Uukuniemi Virus as a Tick-Borne Virus Model

Area of Science:

• Virology
• Arthropod-borne viruses
• Molecular biology

Background:

• Novel tick-borne phleboviruses, related to Uukuniemi virus (UUKV), are emerging globally.
• Previous studies often use mammalian cell-produced viruses, potentially overlooking host-specific adaptations.
• Understanding tick-to-mammal transmission requires studying viruses in their native vector environment.

Purpose of the Study:

• To establish an in vitro system for rescuing and producing Uukuniemi virus (UUKV) in tick cells.
• To investigate the structural and glycosylation differences of UUKV produced in tick versus mammalian cells.
• To assess the impact of these differences on viral infectivity and host-cell interactions.

Main Methods:

• Established a reverse genetics system to rescue UUKV in Ixodes ricinus tick cell lines (IRE/CTVM19, IRE/CTVM20).
• Analyzed viral glycoproteins (GC and GN) glycosylation using glycosidases and SDS-PAGE.
• Compared viral nucleoprotein content per focus-forming unit in tick-derived vs. mammalian cell-derived viruses.

Main Results:

• UUKV was successfully rescued and persistently produced in tick cell lines.
• Tick cell-derived UUKV exhibited distinct glycoprotein (GC, GN) glycosylation patterns compared to mammalian cell-derived UUKV.
• Tick cell-derived UUKV showed higher infectivity (more nucleoprotein per FFU) in mammalian cells.

Conclusions:

• UUKV particles derived from tick cells possess unique glycosylation and structural features.
• These features may play a crucial role in the initial stages of mammalian host infection.
• Studying arboviruses in arthropod vector cells is vital for understanding transmission and host entry.