Generation of attenuated duck enteritis virus as viral vector for chicken disease control using CRISPR-Cas9 technology
Dr. Pengxiang Chang, The Pirbright Institute

Duck enteritis virus (DEV) has advantages over turkey herpesvirus (HVT) as a viral vector for chicken diseases. DEV can be released into the supernatant, eliminating the need for liquid nitrogen storage like HVT. However, DEV-vectored vaccines are highly virulent in young chickens, limiting their suitability. We attempted to use CRISPR-Cas9 to attenuate DEV virulence in chickens, but the editing efficiency was lower compared to Marek's disease virus. Silencing DEV genes by inserting a GFP reporter encountered instability issues, possibly due to large insertion sizes. Exploring smaller GFP expression cassettes is a promising next step.

Research Highlights

• Attempts to attenuate DEV virulence using CRISPR-Cas9 editing to remove DEV gene were less efficient than expected, possibly due to differences in replication properties compared to HVT.
• Attempts to attenuate DEV virulence using CRISPR-Cas9 editing by silencing DEV gene (US10) via insertion a GFP reporter encountered instability issues possibly linked to the size of the inserted expression cassettes.

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