Mutant HSV-1 KOS-NA UL39 Gene Attenuation
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Solution Overview
Problem
Current therapies for recurrent herpes simplex virus (HSV) infections are limited, and there is no cure for HSV, which can cause life-threatening diseases, especially in neonates or immunocompromised individuals, with existing treatments only reducing the likelihood of viral shedding.
Innovation Solution
A mutant HSV-1, referred to as KOS-NA, is generated with novel mutations in the UL39 gene encoding the large subunit of ribonucleotide reductase (ICP6), which attenuates the virus, impairing replication and latent infection establishment, while allowing limited replication in non-neural tissue to induce a strong immune response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mutant HSV-1 with UL39 mutations is used, then the virus is attenuated and cannot establish latent infection, but the immune response is diminished compared to wild-type virus
Solution Approach 1:
The patent utilizes the harmful effect of UL39 mutations (attenuated immune response) by combining it with another mutation (ICP0 phosphorylation site mutation) that enhances replication. The combined effect converts the originally harmful attenuation into a beneficial outcome: the virus replicates sufficiently to induce immunity but cannot establish latent infection due to the UL39 defect, creating an effective vaccine candidate that is safer than wild-type virus.
2Productivity
If wild-type HSV-1 is used for vaccination, then a strong immune response is induced, but the virus can cause disease and establish latent infection
Solution Approach 1:
The patent segments the viral genome into functional modules with different roles: the ICP0 phosphorylation site mutation (in UL8) controls replication capacity and disease severity, while the UL39 mutations control latent infection capability. By separating these functions into different mutated components, the vaccine achieves strong immunity (from sufficient replication) without the harmful effects of disease and latency.
Solution Approach 2:
The patent changes multiple genetic parameters simultaneously: phosphorylation sites in ICP0 (affecting replication) and amino acid residues in ICP6 (affecting latency). These parameter changes collectively transform the virus from a pathogenic wild-type strain into an attenuated vaccine candidate that induces immunity without causing disease or establishing latency.
3Reliability
If replication is impaired to prevent disease, then safety is improved, but the ability to induce long-lasting immune response is reduced
Solution Approach 1:
The patent applies local quality by creating tissue-specific replication patterns: the mutant virus replicates efficiently in non-neuronal tissues (inducing strong immune response) but is impaired in neural tissue (preventing latency). This localized replication strategy allows the virus to provide immunogenicity where needed while avoiding pathogenicity in vulnerable tissues.
Data Source
AI summary
A mutant HSV-1 (referred to herein as KOS-NA) was generated. KOS-NA contains novel mutations in the UL39 gene, which encodes for a protein that is a large subunit of ribonucleotide reductase (i.e., ICP6). These UL39 mutations were found to alter two amino acids in ICP6 (R950H and L393P) and are responsible for attenuation of KOS-NA in vivo, and resulted in diminished ICP6 protein levels. These novel UL39 mutations regulate the expression and/or stability of ICP6 and severely impact HSV-1 pathogenesis. Mutant HSV viruses containing these mutations appear to protect against HSV infection and can serve as therapeutic vaccines to help combat preexisting HSV infection in infected individuals.