FMDV L Protein SAP Domain Mutations for Vaccine Attenuation
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Solution Overview
Problem
Current live-attenuated Foot-and-mouth disease (FMD) vaccines face challenges such as instability, excessive attenuation, species-specific differences, and the possibility of reversion to virulence, limiting their effectiveness and safety for swine, cattle, goats, and sheep.
Innovation Solution
A double point mutation in the SAP domain of the leader protein of FMDV, specifically at residues I55 and L58, results in a stable and attenuated virus phenotype that induces a strong neutralizing antibody response and provides protection against FMD, while maintaining the ability to differentiate between vaccinated and infected animals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If live-attenuated FMD vaccines are developed to induce strong immune response, then protective immunity is improved, but stability and risk of reversion to virulence worsen
Solution Approach 1:
The patent applies parameter changes by introducing specific point mutations in the L protein coding region (C23S substitution and additional mutations in the SAP domain) to alter the viral properties. These parameter changes in the protein sequence achieve attenuation while maintaining stability, resolving the contradiction between inducing protective immunity and preventing reversion to virulence.
2Loss of time
If FMD vaccines are developed to provide rapid protection, then response time is improved, but manufacturing complexity and cost worsen
Solution Approach 1:
The patent employs a replicating RNA virus vaccine that can be produced using standard BSL-2 facilities rather than complex BSL-3 infrastructure. The vaccine utilizes the virus's natural replication capability to rapidly induce immunity without requiring complex manufacturing processes, thereby reducing both time and complexity constraints.
3Object-affected harmful factors
If inactivated FMD vaccines are used to ensure safety, then risk of reversion is reduced, but ability to differentiate vaccinated from infected animals worsens
Solution Approach 1:
The patent introduces specific amino acid substitutions (such as C23S and SAP domain mutations) that create immunodominant epitopes distinguishable from wild-type virus. These molecular 'color changes' in the protein structure enable serological differentiation between vaccinated and naturally infected animals while maintaining the safety of an attenuated vaccine.
Data Source
AI summary
Previously we have identified a conserved domain (SAP, for SAF-A/B, Acinus, and PIAS) in the foot-and-mouth disease virus (FMDV) leader (L) protein coding region that is required for proper sub-cellular localization and function. Mutation of isoleucine 55 and leucine 58 to alanine (I55A, L58A) within the SAP domain resulted in a viable virus that displayed a mild attenuated phenotype in cell culture, along with altered sub-cellular distribution of L and failure to induce degradation of the transcription factor nuclear factor kappa-B. Here we report that inoculation of swine and cattle with this mutant virus results in the absence of clinical disease, the induction of a significant FMDV-specific neutralizing antibody response, and protection against subsequent homologous virus challenge. Remarkably, swine vaccinated with SAP mutant virus are protected against wild type virus challenge as early as two days post-vaccination suggesting that a strong innate as well as adaptive immunity is elicited. This variant could serve as the basis for construction of a live-attenuated FMD vaccine candidate.