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[Biochemical features of protein matrix M1 of the influenza C virus]
Abstract:
Influenza viruses A, B, and C belonging to Orthomyxoviridae comprise an internal ribonucleoprotein (RNP) and an outer lipoprotein envelope with surface spike glycoproteins and the M1 protein matrix. The lipoprotein envelope and spike glycoproteins are solubilized by nonionic detergent treatment in a pH-independent manner. In contrast, disassembly of the M1 protein matrix appears to depend on pH. Treatment of influenza C viruses with nonionic detergent in neutral or alkaline medium (pH 9.0-7.2) results in disintegration of the virion M1 matrix and leads to a significant release of RNP free of the M1 protein. In acidic medium (pH 6.0-5.0) the M1 matrix fails to be removed and the viral core-like complex of RNP along with the M1 matrix cover is released. Since influenza A and B viruses were characterised by acid-dependent disassembly of the virion M1 matrix, influenza C viruses seem to be more resemble the paramyxoviruses, which also show a neutral-alkaline pH dependence of the matrix disintegration. These observations suggest that uncoating of influenza C viruses and paramyxoviruses in target cells may have similar events.
Insights
Influenza C viruses, unlike influenza A and B, show pH-dependent M1 matrix disassembly in neutral or alkaline conditions. This suggests similar uncoating mechanisms with paramyxoviruses in host cells.
Area of Science:
- Virology
- Molecular Biology
Context:
- Influenza viruses (A, B, C) possess an RNP core and a lipoprotein envelope with surface glycoproteins and M1 matrix protein.
- Envelope and glycoproteins solubilize with nonionic detergents independently of pH.
- M1 matrix disassembly is pH-dependent.
Purpose:
- To investigate the pH-dependent disassembly of the M1 protein matrix in influenza C viruses.
- To compare the M1 matrix disassembly characteristics of influenza C viruses with those of influenza A and B viruses, and paramyxoviruses.
Summary:
- Influenza C viruses treated with nonionic detergent in neutral/alkaline medium (pH 7.2-9.0) release RNP, with M1 matrix disintegration.
- In acidic medium (pH 5.0-6.0), the M1 matrix remains intact, releasing RNP with the M1 matrix cover.
- Influenza C virus M1 matrix disassembly shows neutral-alkaline pH dependence, unlike the acid-dependent disassembly in influenza A and B viruses.
Impact:
- Influenza C viruses resemble paramyxoviruses in their neutral-alkaline pH-dependent matrix disassembly.
- This suggests potentially similar uncoating events for influenza C viruses and paramyxoviruses within target cells.