Structure of the St. Louis encephalitis virus postfusion envelope trimer

Area of Science:

• Virology
• Structural Biology
• Molecular Biology

Background:

• St. Louis encephalitis virus (SLEV) is a mosquito-borne flavivirus causing human encephalitis.
• Mature flavivirus virions possess envelope (E) proteins crucial for host cell attachment and fusion.
• E proteins are class II fusion proteins undergoing dimer-to-trimer rearrangement during infection.

Purpose of the Study:

• To determine the crystal structure of the SLEV E protein in its postfusion trimer conformation.
• To identify structural features differentiating SLEV E from related viral E proteins.
• To understand how SLEV E structure influences its interaction with host cells and pathogenesis.

Main Methods:

• X-ray crystallography was used to determine the structure of the SLEV E protein.
• Comparative structural analysis was performed with E proteins from other flaviviruses and alphaviruses.
• Surface potential analysis was conducted to investigate potential interactions with lipid membranes.

Main Results:

• The crystal structure of SLEV E in the postfusion trimer conformation was elucidated.
• SLEV E exhibits unique fusion loop spacing and domain angles compared to other flaviviruses.
• A conserved basic platform beneath the fusion loops suggests interaction with anionic lipid head groups.

Conclusions:

• The distinct structural features of SLEV E likely contribute to virus-specific interactions with host factors.
• Variations in E protein structure and assembly play a role in SLEV pathogenesis.
• Understanding these structural nuances can inform strategies against SLEV infections.