An inactivated SARS-CoV-2 vaccine based on a Vero cell culture-adapted high-titer virus confers cross-protection in small animals.

Rapidly waning immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires continued global access to affordable vaccines. Globally, inactivated SARS-CoV-2 vaccines have been widely used during the SARS-CoV-2 pandemic. In this proof-of-concept study we adapted an original-D614G SARS-CoV-2 virus to Vero cell culture as a strategy to enhance inactivated vaccine manufacturing productivity.

Substitutions in SARS-CoV-2 Mpro Selected by Protease Inhibitor Boceprevir Confer Resistance to Nirmatrelvir.

Nirmatrelvir, which targets the SARS-CoV-2 main protease (Mpro), is the first-in-line drug for prevention and treatment of severe COVID-19, and additional Mpro inhibitors are in development. However, the risk of resistance development threatens the future efficacy of such direct-acting antivirals. To gain knowledge on viral correlates of resistance to Mpro inhibitors, we selected resistant SARS-CoV-2 under treatment with the nirmatrelvir-related protease inhibitor boceprevir.

Hepatitis C virus RNA is 5'-capped with flavin adenine dinucleotide.

RNA viruses have evolved elaborate strategies to protect their genomes, including 5' capping. However, until now no RNA 5' cap has been identified for hepatitis C virus (HCV), which causes chronic infection, liver cirrhosis and cancer. Here we demonstrate that the cellular metabolite flavin adenine dinucleotide (FAD) is used as a non-canonical initiating nucleotide by the viral RNA-dependent RNA polymerase, resulting in a 5'-FAD cap on the HCV RNA.

Toward a vaccine against hepatitis C virus.

Recent advances aid the development of vaccines to prevent chronic liver diseases.

Effect of Glycan Shift on Antibodies against Hepatitis C Virus E2 412-425 Epitope Elicited by Chimeric sHBsAg-Based Virus-Like Particles.

Two of the most important mechanisms of hepatitis C virus (HCV) immune evasion are the high variability of the amino acid sequence and epitope shielding via heavy glycosylation of the envelope (E) proteins. Previously, we showed that chimeric sHBsAg (hepatitis B virus [HBV] small surface antigen)-based virus-like particles (VLPs) carrying highly conserved epitope I from the HCV E2 glycoprotein (sHBsAg_412-425) elicit broadly neutralizing antibodies (bnAbs). However, many reports have identified escape mutations for such bnAbs that shift the N-glycosylation site from N417 to N415.

An inactivated SARS-CoV-2 vaccine induced cross-neutralizing persisting antibodies and protected against challenge in small animals.

Vaccines have relieved the public health burden of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and globally inactivated vaccines are most widely used. However, poor vaccination accessibility and waning immunity maintain the pandemic, driving emergence of variants. We developed an inactivated SARS-CoV-2 (I-SARS-CoV-2) vaccine based on a viral isolate with the Spike mutation D614G, produced in Vero cells in a scalable bioreactor, inactivated with β-propiolactone, purified by membrane-based steric exclusion chromatography, and adjuvanted with MF59-like adjuvant AddaVax.

Nirmatrelvir-resistant SARS-CoV-2 variants with high fitness in an infectious cell culture system.

The oral protease inhibitor nirmatrelvir is of key importance for prevention of severe coronavirus disease 2019 (COVID-19). To facilitate resistance monitoring, we studied severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) escape from nirmatrelvir in cell culture. Resistant variants harbored combinations of substitutions in the SARS-CoV-2 main protease (Mpro).

Identification of novel neutralizing determinants for protection against HCV.

Background And Aims: HCV evasion of neutralizing antibodies (nAb) results in viral persistence and poses challenges to the development of an urgently needed vaccine. N-linked glycosylation of viral envelope proteins is a key mechanism for such evasion. To facilitate rational vaccine design, we aimed to identify determinants of protection of conserved neutralizing epitopes.

Inactivated genotype 1a, 2a and 3a HCV vaccine candidates induced broadly neutralising antibodies in mice.

Objective: A prophylactic vaccine is needed to control the HCV epidemic, with genotypes 1-3 causing >80% of worldwide infections. Vaccine development is hampered by HCV heterogeneity, viral escape including protection of conserved neutralising epitopes and suboptimal efficacy of HCV cell culture systems. We developed cell culture-based inactivated genotype 1-3 HCV vaccine candidates to present natively folded envelope proteins to elicit neutralising antibodies.

High-Titer Hepatitis C Virus Production in a Scalable Single-Use High Cell Density Bioreactor.

Hepatitis C virus (HCV) infections pose a major public health burden due to high chronicity rates and associated morbidity and mortality. A vaccine protecting against chronic infection is not available but would be important for global control of HCV infections. In this study, cell culture-based HCV production was established in a packed-bed bioreactor (CelCradle™) aiming to further the development of an inactivated whole virus vaccine and to facilitate virological and immunological studies requiring large quantities of virus particles.

Inactivated whole hepatitis C virus vaccine employing a licensed adjuvant elicits cross-genotype neutralizing antibodies in mice.

Background & Aims: A prophylactic vaccine is required to eliminate HCV as a global public health threat. We developed whole virus inactivated HCV vaccine candidates employing a licensed adjuvant. Further, we investigated the effects of HCV envelope protein modifications (to increase neutralization epitope exposure) on immunogenicity.

Efficacy of Ion-Channel Inhibitors Amantadine, Memantine and Rimantadine for the Treatment of SARS-CoV-2 In Vitro.

We report the in vitro efficacy of ion-channel inhibitors amantadine, memantine and rimantadine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In VeroE6 cells, rimantadine was most potent followed by memantine and amantadine (50% effective concentrations: 36, 80 and 116 µM, respectively). Rimantadine also showed the highest selectivity index, followed by amantadine and memantine (17.

In vitro efficacy of artemisinin-based treatments against SARS-CoV-2.

Effective and affordable treatments for patients suffering from coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are needed. We report in vitro efficacy of Artemisia annua extracts as well as artemisinin, artesunate, and artemether against SARS-CoV-2. The latter two are approved active pharmaceutical ingredients of anti-malarial drugs.

SARS-CoV-2 Production in a Scalable High Cell Density Bioreactor.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has demonstrated the value of pursuing different vaccine strategies. Vaccines based on whole viruses, a widely used vaccine technology, depend on efficient virus production. This study aimed to establish SARS-CoV-2 production in the scalable packed-bed CelCradle 500-AP bioreactor.

Hepatitis C Virus Protease Inhibitors Show Differential Efficacy and Interactions with Remdesivir for Treatment of SARS-CoV-2 .

Antivirals targeting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could improve treatment of COVID-19. We evaluated the efficacy of clinically relevant hepatitis C virus (HCV) NS3 protease inhibitors (PIs) against SARS-CoV-2 and their interactions with remdesivir, the only direct-acting antiviral approved for COVID-19 treatment. HCV PIs showed differential potency in short-term treatment assays based on the detection of SARS-CoV-2 spike protein in Vero E6 cells.

Development of a downstream process for the production of an inactivated whole hepatitis C virus vaccine.

There is a large unmet need for a prophylactic hepatitis C virus (HCV) vaccine to control the ongoing epidemic with this deadly pathogen. Many antiviral vaccines employ whole viruses as antigens. For HCV, this approach became feasible following the development of infectious cell culture systems for virus production.

Specific Antibodies Induced by Immunization with Hepatitis B Virus-Like Particles Carrying Hepatitis C Virus Envelope Glycoprotein 2 Epitopes Show Differential Neutralization Efficiency.

Hepatitis C virus (HCV) infection with associated chronic liver diseases is a major health problem worldwide. Here, we designed hepatitis B virus (HBV) small surface antigen (sHBsAg) virus-like particles (VLPs) presenting different epitopes derived from the HCV E2 glycoprotein (residues 412-425, 434-446, 502-520, and 523-535 of isolate H77C). Epitopes were selected based on their amino acid sequence conservation and were previously reported as targets of HCV neutralizing antibodies.

High density Huh7.5 cell hollow fiber bioreactor culture for high-yield production of hepatitis C virus and studies of antivirals.

Chronic hepatitis C virus (HCV) infection poses a serious global public health burden. Despite the recent development of effective treatments there is a large unmet need for a prophylactic vaccine. Further, antiviral resistance might compromise treatment efficiency in the future.