Title: Viremia Profiles in Children With Chronic Hepatitis B Virus Infection and Spontaneous e Antigen Seroconversion
Abstract: Background & Aims: This study investigated the viremia profiles in children with chronic hepatitis B virus (HBV) infection and spontaneous hepatitis B e antigen (HBeAg) seroconversion. Methods: Fifty-eight children with chronic HBV infection met the following criteria: normal alanine aminotransferase (ALT) level at enrollment, followed up for more than 10 years, no antiviral treatment, and having undergone spontaneous HBeAg seroconversion during follow-up evaluation. They were grouped according to the post-HBeAg seroconversion HBV-DNA levels: (1) low viremia: transient or never 104 copies/mL or greater (n = 35) (2) fluctuating high viremia: 104 copies/mL or greater at least twice at intervals more than 1 year apart (n = 23). Abdominal sonography, ALT, and HBV-DNA levels were assessed annually. Another 14 nonseroconverted children served as controls. The precore mutant (nt1896) and genotypes were examined. Results: The initial HBV-DNA level of the 58 seroconverters was 108.4±1.0 copies/mL and decreased to 102.9±2.0 copies/mL at the end of follow-up period. Their mean ages at enrollment, at peak HBV-DNA, at peak ALT, at HBeAg seroconversion, and at final follow-up were 7.0 ± 3.7, 13.4 ± 5.8, 16.3 ± 6.0, 17.2 ± 5.8, and 23.7 ± 4.1 years, respectively. The precore mutant appeared more often in the fluctuating-high-viremia group than in the low-viremia group (60.9% vs 22.9%, P = .004). HBV genotypes had no effect on the viremia profiles. After HBeAg seroconversion, none had persistent abnormal ALT levels. Conclusions: Generally, these young seroconverters had decreased viral loads, normal ALT levels, and uneventful courses after HBeAg seroconversion. A longer follow-up period is necessary to elucidate the significance of HBeAg seroconversion occurring in childhood and young adulthood. Background & Aims: This study investigated the viremia profiles in children with chronic hepatitis B virus (HBV) infection and spontaneous hepatitis B e antigen (HBeAg) seroconversion. Methods: Fifty-eight children with chronic HBV infection met the following criteria: normal alanine aminotransferase (ALT) level at enrollment, followed up for more than 10 years, no antiviral treatment, and having undergone spontaneous HBeAg seroconversion during follow-up evaluation. They were grouped according to the post-HBeAg seroconversion HBV-DNA levels: (1) low viremia: transient or never 104 copies/mL or greater (n = 35) (2) fluctuating high viremia: 104 copies/mL or greater at least twice at intervals more than 1 year apart (n = 23). Abdominal sonography, ALT, and HBV-DNA levels were assessed annually. Another 14 nonseroconverted children served as controls. The precore mutant (nt1896) and genotypes were examined. Results: The initial HBV-DNA level of the 58 seroconverters was 108.4±1.0 copies/mL and decreased to 102.9±2.0 copies/mL at the end of follow-up period. Their mean ages at enrollment, at peak HBV-DNA, at peak ALT, at HBeAg seroconversion, and at final follow-up were 7.0 ± 3.7, 13.4 ± 5.8, 16.3 ± 6.0, 17.2 ± 5.8, and 23.7 ± 4.1 years, respectively. The precore mutant appeared more often in the fluctuating-high-viremia group than in the low-viremia group (60.9% vs 22.9%, P = .004). HBV genotypes had no effect on the viremia profiles. After HBeAg seroconversion, none had persistent abnormal ALT levels. Conclusions: Generally, these young seroconverters had decreased viral loads, normal ALT levels, and uneventful courses after HBeAg seroconversion. A longer follow-up period is necessary to elucidate the significance of HBeAg seroconversion occurring in childhood and young adulthood. Chronic hepatitis B virus (HBV) infection is a health problem worldwide.1Beasley R.P. Stevens C.E. Epidemiology of hepatitis B virus infection in Taiwan.in: Sung J.L. Yu J.Y. Wang T.H. Proceedings of the International Symposium on Hepatitis in Taipei. Gastroenterologic Society of the Republic of China, Taipei1974: 1-10Google Scholar In hyperendemic areas such as Taiwan, most chronic HBV infections begin in infancy and early childhood.2Hsu H.Y. Chang M.H. Chen D.S. Lee C.Y. Sung J.L. Baseline seroepidemiology of hepatitis B virus in children in Taipei, 1984: a study just before mass hepatitis B vaccination program in Taiwan.J Med Virol. 1986; 18: 301-307Crossref PubMed Scopus (178) Google Scholar, 3Stevens C.E. Beasley R.P. Tsui J. Lee W.C. Vertical transmission of hepatitis B antigen in Taiwan.N Engl J Med. 1975; 292: 771-774Crossref PubMed Scopus (867) Google Scholar It usually leads to a chronic infection,4Chang M.H. Chronic hepatitis virus infection in children.J Gastroenterol Hepatol. 1998; 13: 541-548Crossref PubMed Scopus (40) Google Scholar which may result in serious complications in adult life.5Chu C.M. Toward control of hepatitis B in the Asia–Pacific Region—natural history of chronic hepatitis B virus infection adults with emphasis on the occurrence of cirrhosis and hepatocellular carcinoma.J Gastroenterol Hepatol. 2000; 15: E25-E30Crossref PubMed Scopus (165) Google Scholar, 6Yuen M.F. Lai C.L. Toward control of hepatitis B in the Asia–Pacific region—natural history of chronic hepatitis B virus infection.J Gastroenterol Hepatol. 2000; 15: E20-E24Crossref PubMed Scopus (58) Google Scholar After HBV acquisition in infancy or childhood, the virus replicates actively in the initial years, which is an immune-tolerant stage, with high HBV-DNA levels and normal alanine aminotransferase (ALT) levels in most patients. Although adults generally show a gradual loss of tolerance to HBV and enter an immune-clearance stage,7Lee P.I. Chang M.H. Lee C.Y. Hsu H.Y. Chen J.S. Chen P.J. Chen D.S. Changes of serum hepatitis B virus DNA and aminotransferase levels during the course of chronic hepatitis B virus infection in children.Hepatology. 1990; 12: 657-660Crossref PubMed Scopus (60) Google Scholar there are few viremia profile reports in children. The host-virus interaction leads to acute exacerbation and subsequent hepatitis B e antigen (HBeAg) seroconversion. Previously, we observed the mutations of the precore gene,8Chang M.H. Hsu H.Y. Ni Y.H. Tsai K.S. Lee P.I. Chen P.J. Hsu Y.L. Chen D.S. Precore stop codon mutant in chronic hepatitis B virus infection in children: its relation to hepatitis B seroconversion and maternal hepatitis B surface antigen.J Hepatol. 1998; 28: 915-922Abstract Full Text PDF PubMed Scopus (46) Google Scholar basal core promoter,9Ni Y.H. Chang M.H. Hsu H.Y. Tsuei D.J. Longitudinal study on mutation profiles of core promoter and precore regions of hepatitis B virus genome in children.Pediatr Res. 2004; 56: 396-399Crossref PubMed Scopus (25) Google Scholar and core gene deletion10Ni Y.H. Chang M.H. Hsu H.Y. Chen H.L. Long-term follow-up study of core gene deletion mutants in children with chronic hepatitis B virus infection.Hepatology. 2000; 32: 124-128Crossref PubMed Scopus (19) Google Scholar in the process of HBeAg seroconversion in children. Current treatment modalities for chronic hepatitis B seek to achieve HBeAg seroconversion, normal ALT levels, and a sustained suppression of the HBV-DNA replication.11Lok A.S.F. McMahon B.J. Chronic hepatitis B: update of recommendations.Hepatology. 2004; 39: 857-861Crossref PubMed Scopus (498) Google Scholar These goals can occur spontaneously or can be achieved with antiviral therapy. Some adult HBeAg seroconverters would experience rebound viral replication, and generally are regarded as difficult to manage.12Hadziyannis S.J. Papatheodoridis G.V. Hepatitis B e antigen-negative chronic hepatitis B: natural history and treatment.Semin Liver Dis. 2006; 26: 130-141Crossref PubMed Scopus (220) Google Scholar This study aimed to investigate whether HBeAg seroconversion in childhood, adolescence, or young adulthood might lower the HBV replication early and lead to a relatively benign course of chronic HBV infection. Most of the previous studies had several pitfalls: (1) the blood sampling was performed mostly in a cross-sectional manner when ALT levels were increased, which often reflects the results of the virus-host interaction; (2) the study subjects were a biased diseased population, not a community-based population; and (3) previous pediatric reports did not use real-time polymerase chain reaction (PCR), the most sensitive method to measure the viral load. A prospective cohort study recruiting a large community-based population starting from the initial phase of HBV infection, perhaps in early childhood, would be more revealing. Such a prospective study would allow us to observe the natural history and monitor the disease outcome in children, adolescents, and young adults who undergo spontaneous HBeAg seroconversion. Children with chronic HBV infection were recruited from a community-based general population through the following: (1) 4 cross-sectional seroepidemiologic surveys of HBV markers conducted in 1984, 1989, 1994, and 1999,13Ni Y.H. Chang M.H. Huang L.M. Chen H.L. Hsu H.Y. Chiu T.Y. Tsai K.S. Chen D.S. Hepatitis B virus infection in children and adolescents in a hyperendemic area: 15 years after universal hepatitis B vaccination.Ann Intern Med. 2001; 135: 796-800Crossref PubMed Scopus (315) Google Scholar (2) a prospective screening program for children of hepatitis B surface antigen (HBsAg)-seropositive mothers, and (3) the outpatient clinic of the National Taiwan University Hospital as part of a prospective study that began 25 years ago. A physical examination, blood tests to determine ALT level, HBV seromarkers (including hepatitis B surface antigen [HBsAg], antibody to hepatitis B surface antigen [anti-HBs], antibody to hepatitis B core antigen [anti-HBc], hepatitis B e antigen [HBeAg], antibody to hepatitis B e antigen [anti-HBe]), α-fetoprotein levels, and abdominal sonography were performed at each visit at 6-month intervals. Of these children with chronic HBV infection, 72 became the subjects of this study. Of these, 58 met the following criteria and were enrolled in this study: (1) HBeAg positive and normal ALT level at enrollment, (2) age at enrollment younger than 15 years, (3) follow-up duration more than 10 years, (4) no antiviral treatment given, and (5) underwent spontaneous HBeAg seroconversion to anti-HBe during follow-up evaluation. The other 14 patients served as the control group. They met the same criteria except the last: they were persistently HBeAg positive and did not undergo HBeAg seroconversion. The sex ratio and follow-up duration of the control group were similar to those of the study group (Table 1). HBV DNA was quantified using real-time PCR at least once each year. The study protocol was approved by the Institutional Review Board of the National Taiwan University Hospital, and the patients themselves or their guardians signed the informed consent to collect serum samples.Table 1HBV DNA and ALT Profiles Before and After HBeAg Seroconversion in Nonseroconverters and SeroconvertersNonseroconvertersSeroconvertersBefore seroconversionAfter seroconversionMale: female9:535:23Genotype B:C12:253:5Follow-up, y16.6 ± 2.810.3 ± 4.96.5 ± 5.0Peak ALT (U/L) median (range)aNo difference between nonseroconverters and seroconverters in pre-HBeAg phase (Kruskal–Wallis test, P = .27, .52, and .29 for ALT, peak HBV DNA level, and lowest HBV DNA level, respectively).159 (80–1166)277 (10–1254)26 (14–164)Peak HBV DNA (log10 copies/mL)aNo difference between nonseroconverters and seroconverters in pre-HBeAg phase (Kruskal–Wallis test, P = .27, .52, and .29 for ALT, peak HBV DNA level, and lowest HBV DNA level, respectively).9.2 ± 0.59.0 ± 0.95.0 ± 1.7Lowest HBV DNA (log10 copies/mL)bNo data available for the mean lowest HBV DNA after HBeAg seroconversion because 20 of the children had <102 copies/mL, which is below the detection level.7.0 ± 1.66.4 ± 1.7– <102 (copies/mL), % (no.)01.7% (1)34.5% (20) 102–104 (copies/mL), % (no.)7.1% (1)13.8% (8)60.3% (35) >104 (copies/mL), % (no.)92.9% (13)84.5% (49)5.2% (3)a No difference between nonseroconverters and seroconverters in pre-HBeAg phase (Kruskal–Wallis test, P = .27, .52, and .29 for ALT, peak HBV DNA level, and lowest HBV DNA level, respectively).b No data available for the mean lowest HBV DNA after HBeAg seroconversion because 20 of the children had <102 copies/mL, which is below the detection level. Open table in a new tab We subdivided the 58 seroconverters into 2 groups based on their postseroconversion serum HBV-DNA levels: (1) the low-viremia group had viral loads of persistently less than 104 copies/mL (n = 35) and (2) the fluctuating-high-viremia group had occasional episodes of viremia greater than 104 copies/mL more than 6 months after HBeAg seroconversion (n = 23). We used 104 copies/mL as the cut-off level because this is the current indication for antiviral treatment for HBeAg-negative hepatitis patients.14Liaw Y.F. Leung N. Guan R. Lau G.K.K. Merican I. McCaughan G. Gane E. Kao J.H. Omata M. Asian-Pacific Consensus Update Working Party on Chronic Hepatitis BAsian-Pacific consensus statement on the management of chronic hepatitis B: a 2005 update.Liver Int. 2005; 25: 472-489Crossref PubMed Scopus (331) Google Scholar To ensure that the high viremia episodes were not insignificant transient phenomena, we defined the fluctuating-high-viremia group as having 2 or more episodes of greater than 104 copies/mL in an interval of more than 1 year. The HBV seromarkers were measured using enzyme immunoassays (Abbott Laboratories, North Chicago, IL). ALT levels were determined by an autoanalyzer (model 7450; Hitachi, Tokyo, Japan). The detailed nucleotide sequences and PCR procedures were described previously.15Ni Y.H. Chang M.H. Wang K.J. Hsu H.Y. Chen H.L. Kao J.H. Yeh S.H. Jeng Y.M. Tsai K.S. Chen D.S. Clinical relevance of hepatitis B virus genotype in children with chronic infection and hepatocellular carcinoma.Gastroenterology. 2004; 127: 1733-1738Abstract Full Text Full Text PDF PubMed Scopus (171) Google Scholar, 16Yeh S.H. Tsai C.Y. Kao J.H. Liu C.J. Kuo T.J. Lin M.W. Huang W.L. Jih J. Chen D.S. Chen P.J. Combined real time PCR quantification and signature single nucleotide polymorphism genotyping of hepatitis B virus in one-tube reaction.J Hepatol. 2004; 41: 659-666Abstract Full Text Full Text PDF PubMed Scopus (192) Google Scholar Briefly, HBV DNA was extracted from 50 μL of serum and the nucleic acids were redissolved in 50 μL of H2O and subjected to PCR. The primers cover HBV nucleotide positions 1261-1279 and 1600-1580. The anchor probe is at nucleotide positions 1552-1576 and the sensor probe is at nucleotide positions 1533-1550 of HBV DNA. The real-time PCR measurement was performed by using LightCycler analysis software 3.5 (Roche Diagnostics Applied Science, Mannheim, Germany). The linear range of HBV DNA was 102–1011 copies/mL and the sensitivity of this method was 5 × 102 copies/mL of HBV in serum.16Yeh S.H. Tsai C.Y. Kao J.H. Liu C.J. Kuo T.J. Lin M.W. Huang W.L. Jih J. Chen D.S. Chen P.J. Combined real time PCR quantification and signature single nucleotide polymorphism genotyping of hepatitis B virus in one-tube reaction.J Hepatol. 2004; 41: 659-666Abstract Full Text Full Text PDF PubMed Scopus (192) Google Scholar The latest serum samples of the 58 seroconverters were analyzed. Briefly, the HBV genotypes were analyzed by using PCR with type-specific primers.17Naito H. Hayashi S. Abe K. Rapid and specific genotyping system for hepatitis B virus corresponding to six major genotypes by PCR using type-specific primers.J Clin Microbiol. 2001; 39: 362-364Crossref PubMed Scopus (246) Google Scholar The procedures were described previously.16Yeh S.H. Tsai C.Y. Kao J.H. Liu C.J. Kuo T.J. Lin M.W. Huang W.L. Jih J. Chen D.S. Chen P.J. Combined real time PCR quantification and signature single nucleotide polymorphism genotyping of hepatitis B virus in one-tube reaction.J Hepatol. 2004; 41: 659-666Abstract Full Text Full Text PDF PubMed Scopus (192) Google Scholar The latest serum samples of the 58 seroconverters were used to detect the precore 1896 stop codon mutant. Nested PCR was performed using 2 pairs of primers covering the HBV precore and core regions. The procedures were described previously.8Chang M.H. Hsu H.Y. Ni Y.H. Tsai K.S. Lee P.I. Chen P.J. Hsu Y.L. Chen D.S. Precore stop codon mutant in chronic hepatitis B virus infection in children: its relation to hepatitis B seroconversion and maternal hepatitis B surface antigen.J Hepatol. 1998; 28: 915-922Abstract Full Text PDF PubMed Scopus (46) Google Scholar To compare the low-viremia, fluctuating-high-viremia, and nonseroconverter groups, the following statistical methods were used. The χ2 test with Yates’ correction was used to analyze the variables of sex and precore mutant. The Fisher exact test was used to analyze the genotype. The Kruskal–Wallis test was used to compare the peak ALT levels with ALT levels expressed as the median and range. HBV-DNA levels were log transformed and subjected to the Student t test. A P value of less than .05 was considered statistically significant. The data were expressed as the mean ± SD. The general profiles of the serum HBV DNA of the 58 HBeAg seroconverter children are described in Table 2. The majority (77.6%, 45 of 58) of these patients were thought to have acquired the HBV infection from their mothers because their mothers were HBsAg positive. They initially had a high serum HBV-DNA level (108.4 ± 1.0 copies/mL), which increased further to peak levels of 109.1 ± 0.9 copies/mL, and then decreased to 102.9 ± 2.0 copies/mL at the end of the follow-up period.Table 2The Time Course of Viremia Profiles of 58 Children With Chronic HBV Infection and Spontaneous HBeAg SeroconversionMaternal HBsAg status (positive:negative)45:13Age at enrollment, y7.0 ± 3.7Age at peak HBV-DNA level, y13.4 ± 5.8Age at peak ALT level, y16.3 ± 6.0Age at HBeAg seroconversion, y17.2 ± 5.8 Age at HBeAg seroconversion in those with positive maternal HBsAg, y16.8 ± 5.5 Age at HBeAg seroconversion in those with negative maternal HBsAg, yaThe ages at HBeAg seroconversion between those with positive and negative maternal HBsAg did not differ (Student t test, P = .22).19.0 ± 6.8Age at final follow-up evaluation, y23.7 ± 4.1Interval between the ages at peak ALT level and HBeAg seroconversion, ybCalculated as the age at HBeAg seroconversion minus the the age at peak ALT level.1.0 ± 4.2Interval between the ages at peak HBV-DNA and ALT level, ycCalculated as the age at peak ALT level minus the age at peak HBV-DNA level.2.9 ± 4.2Interval between the ages at peak HBV-DNA level and HBeAg seroconversion, ydCalculated as the age at HBeAg seroconversion minus the age at peak HBV-DNA level.3.9 ± 3.8HBV-DNA level at enrollment, log10 copies/mL8.4 ± 1.0Peak HBV-DNA level, log10 copies/mLeThe peak HBV-DNA level is higher than the level at enrollment (Student t test, P = .001).9.1 ± 0.9HBV-DNA level at final follow-up evaluation, % (no.) <102 copies/mL29.3% (17) 102−104 copies/mL36.2% (21) >104 copies/mL34.5% (20)NOTE. Mean ± SD shown except where indicated.a The ages at HBeAg seroconversion between those with positive and negative maternal HBsAg did not differ (Student t test, P = .22).b Calculated as the age at HBeAg seroconversion minus the the age at peak ALT level.c Calculated as the age at peak ALT level minus the age at peak HBV-DNA level.d Calculated as the age at HBeAg seroconversion minus the age at peak HBV-DNA level.e The peak HBV-DNA level is higher than the level at enrollment (Student t test, P = .001). Open table in a new tab NOTE. Mean ± SD shown except where indicated. Generally, the seroconverters had a peak HBV-DNA level at a mean age of 13.4 years, followed by a peak ALT level at 16.3 years, and then HBeAg seroconversion occurred at 17.2 years of age (Table 2 and Figure 1). There were exceptions: (1) the peak ALT occurred before the peak HBV DNA in 7 patients and the interval between these 2 events ranged from 0.2 to 6.8 years; (2) the peak HBV DNA occurred 6.6 and 1.0 years after HBeAg seroconversion in 2 patients; and (3) the peak ALT occurred after HBeAg seroconversion in 7 patients at intervals ranging from 0.2 to 15.1 years. No children underwent HBsAg seroconversion at the final follow-up evaluation. The mean age at enrollment and the age at the final follow-up evaluation of the 14 nonseroconverted children in the control group were 8.7 ± 4.5 and 25.2 ± 3.5 years, respectively. Their peak ALT and highest and lowest HBV-DNA levels did not differ from those of the seroconverters in the pre-HBeAg seroconversion phase (Table 1). All of the children are still being followed up and none of them show any signs of decompensated liver diseases, or hepatocellular carcinoma on physical examination, blood tests, and abdominal ultrasound. HBV-DNA and ALT profiles before and after HBeAg seroconversion of these 58 seroconverter children are described in Table 1. A transient viremia of greater than 104 copies/mL was found in 21 of the 35 patients (60%) in the low-viremia group. Such events occurred an average of 2.0 ± 1.5 years after HBeAg seroconversion. In the post-HBeAg seroconversion phase, the first upsurge of viremia of greater than 104 copies/mL occurred 2.1 ± 2.2 years after HBeAg seroconversion; the second episode of high viremia came 4.1 ± 2.8 years after HBeAg seroconversion. There were 3.3 ± 1.3 episodes of high viremia during the 9.2 ± 5.5 year follow-up period after HBeAg seroconversion in the fluctuating-high-viremia group. All of the viremia episodes fluctuated above 104 copies/mL, but never persisted for longer than 1 year. Precore mutant was detected in 38% of the seroconverters (22 of 58). Fourteen seroconverters with the precore mutant were in the fluctuating-high-viremia group (14 of 23, 60.9%), which was much higher than the rate in the low-viremia group (8 of 35, 22.9%; Table 3). Because of the longer follow-up duration after HBeAg seroconversion in the former group, there was concern that the emergence of the precore mutant simply reflected the natural history (ie, the longer the duration of infection after seroconversion, the more likely the precore mutant is to occur). A multiple logistic regression analysis was performed, and the precore mutation was found to be associated significantly with the fluctuating-high-viremia vs the low-viremia group (odds ratio, 4.4; 95% confidence interval, 1.3–14.3; P = .016), but not the follow-up duration after HBeAg seroconversion of 9 years or longer vs less than 9 years (odds ratio, 2.3; 95% confidence interval, 0.56–9.09; P = .25). Nine years is the mean follow-up duration for the fluctuating-high-viremia group, and was used as the cut-off level. The viremia profile, rather than a longer follow-up duration, was the significant independent factor associated with the precore mutation.Table 3Basic Characteristics, ALT Levels, and Precore Mutants After Spontaneous HBeAg Seroconversion in 58 SeroconvertersLow viremiaFluctuating high viremiaPMale:female23:1212:11.30Mother HBsAg positive (%)9/35 (25.7)4/23 (17.4).48Age at enrollment, y7.0 ± 3.47.0 ± 4.1.99Final age at end of study, y23.0 ± 3.124.9 ± 4.0.09HBeAg seroconversion age, y18.3 ± 4.815.7 ± 6.9.09Genotype B:C33:220:3.33Follow-up duration after seroconversion, y4.6 ± 3.89.2 ± 5.5.0005Median peak ALT level, U/L (range)24 (14–64)28 (15–91).80Abnormal ALT level (%)6/35 (17.1%)6/23 (26.1%).41Precore 1896 mutant8/35 (22.9%)14/23 (60.9%).004Peak HBV-DNA level, log10 copies/mL3.9 ± 1.65.5 ± 1.0.0001Lowest HBV-DNA level.03 <102, copies/mL, % (no.)54.3% (19)21.7% (5) 102−104, copies/mL, % (no.)45.8% (16)69.6% (16) >104, copies/mL, % (no.)08.7% (2) Open table in a new tab In the fluctuating-high-viremia group, there were 6 patients with an abnormal ALT level after HBeAg seroconversion and 4 of them had the precore mutant (see later). Of the remaining 17 patients with a normal ALT level in this group, 10 had the precore mutant. The prevalence of the precore mutant did not differ between those with normal and abnormal ALT levels in the fluctuating-high-viremia group (P = .73, Fisher exact test with Yates’ correction). In the low-viremia group, 4 of the 6 patients with an abnormal ALT level had the precore mutant. Of the 29 patients with a normal ALT level in the low-viremia group, only 4 patients had the precore mutant. The precore mutant was more prevalent in those with an abnormal ALT level (Fisher exact test with Yates’ correction, P = .005). Six patients had an abnormal ALT level in the fluctuating-high-viremia group after HBeAg seroconversion. In the 4 patients who had precore mutants, their ALT level continued to fluctuate but never exceeded 80 U/L after HBeAg seroconversion. Their peak HBV-DNA levels were 104.6, 106.7, 105.7, and 107.4 copies/mL. The remaining 2 patients lacked the precore mutant and had mild increases in their ALT level after HBeAg seroconversion of 54 and 56 U/L. Their peak HBV-DNA levels were 104.6 and 104.3 copies/mL, respectively. Forty-five mothers of the 58 seroconverters were HBsAg positive and the children were thus presumed to have acquired the HBV infection perinatally. There was no difference between the children infected perinatally or horizontally in terms of the age of HBeAg seroconversion (16.8 ± 5.5 y vs 19.0 ± 6.8 y, P = .22). However, none of the horizontally infected children (0 of 13) had an ALT flare-up after HBeAg seroconversion as compared with 9 of the perinatally transmitted children who had an abnormal ALT level after HBeAg seroconversion (9 of 45; P = .08, Fisher exact test). This prospective long-term follow-up study illustrated the natural course of serum HBV-DNA levels and their relationship to ALT levels and HBeAg seroconversion in children and young adults. A high HBV-DNA viral load is found universally in the immune-tolerant phase in children with chronic HBV infection. The immune-clearance phase follows, during which ALT flare-ups occurred frequently and the peak ALT level usually occurred after the peak HBV-DNA level.18Liu C.J. Chen P.J. Lai M.Y. Kao J.H. Chang C.F. Wu H.L. Shau W.Y. Chen D.S. A prospective study characterizing full-length hepatitis B virus genomes during acute exacerbation.Gastroenterology. 2003; 124: 80-90Abstract Full Text Full Text PDF PubMed Scopus (58) Google Scholar We determined the average intervals between the successive peak HBV-DNA levels, peak ALT levels, and HBeAg seroconversion in children and adolescents in the natural history of chronic HBV infection (Figure 1). The current goals of antiviral treatments are to achieve sustained low viral replication after HBeAg seroconversion. How many subjects with spontaneous HBeAg seroconversion in childhood, adolescence, or young adulthood eventually develop a flare-up of viremia (>104 copies/mL) and become HBeAg-negative chronic hepatitis B victims? We found that 40% (23 of 58) of the seroconverters had more than 1 flare-up of HBV-DNA levels and 20% (12 of 58) of them had ALT flare-ups after spontaneous HBeAg seroconversion. Nevertheless, all the peak ALT levels were less than 2 times the upper limit of normal. Therefore, none of these young seroconverters, who might experience both persistent high viremia episodes and an occasional ALT flare-up, met the current indications for antiviral treatment as a case of HBeAg-negative chronic hepatitis. We need to continue monitoring these patients to see if they develop persistent liver damage later in life. The precore 1896 stop codon mutant is an important factor for persistent viral replication after HBeAg seroconversion, and may prevail in one half to two thirds of HBeAg-negative children and adults with chronic HBV infection in Taiwan.8Chang M.H. Hsu H.Y. Ni Y.H. Tsai K.S. Lee P.I. Chen P.J. Hsu Y.L. Chen D.S. Precore stop codon mutant in chronic hepatitis B virus infection in children: its relation to hepatitis B seroconversion and maternal hepatitis B surface antigen.J Hepatol. 1998; 28: 915-922Abstract Full Text PDF PubMed Scopus (46) Google Scholar, 9Ni Y.H. Chang M.H. Hsu H.Y. Tsuei D.J. Longitudinal study on mutation profiles of core promoter and precore regions of hepatitis B virus genome in children.Pediatr Res. 2004; 56: 396-399Crossref PubMed Scopus (25) Google Scholar, 19Lin C.L. Liao L.Y. Liu C.J. Chen P.J. Lai M.Y. Kao J.H. Chen D.S. Hepatitis B genotypes and precore/basal core promoter mutants in HBeAg-negative chronic hepatitis B.J Gastroenterol. 2002; 37: 283-287Crossref PubMed Scopus (37) Google Scholar An abnormal ALT level after HBeAg seroconversion is associated with the emergence of the precore mutant in adults.20Chu C.M. Yeh C.T. Lee C.S. Sheen I.S. Liaw Y.F. Precore stop mutant in HBeAg-positive patients with chronic hepatitis B: clinical characteristics and correlation with the course of HBeAg-to-anti-HBe seroconversion.J Clin Microbiol. 2002; 40: 16-21Crossref PubMed Scopus (79) Google Scholar As expected, this mutant appeared more frequently (60.9%) in the fluctuating-high-viremia group than in the low-viremia group (22.9%). We recognized its association with an abnormal ALT level in the low-viremia group, but not in the fluctuating-high-viremia group. It is likely that fluctuating high viremia itself is important enough in inducing an abnormal ALT level and minimized the role of the precore mutant. Continuous monitoring of such patients, including the ALT and viremia profiles, can help to elucidate the role of the precore mutant in the post-HBeAg seroconversion phase. In conclusion, children with chronic HBV infection carry a high viral load in the immune-tolerant phase, and it decreases dramatically after they undergo HBeAg seroconversion. Forty percent of these spontaneous seroconverters still had fluctuating high viremia (>104 copies/mL) after HBeAg seroconversion. The precore 1896 mutant after HBeAg seroconversion is more prominent in the fluctuating-high-viremia group. None of them warranted treatment after HBeAg seroconversion. The outcome of these young HBeAg seroconverters appeared to be relatively benign during our follow-up period, however, continuous follow-up evaluation is necessary to make a final conclusion. The authors thank Mr Guan-Jan Wang for his technical assistance, Ms Li-Jin Huang for her help in following up the patients, Ms Jin-Yi Shan and Ms Jia-Pao Pan for the laboratory work, and Dr Luan-Yin Chang for her assistance with the statistics.