BackgroundA highly purified 10% liquid intravenous immunoglobulin, IQYMUNE®, has been developed using an innovative manufacturing process including an affinity chromatography step for the removal of anti-A and anti-B hemagglutinins.ObjectivesThe pathogen (viruses and prions) clearance efficacy of the manufacturing process and its robustness for critical steps were investigated.MethodsThe manufacturing process of IQYMUNE® includes two dedicated complementary virus reduction steps: solvent/detergent (S/D) treatment and 20 nm nanofiltration as well as two contributing steps, namely caprylic acid fractionation and anion-exchange chromatography. The clearance capacity and robustness of these steps were evaluated with a wide range of viruses (enveloped and non-enveloped) and with a model of human transmissible spongiform encephalopathies (TSEs).ResultsThe IQYMUNE® manufacturing process demonstrated a high and robust virus removal capacity with global reduction factors (RFs) of relevant and model viruses: ≥14.8 log10 for human immunodeficiency virus type 1 (HIV-1), ≥16.9 log10 for bovine viral diarrhoea virus (BVDV)/Sindbis virus, ≥15.7 log10 for pseudorabies virus (PRV), ≥12.8 log10 for encephalomyocarditis virus (EMCV) and 11.0 log10 for porcine parvovirus (PPV). The process also exhibited a high removal capacity for the TSE agent with an overall RF of ≥12.9 log10 due to the complementary actions of the caprylic acid fractionation, anion-exchange chromatography and nanofiltration steps.ConclusionData from virus and prion clearance studies fully support the high safety profile of IQYMUNE®, with a minimal reduction of 11 log10 for the smallest and most resistant non-enveloped virus, PPV, and more than 12 log10 for the TSE agent.
Here we provide strong evidence that a highly conserved stem loop structure in the U5 region of the HIV-1 RNA leader harbours a repressor of reverse transcription (RRT). We showed that two sequences in U5, at +143-145 and +151-153, are essential for RRT function. Mutation of either site strongly and unexpectedly increased endogenous reverse transcription, and cell infection assays showed that both mutations dramatically increased negative strand strong stop DNA synthesis. Early, late, 1-LTR and 2-LTR reverse transcription products were present proportionally, indicating that the downstream reverse transcription events were not affected. In vitro structural probing of the wild type and mutant RNA revealed an unexpected destabilization effect of the mutations on the whole U5 stem loop, which would explain the loss of regulation of reverse transcription. This functional effect was not observed in vitro, where, in the absence of viral proteins other than RT and cellular factors, all RNA performed similarly. These U5 mutations decreased virus replication in Jurkat and primary T-cells, which could be attributed to a marked defect in viral integration. Analysis of 1-LTR and 2-LTR circular DNA isolated from infected cells revealed that substantial deletions were present, indicating that the viral DNA was degraded by cellular nucleases. Together, our experiments suggest that regulated reverse transcription initiation is essential to allow synthesis of the viral DNA in a cellular environment that supports the assembly of a functional HIV-1 pre-integration complex, which also protects the proviral DNA from cellular degradation processes.from Frontiers of Retrovirology: Complex retroviruses, retroelements and their hosts
Human parvovirus B19 (B19V) causes various human diseases, ranging from childhood benign infection to arthropathies, severe anemia and fetal hydrops, depending on the health state and hematological status of the patient. To counteract B19V blood-borne contamination, evaluation of B19 DNA in plasma pools and viral inactivation/removal steps are performed, but nucleic acid testing does not correctly reflect B19V infectivity. There is currently no appropriate cellular model for detection of infectious units of B19V. We describe here an improved cell-based method for detecting B19V infectious units by evaluating its host transcription. We evaluated the ability of various cell lines to support B19V infection. Of all tested, UT7/Epo cell line, UT7/Epo-STI, showed the greatest sensitivity to B19 infection combined with ease of performance. We generated stable clones by limiting dilution on the UT7/Epo-STI cell line with graduated permissiveness for B19V and demonstrated a direct correlation between infectivity and S/G2/M cell cycle stage. Two of the clones tested, B12 and E2, reached sensitivity levels higher than those of UT7/Epo-S1 and CD36+ erythroid progenitor cells. These findings highlight the importance of cell cycle status for sensitivity to B19V, and we propose a promising new straightforward cell-based method for quantifying B19V infectious units.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.