Anti-Chikungunya E2 Protein [Clone CHK152] — Purified in vivo GOLD™ Functional Grade

Clone CHK-152 in In Vivo Mouse Studies:

Clone CHK-152 is a monoclonal antibody (MAb) that has been extensively studied for its potential as a therapeutic agent against Chikungunya virus (CHIKV) in mouse models. Here's how it is used in in vivo mouse studies:

1. Protection Against CHIKV Mortality and Disease:

   • CHK-152 has been shown to protect mice against CHIKV-induced mortality and disease. It is particularly effective when administered as prophylaxis or early post-exposure therapy in both wild-type (WT) C57BL/6 and immunocompromised Ifnar^?/?^ mice.

2. Mechanism of Action:

   • CHK-152 targets the A domain of the CHIKV E2 protein, which is crucial for viral entry and replication. By neutralizing this protein, CHK-152 inhibits viral infection and reduces disease severity.

3. Combination Therapy:

   • To prevent the emergence of viral resistance, CHK-152 is often used in combination with other MAbs such as CHK-102 or CHK-166. This combination approach extends the treatment window and enhances protection against CHIKV in Ifnar^?/?^ mice.

4. Humanization and Further Development:

   • The humanized form of CHK-152 (hu-CHK-152) has been developed to advance it as a therapeutic option for humans. It retains similar affinity and neutralizing activity compared to the mouse version of CHK-152.

Overall, CHK-152 is a promising candidate for CHIKV treatment due to its ability to protect against infection and its potential for use in combination therapies to circumvent resistance.

The correct storage temperature for the sterile packaged clone CHK152 (Anti-Chikungunya virus E2 monoclonal antibody) is:

• 4°C for short term storage (such as days to a few weeks)
• -20°C or -80°C for long term storage (months to years)
• Avoid repeated freeze-thaw cycles by aliquoting the antibody before freezing.

Authoritative sources specify that storage at 4°C is suitable if you plan to use the antibody soon, while aliquoting and storing at -20°C (or lower, such as -80°C) preserves activity for long-term use. Ensure that you do not repeatedly freeze and thaw the same aliquot, as this degrades antibody quality.

Shipping commonly occurs at ambient temperature with ice packs, but immediate refrigeration or freezing is required upon receipt.

This guidance aligns with general best practices for monoclonal antibody storage.

In the literature, CHK-152, a highly protective monoclonal antibody against Chikungunya virus (CHIKV), is commonly used in combination with other antibodies to enhance effectiveness and prevent viral resistance. Some of these antibodies include:

• CHK-102: This antibody is often paired with CHK-152 to provide a combination therapy that can limit the development of resistance and protect against CHIKV-induced disease in immunocompromised mice.

• CHK-166: Similar to CHK-102, CHK-166 is also used in combination with CHK-152. This combination is effective in extending the treatment window and preventing the emergence of viral resistance.

• CHK-263: While not explicitly mentioned as part of combination therapies with CHK-152, CHK-263 is another neutralizing antibody that targets CHIKV, though its use in combination with CHK-152 is less documented.

These antibodies work by targeting distinct epitopes on CHIKV's structural proteins, such as the E1 and E2 proteins, thus providing a robust defense against the virus.

Key Findings from Clone CHK-152 in Scientific Literature

CHK-152 is a monoclonal antibody (MAb) developed for its therapeutic potential against Chikungunya virus (CHIKV). Below are the main findings from published studies that directly cite or investigate this clone:

Molecular Basis of Neutralization and Structural Insights

• CHK-152 binds the E2 protein of CHIKV with high affinity (KD of 3–4 nM), and this binding is maintained even when the antibody is modified to remove effector functions (e.g., ch-CHK-152 N297Q), indicating that neutralization is primarily driven by direct binding rather than by Fc-mediated mechanisms.
• Structural analyses indicate that CHK-152 stabilizes the viral surface, interfering with the exposure of the fusion loop, which is critical for viral fusion with host cell membranes. This suggests CHK-152 directly blocks the conformational changes needed for CHIKV entry.
• CHK-152 demonstrates strong protective activity in vivo. In mouse models, it significantly reduces viral load and disease severity, even when administered after infection.

Escape Mutants and Antibody Resistance

• Viral resistance to CHK-152 emerges under selective pressure. The predominant escape mutation selected both in cell culture and in vivo is an E2-D59N substitution in the viral E2 protein. This mutation allows CHIKV to evade neutralization by CHK-152.
• Escape mutants remain sensitive to other neutralizing antibodies (e.g., CHK-102, CHK-166, CHK-263), indicating that CHK-152 targets a distinct epitope on the E2 protein.
• Combining CHK-152 with another MAb (e.g., CHK-166) prevents the emergence of escape mutants, highlighting the advantage of combination therapy.
• Escape variants (e.g., E2-D59N) retain viral fitness in cell culture and in mosquitoes, but are clinically attenuated in mice, causing less severe disease and a prolonged survival time in immunocompromised animals.

Therapeutic Efficacy

• In non-human primates, combination therapy with CHK-152 and CHK-166 reduces viral spread and neutralizes reservoirs of infectious virus in distant tissues. No escape mutants were detected in residual viral RNA from treated animals.
• Single-agent therapy with CHK-152 is limited by the rapid emergence of resistant strains, reinforcing the need for combination approaches in clinical applications.
• Resistance-associated mutations (e.g., E2-D59N) are highly conserved among CHIKV strains, suggesting a critical functional role for these residues in the virus lifecycle.

Mechanism of Action

• CHK-152 neutralizes CHIKV by direct binding to a conserved region of the E2 protein, inhibiting viral entry and potentially stabilizing the virus particle in a non-fusogenic state.
• Effector functions (e.g., complement activation, ADCC) contribute to protection in vivo, but are not essential for in vitro neutralization.

Summary Table: Key Features of CHK-152

Conclusion

CHK-152 is a highly potent neutralizing antibody against CHIKV, targeting a conserved epitope on the E2 protein and offering strong protection in animal models. Its clinical use as a single agent is limited by the rapid emergence of resistant variants, but combination therapy with other MAbs overcomes this limitation and provides robust antiviral effects. Escape mutants remain viable but are less pathogenic, reducing concerns about the emergence of highly virulent resistant strains.