Attenuated Duck Enteritis Virus Vector for Safe In Ovo Vaccination
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Solution Overview
Problem
Current poultry vaccination strategies using recombinant viruses, such as those based on avipox, herpes, and adenoviruses, are not effective for providing long-lasting immunity and are unsafe for administration to young chickens or in ovo, as they can be lethal and do not persist in chickens, necessitating the development of alternative viral vectors for early-stage vaccination.
Innovation Solution
Development of attenuated Duck Enteritis Virus (DEV) constructs with inactive US4 and US5 genes, which are safe for young chickens and can be administered in ovo, allowing for early protein expression and stable immunity induction without risk of dissemination to non-vaccinated animals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wild-type DEV is administered to young chicken (3 days or less) or in ovo, then viral replication and protein expression occur, but animal mortality increases to 80-100%
Solution Approach 1:
The US4 and US5 genes are extracted (deleted) from the DEV genome to create a safe attenuated virus. This removal eliminates the harmful factors causing high mortality in young chickens while preserving the virus's ability to replicate and express foreign proteins for vaccination purposes.
Solution Approach 2:
The natural virulence of DEV, which causes high mortality in young chickens, is converted into a benefit by deliberately inactivating specific genes (US4 and US5) to create an attenuated strain. This attenuated strain is safe for use in young poultry while still capable of inducing strong immune responses and expressing foreign antigens effectively.
2Reliability
If recombinant viruses (avipox, herpes, adenoviruses) are used for vaccination, then immunity is induced, but the viruses do not persist in chickens and provide limited long-term protection
Solution Approach 1:
The viral vector platform is changed from transient viruses (avipox, herpes, adenoviruses) to a persistent virus (DEV). This parameter change in viral persistence enables long-term immunity duration while maintaining the capability to induce both humoral and cell-mediated immune responses through expression of foreign pathogen antigens.
3Ease of operation
If existing viral vectors are used for in ovo or early-stage vaccination, then vaccination is performed, but the viruses can be lethal to very young animals
Solution Approach 1:
The harmful genes (US4 and US5) are extracted from the DEV genome to create an attenuated strain that is safe for in ovo and early-stage chick vaccination. This extraction maintains the virus's ability to infect and express proteins while eliminating the lethality that prevented use in very young animals.
4Object-affected harmful factors
If DEV is modified to reduce virulence, then safety improves, but viral growth rate and titer may decrease
Solution Approach 1:
Only specific local regions (US4 and US5 genes) of the DEV genome are modified to reduce virulence, while the rest of the viral genome remains intact. This localized modification preserves the overall viral growth rate and replication efficiency while eliminating the harmful effects in young chickens.
Data Source
AI summary
The present invention relates to DEV and the uses thereof. The invention is particularly suited to vaccinate poultry against avian pathogens.