Abstract
BackgroundMeasles (MEV) and mumps virus (MUV) are enveloped, non-segmented, negative single stranded RNA viruses of the family Paramyxoviridae, and are the cause of measles and mumps, respectively, both preventable by vaccination. Aside from proteins coded by the viral genome, viruses are considered to contain host cell proteins (HCPs). The presence of extracellular vesicles (ECVs), which are often co-purified with viruses due to their similarity in size, density and composition, also contributes to HCPs detected in virus preparations, and this has often been neglected. The aim was to identify which virus-coded proteins are present in MEV and MUV virions, and to try to detect which HCPs, if any, are incorporated inside the virions or adsorbed on their outer surface, and which are more likely to be a contamination from co-purified ECVs.MethodsMUV, MEV and ECVs were purified by ultracentrifugation, hydrophobic interaction chromatography and immunoaffinity chromatography, proteins in the samples were resolved by SDS-PAGE and subjected to identification by MALDI-TOF/TOF-MS. A comparative analysis of HCPs present in all samples was carried out.ResultsBy proteomics approach, it was verified that almost all virus-coded proteins are present in MEV and MUV particles. Protein C in MEV which was until now considered to be non-structural viral protein, was found to be present inside the MeV virions. Results on the presence of HCPs in differently purified virus preparations imply that actin, annexins, cyclophilin A, moesin and integrin β1 are part of the virions.ConclusionsAll HCPs detected in the viruses are present in ECVs as well, indicating their possible function in vesicle formation, or that most of them are only present in ECVs. Only five HCPs were constantly present in purified virus preparations, regardless of the purification method used, implying they are likely the integral part of the virions. The approach described here is helpful for further investigation of HCPs in other virus preparations.
Highlights
Measles (MEV) and mumps virus (MUV) are enveloped, non-segmented, negative single stranded RNA viruses of the family Paramyxoviridae, and are the cause of measles and mumps, respectively, both preventable by vaccination
A comparison of the proteomes of viruses purified by different purification methods, as well as the comparison with proteomes of Extracellular vesicle (ECV) purified from non-infected cell culture supernatants by the same methods, was carried out to try and determinate which Host cell protein (HCP) are virion-associated
The protein composition of ECVs might change during infection, since ECVs produced by infected cells cannot be distinguished and separated from viral particles in the supernatant of the infected cell culture, the results presented here still give a valuable insight into which HCPs are more likely to be present in viral preparations due to their association with viral particles, and which due to inevitable presence of ECVs in virus preparations
Summary
Measles (MEV) and mumps virus (MUV) are enveloped, non-segmented, negative single stranded RNA viruses of the family Paramyxoviridae, and are the cause of measles and mumps, respectively, both preventable by vaccination. The aim was to identify which virus-coded proteins are present in MEV and MUV virions, and to try to detect which HCPs, if any, are incorporated inside the virions or adsorbed on their outer surface, and which are more likely to be a contamination from co-purified ECVs. Measles (MEV) and mumps (MUV) viruses are non-segmented, negative single stranded RNA viruses from the family Paramyxoviridae which cause measles and mumps, respectively. Viral RNA is packed into a filamentous complex called nucleocapsid by the nucleoprotein (denoted NP for MUV and N for MEV) which interacts with large polymerase (L) through phosphoprotein (P) This core unit, referred to as ribonucleocapsid, is linked to the matrix protein (M) found directly below virion’s lipid bilayer [6,7,8,9].
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