La Crosse bunyavirus can mediate pH-dependent fusion from without

Area of Science:

• Virology
• Cell Biology
• Molecular Biology

Background:

• Enveloped viruses utilize lipid-binding properties for cellular entry.
• Acid pH exposure is a critical factor in the entry mechanism of some viruses and macromolecules.
• Cell-to-cell fusion assays are employed to study these viral entry functions.

Purpose of the Study:

• To investigate the pH-dependent cell fusion capabilities of La Crosse virus (Bunyaviridae family).
• To determine the optimal conditions for La Crosse virus-mediated cell fusion.
• To compare the pH requirements for La Crosse virus fusion with other viral families.

Main Methods:

• La Crosse virus was used to induce fusion of BHK-21 cells from without (FFWO).
• Virus exposure to specific acidic pH levels (≤6.3) was tested.
• Fusion efficiency was assessed under varying conditions, including multiplicity of infection and temperature (37°C).
• UV-inactivated virus was also used to mediate fusion.

Main Results:

• La Crosse virus induced FFWO at pH 6.3 or below.
• Optimal fusion required high multiplicity of infection and 37°C.
• The pH requirement for La Crosse virus fusion is comparable to Semliki forest virus (alphavirus) but higher than Orthomyxoviridae.
• UV-inactivated virus retained the ability to mediate FFWO.

Conclusions:

• This study provides the first report of pH-mediated fusion for the Bunyaviridae family.
• The findings suggest that La Crosse virus cellular entry involves exposure to acidic environments.
• The mechanism of viral entry for Bunyaviridae shares similarities with other enveloped viruses dependent on acid pH.