Chimeric PRRSV Replicon for Cross-Protective Vaccine
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Solution Overview
Problem
Current PRRSV vaccines lack sufficient immunoprotection and safety, and fail to provide cross-protection against genetically diversified strains, with high mutation rates leading to antigenic variation and reduced efficacy against homologous and heterologous challenges.
Innovation Solution
Development of a chimeric PRRSV replicon combining a 5' sequence from an avirulent strain with a 3' sequence from a virulent strain, creating an attenuated virus that is non-pathogenic but induces a protective immune response, offering cross-protection against diverse PRRSV isolates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional attenuated vaccines are used, then virus replication ability is reduced, but antigenic variation increases due to high mutation rate
Solution Approach 1:
The viral genome is divided into two functional segments: a 5' region from an avirulent strain that provides replication capability and a 3' region from a virulent strain that provides antigenic diversity and protective immunity. This segmentation allows the vaccine virus to maintain stability while generating cross-protective antibodies against diverse PRRSV isolates.
Solution Approach 2:
The patent creates a composite viral genome combining sequences from both avirulent and virulent strains. The resulting chimeric virus exhibits properties of both parent strains: it replicates efficiently like the avirulent strain while providing cross-protection like the virulent strain, resolving the contradiction between vaccine stability and antigenic diversity.
2Object-affected harmful factors
If serial passage is used to attenuate the virus, then virulence is reduced, but replication ability is affected under fitness selection
Solution Approach 1:
Instead of achieving attenuation through sequential passage (a time-consuming process), the patent directly constructs an attenuated virus by incorporating a specific 5' region from an avirulent strain into the viral genome. This preliminary genetic modification achieves both attenuation and maintained replication ability simultaneously, eliminating the need for serial passage.
3Reliability
If current vaccines are used, then some protection is provided, but cross-protection against heterologous challenge is insufficient
Solution Approach 1:
The chimeric virus is designed to perform multiple functions simultaneously: it provides immunoprotection against the specific strain it was constructed from while also inducing cross-protective antibodies against heterologous PRRSV isolates. The 3' region from the virulent strain contains epitopes that are conserved across different strains, enabling universal protection.
Data Source
AI summary
Chimeric replicons of North American Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) containing the 5′ sequence of an avirulent strain of PRRSV and a 3′ sequence of a virulent strain of PRRSV are provided. Further provided is a method of producing attenuated PRRSV from the chimeric replicon. Also provided are compositions containing the replicon or attenuated virus. Vaccines and a method of vaccinating pigs against PRRSV are also provided.