Structural insight into African horsesickness virus infection

Area of Science:

• Structural virology
• Molecular biology
• Veterinary science

Background:

• African horsesickness (AHS) is a severe equine disease caused by the African horsesickness virus (AHSV), an orbivirus.
• Understanding AHSV structure is crucial for developing effective control strategies and vaccines.

Purpose of the Study:

• To elucidate the three-dimensional architecture of the African horsesickness virus (AHSV) serotype 4 (AHSV-4) using electron cryomicroscopy.
• To compare AHSV-4 structure with related orbiviruses like bluetongue virus (BTV) and identify key structural features relevant to infection and host interactions.

Main Methods:

• Electron cryomicroscopy (cryo-EM) and three-dimensional image reconstruction were employed to determine the AHSV-4 virion structure.
• Comparative structural analysis was performed between AHSV-4, AHSV-7 (with truncated VP2), and bluetongue virus.

Main Results:

• The AHSV-4 virion possesses a triple-layered structure enclosing its segmented dsRNA genome and transcriptase complex.
• The innermost layer features VP3 with associated viral polymerase, capping enzyme, and helicase; an outer VP7 layer forms a T=13 structure.
• Comparative analysis identified VP2 domains crucial for infection and revealed a protein occluding the 5-fold vertices in AHSV-4.

Conclusions:

• The determined AHSV-4 structure provides a detailed molecular blueprint of this economically significant orbivirus.
• Insights into AHSV structural components and their roles in virus-host interactions can guide the rational design of novel vaccines and antiviral strategies.