Nutchanart Thawornsuk

Molecular epidemiological study of hepatitis B virus in Thailand based on the analysis of pre-S and S genes.

Aims:  This study was undertaken to determine the prevalence and characteristics of hepatitis B virus (HBV) genotypes, antigen subtypes, “a” determinant variants and pre‐S gene mutations circulating on a large scale in Thailand.

Molecular epidemiological study of hepatitis B virus among migrant workers from Cambodia, Laos, and Myanmar to Thailand.

Although hepatitis B virus (HBV) infection is endemic in Southeast Asia, molecular epidemiological data on HBV circulating in some countries are limited. The aims of this study were to evaluate the seroprevalence of HBV and its genetic variability among migrant workers from Cambodia, Laos, and Myanmar in Thailand. Sera collected from 1,119 Cambodian, 787 Laotian, and 1,103 Myanmarese workers were tested for HBsAg. HBV DNA was amplified and the pre‐S/S region was sequenced for genotyping and genetic mutation analysis. HBsAg was detected in 282 (9.4%). The prevalence of HBsAg among migrant workers from Cambodia, Laos, and Myanmar was 10.8%, 6.9%, and 9.7%, respectively. Of 224 subjects positive for HBV DNA, 86% were classified as genotype C (99% were sub‐genotype C1) and 11.6% were genotype B (30.8%, 34.6%, and 30.8% were sub‐genotypes B2, B3, and B4, respectively). Various point mutations in the “a” determinant region were detected in approximately 18% of these samples, of which Ile126Ser/Asn was the most frequent variant. Sequencing analysis showed that 19.1% of samples had pre‐S mutations, with pre‐S2 deletion as the most common mutant (7.7%) followed by pre‐S2 start codon mutation (3.8%) and both pre‐S2 deletion and start codon mutation (3.3%). High prevalence of HBV infection (approximately 7–11%) was found among migrant workers from Cambodia, Laos, and Myanmar, which may reflect the current seroprevalence in their respective countries. The data also demonstrated that HBV sub‐genotype C1 was the predominant strain and various mutations of HBV occurring naturally were not uncommon among these populations. J. Med. Virol. 82:1341–1349, 2010.

Molecular analysis of hepatitis B virus associated with vaccine failure in infants and mothers: A case–control study in Thailand

Perinatal transmission of hepatitis B virus (HBV) has been controlled incompletely despite adequate immunoprophylaxis in infants. The aim of this study was to characterize virological factors of HBV associated with vaccine failure in Thailand. Sera of 14 infected infants (13 HBeAg‐positive and one HBeAg‐negative) with vaccine failure and their respective mothers (group M1) were tested quantitatively for HBV DNA by real‐time PCR, HBV genotypes and mutations were characterized by direct sequencing. Sera collected from 15 HBeAg‐positive (group M2) and 15 HBeAg‐negative (group M3) mothers whose infants had been vaccinated successfully served as controls. The results showed that group M1 and group M2 mothers had equal titers of HBV DNA but higher titers than group M3. All infected infants and their respective mothers had the same HBeAg status and HBV genotypes. DNA analysis in a pair of HBeAg‐negative infant and mother revealed that both were infected with an HBV precore mutant (G1896A). Escape mutants in the “a” determinant region (residues 144 and 145) were detected in two (14%) infected infants. The prevalence of BCP mutations/deletions in groups M2 and M3 was higher significantly than in group M1 (P = 0.022 and P < 0.001, respectively). In conclusion, instead of the HBeAg status, a high titer of HBV DNA in mothers was the major contributor to perinatal transmission of HBV. Escape mutants might be associated with vaccine failure in some infants. BCP mutations/deletions in mothers might contribute to the prevention of mother‐to‐infant transmission of HBV. J. Med. Virol. 84: 1177–1185, 2012.

Circulating leptin levels and bone mineral density in children with biliary atresia

Aim: To investigate circulating leptin levels in biliary atresia (BA) patients and the association of leptin with bone mineral density (BMD) and the severity of BA.

Elevation of serum stem‐cell factor in postoperative biliary atresia

Background: Biliary atresia (BA) is one of the most common causes of neonatal cholestasis. Stem‐cell factor (SCF) has been implicated in the development of fibrosis in various diseases. The objective of the present study was to examine the significant role of SCF in BA.