Can bluetongue virus (BTV) be transmitted via caprine embryo transfer?

Area of Science:

• Veterinary Virology
• Embryology
• Molecular Biology

Background:

• Bluetongue virus (BTV) poses a significant threat to livestock.
• Understanding BTV's interaction with early embryonic cells is crucial for disease control and embryo transfer safety.
• Caprine (goat) embryos are utilized in this study to investigate viral susceptibility.

Purpose of the Study:

• To determine if early goat embryonic cells interact with BTV in vitro.
• To assess the protective role of the zona pellucida (ZP) against BTV infection in goat embryos.
• To evaluate the efficacy of International Embryo Transfer Society (IETS) recommended washing protocols in decontaminating BTV-exposed caprine embryos.

Main Methods:

• Early stage (8-16 cell) caprine embryos (ZP-free and ZP-intact) were co-cultured with BTV-infected Vero cells.
• Embryos underwent 10 wash cycles as per IETS guidelines.
• Viral presence and infectivity were assessed using RT-qPCR, CPE observation on indicator cells, and viral titration (TCID50).

Main Results:

• BTV infection caused cytopathic effects (CPE) in feeder Vero cells.
• BTV RNA was detected in the wash fluids and within both ZP-free and ZP-intact embryos.
• Embryonic cells demonstrated productive BTV infection, producing infectious virus particles.

Conclusions:

• Caprine early embryonic cells are susceptible to productive BTV infection.
• The standard 10-wash decontamination protocol is ineffective against BTV in caprine embryos.
• BTV may bind to the zona pellucida, necessitating further investigation into decontamination strategies.