Not uncommon: HBV genotype G co-infections among healthy European HBV carriers with genotype A and E infection.

BACKGROUND & AIMS: HBV genotype G (HBV/G) is mainly found in co-infections with other HBV genotypes and was identified as an independent risk factor for liver fibrosis. This study aimed to analyse the prevalence of HBV/G co-infections in healthy European HBV carriers and to characterize the crosstalk of HBV/G with other genotypes. METHODS: A total of 560 European HBV carriers were tested via HBV/G-specific PCR for HBV/G co-infections. Quasispecies distribution was analysed via deep sequencing, and the clinical phenotype was characterized regarding qHBsAg-/HBV-DNA levels and frequent mutations. Replicative capacity and expression of HBsAg/core was studied in hepatoma cells co-expressing HBV/G with either HBV/A, HBV/D or HBV/E using bicistronic vectors. RESULTS: Although no HBV/G co-infection was found by routine genotyping PCR, HBV/G was detected by specific PCR in 4%-8% of patients infected with either HBV/A or HBV/E but only infrequently in other genotypes. In contrast to HBV/E, HBV/G was found as the quasispecies major variant in co-infections with HBV/A. No differences in the clinical phenotype were observed for HBV/G co-infections. In vitro RNA and DNA levels were comparable among all genotypes, but expression and release of HBsAg was reduced in co-expression of HBV/G with HBV/E. In co-expression with HBV/A and HBV/E expression of HBV/G-specific core was enhanced while core expression from the corresponding genotype was markedly diminished. CONCLUSIONS: HBV/G co-infections are common in European inactive carriers with HBV/A and HBV/E infection, but sufficient detection depends strongly on the assay. HBV/G regulated core expression might play a critical role for survival of HBV/G in co-infections.

Performance of Three Common Hepatitis C Virus (HCV) Genotyping Assays for Identification of HCV Genotype 2/1 Chimeras.

Besides seven major hepatitis C virus (HCV) genotypes (GT), a number of intergenotypic recombinant strains have been described. These so-called chimeras combine genetic characteristics of different HCV genotypes. However, correct genotype classification is important, as choice and duration of direct-acting antiviral (DAA) treatment is mainly based on the viral genotype. Therefore, misclassification of chimeras might lead to suboptimal treatment of patients infected with these strains. For example, 2k/1b chimeras are typically described as HCV genotype 2 strains by commercially available hybridization assays, but real-time PCR-based tests recognizing another HCV region might be more suitable for correct chimera detection. In this study, the analytic capacity of the hybridization-assay Versant HCV Genotype 2.0 (LiPA 2.0) and the real-time PCR-based-assays cobas HCV GT and Abbott RealTime HCV Genotype II were tested in a selected cohort of 230 patients infected with HCV genotype 1 (n = 53) and 2 (n = 177) and 48 patients infected with HCV 2/1 chimeric strains. While the Versant HCV Genotype 2.0 (LiPA 2.0) assay failed to identify chimeras in all of the patients (48/48, 100%), cobas HCV GT and Abbott HCV Genotype II assays identified chimeras correctly in 90% (43/48) and 65% (31/48) of the cases, respectively. In conclusion, while the hybridization-based Versant HCV Genotype 2.0 (LiPA 2.0) assay seems to be unsuitable for detection of HCV 2/1 chimeras, use of the real-time PCR-based assays cobas HCV GT and Abbott RealTime HCV Genotype II led to a higher rate of chimera detection.

Divergent preS Sequences in Virion-Associated Hepatitis B Virus Genomes and Subviral HBV Surface Antigen Particles From HBV e Antigen-Negative Patients.

Background: Hepatitis B virus (HBV) surface proteins (HBsAg) coat the viral particle and form subviral particles (SVPs). Loss of HBsAg represents a functional cure and is an important treatment goal. Methods: We analyzed the impact of the HBV genotypes A-E and pre-S mutations on SVP expression in hepatitis B virus e antigen (HBeAg)-negative chronic HBV-infected patients. A HBV genome harboring a preS1-deletion was analyzed in hepatoma cells. Results: We observed a genotype-specific ratio of the 3 surface proteins (SHBs/MHBs/LHBs), reflecting differences in the morphology and composition of SVPs. Deletions/mutations in the preS1/preS2 domain, detected in released viral genomes, did not affect the molecular weight of MHBs and LHBs in these patients. In contrast, LHB molecular weight was altered in vitro using an HBV genome harboring a preS1-deletion derived from one of these patients. Conclusion: Differences in composition of SVPs may result in genotype-specific immunogenicity and pathogenesis. In the patients with preS-mutations, secreted HBsAg and released viral genomes cannot be derived from the same genetic source. As viral genomes are derived from covalently closed circular DNA (cccDNA), HBsAg is presumably derived from integrated DNA. This important HBsAg source should be considered for novel antiviral strategies in HBeAg-negative chronic HBV-infected patients.

Interferon-free treatment choice according to baseline RASs leads to high SVR rates in HCV genotype 1 infected patients.

AIM: Different combinations of direct antiviral agents (DAA) lead to high SVR rates in HCV genotype 1 infected patients. However, presence of baseline resistance-associated substitutions (RASs) represents a major risk factor for treatment failure. It is unknown whether choice of treatment based on RASs has the potential to decrease virologic failure rates. METHODS: Population-based sequencing of NS3 and NS5A genes was performed in HCV genotype 1 infected patients at a German university hospital. Treatment was individually selected based on resistance analyses. RESULTS: In total, 319 patients (50% treatment-experienced and 30% with cirrhosis) were included. With the treatment choice based on the baseline NS3 and NS5A resistance profile SVR rates between 96 and 100% were observed in all subgroups, including treatment-experienced patients with cirrhosis and HCV genotype 1a infected cirrhotic patients. CONCLUSIONS: The choice of treatment based on the RASs status at baseline may be beneficial for optimizing treatment efficacy in patients with HCV genotype 1 infection and risk factors for treatment failure.

Assessment of SARS-CoV-2 Infection among Healthcare Workers of a German COVID-19 Treatment Center.

To date, more than 160 million people have been infected with COVID-19 worldwide. In the present study, we investigated the history of SARS-CoV-2 infection among 3067 healthcare workers (HCW) in a German COVID-19 treatment center during the early phase of the pandemic (July 2020) based on the seroprevalence of SARS-CoV-2 antibodies and self-reported previous PCR results. The results demonstrate a low prevalence of SARS-CoV-2 infection (n = 107 [3.5%]) with no increased risk for employees with a high level of patient exposure in general or working in COVID-19-confined areas in particular. This suggests that the local hygiene standards implemented in our hospital during the first wave of COVID-19 pandemic were effective in preventing patient-to-HCW transmission. No evidence for highly mobile staff serving as a vector for SARS-CoV-2 transmission could be found. In addition, impairment of smell and/or taste was strongly associated with SARS-CoV-2 history.

Quadruple mutation GCAC1809-1812TTCT acts as a biomarker in healthy European HBV carriers.

Many mutation analyses of the HBV genome have been performed in the search for new prognostic markers. However, the Kozak sequence preceding precore was covered only infrequently in these analyses. In this study, the HBV core promoter/precore region was sequenced in serum samples from European inactive HBV carriers. Quadruple mutation GCAC1809-1812TTCT was found with a high prevalence of 42% in the Kozak sequence preceding precore among all HBV genotypes. GCAC1809-1812TTCT was strongly associated with coexistence of basal core promoter (BCP) double mutation A1762T/G1764A and lower HBV DNA levels. In vitro GCAC1809-1812TTCT lead to drastically diminished synthesis of pregenomic RNA (pgRNA), precore mRNA, core, HBsAg, and HBeAg. Calculation of the pgRNA secondary structure suggests a destabilization of the pgRNA structure by A1762T/G1764A that was compensated by GCAC1809-1812TTCT. In 125 patients with HBV-related cirrhosis, GCAC1809-1812TTCT was not detected. While a strong association of GCAC1809-1812TTCT with inactive carrier status was observed, BCP double mutation was strongly correlated with cirrhosis, but this was only observed in absence of GCAC1809-1812TTCT. In conclusion, our data reveal that GCAC1809-1812TTCT is highly prevalent in inactive carriers and acts as a compensatory mutation for BCP double mutation. GCAC1809-1812TTCT seems to be a biomarker of good prognosis in HBV infection.

Formation of semi-enveloped particles as a unique feature of a hepatitis B virus PreS1 deletion mutant.

BACKGROUND: Naturally occurring variants with deletions or mutations in the C-terminal PreS1 domain from hepatitis B virus (HBV) chronically infected patients have been shown to promote HBsAg retention, inhibit HBsAg secretion and change the extracellular appearance of PreS1-containing HBV particles (filaments and virions). AIMS: To study the impact of N-terminal deletion in preS1 domain on viral secretion and morphogenesis. METHODS: An HBV mutant with 15 amino acids (aa 25-39) deletion in N-terminal preS1 was isolated. Intracellular and extracellular HBsAg were quantified by Western blot. Subcellular HBsAg distribution was analysed by confocal laser scanning microscopy. The viral morphology was characterised by sucrose density gradient ultracentrifugation, Western blot, electron microscopy, HBV mixed ELISA and HBV particle gel essay. RESULTS: Expression of this mutant genome released higher amounts of HBsAg in the form of shorter filaments. A significant fraction of semi-enveloped virions was observed in the supernatant that has been unprecedented so far. Stepwise insertion of aa 25-31, aa 32-39 and aa 25-39 increased the length of filaments. The rescue of aa 25-31 and aa 25-39 drastically reduced the amounts of extracellular HBsAg and semi-enveloped virions, while such effects could not be observed after insertion of aa 32-39, arguing against a simple spacer function of this region. The deletion and rescued mutants do not differ in subcellular HBsAg distribution and colocalisation with ER, Golgi and multivesicular bodies markers arguing against differences in release pathways. CONCLUSION: N-terminal PreS1-domain (aa 25-31) determines HBsAg secretion and triggers proper assembly of PreS1-containing particles.