Title: Clinical relevance of hepatitis B virus genotype in children with chronic infection and hepatocellular carcinoma
Abstract: Background & Aims: The aim of this study was to investigate the influence of hepatitis B virus (HBV) genotypes on the clinical outcome of chronic childhood HBV infection and hepatocellular carcinoma (HCC). Methods: A total of 460 HBV carrier children were followed-up for 15 years and 26 children with HBV-related HCC were recruited. HBV genotyping was examined at enrollment and the latest follow-up of these carrier children and at diagnosis in HCC children. Viral load was checked at enrollment for the carrier children. These carriers were grouped based on their initial hepatitis B e antigen (HBeAg) and antibody to hepatitis B e antigen (anti-HBe) status. The HBeAg positive (+) group was divided further into an HBeAg(+/+) group and HBeAg(+/−) group, depending on whether spontaneous HBeAg seroconversion occurred during the follow-up period. Results: Genotype B constituted 73%, 86%, and 76% in the HBeAg(+/+), HBeAg(+/−), and anti-HBe(+) groups, respectively. Genotype C was found in 27%, 8%, and 6% in the HBeAg(+/+), HBeAg(+/−), and anti-HBe(+) group, respectively. Genotype C carriers were more prevalent in the HBeAg(+/+) group than the other 2 groups (P = .01), and had a delayed HBeAg seroconversion compared with the genotype B carriers (P < .001). Changes of genotype during the follow-up period were rare (2.8%). In those with HCC, genotype B was also the major type (74%). There was no difference in the baseline viral load between genotypes B and C. Conclusions: Although HBV genotype B dominates in children with chronic HBV infection and HCC in Taiwan, genotype C delays HBeAg seroconversion in pediatric chronic HBV infection. Background & Aims: The aim of this study was to investigate the influence of hepatitis B virus (HBV) genotypes on the clinical outcome of chronic childhood HBV infection and hepatocellular carcinoma (HCC). Methods: A total of 460 HBV carrier children were followed-up for 15 years and 26 children with HBV-related HCC were recruited. HBV genotyping was examined at enrollment and the latest follow-up of these carrier children and at diagnosis in HCC children. Viral load was checked at enrollment for the carrier children. These carriers were grouped based on their initial hepatitis B e antigen (HBeAg) and antibody to hepatitis B e antigen (anti-HBe) status. The HBeAg positive (+) group was divided further into an HBeAg(+/+) group and HBeAg(+/−) group, depending on whether spontaneous HBeAg seroconversion occurred during the follow-up period. Results: Genotype B constituted 73%, 86%, and 76% in the HBeAg(+/+), HBeAg(+/−), and anti-HBe(+) groups, respectively. Genotype C was found in 27%, 8%, and 6% in the HBeAg(+/+), HBeAg(+/−), and anti-HBe(+) group, respectively. Genotype C carriers were more prevalent in the HBeAg(+/+) group than the other 2 groups (P = .01), and had a delayed HBeAg seroconversion compared with the genotype B carriers (P < .001). Changes of genotype during the follow-up period were rare (2.8%). In those with HCC, genotype B was also the major type (74%). There was no difference in the baseline viral load between genotypes B and C. Conclusions: Although HBV genotype B dominates in children with chronic HBV infection and HCC in Taiwan, genotype C delays HBeAg seroconversion in pediatric chronic HBV infection. In the natural course of chronic hepatitis B virus (HBV) infection, seroconversion from hepatitis B e antigen (HBeAg) to antibody to hepatitis B e antigen (anti-HBe) is important in implying that the host breaks the immune tolerance and enters into a low replication phase.1Chang M.H. Chronic hepatitis virus infection in children.J Gastroenterol Hepatol. 1998; 13: 541-548Crossref PubMed Scopus (40) Google Scholar According to our previous longitudinal follow-up studies, the precore stop codon mutation,2Chang 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 (48) Google Scholar core gene deletion,3Ni 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 and basal core promoter mutation may account for HBeAg seroconversion in children. Nevertheless, additional determinant factors still need to be examined. HBV currently is divided into 8 genotypes: A–H.4Okamoto H. Tsuda F. Sakugawa H. Sastrosoewignjo R.I. Imai M. Miyakawa Y. Mayumi M. Typing hepatitis B virus by homology in nucleotide sequence comparison of surface antigen subtypes.J Gen Virol. 1988; 69: 2575-2583Crossref PubMed Scopus (950) Google Scholar, 5Stuyver L. De Gendt S. Van Geyt C. Xoulin F. Fried M. Schinazi R.F. Rossau R. A new genotype of hepatitis B virus complete genome and phylogenetic relatedness.J Gen Virol. 2000; 81: 67-74Crossref PubMed Scopus (833) Google Scholar, 6Arauz-Ruiz P. Norder H. Robertson B.H. Magnius L.O. Genotype H a new Amerindian genotype of hepatitis B virus revealed in Central America.J Gen Virol. 2002; 83: 2059-2073Crossref PubMed Scopus (632) Google Scholar Different HBV genotypes are associated with different mutations in the HBV precore and core promoter gene regions during HBeAg seroconversion.7Chan H.L.Y. Hussan M. Lok A.S. Different hepatitis B genotypes are associated with different mutations in the core promoter and precore regions during hepatitis B e antigen seroconversion.Hepatology. 1999; 29: 976-984Crossref PubMed Scopus (252) Google Scholar, 8Lindh M. Hannoun C. Dhillon A.P. Norkrans G. Horal P. Core promoter mutations and genotypes in relation to viral replication and liver damage in east Asian hepatitis B virus carriers.J Infect Dis. 1999; 179: 775-782Crossref PubMed Scopus (298) Google Scholar, 9Yuen M.F. Sablon E. Yuan H.J. Wong D.K. Hui C.K. Wong B.C. Chan A.O. Lai C.L. Significance of hepatitis B genotype in acute exacerbation, HBeAg seroconversion, cirrhosis-related complications, and hepatocellular carcinoma.Hepatology. 2003; 37: 562-567Crossref PubMed Scopus (163) Google Scholar In adult studies, patients infected with genotype C have been shown to run a more progressive course of liver diseases than those with genotype B infection.10Sumi H. Yokosuka O. Seki N. Arai M. Imazeki F. Kurihara T. Kanda T. Fukai K. Kato M. Saisho H. Influence of hepatitis B virus genotypes on the progression of chronic type B liver disease.Hepatology. 2003; 37: 19-26Crossref PubMed Scopus (372) Google Scholar, 11Kao J.H. Hepatitis B viral genotypes clinical relevance and molecular characteristics.J Gastroenterol Hepatol. 2002; 17: 643-650Crossref PubMed Scopus (280) Google Scholar Compared with genotype B, genotype C is associated with a higher frequency of core promoter mutation in HBV carrier children undergoing HBeAg seroconversion, higher transaminase activities, and a lower response rate to interferon therapy.12Kao J.H. Wu N.H. Chen P.J. Lai M.Y. Chen D.S. Hepatitis B genotypes and the response to interferon therapy.J Hepatol. 2000; 33: 998-1002Abstract Full Text Full Text PDF PubMed Scopus (453) Google Scholar We have documented further that HBV genotype C is prevalent in HCC patients who are >50 years, whereas genotype B is prevalent in HCC patients without cirrhosis and who are <50 years of age.13Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Hepatitis B genotypes correlate with clinical outcomes in patients with chronic hepatitis B.Gastroenterology. 2000; 118: 554-559Abstract Full Text Full Text PDF PubMed Scopus (878) Google Scholar Studies for the clinical relevance of HBV genotypes were performed in adults only. Furthermore, most studies were cross-sectional, or had a relatively short follow-up duration. One cross-sectional study briefly mentioned that the genotype of HBV had no effect on liver damage in children.14Söderström A. Norkrans G. Conradi N. Krantz M. Horal P. Lindh M. Histologic activity of childhood chronic hepatitis B related to viremia levels, genotypes, mutations, and epidemiologic factors.J Pediatr Gastroenterol Nutr. 2002; 35: 487-494Crossref PubMed Scopus (15) Google Scholar Longitudinal studies spanning decades would be more revealing15Yuen M.F. Sablon E. Yuan H.J. Wang D.K.H. Hui C.K. Wong B.C.Y. Chan A.O.O. Lai C.L. Significance of hepatitis B genotype in acute exacerbation, HBeAg seroconversion, cirrhosis-related complications, and hepatocellular carcinoma.Hepatology. 2003; 37: 562-567Crossref PubMed Scopus (124) Google Scholar, 16Chu C.J. Hussain M. Lok A.S.F. Hepatitis B virus genotype B is associated with earlier HBeAg seroconversion compared with hepatitis B virus genotype C.Gastroenterology. 2002; 122: 1756-1762Abstract Full Text Full Text PDF PubMed Scopus (424) Google Scholar than cross-sectional studies because the extrinsic factors confounding the natural course of chronic HBV infection can be avoided.17Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Acute exacerbations of chronic hepatitis B are rarely associated with superinfection of hepatitis B virus.Hepatology. 2001; 34: 817-823Crossref PubMed Scopus (73) Google Scholar We took advantage of our long-term follow-up evaluation of hepatitis B surface antigen (HBsAg) carrier children1Chang M.H. Chronic hepatitis virus infection in children.J Gastroenterol Hepatol. 1998; 13: 541-548Crossref PubMed Scopus (40) Google Scholar, 2Chang 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 (48) Google Scholar, 3Ni 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 and focused on the following aims in the present study: (1) to study the influence of HBV genotypes on the clinical course of chronic HBV infection in children, especially on HBeAg seroconversion; (2) to examine the possibility of superinfections by different genotypes of HBV or transition from one genotype to another during the long-term follow-up period; and (3) to investigate the genotype distribution pattern in childhood hepatocellular carcinoma (HCC). Under parental written consent, 460 HBsAg carrier children were followed-up consecutively every 6 months. These carrier children were enrolled from (1) the outpatient clinic of the National Taiwan University Hospital in a prospective study beginning approximately 23 years ago,18Chang M.H. Hsu H.Y. Hsu H.C. Ni Y.H. Chen J.S. Chen D.S. The significance of spontaneous hepatitis B e antigen seroconversion in childhood with special emphasis on the clearance of hepatitis B e antigen before 3 years of age.Hepatology. 1995; 22: 1387-1392PubMed Google Scholar (2) a prospective screening program for carrier children of HBsAg-seropositive mothers, and (3) 4 cross-sectional studies regarding a hepatitis B vaccination efficacy survey in 1984, 1989, 1994, and 1999.19Ni 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 (317) Google Scholar Each child was examined at 6-month intervals or more frequently if possible. A physical examination and blood test for HBV markers and liver function were taken at each visit. Those who were enrolled for therapeutic trials during the follow-up period were excluded from this study to keep this study an intact natural history of chronic HBV infection. The institutional review board of the National Taiwan University Hospital approved the study protocol. These children were grouped according to their HBeAg/anti-HBe status at enrollment. The HBeAg positive (+) group was divided further into the following groups: (1) the HBeAg(+/+) group representing children with persistent HBeAg positivity during the follow-up period; and (2) the HBeAg(+/−) group representing those who underwent HBeAg seroconversion during the follow-up period. HBeAg seroconversion was defined as the loss of serum HBeAg and the emergence of positive anti-HBe on at least 2 consecutive follow-up visits. The anti-HBe(+) group consisted of children who already were HBeAg negative and anti-HBe positive at enrollment. The HCC group consisted of 26 HBsAg-positive children. The diagnosis of all tumors was confirmed by histologic examination except in 1 patient. The only patient without tissue proof was diagnosed by radiologic finding and a serum α-fetoprotein level of 343,000 ng/mL. The serum samples were assayed for HBV genotypes at the time of the diagnosis of HCC (Table 1). None of the children received interferon or lamivudine therapy during the study period.Table 1The Biochemical Data in Children With Chronic HBV Infection and HCCGroupSex (M:F)Peak ALT (U/L) mean ± SD (range)Age at enrollment (mean ± SD)aaThe ages at enrollment are statistically different among the 4 groups (Mann–Whitney rank test, P < .001).Age at latest follow-up evaluation (mean ± SD)HBeAg(+) group HBeAg(+/+)97:6342 ± 102 (1–878)5.6 ± 4.420.1 ± 5.2 HBeAg(+/−)139:9963 ± 65 (2–663)6.9 ± 4.422.3 ± 4.9Anti-HBe(+) group43:1926 ± 45 (3–308)8.1 ± 4.424.6 ± 5.3HCC group18:848 ± 36 (10–185)10.9 ± 4.3F, female; M, male.a aThe ages at enrollment are statistically different among the 4 groups (Mann–Whitney rank test, P < .001). Open table in a new tab F, female; M, male. Serum HBV markers (including HBsAg, anti–hepatitis B surface antigen, anti–hepatitis B core antigen, HBeAg, anti-HBe) were assayed by radioimmunoassays by using commercial kits (Abbott Laboratories, North Chicago, IL). The level of alanine transaminase (ALT) was determined by an autoanalyzer (7450; Hitachi, Tokyo, Japan). Liver biopsy examination was suggested when there were ALT level surges greater than 2 times the upper normal value and were performed in those patients whose parents had given consent. This examination was not an absolute requirement in this study. In total, 37 patients received this procedure in this study. The histologic examination was processed by the routine H&E stain. The results were interpreted by 1 pathologist and were expressed as Knodell histologic activity index score.20Brunt E.M. Grading and staging: the histopathological lesions of chronic hepatitis: the Knodell histologic activity index and beyond.Hepatology. 2000; 31: 241-246Crossref PubMed Scopus (421) Google Scholar The serum samples at enrollment and the latest serum sample available were submitted for HBV genotype analysis. The HBV genotypes were analyzed by using polymerase chain reaction (PCR) with type-specific primers.21Naito 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 (250) Google Scholar If we were unable to interpret the results after a double check, we applied the restriction fragment length polymorphism method developed by Lindh et al.22Lindh M. Anderson A.S. Gusdal A. Genotypes, nt 1858 variants, and geographic origin of hepatitis B virus—large scale analysis using a new genotyping method.J Infect Dis. 1997; 175: 1285-1293Crossref PubMed Scopus (428) Google Scholar In brief, DNA was extracted from 20 μL of serum by the sodium dodecyl sulfate–proteinase K/phenol/chloroform method, and dissolved in 10 μL of RNase-free water. Two microliters of the product were used for PCR and the first pair of primers: P1 and P2 covering nucleotide 2823–704 of the HBV genome. The condition of the first-run PCR was described previously.22Lindh M. Anderson A.S. Gusdal A. Genotypes, nt 1858 variants, and geographic origin of hepatitis B virus—large scale analysis using a new genotyping method.J Infect Dis. 1997; 175: 1285-1293Crossref PubMed Scopus (428) Google Scholar The product of the first PCR was subjected to nested PCR using mix A (for identifying genotypes A, B, and C) and mix B (for identifying genotypes D, E, and F) with a universal sense primer and type-specific antisense primer, respectively. The procedure condition was the same as for the first PCR. The nested PCR sensitivity was 10−5 pg of HBV DNA. The PCR–restriction fragment length polymorphism method adapted primers that spanned from nucleotide position 256–796, as described by Lindh et al.22Lindh M. Anderson A.S. Gusdal A. Genotypes, nt 1858 variants, and geographic origin of hepatitis B virus—large scale analysis using a new genotyping method.J Infect Dis. 1997; 175: 1285-1293Crossref PubMed Scopus (428) Google Scholar The PCR product then was subjected to the digestion of Tsp5091 and HinfI, respectively. After incubation with the enzymes, the PCR product was electrophoresed in a 3% agarose gel. The restriction fragment length polymorphism patterns then were compared with those published previously.22Lindh M. Anderson A.S. Gusdal A. Genotypes, nt 1858 variants, and geographic origin of hepatitis B virus—large scale analysis using a new genotyping method.J Infect Dis. 1997; 175: 1285-1293Crossref PubMed Scopus (428) Google Scholar All experiments were performed at least in duplicate to confirm the results. HBV DNA was extracted from 50 μL of serum and the nucleic acid was redissolved in 50 μL of H2O. The PCR reaction was prepared in a total volume of 10 μL containing 2 μL of DNA template, 1 μL of LightCycler FastStart DNA Master Hybridization Mixture (Roche Diagnostics Applied Science, Mannheim Germany), 0.8 μL of 25 mmol/L MgCl2, 0.3 μmol/L of anchor and sensor probes, and 5 μmol/L primers. The primers covered nucleotide positions 1261–1279 and 1600–1580, and the anchor probe was nucleotide position 1552–1576, and the sensor probe was from nucleotide position 1533–1550. The detail nucleotide sequences were described previously.23Yeh 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 (194) Google Scholar The PCR reaction was performed as follows: initial hot start denaturation at 95° for 10 minutes, followed by 45 cycles of denaturation at 95° for 5 seconds, annealing at 53° for 10 seconds, and extension at 72° for 20 seconds. Real-time PCR monitoring was achieved by measuring the fluorescence at the end of the annealing phase for each cycle. The measurement was performed by using LightCycler analysis software 3.5 (Roche Diagnostics Applied Science). The sensitivity of this method was 102 copies/mL. To determine the age difference of HBeAg seroconversion between genotypes B and C, we pooled the cases in the HBeAg(+) group, and plotted the curve of age vs. percentage of HBeAg seroconversion by their respective genotypes (Kaplan–Meier survival analysis). The anti-HBe(+) group was not included in the analysis because they already had undergone HBeAg seroconversion at enrollment. Acute exacerbation was defined as an abrupt increase in the ALT level up to >5-fold the upper limit of normal (200 U/L in this study), but the other causes, such as drugs or other viruses, were excluded.24Liaw Y.F. Hepatitis flares and hepatitis B e antigen seroconversion implication in anti-hepatitis B virus therapy.J Gastroenterol Hepatol. 2003; 18: 246-252Crossref PubMed Scopus (143) Google Scholar The χ2 test with Yates' correction, the Mann–Whitney rank test, and the Kaplan–Meier survival analysis were applied where appropriate. HBV-DNA levels were log transformed and subjected to Student t test. A P value of < .05 was considered statistically significant. The baseline and peak ALT levels of the 3 groups of chronic HBV-infected children and the HCC group are shown in Table 1. Their ages at enrollment and at diagnosis were statistically different, the children in the HCC group were older than those in the HBV-infected groups (Mann–Whitney rank test, P < .001). At the latest follow-up evaluation, the ages of the 3 HBV carrier groups were approximately the same (P > .5). Genotype B is the predominant strain of HBV in these children, but the distribution was not even in the HBV chronic infection groups; it accounted for 73%, 86%, and 76% in the HBeAg(+/+), HBeAg(+/−), and anti-HBe(+) groups, respectively, whereas genotype C accounted for 27%, 8%, and 6% in the 3 groups, respectively (Figure 1). Genotype C was significantly more common in the HBeAg(+/+) group than in the HBeAg(+/−) and anti-HBe(+) groups (P < .001). A total of 13 children (2.8%) had changes in HBV genotypes in the 460 children during our long-term follow-up period. They occurred in 2 sequential serum samples (4% and 8% in HBeAg(+/−) and anti-HBe(+) groups, respectively). Also, on a few occasions a mixed infection with genotypes B and C was found in the same serum samples; 2% and 10% in HBeAg(+/−) and anti-HBe(+) groups, respectively. Genotype changes or mixed genotype infections were not observed in the HBeAg(+/+) group. In the 26 children with HCC, serum samples in 7 patients yielded no PCR product. Genotype B was found in 79% (15 of 19); genotype C was found in 11% (2 of 19), and mixed genotypes of B and C and genotype A was found in 1 each of the HCC children (5%). To study the possible effect of genotype on the rate of HBeAg seroconversion, all children with positive HBeAg at enrollment (ie, the HBeAg[+] group), were analyzed by their respective genotypes. Those with mixed genotypes or genotype changes were excluded from this analysis. The patient characteristics, including peak ALT level, HBV DNA level, acute exacerbation, and histologic findings between children with these 2 genotypes were comparable (Table 2). Severe HBV-related parenchymal liver disease is rare. The histologic activity index score was, on average, approximately 6, and all were less than 14 regardless of the genotypes. We plotted the cumulative HBeAg seropositive percentage vs. the ages of carrier children with these 2 genotypes and found genotype C had a delayed HBeAg seroconversion (P < .0001, Figure 2). To avoid the confounding effect of early HBeAg seroconversion caused by the increased ALT levels at enrollment, we excluded 40 patients (30 in genotype B and 10 in genotype C) who presented with increased ALT levels (>60 U/L). We then analyzed the 340 children again for HBeAg seroconversion according to their follow-up duration. Genotype C still showed a delay of HBeAg seroconversion compared with genotype B (Kaplan–Meier survival analysis, median of follow-up duration when the seroconversion occurred: genotype C vs. genotype B = 18.2 vs. 10.2 y, P = .0001).Table 2Comparisons of Patients With Genotypes B and C in HBeAg(+) GroupGenotype B (n = 320)Genotype C (n = 60)Sex (M:F)187:13338:22Age at enrollment (y)6.3 ± 4.36.2 ± 4.2Follow-up duration (y)14.8 ± 4.614.7 ± 4.0Peak ALT level (U/L)172 ± 221159 ± 289HBV DNA (copies/mL)aHBV DNA is expressed as median (range), P = .35 by Student t test after log transformation of the HBV-DNA value.8.0 × 108 (4.8 × 102–3.1 × 1011)3.7 × 108 (4.0 × 103–7.0 × 1011)Histologic activity index scorebScores for the histologic activity index can range from 0 (normal) to 22 (severely abnormal) and are the sum of 4 histologic components: the severity of periportal necrosis (score range, 0–10), intralobular necrosis (score range, 0–4), portal inflammation (score range, 0–4), and fibrosis (score range, 0–4). Thirty-three patients of genotype B and 4 patients of genotype C received this procedure and this examination was performed when ALT level surged, not at enrollment. P = .73 by Student t test. (range)6.5 ± 4.0 (0–14)5.8 ± 6.1 (0–12)Acute exacerbation (%)2515HBeAg seroconversioncP < .0001 by χ2 test with Yates' correction. The differences in the other parameters were not statistically significant. Those with mixed genotype and genotype changes were excluded. (%)6433F, female; M, male.a HBV DNA is expressed as median (range), P = .35 by Student t test after log transformation of the HBV-DNA value.b Scores for the histologic activity index can range from 0 (normal) to 22 (severely abnormal) and are the sum of 4 histologic components: the severity of periportal necrosis (score range, 0–10), intralobular necrosis (score range, 0–4), portal inflammation (score range, 0–4), and fibrosis (score range, 0–4). Thirty-three patients of genotype B and 4 patients of genotype C received this procedure and this examination was performed when ALT level surged, not at enrollment. P = .73 by Student t test.c P < .0001 by χ2 test with Yates' correction. The differences in the other parameters were not statistically significant. Those with mixed genotype and genotype changes were excluded. Open table in a new tab F, female; M, male. This childhood study supplements the lack of data regarding HBV genotype during the natural history of chronic HBV infection in the first 2 decades of life. Our results confirmed previous observations in adults that HBV genotype B is most common in Taiwan.25Liu C.J. Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Molecular epidemiology of hepatitis B viral serotypes and genotypes in Taiwan.J Biomed Sci. 2002; 9: 166-170Crossref PubMed Google Scholar In the meantime, we confirmed that genotype C rather than genotype B delays HBeAg seroconversion in carrier children by 2 approaches: first, genotype C constituted a larger proportion in the HBeAg(+/+) than the other groups; and second, genotype C children seroconverted at an older age. Taiwanese adults seem to have a similar trend.26Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Hepatitis B virus genotypes and spontaneous hepatitis B e antigen seroconversion in Taiwanese hepatitis B carriers.J Med Virol. 2004; 72: 363-369Crossref PubMed Scopus (151) Google Scholar Genotype shifting during the follow-up period is a rare and interesting finding in the present study. Such a phenomenon was seen infrequently in adults and occurred in acute exacerbation.17Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Acute exacerbations of chronic hepatitis B are rarely associated with superinfection of hepatitis B virus.Hepatology. 2001; 34: 817-823Crossref PubMed Scopus (73) Google Scholar Although we did not specifically detect the superinfection or genotype change during acute exacerbation in our prospective study, we showed that these incidents were found exclusively in carrier children after HBeAg seroconversion. This fact may imply that chances of repeated superinfection in childhood may occur in these children and resulted in genotype changes. The other possibility is that they might have mixed genotypes initially, with one genotype dominating the other. After HBeAg seroconversion, the major type was cleared by the host immune response and the minor type then dominated. Because either genotype B to C conversion or genotype C to B conversion was shown, it seems no genotype is dominant in this genotype-shift condition. HBeAg seroconversion usually marks the subsidence of HBV replication and reflects the inactive disease status.7Chan H.L.Y. Hussan M. Lok A.S. Different hepatitis B genotypes are associated with different mutations in the core promoter and precore regions during hepatitis B e antigen seroconversion.Hepatology. 1999; 29: 976-984Crossref PubMed Scopus (252) Google Scholar, 27Lee P.I. Chang M.H. Lee C.Y. Hsu H.Y. Chen P.J. Chen D.S. Changes of serum hepatitis B virus DNA and transaminase level in the natural course of chronic hepatitis B virus infection in children.Hepatology. 1990; 12: 657-660Crossref PubMed Scopus (61) Google Scholar The HBeAg(+/+) group consisted of children who did not undergo HBeAg seroconversion in the whole follow-up period up to a mean age of 20 years. That means they would have HBeAg seroconversion after the age of 20 (Table 1). Genotype C constituted a relatively larger proportion in the HBeAg(+/+) group in comparison with the HBeAg(+/−) and anti-HBe(+) groups (P < .001). Thus, we speculate that those with genotype C infection may be more resistant to HBeAg seroconversion as is seen in HBV carrier adults.28Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Genotypes and clinical phenotypes of hepatitis B virus in patients with chronic hepatitis B virus infection.J Clin Microbiol. 2002; 40: 1207-1209Crossref PubMed Scopus (176) Google Scholar The delayed HBeAg seroconversion may prolong the inflammatory process and subsequently result in more severe liver damage.29Chen D.S. Sung J.L. Hepatitis B e antigen and its antibody in chronic type B hepatitis.J Gastroenterol Hepatol. 1987; 2: 255-270Crossref Scopus (11) Google Scholar We have studied the correlation between HBV genotypes and the precore and core promoter 1762+1764 mutations in children.30Ni 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 (27) Google Scholar The HBV genotype distribution was not different between those with and those without precore mutation. Although carrier children with genotype C were associated with higher core promoter 1762+1764 mutations in HBeAg seroconverters, such mutations did not contribute to the effect of delaying HBeAg seroconversion by genotype C in our previous observation.30Ni 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 (27) Google Scholar HCC is regarded to be the gravest complication of chronic HBV infection. In Taiwan, it was shown that genotype B is the predominant type in patients with HCC who are younger than 35 years, whereas genotype C is more prevalent as age increases.13Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Hepatitis B genotypes correlate with clinical outcomes in patients with chronic hepatitis B.Gastroenterology. 2000; 118: 554-559Abstract Full Text Full Text PDF PubMed Scopus (878) Google Scholar Although the present study consistently showed genotype B was also the most common genotype in childhood HCC, differences existed in cases of young adult HCC. First, most childhood cases of HCC (>80%) were accompanied by cirrhosis,31Chang M.H. Chen D.S. Hsu H.C. Hsu H.Y. Lee C.Y. Maternal transmission of hepatitis B virus in childhood hepatocellular carcinoma.Cancer. 1989; 64: 2377-2380Crossref PubMed Scopus (100) Google Scholar whereas the young adult cases of HCC infected by genotype B HBV were mostly noncirrhotic.13Kao J.H. Chen P.J. Lai M.Y. Chen D.S. Hepatitis B genotypes correlate with clinical outcomes in patients with chronic hepatitis B.Gastroenterology. 2000; 118: 554-559Abstract Full Text Full Text PDF PubMed Scopus (878) Google Scholar Second, a minority of childhood cases of HCC belonged to genotype C, whereas none of the young adult cases of HCC were genotype C. Thus, the carcinogenesis of childhood HCC may not be exactly the same as that in adult HCC. Further study is mandatory to address this question. In conclusion, HBV genotype B accounts for >70% of chronic HBV infection in Taiwan, and HBeAg seroconversion is delayed in those infected with HBV genotype C. Changing and mixing genotypes occur only in those who had undergone HBeAg seroconversion in childhood HBV chronic infection. For childhood cases of HCC, genotype B is still dominant, and the proportion approximates that in HBsAg carrier children. The authors thank Dr. Pei-Jer Chen for help with real-time polymerase chain reaction. The authors also thank Yin-Lien Chen for his technical assistance and Show-Ping Huang and Su-Main Huang for their help in following up the patients.
Publication Year: 2004
Publication Date: 2004-12-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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