nucleic acid testing (NAT) holds the promise of closing the window of infectiousness for hepatitis C virus (HCV) and the human immunodeficiency virus (HIV) in the general blood supply. Pioneering work by the source plasma industry with NAT for hepatitis A virus (HAV), hepatitis B virus (HBV), and parvovirus B19 suggests that, in the future, the risk of other viral infections may be reduced using similar technology. The European Commission decree that, by July 1999, all source plasma for fractionation should be NAT nonreactive for HCV at a sensitivity of 100 viral IU/mL, has driven the implementation of NAT in the United States. It is estimated that more than 95% of the US blood supply is currently tested by one of two investigational tests for HCV and HIV, and many institutions restrict the release of red blood cell (RBC) and plasma products prior to the release of NAT results. NAT implementation has been hampered by a lack of fully automated, low-cost technologies; the absence of Food and Drug Administration (FDA)-approved and validated clinical tests; and lagging turnaround times. Results from US investigational trials of the Procleix Transcription Mediated Amplification (TMA) HCV/HIV (Chiron Corp, Emeryville, CA) and the COBAS AmpliScreen (Roche Diagnostics, Indianapolis, IN) polymerase chain reaction (PCR) assays have begun to substantiate their value. While NAT assays will not replace serologic tests, they lay the groundwork for further reducing the already low risk of infection transmission through transfusion of blood components and their factor derivatives.

Presence of oligoclonal T cells in cerebrospinal fluid of a child with multiphasic disseminated encephalomyelitis following hepatitis A virus infection

We have investigated the clonality of beta-chain T-cell receptor (TCR) transcripts from the cerebrospinal fluid (CSF) and peripheral blood from a 7-year old child who developed a multiphasic disseminated encephalomyelitis following an infection with hepatitis A virus. We amplified beta-chain TCR transcripts by nonpalindromic adaptor (NPA)-PCR-Vbeta-specific PCR. TCR transcripts from only five Vbeta families (Vbeta13, Vbeta3, Vbeta17, Vbeta8, and Vbeta20) were detected in CSF. The amplified products were combined, cloned, and sequenced. Sequence analysis revealed in the CSF substantial proportions of identical beta-chain of TCR transcripts, demonstrating oligoclonal populations of T cells. Seventeen of 35 (48%) transcripts were 100% identical, demonstrating a major Vbeta13.3 Dbeta2.1 Jbeta1.3 clonal expansion. Six of 35 (17%) transcripts were also 100% identical, revealing a second Vbeta13 clonal expansion (Vbeta13.1 Dbeta2.1 Jbeta1.2). Clonal expansions were also found within the Vbeta3 family (transcript Vbeta3.1 Dbeta2.1 Jbeta1.5 accounted for 5 of 35 transcripts [14%]) and within the Vbeta20 family (transcript Vbeta20.1 Dbeta1.1 Jbeta2.4 accounted for 3 of 35 transcripts [8%]). These results demonstrate the presence of T-cell oligoclonal expansions in the CSF of this patient following infection with hepatitis A virus. Analysis of the CDR3 motifs revealed that two of the clonally expanded T-cell clones exhibited substantial homology to myelin basic protein-reactive T-cell clones. In contrast, all Vbeta TCR families were expressed in peripheral blood lymphocytes. Oligoclonal expansions of T cells were not detected in the peripheral blood of this patient. It remains to be determined whether these clonally expanded T cells are specific for hepatitis A viral antigen(s) or host central nervous system antigen(s) and whether molecular mimicry between hepatitis A viral protein and a host protein is responsible for demyelinating disease in this patient.