Hoang van Tong

Universitätsklinikum Tübingen, Tübingen, Baden-Württemberg, Germany

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Publications (11)38.73 Total impact

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    ABSTRACT: Hepatitis D virus (HDV) infection is acquired as a co- /superinfection of Hepatitis B virus (HBV) and can modulate the pathophysiology of chronic hepatitis B and related liver diseases including hepatocellular carcinoma. Among the eight distinct HDV genotypes reported, relatively few studies have attempted to investigate the prevalence of HDV mixed genotypes and RNA recombination of HDV. With a recorded prevalence of 10-20% HBV infection in Vietnam, this study investigated the HDV variability, HDV genotypes and HDV recombination among twenty-one HDV isolates in Vietnamese HBsAg-positive patients. HDV subgenomic and full-length genome sequences were obtained using newly established HDV-specific RT-PCR techniques. The nucleotide homology was observed from 74.6% to 99.4% among the investigated full-length genome of the HDV isolates. We observed HDV genotype 1 and HDV genotype 2 in the investigated Vietnamese patients. Although no HDV genotype mixtures were observed, we report here a newly identified recombinant of HDV genotypes (HDV 1 and HDV 2). The identified recombinant HDV isolate C03 revealed sequence homology to both HDV genotype 1 (nt1 to nt907) and HDV genotype 2 (nt908 to nt1675; HDAg coding region) with a breakpoint at nt908. Our findings demonstrate the prevalence of intergenotypic recombination between HDV genotypes 1 and 2 in a Vietnamese HBsAg-positive patient. Extended investigation on the distribution and prevalence of HDV, HDV mixed genotypes and recombinant HDV genotypes in a larger Vietnamese population offers vital insights into understanding of the micro-epidemiology of HDV and subsequent pathophysiology in chronic HBV- /HDV-related liver diseases.
    Journal of Viral Hepatitis 02/2014; · 3.08 Impact Factor
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    ABSTRACT: Leprosy is one of the most neglected infectious tropical diseases of the skin and the nerves caused by the intracellular pathogen Mycobacterium leprae. The inducible NOS isoform encoded by NOS2A plays a vital role in host defence against bacterial infections. The functional promoter polymorphisms in NOS2A are associated with various autoimmune and infectious diseases. We investigated the association of NOS2A variants with progression of leprosy in a Brazilian cohort including 221 clinically classified patients and 103 unrelated healthy controls. We observed a novel variant ss528838018A/G in the promoter region at position -6558. The other functional variants were observed with low frequency of minor allele (<0.005). NOS2A promoter variant (-954G/C) was not observed in Brazilian populations, and the new observed promoter variant (ss528838018A/G) as well as other promoter variants were not associated with any clinical forms of leprosy in the Brazilian populations.
    International Journal of Immunogenetics 02/2014; · 1.36 Impact Factor
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    ABSTRACT: Hepatitis B virus infection is a high-risk factor for hepatocellular carcinoma. The human major histocompatibility complex class I chain-related gene A (MICA) is a ligand of the NKG2D receptor that modulates the NK and T-cell-mediated immune responses and is associated with several diseases. This study determined the effects of MICA polymorphisms during HBV infection and HBV-induced HCC. We conducted a case-controlled study in a Vietnamese cohort and genotyped ten functional MICA polymorphisms including the microsatellite motif in 552 clinically classified hepatitis B virus patients and 418 healthy controls. The serum soluble MICA levels (sMICA) were correlated with MICA variants and liver enzyme levels. We demonstrated a significant contribution of MICA rs2596542G/A promoter variant and nonsynonymous substitutions MICA-129Met/Val, MICA-251Gln/Arg, MICA-175Gly/Ser, triplet repeat polymorphism and respective haplotypes with HBV-induced HCC and HBV persistence. The circulating sMICA levels in HBV patient groups were elevated significantly compared with healthy controls. A significant contribution of studied MICA variants to sMICA levels was also observed. The liver enzymes alanine amino transferase (ALT), aspartate transaminase (AST), total bilirubin and direct bilirubin were positively correlated with sMICA levels suggesting sMICA as a biomarker for liver injury. We conclude that MICA polymorphisms play a crucial role in modulating innate immune responses, tumour surveillance and regulate disease susceptibility during HBV infection.
    Journal of Viral Hepatitis 10/2013; 20(10):687-98. · 3.08 Impact Factor
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    ABSTRACT: Two polymorphisms in the STAT4 and HLA-DQ loci were more recently reported to associate with chronic hepatitis B (CHB) induced hepatocellular carcinoma (HCC). We utilised an independent Vietnamese cohort of clinically classified HBV patients of chronic hepatitis B carriers (n=206), liver cirrhosis (n=222) and hepatocellular carcinoma (n=239) and assessed the influence of the reported variants. The STAT4 variant (rs7574865) was marginally associated with HCC susceptibility in CHB carriers in allelic and recessive genetic models (OR=0.84, 95%CI=0.7-0.99, P=0.048 and OR=0.7, 95%CI=0.5-0.99, P=0.047). No significant association between the studied variant with several clinical parameters such as liver enzymes (ALT, AST), total and direct bilirubin, AFP, HBV genotype and viral loads were observed. Our study highlights the reported variant to be a trivial factor and possibly other confounding factors may regulate STAT4 expression during HCC development.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 06/2013; · 3.22 Impact Factor
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    ABSTRACT: Background. The human ficolin-2 (FCN2) and Mannose-binding lectin (MBL2) binds to specific pathogen-associated molecular patterns and activates the complement lectin cascade in a similar manner and is associated with several infectious diseases. Our recently published study has established FCN2 promoter variants and ficolin-2 serum levels as a protective factor in schistosomiasis.Methods. We utilized the Nigerian cohort from our recently published study including 163 Schistosoma haematobium infected individuals and 183 matched healthy subjects and investigated whether MBL deficiency and MBL2 polymorphisms are associated with schistosomiasis.Results. MBL serum levels were significantly higher in controls and are associated with protection (P<0.0001). The '-550H' minor allele was significantly associated with protection (P=0.03) and the heterozygous genotypes -550HL were observed to confer protection (P=0.03). The MBL2*HYPA haplotype (P=0.03) was significantly associated with protection and had higher serum MBL levels (P=0.00073) in controls. The heterozygous 6&emsp14;bp deletion in the promoter was observed to be a susceptibility factor in schistosomiasis (P=0.03).Conclusions. In agreement with our recently published study, our findings support the observation that mannan binding lectin is also associated with protection in schistosomiasis.
    The Journal of Infectious Diseases 02/2013; · 5.85 Impact Factor
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    ABSTRACT: BACKGROUND: Regulatory T cells (Tregs) are a subset of T cells that play an important role in modulating T effector responses during infectious challenges. The aim of this study was to evaluate possible associations between regulatory gene polymorphisms and the risk of uncomplicated malaria and the control of Plasmodium falciparum parasite density levels. METHODS: Twelve regulatory single nucleotide polymorphisms (SNPs) in the promoter regions of FOXP3 (ss270137548, rs11091253), IL10RA (rs56356146, rs7925112), IL10RB (rs8178433, rs8178435, rs999788), STAT6 (rs3024941, rs3024943, rs3024944) and TNFRSF18 (ss2080581728, rs3753344) were genotyped in a cohort of Congolese children. Studied subjects were followed up (passively) during one year. The children who experienced one or several clinical episodes were genotyped as "uncomplicated malaria" group (n=179) and those children who did not experience any episode were genotyped as "asymptomatic children" group (n=138). RESULTS: The prevalence of rs3024944CC genotype of STAT6 was significantly higher in the group of asymptomatic children compared to that of uncomplicated malaria (P=0.003). Similarly, the minor allele rs3024944C was more prevalent in the group of asymptomatic children (P=0.019). Two novel SNPs were observed including -163T/G (ss491228441) in IL10RA gene and -163C/T (ss491228440) in TNFRSF18 gene. The genotype ss491228441TT and the minor allele ss491228441G of the IL10RA were more frequent in the group of asymptomatic children (P=0.006 and P=0.007, respectively). The genotype rs11091253CT of the FOXP3 was associated with high parasite density levels. In addition, a new promoter IL10RA variant (ss491228441) contributes to shield against mild malaria. CONCLUSION: The study indicated that the STAT6 promoter polymorphism rs3024944 was associated with uncomplicated malaria, whereas the FOXP3 promoter variant rs11091253 was associated with significant P. falciparum parasitaemia levels. These genetic data may contribute to the understanding of molecular mechanisms that regulate immune response to P. falciparum infections.
    Malaria Journal 01/2013; 12(1):9. · 3.40 Impact Factor
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    ABSTRACT: In recent years, genome wide association studies have discovered a large number of gene loci that play a functional role in innate and adaptive immune pathways associated with leprosy susceptibility. The immunological control of intracellular bacteria M. leprae is modulated by NOD2-mediated signaling of Th1 responses. In this study, we investigated 211 clinically classified leprosy patients and 230 ethnically matched controls in Indian population by genotyping four variants in NOD2 (rs9302752A/G), LRRK2 (rs1873613A/G), RIPK2 (rs40457A/G and rs42490G/A). The LRRK2 locus is associated with leprosy outcome. The LRRK2 rs1873613A minor allele and respective rs1873613AA genotypes were significantly associated with an increased risk whereas the LRRK2 rs1873613G major allele and rs1873613GG genotypes confer protection in paucibacillary and leprosy patients. The reconstructed GA haplotypes from RIPK2 rs40457A/G and rs42490G/A variants was observed to contribute towards increased risk whereas haplotypes AA was observed to confer protective role. Our results indicate that a possible shared mechanisms underlying the development of these two clinical forms of the disease as hypothesized. Our findings confirm and validates the role of gene variants involved in NOD2-mediated signalling pathways that play a role in immunological control of intracellular bacteria M. leprae.
    PLoS ONE 01/2013; 8(8):e73103. · 3.73 Impact Factor
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    ABSTRACT: Human ficolin-2 (L-ficolins) encoded by the FCN2 gene are pattern-recognition proteins involved in innate immunity and are associated with several infectious diseases. A Nigerian cohort of 168 Schistosoma haematobium-infected individuals and 192 healthy controls were examined for functional single-nucleotide polymorphisms in the promoter region (-986G>A, -602G>A, -4A>G) and in exon 8 (+6424G>T) using real-time polymerase chain reaction. The FCN2 -986A and -4G alleles were significantly associated with the occurrence of schistosomiasis (P = .0004 for -986G>A; P = .0001 for -4A>G). The heterozygous genotypes (P = .0006 for -986G>A; P = .0002 for -4A>G) were observed to be a risk factor for susceptibility to schistosomiasis, whereas the homozygous genotypes of major alleles (P = .0002 for -986G>A; P = .0001 for -4A>G) were observed to shield against schistosomiasis. The haplotype AGGG (P = .0002) was observed to be a risk factor for susceptibility to schistosomiasis compared with controls, and the haplotype GGAG (P = .04) was observed to confer protection compared with patients. Ficolin-2 serum level was significantly higher in controls (P < .005) and in controls with GGAG haplotypes (P < .0001). Our findings demonstrate that FCN2 promoter variants (-986G>A and -4A>G) influence ficolin-2 serum levels and susceptibility to schistosomiasis.
    The Journal of Infectious Diseases 06/2012; 206(4):562-70. · 5.85 Impact Factor
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    ABSTRACT: Ficolin-2 coded by FCN2 gene is a soluble serum protein and an innate immune recognition element of the complement system. FCN2 gene polymorphisms reveal distinct geographical patterns and are documented to alter serum ficolin levels and modulate disease susceptibility. We employed a real-time PCR based on Fluorescence Resonance Energy Transfer (FRET) method to genotype four functional SNPs including -986 G > A (#rs3124952), -602 G > A (#rs3124953), -4A > G (#rs17514136) and +6424 G > T (#rs7851696) in the ficolin-2 (FCN2) gene. We characterized the FCN2 variants in individuals representing Brazilian (n = 176), Nigerian (n = 180), Vietnamese (n = 172) and European Caucasian ethnicity (n = 165). We observed that the genotype distribution of three functional SNP variants (-986 G > A, -602 G > A and -4A > G) differ significantly between the populations investigated (p < 0.0001). The SNP variants were highly linked to each other and revealed significant population patterns. Also the distribution of haplotypes revealed distinct geographical patterns (p < 0.0001). The observed distribution of the FCN2 functional SNP variants may likely contribute to altered serum ficolin levels and this may depend on the different disease settings in world populations. To conclude, the use of FRET based real-time PCR especially for FCN2 gene will benefit a larger scientific community who extensively depend on rapid, reliable method for FCN2 genotyping.
    BMC Medical Genetics 05/2012; 13:37. · 2.54 Impact Factor
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    ABSTRACT: Cytokine-inducible SRC homology 2 domain protein (CISH) is a suppressor of cytokine signaling that controls interleukin-2 signaling pathway. We investigated the single nucleotide polymorphism (SNP) -292A>T in 473 Vietnamese hepatitis B virus (HBV) carriers and 416 healthy controls. CISH variants at -292A>T were associated to HBV infection (Allelic: OR, 1.22 95% CI, 1-1.49; P = 0.04; Recessive: OR, 1.69 95% CI 1.23-2.54; P = 0.007). A gene dose effect for the risk allele -292T was observed (P = 0.04). The level of interleukin 2 and liver enzymes such as alanine transaminase, aspartate transaminase, total bilirubin, and direct bilirubin were not associated to CISH polymorphism at position -292A>T This study associated the vital role of CISH SNP -292A>T variant to hepatitis B virus infection in a Vietnamese population.
    Immunogenetics 04/2012; 64(4):261-5. · 2.89 Impact Factor
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    ABSTRACT: Interleukin 4 (IL-4) is an anti-inflammatory cytokine, which regulates balance between T(H)1 and T(H)2 immune response, immunoglobulin class switching and humoral immunity. Polymorphisms in this gene have been reported to affect the risk of infectious and autoimmune diseases. We have analyzed three regulatory IL-4 polymorphisms; -590C>T, -34C>T and 70 bp intron-3 VNTR, in 4216 individuals; including: (1) 430 ethnically matched case-control groups (173 severe malaria, 101 mild malaria and 156 asymptomatic); (2) 3452 individuals from 76 linguistically and geographically distinct endogamous populations of India, and (3) 334 individuals with different ancestry from outside India (84 Brazilian, 104 Syrian, and 146 Vietnamese). The -590T, -34T and intron-3 VNTR R2 alleles were found to be associated with reduced malaria risk (P<0.001 for -590C>T and -34C>T, and P = 0.003 for VNTR). These three alleles were in strong LD (r(2)>0.75) and the TTR2 (-590T, -34T and intron-3 VNTR R2) haplotype appeared to be a susceptibility factor for malaria (P = 0.009, OR = 0.552, 95% CI = 0.356 -0.854). Allele and genotype frequencies differ significantly between caste, nomadic, tribe and ancestral tribal populations (ATP). The distribution of protective haplotype TTR2 was found to be significant (χ(2) (3) = 182.95, p-value <0.001), which is highest in ATP (40.5%); intermediate in tribes (33%); and lowest in caste (17.8%) and nomadic (21.6%). Our study suggests that the IL-4 polymorphisms regulate host susceptibility to malaria and disease progression. TTR2 haplotype, which gives protection against malaria, is high among ATPs. Since they inhabited in isolation and mainly practice hunter-gatherer lifestyles and exposed to various parasites, IL-4 TTR2 haplotype might be under positive selection.
    PLoS ONE 01/2012; 7(10):e48136. · 3.73 Impact Factor

Publication Stats

22 Citations
38.73 Total Impact Points

Institutions

  • 2014
    • Universitätsklinikum Tübingen
      Tübingen, Baden-Württemberg, Germany
  • 2012
    • University of Tuebingen
      • Department of Tropical Medicine
      Tübingen, Baden-Wuerttemberg, Germany