Comparative pathogenesis of turkey reoviruses

Area of Science:

• Avian pathology
• Virology
• Poultry disease

Background:

• Turkey reoviruses cause significant economic losses in the poultry industry.
• Turkey enteric reovirus (TERV) is linked to poult enteritis, while turkey arthritis reovirus (TARV) causes tenosynovitis.
• Turkey hepatitis reovirus (THRV) was recently identified as a cause of hepatitis in turkeys.

Purpose of the Study:

• To comparatively analyze the pathogenesis of THRV, TARV, and TERV strains in turkeys.
• To correlate viral genetic makeup with observed disease manifestations.
• To understand the disease progression and tissue tropism of different reovirus strains.

Main Methods:

• Oral inoculation of 1-week-old turkey poults with nine different reovirus strains (2 THRV, 5 TARV, 2 TERV) and a control group.
• Euthanasia of birds at multiple time points (3, 5, 7, 14, 21, 28 days post-inoculation) for tissue collection.
• Histological examination and real-time RT-PCR for viral gene copy number analysis in collected tissues.

Main Results:

• All reovirus strains demonstrated enterotropic properties, with peak intestinal viral load at 5 days post-inoculation.
• All inoculated birds exhibited reduced body weight gain compared to controls.
• TARV and THRV replicated in tendons, causing tenosynovitis lesions; THRV exclusively caused hepatic lesions and fulfilled Koch's postulates for hepatitis.

Conclusions:

• THRV, TARV, and TERV exhibit distinct pathogenic profiles, with THRV being hepatotropic and enterotropic, and TARV and THRV also affecting tendons.
• Understanding these distinct pathogenicities is crucial for accurate diagnosis and effective disease management strategies in turkeys.
• This comparative pathogenesis study provides foundational data for developing targeted mitigation plans against economically significant turkey reoviruses.