Opportunity
Enterovirus A71 (EV-A71) is a primary causative agent of hand-foot-and-mouth disease (HFMD), a common illness in children that can lead to severe and potentially fatal neurological complications such as brainstem encephalitis and acute flaccid paralysis. While a vaccine exists in China, there is currently no approved therapeutic drug specifically targeting EV-A71 infections. The standard of care remains supportive therapy, highlighting a critical unmet medical need for effective antiviral treatments. The virus relies on host cell machinery for replication, particularly exploiting cellular proteins like heat shock protein 27 (Hsp27). Upon infection, EV-A71 activates the p38 MAPK signaling pathway, leading to the phosphorylation of Hsp27 at specific serine residues (Ser78 being crucial). This phosphorylation triggers the relocation of Hsp27 from the cytoplasm to the nucleus and, subsequently, causes the redistribution of another host protein, hnRNP A1, from the nucleus to the cytoplasm. hnRNP A1 is an IRES trans-acting factor (ITAF) essential for the viral internal ribosome entry site (IRES)-mediated translation of viral proteins, a key step in the EV-A71 life cycle. The lack of drugs that disrupt this specific host-virus interaction presents a significant opportunity for therapeutic intervention.
Technology
This patent discloses novel short synthetic peptides designed to inhibit EV-A71 replication by targeting the phosphorylation-dependent mechanism involving Hsp27. The core innovation is a peptide sequence (PKKRRQRRRAYSRAX1X2X3QLX4S, SEQ ID NO: 1) that is derived from and mimics a region of Hsp27. Key variants include peptides designated S78 (SEQ ID NO: 2), S78A (SEQ ID NO: 3), S82A (SEQ ID NO: 4), and S78-3A (SEQ ID NO: 5). These peptides are acetylated at the N-terminus and amidated at the C-terminus for stability and include a TAT-derived cell-penetrating sequence (PKKRRQRRR). They function by interfering with the phosphorylation of Hsp27 at Serine 78, a critical event induced by EV-A71's 2A protease (2A^pro). By suppressing this phosphorylation, the peptides prevent the infection-induced nuclear translocation of Hsp27 and the subsequent cytosol redistribution of hnRNP A1. Consequently, they inhibit the viral IRES activity, which is essential for translating viral proteins, thereby blocking viral replication and propagation within the host cell.
Advantages
- Provides a novel therapeutic strategy targeting a host protein mechanism (Hsp27 phosphorylation) crucial for EV-A71 replication, potentially reducing the likelihood of viral resistance compared to direct antiviral agents.
- The synthetic peptides, particularly S78 and S82A, demonstrate potent inhibition of EV-A71 replication and propagation in cellular models.
- Exhibits a high selectivity index with low cytotoxicity (CC50 >600 μM) in tested cells.
- The peptides can be administered via various routes, including intravascular, oral, topical, and pulmonary, offering formulation flexibility.
- Can be used in combination with other antiviral agents (e.g., ribavirin, suramin) for potential synergistic effects.
Applications
- Development of pharmaceutical compositions for the treatment and prophylaxis of infections caused by enteroviruses, specifically EV-A71.
- Potential application in treating severe complications of hand-foot-and-mouth disease (HFMD), such as neurological disorders.
- Use as a research tool to study the mechanisms of enterovirus replication and host-pathogen interactions.
- Formulation into various drug delivery systems, including injectables, oral tablets, topical creams, or inhalants.
- Combination therapy with existing supportive care or other antiviral drugs to enhance treatment efficacy.
