Rhinovirus induces an anabolic reprogramming in host cell metabolism essential for viral replication.

Rhinoviruses (RVs) are responsible for the majority of upper airway infections; despite their high prevalence and the resulting economic burden, effective treatment is lacking. We report here that RV induces metabolic alterations in host cells, which offer an efficient target for antiviral intervention. We show that RV-infected cells rapidly up-regulate glucose uptake in a PI3K-dependent manner. In parallel, infected cells enhance the expression of the PI3K-regulated glucose transporter GLUT1. In-depth metabolomic analysis of RV-infected cells revealed a critical role of glucose mobilization from extracellular and intracellular pools via glycogenolysis for viral replication. Infection resulted in a highly anabolic state, including enhanced nucleotide synthesis and lipogenesis. Consistently, we observed that glucose deprivation from medium and via glycolysis inhibition by 2-deoxyglucose (2-DG) potently impairs viral replication. Metabolomic analysis showed that 2-DG specifically reverts the RV-induced anabolic reprogramming. In addition, treatment with 2-DG inhibited RV infection and inflammation in a murine model. Thus, we demonstrate that the specific metabolic fingerprint of RV infection can be used to identify new targets for therapeutic intervention.

Antibody-enhanced hepatitis E virus nanofiltration during the manufacture of human immunoglobulin.

BACKGROUND: Circulation of hepatitis E virus (HEV) in areas where plasma is sourced for the manufacture of plasma-derived medicinal products (PDMPs) has prompted verification of HEV clearance. HEV exists as quasi lipid-enveloped (LE) and non-lipid-enveloped (NLE) forms, which might be of relevance for HEV clearance from manufacturing processes of antibody-containing PDMPs with solvent/detergent (S/D) treatment upstream of further clearance steps. STUDY DESIGN AND METHODS: Presence of different HEV particles in stocks used in clearance studies was investigated, with nanofilters graded around the assumed HEV particle sizes and by gradient centrifugation. HEV removal by 35-nm nanofiltration was investigated in the presence or absence of HEV antibodies, in buffer as well as in immunoglobulin (IG) manufacturing process intermediates. RESULTS: HEV particles consistent with LE, NLE, and an "intermediate" (IM) phenotype, obtained after S/D treatment, were seen in different HEV stocks. In the absence of HEV antibodies, log reduction factors (LRFs) of 4.0 and 2.5 were obtained by 35-nm nanofiltration of LE and IM HEV, consistent with the larger and smaller sizes of these phenotypes. Addition of HEV antibodies enhanced IM HEV removal around 1000-fold (LRF, 5.6). Effective (LRF, >4.8 and >4.0) HEV removal was obtained for the nanofiltration processing step for IG intermediates with varying HEV antibody content. CONCLUSION: HEV spikes used in clearance studies should be carefully selected, as differences in physicochemical properties might affect HEV clearance. Antibody-mediated enhancement of HEV nanofiltration was demonstrated in IG process intermediates even at low HEV antibody concentration, illustrating the robustness of this manufacturing step.

A nonenveloped virus with a lipid envelope: hepatitis A virus as used in virus-reduction studies.

BACKGROUND: Recently, a quasi-lipid-enveloped (LE) form of the traditionally nonlipid-enveloped (NLE) hepatitis A virus (HAV) was described in human serum and cell culture-derived HAV stocks. This discovery challenges the understanding of HAV reduction in virus clearance studies of plasma products, which were performed under the premise of an NLE nature of this virus. Here, the presence of LE particles in HAV stocks used for reduction studies was verified, and the hypothesis that LE and NLE particles might contribute to the differential heat sensitivity of HAV variants during heat treatment of human serum albumin was evaluated. STUDY DESIGN AND METHODS: Cell culture lysates and supernatants of two cytopathic HAV variants, HM175/18f and HM175/24a, were characterized for their LE and NLE particle content by isopycnic gradient centrifugation. The obtained fractions were characterized for relative infectivity and then subjected to heat treatment (58.0 ± 1.0°C for 590 ± 10 minutes) in 12.5% human serum albumin to investigate their respective heat sensitivity. RESULTS: Preparations of the two HAV variants contained either LE particles (HM175/24a) or LE and NLE particles (HM175/18f) with equivalent specific infectivity. For HM175/18f, heat sensitivity of LE and NLE fractions did not differ significantly, and inactivation of the whole virus stock was identical to the NLE particle inactivation profile, whereas the HM175/24a variant was more heat sensitive. CONCLUSION: The results indicate that, in heat-treatment studies, the LE or NLE HAV phenotype is less important than the choice of HAV variant, and the most heat-resistant HM175/18f should be used.