A block in virus-like particle maturation following assembly of murine leukaemia virus in insect cells

Abstract

Expression of the murine leukaemia virus (MLV) major Gag antigen p65(Gag) using the baculovirus expression system leads to efficient assembly and release of virus-like particles (VLP) representative of immature MLV. Expression of p180(Gag-Pol), facilitated normally in mammalian cells by readthrough of the p65(Gag) termination codon, also occurs efficiently in insect cells to provide a source of the MLV protease and a pattern of p65(Gag) processing similar to that observed in mammalian cells. VLP release from p180(Gag-Pol)-expressing cells however remains essentially immature with disproportionate levels of the uncleaved p65(Gag) precursor when compared to the intracellular Gag profile. Changing the p65(Gag) termination codon altered the level of p65(Gag) and p180(Gag-Pol) within expressing cells but did not alter the pattern of released VLP, which remained immature. Coexpression of p65(Gag) with a fixed readthrough p180(Gag-Pol) also led to only immature VLP release despite high intracellular protease levels. Our data suggest a mechanism that preferentially selects uncleaved p65(Gag) for the assembly of MLV in this heterologous expression system and implies that, in addition to their relative levels, active sorting of the correct p65(Gag) and p180(Gag-Pol) ratios may occur in producer cells.

Functional and structural characterization of the chikungunya virus translational recoding signals

“…Ϫ1 PRF also presents a target for alphaviruses: in mice, ablation of Ϫ1 PRF attenuated the symptoms of Sindbis virus (20) and VEEV (21) infections. Although less well-studied than Ϫ1 PRF, five published studies report that alteration of TCR also has negative impacts on virus replication (15,(55)(56)(57)(58). Three of these studies (55)(56)(57) examined the impact of TCR ablation in a retrovirus (murine leukemia virus).…”

“…Although less well-studied than Ϫ1 PRF, five published studies report that alteration of TCR also has negative impacts on virus replication (15,(55)(56)(57)(58). Three of these studies (55)(56)(57) examined the impact of TCR ablation in a retrovirus (murine leukemia virus). Pertinent to this study, TCR ablation was shown to reduce the pathogenicity of two alphaviruses, O'nyong-nyong and Sindbis viruses (15,58).…”

Review: A systematic review of virus-like particles of coronavirus: Assembly, generation, chimerism and their application in basic research and in the clinic

“…VLPs have also been created from expression of the major retrovirus capsid, gag, in a number of systems including bacterial, insect and mammalian cells [111] . During the budding process, gag VLPs can be incorporated with glycoproteins present in the plasma membrane of the producer cells [112] .…”

Direct Observation of Membrane Insertion by Enveloped Virus Matrix Proteins by Phosphate Displacement

“…Lymphocytic choriomeningitis virus-Arm53b, Pichinde virus-AN3739 and Tacaribe virus-TRVL11573 was grown on BHK-21 cells; Junin virus-Candid#1 and SARS coronavirus-Tor2 were grown on Vero-E6 cells; Porcine respiratory and reproductive syndrome virus-SD-23983 was grown on MARC145 cells; Type II Feline coronavirus was grown on AK-D cells; Mouse hepatitis virus-A59 was grown on mouse 17Cl-1 cells; Influenza A virus-Udorn/307/72 was grown on MDCK cells; Influenza B virus-Beijing/1/87 was grown in embryonated chicken eggs; and Murine leukaemia virus Gag particles were expressed in SF9 cells using a recombinant baculovirus expression system [20].…”