Differentiation of filoviruses by electron microscopy

Area of Science:

• Virology
• Cell Biology
• Microscopy

Background:

• Filoviruses, including Marburg (MBG) and Ebola viruses (EBO-S, EBO-Z, EBO-R), are significant human pathogens.
• Understanding their ultrastructural morphology and morphogenesis is crucial for diagnosis and research.

Purpose of the Study:

• To provide ultrastructural details of Marburg and Ebola virus morphology and morphogenesis.
• To identify ultrastructural differences between filovirus serotypes and in various cell systems.
• To assess the utility of electron microscopy for definitive filoviral diagnosis.

Main Methods:

• Infection of cultured cell lines (MA-104, Vero 76, SW-13, DBS-FRhL-2) with MBG, EBO-S, EBO-Z, and EBO-R viruses.
• Examination of infected cells and virions using electron microscopy.
• Immunoelectron microscopy to identify viral proteins (VP40, NP) during morphogenesis.

Main Results:

• All filoviruses replicated in all tested cell systems, entering cells via endocytosis.
• Filoviruses exhibited similar morphogenic progression, with mature virions budding from plasma membranes.
• Marburg virus (MBG) virions were consistently shorter than Ebola virus (EBO-S, EBO-Z, EBO-R) particles.
• Intermediate MBG inclusions were morphologically distinct from those of EBO-S, EBO-Z, and EBO-R.
• No structural differences were observed among EBO-S, EBO-Z, and EBO-R inclusions.
• Viral matrix protein (VP40) and nucleoprotein (NP) accumulated and associated during EBO-Z morphogenesis.

Conclusions:

• Ultrastructural differences exist between Marburg virus and Ebola viruses.
• Electron microscopy, particularly with immunolabeling, is a valuable tool for the definitive diagnosis of filoviral infections.
• These ultrastructural findings enhance the understanding of filovirus replication and pathogenesis.