Predominance of HBV Genotype B and HDV Genotype 1 in Vietnamese Patients with Chronic Hepatitis

Abstract

Hepatitis delta virus (HDV) coinfection will additionally aggravate the hepatitis B virus (HBV) burden in the coming decades, with an increase in HBV-related liver diseases. Between 2018 and 2019, a total of 205 HBV patients clinically characterized as chronic hepatitis B (CHB; n = 115), liver cirrhosis (LC; n = 21), and hepatocellular carcinoma (HCC; n = 69) were recruited. HBV surface antigen (HBsAg), antibodies against surface antigens (anti-HBs), and core antigens (anti-HBc) were determined by ELISA. The presence of hepatitis B viral DNA and hepatitis delta RNA was determined. Distinct HBV and HDV genotypes were phylogenetically reconstructed and vaccine escape mutations in the "a" determinant region of HBV were elucidated. All HBV patients were HbsAg positive, with 99% (n = 204) and 7% (n = 15) of them being positive for anti-HBc and anti-HBs, respectively. Anti-HBs positivity was higher among HCC (15%; n = 9) compared to CHB patients. The HBV-B genotype was predominant (65%; n = 134), followed by HBV-C (31%; n = 64), HBV-D, and HBV-G (3%; n = 7). HCC was observed frequently among young individuals with HBV-C genotypes. A low frequency (2%; n = 4) of vaccine escape mutations was observed. HBV-HDV coinfection was observed in 16% (n = 33) of patients with the predominant occurrence of the HDV-1 genotype. A significant association of genotypes with alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzyme levels was observed in HBV monoinfections. The prevalence of the HDV-1 genotype is high in Vietnam. No correlation was observed between HDV-HBV coinfections and disease progression when compared to HBV monoinfections.

Keywords: Vietnam; genotypes; hepatitis B virus; hepatitis D virus; hepatocellular carcinoma.

Figure 1

Flow chart of the study design.

Figure 2

Association of enzyme and platelet levels with clinical diagnoses. Boxplots illustrate medians with 25 and 75 percentiles. (∙) p-values were calculated using the Kruskal–Wallis statistical test. Boxplots were created with SPSS (IBM Corp.). AST, aspartate amino transferase; ALT, alanine amino transferase; PLT, platelets.

Figure 3

Maximum likelihood phylogenetic tree of HBV S-gene fragment (309 nucleotides). The reference sequences were retrieved from GenBank and labelled with the HBV genotypes and accession numbers. Generated sequences were labelled with the country code, sample ID, and diagnosis (e.g., VN001CHB = Vietnam 001 chronic hepatitis B). Node values indicate statistical support by approximate likelihood ratio test (aLRT) in PhyML 3.0. The scale bar indicates nucleotide substitutions per site.

Figure 4

Maximum likelihood phylogenetic tree constructed using a fragment of the HDV genome (194 nucleotides). The reference sequences were retrieved from GenBank and labelled with the hepatitis delta virus (HDV) genotypes and the GenBank accession numbers. Sample sequences are labelled with the country code for Vietnam, the sample ID and the diagnosis. Node values indicate statistical support by approximate likelihood ratio test (aLRT) in PhyML 3.0. The scale bar indicates nucleotide substitutions per site.

Figure 5

Alignment of the HBV sequences containing vaccine escape mutations. AY303915.1 represents an HBV vaccine escape mutant containing the G145A substitution [42]. Sites of vaccine escape mutations (aa144 and aa145) are highlighted in red.