Mitigating the risk of Zika virus contamination of raw materials and cell lines in the manufacture of biologicals.

Ensuring the virological safety of biologicals is challenging due to the risk of viral contamination of raw materials and cell banks, and exposure during in-process handling to known and/or emerging viral pathogens. Viruses may contaminate raw materials and biologicals intended for human or veterinary use and remain undetected until appropriate testing measures are employed. The outbreak and expansive spread of the mosquito-borne flavivirus Zika virus (ZIKV) poses challenges to screening human- and animal -derived products used in the manufacture of biologicals.

Schmallenberg virus, an emerging viral pathogen of cattle and sheep and a potential contaminant of raw materials, is detectable by classical in-vitro adventitious virus assays.

Emerging viruses, as potential contaminants of raw materials used in the manufacture of biologicals represent a challenge in the safety testing of biopharmaceutical products intended for human or veterinary use. Here, we report the challenge of an in vitro adventitious virus platform used in safety testing of biologicals, where a broad panel of detector cell lines was challenged to provide evidence that Schmallenberg virus is detectable by a classical reporting endpoint of cytopathic effect with Vero, BHK-21 and CHO-K1 detector cells, within typical in vitro assay timescales. We conclude that Schmallenberg virus is robustly detectable by classical in vitro viral biosafety assays.

TMC647055, a potent nonnucleoside hepatitis C virus NS5B polymerase inhibitor with cross-genotypic coverage.

Hepatitis C virus (HCV) infection is a major global health burden and is associated with an increased risk of liver cirrhosis and hepatocellular carcinoma. There remains an unmet medical need for efficacious and safe direct antivirals with complementary modes of action for combination in treatment regimens to deliver a high cure rate with a short duration of treatment for HCV patients. Here we report the in vitro inhibitory activity, mode of action, binding kinetics, and resistance profile of TMC647055, a novel and potent nonnucleoside inhibitor of the HCV NS5B RNA-dependent RNA polymerase.

Herpes simplex virus type 1 penetrates the basement membrane in human nasal respiratory mucosa.

Background: Herpes simplex virus infections are highly prevalent in humans. However, the current therapeutics suffer important drawbacks such as limited results in neonates, increasing occurrence of resistance and impeded treatment of stromal infections. Remarkably, interactions of herpesviruses with human mucosa, the locus of infection, remain poorly understood and the underlying mechanisms in stromal infection remain controversial.

Resistance to raltegravir highlights integrase mutations at codon 148 in conferring cross-resistance to a second-generation HIV-1 integrase inhibitor.

Raltegravir is the first integrase strand-transfer inhibitor (INSTI) approved for use in highly active antiretroviral therapy (HAART) for the management of HIV infection. Resistance to antiretrovirals can compromise the efficacy of HAART regimens. Therefore it is important to understand the emergence of resistance to RAL and cross-resistance to other INSTIs including potential second-generation INSTIs such as MK-2048.

Molecular mechanisms of retroviral integrase inhibition and the evolution of viral resistance.

The development of HIV integrase (IN) strand transfer inhibitors (INSTIs) and our understanding of viral resistance to these molecules have been hampered by a paucity of available structural data. We recently reported cocrystal structures of the prototype foamy virus (PFV) intasome with raltegravir and elvitegravir, establishing the general INSTI binding mode. We now present an expanded set of cocrystal structures containing PFV intasomes complexed with first- and second-generation INSTIs at resolutions of up to 2.

Requirement of cellular DDX3 for hepatitis C virus replication is unrelated to its interaction with the viral core protein.

The cellular DEAD-box protein DDX3 was recently shown to be essential for hepatitis C virus (HCV) replication. Prior to that, we had reported that HCV core binds to DDX3 in yeast-two hybrid and transient transfection assays. Here, we confirm by co-immunoprecipitation that this interaction occurs in cells replicating the JFH1 virus.

Protection of hepatocytes from cytotoxic T cell mediated killing by interferon-alpha.

Background: Cellular immunity plays a key role in determining the outcome of hepatitis C virus (HCV) infection, although the majority of infections become persistent. The mechanisms behind persistence are still not clear; however, the primary site of infection, the liver, may be critical. We investigated the ability of CD8+ T-cells (CTL) to recognise and kill hepatocytes under cytokine stimulation.

Liver cell lines for the study of hepatocyte functions and immunological response.

Background: Liver cell lines closely resembling primary hepatocyte are essential for research on hepatitis viruses and hepatocyte function. Currently used cell lines are derived from hepatic tumours and have altered gene expression.

Aims: The generation and characterisation of novel human hepatocyte lines (HHLs) derived from healthy human liver, retaining the primary hepatocyte phenotype.

Bunyamwera virus nonstructural protein NSs counteracts interferon regulatory factor 3-mediated induction of early cell death.

The genome of Bunyamwera virus (BUN; family Bunyaviridae, genus Orthobunyavirus) consists of three segments of negative-sense RNA. The smallest segment, S, encodes two proteins, the nonstructural protein NSs, which is nonessential for viral replication and transcription, and the nucleocapsid protein N. Although a precise role in the replication cycle has yet to be attributed to NSs, it has been shown that NSs inhibits the induction of alpha/beta interferon, suggesting that it plays a part in counteracting the host antiviral defense.

Analysis of antigenicity and topology of E2 glycoprotein present on recombinant hepatitis C virus-like particles.

Purification of hepatitis C virus (HCV) from sera of infected patients has proven elusive, hampering efforts to perform structure-function analysis of the viral components. Recombinant forms of the viral glycoproteins have been used instead for functional studies, but uncertainty exists as to whether they closely mimic the virion proteins. Here, we used HCV virus-like particles (VLPs) generated in insect cells infected with a recombinant baculovirus expressing viral structural proteins.

Functional analysis of hepatitis C virus E2 glycoproteins and virus-like particles reveals structural dissimilarities between different forms of E2.

Structure-function analysis of the hepatitis C virus (HCV) envelope glycoproteins, E1 and E2, has been difficult due to the unavailability of HCV virions. Truncated soluble forms of E2 have been used as models to study virus interaction with the putative HCV receptor CD81, but they may not fully mimic E2 structures on the virion. Here, we compared the CD81-binding characteristics of truncated E2 (E2(660)) and full-length (FL) E1E2 complex expressed in mammalian cells, and of HCV virus-like particles (VLPs) generated in insect cells.

Evidence for structural differences in the S domain of L in comparison with S protein of hepatitis B virus.

The structures of the large (L), middle (M) and small (S) versions of the envelope proteins of hepatitis B virus remain poorly characterized due to the complex nature of their conformations. Several groups have proposed transmembrane topological models depicting the lumenally and cytosolically disposed regions of these proteins. Recently, post-translational topological changes in L have been described.