Oligonucleotide chip, real-time PCR and sequencing for genotyping of hepatitis B virus

Prevalence of hepatitis B virus genotypes among patients with liver disease in Eritrea

Eritrea is an East African multiethnic country with an intermediate endemicity for hepatitis B. Our aim was to establish the most prevalent genotypes of hepatitis B virus (HBV) among patients with liver disease. A total of 293 Eritrean patients with liver disease who were hepatitis B surface antigen (HBsAg) positive were enrolled. All sera were tested for liver transaminases, HBV DNA viral load, and hepatitis B seromarkers including HBsAg, anti-HBcAb (total), HBeAg, and anti-HBeAb. Those reactive for HBsAg and anti-HBc (total) were further tested for HBV genotyping. The median (interquartile range) of HBV DNA viral load and ALT levels were 3.47 (1.66) log IU/mL and 28 (15.3) IU/L, respectively. Using type-specific primer-based genotyping method, 122/293 (41.6%) could be genotyped. Irrespective of mode of occurrence, HBV genotype D (21.3%) was the predominant circulating genotype, followed by genotypes C (17.2%), E (15.6%), C/D (13.1%), and C/E (10.7%). Genotypes C/D/E (7.4%), A/D (4.9%), D/E (4.1%), A (2.5%), and B, A/E, B/E, and A/D/C (0.8%) were also present. HBV in Eritrea is comprised of a mixture of HBV genotypes. This is the first study of HBV genotyping among patients with liver disease in Eritrea.

HBV/4DR 9G test and its comparison with INNO-LiPA HBV multi-DR test for the detection of drug-resistant Hepatitis B virus

A significant proportion of patients with chronic Hepatitis B infection require antiviral therapy during their life time. The Antiviral therapy with lamivudine or adefovir or telbivudine has shown to be a major risk factor for selection of resistance. Eighty percent of patients showed a development of lamivudine-resistant strains after five years of treatment with lamivudine alone. Adefovir and telbivudine inhibit HBV with very high efficacy and have moderate incidences of drug resistance. Entecavir and tenofovir have been shown to have a higher barrier to resistance with rates of less than 1.5% after five years of treatment. The rtA181V, rtM204V/I, rtN236T and, rtM250V are high prevalent mutations found in the drug-resistant HBV strains. Therefore, for accurate treatment of HBV-infected patients, it is important to discriminate the drug-resistant HBV strains by using simple and accurate detection method. In this study, we describe the HBV/4DR 9G test and its evaluation by using clinical samples and plasmid DNA standards with a range of HBV mutation sites. In tests with 384 plasmid DNA standards, the HBV/4DR 9G test showed higher than 95% sensitivity and 98% specificity. The HBV/4DR 9G test was compared with the INNO-LiPA HBV Multi DR test for detection of drug-resistant HBV strains only in clinical samples. The plasma samples were collected from patients suspected with HBV drug-resistant strain infection. The results of both tests were cross-checked with the HBV DNA sequence analysis. The HBV/4DR 9G test demonstrated a good agreement with the sequencing results as compared to the INNO-LiPA HBV Multi-DR test. These results indicate that the HBV/4DR 9G test can be a reliable, sensitive, and accurate diagnostic tool for the detection of drug-resistant genotypes of HBV in clinical specimens. HBV/4DR 9G test can genotype 4 drug resistant HBV strains in 1 PCR. The HBV/4DR 9G test will help to minimize the risk of HBV patients from liver cancer.

Hepatitis B virus genotypes A and D in Uganda

BACKGROUND

The prevalence of hepatitis B virus (HBV) infection in Uganda is 10%. Hepatitis B virus genotypes impact on treatment response, rate of spontaneous recovery and progression of chronic HBV infection and hepatocellular carcinoma. There is little information on the HBV genotypic distribution in Uganda.

OBJECTIVES

To determine HBV genotypes in Uganda.

METHODS

The MBN clinical laboratory performs HBV viral load and genotype testing in Uganda. It receives hepatitis B surface antigen (HBsAg)-positive samples from all over the country for additional HBV testing. Samples are stored for 6 months before being discarded. Our study used delinked stored samples. PCR-positive samples had DNA extracted and used as template for HBV genome amplification by nested PCR. Reverse hybridisation was performed and genotypes were determined by the line probe assay method (INNO-LiPA).

RESULTS

One hundred stored HBsAg-positive plasma samples with detectable viral loads were analysed. Of these, 93 samples showed PCR amplification products and gave genotype-specific probe lines on the INNO-LiPA assay. Of the patients, where gender was recorded, 60.9% were female, and the overall median age (IQR) was 25 (2-60) years. There was a predominance of HBV genotype D (47 patients; 50.5%), followed by genotype A, (16 patients; 17.2%). One patient (1.1%) had genotype E. In 28% of the samples mixed infections were detected with genotypes A/E (9.7%) and A/D (6.5%) being most common. Genotypes B, C, E and H only occurred as part of mixed infections.

CONCLUSION

Hepatitis B genotypes D and A were predominant in our study population.

Rapid high-throughput genotyping of HBV DNA using a modified hybridization-extension technique

China has the highest incidence of hepatitis B virus (HBV) infection worldwide. HBV genotypes have variable impacts on disease pathogenesis and drug tolerance. We have developed a technically simple and accurate method for HBV genotyping that will be applicable to pre-treatment diagnosis and individualized treatment. Multiple sequence alignments of HBV genomes from GenBank were used to design primers and probes for genotyping of HBV A through H. The hybridization was carried out on nitrocellulose (NC) membranes with probes fixed in an array format, which was followed by hybrid amplification by an extension step with DNA polymerase to reinforce the double-stranded DNA hybrids on the NC membrane and subsequent visualization using an avidin-biotin system. Genotyping results were confirmed by DNA sequencing and bioinformatics analysis using the National Center for Biotechnology Information genotyping database, and compared with results from the line probe assay. The data show that multiple sequence alignment defined a 630 bp region in the HBV PreS and S regions that was suitable for genotyping. All genotyping significant single nucleotides in the region were defined. Two-hundred-and-ninety-one HBV-positive serum samples from Northwest Chinese patients were genotyped, and the genotyping rate from the new modified hybridization-extension method was 100% compared with direct sequencing. Compared with line probe assay, the newly developed method is superior, featuring reduced reaction time, lower risk of contamination, and increased accuracy for detecting single nucleotide mutation. In conclusion, a novel hybridization-extension method for HBV genotyping was established, which represents a new tool for accurate and rapid SNP detection that will benefit clinical testing.

Hepatitis B virus genotyping: is the time ripe for routine clinical use?

Hepatitis B is one of the major causes of end-stage liver disease and liver cancer worldwide. A number of host and viral factors influence the disease course and outcomes. One such viral factor is hepatitis B virus (HBV) genotypes. There are eight major HBV genotypes described from various geographic regions of the world. Although direct sequencing appears to be the gold standard for HBV genotyping, it is expensive and laborintensive and therefore cannot be applied for routine clinical use. The newer molecular methods including serotyping have made genotyping easier and simple to apply to large number of samples rapidly. The data collected mainly over the last decade have suggested that HBV genotypes may have a bearing over the natural course of the disease and its response to therapy. This review summarizes the available literature and highlights how genotyping could be incorporated into routine clinical practice in order to improve delivery of care to HBV-infected individuals.

Prevalence of HBV genotypes among Egyptian hepatitis patients

Phylogenetic analysis has led to the classification of hepatitis B virus into eight genotypes, designated A to H. The genotypes have differences in biological properties and show heterogeneity in their global distribution. These attributes of the genotypes may account not only for differences in the prevalence of hepatitis B virus mutants in various geographic regions, but also makes them responsible for differences in the clinical outcome and response to antiviral treatment in different population groups. Africa is one of the highly endemic regions of HBV with five genotypes (A-E) identified. Almost all patients in the Mediterranean area are infected with genotype D. However, there is little information of genotype distribution in Egypt. A total of 140 Egyptian patients with hepatitis B surface antigen (HBsAg) positive were enrolled in this study. Of the 140 patients, only 100 patients were HBV DNA positive and only these were included in the study. They were classified into 20 patients with acute hepatitis (AH), 75 patients with chronic active hepatitis (CAH) and 5 patients with hepatocellular carcinoma (HCC). HBV genotypes were determined using INNO-LiPA methodology which is based on the reversed hybridization principle. This study showed that genotype D constituted 87% of the total infections (75 CAH cases, 7 AH cases and 5 HCC cases). The other 13% showed mixed infections of D/F. These findings show that the most prevalent genotype in Egypt is genotype D especially in CAH and HCC patients while the mixed type D/F is only encountered in AH.