VIRUS LIKE PARTICLES

Source: Hindu

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Context

• Scientists at the Institute of Advanced Virology (IAV) in Thiruvananthapuram have developed a novel technique for generating non-infectious Nipah virus-like particles (VLPs).
• This breakthrough enables crucial tests for vaccine and therapeutic development to be conducted in biosafety level-2 (BSL-2) labs, a significant improvement from the previous requirement of biosafety level-4 (BSL-4) labs.

Details

Importance of the New Method

• Enhanced Safety: The newly developed Nipah VLPs mimic the wild type Nipah virus but are non-infectious, allowing research in BSL-2 labs.
• Research Accessibility: This method reduces the biosafety risk and logistical challenges, making research more accessible and less resource-intensive.

Characteristics of Nipah Virus-Like Particles (NiV-VLPs)

• Structure and Components: NiV-VLPs are produced using plasmid-based expression systems that encode the structural proteins G (glycoprotein), F (fusion protein), and M (matrix protein) of the Nipah virus.
• HiBiT Tag: The inclusion of a highly sensitive HiBiT tag, an 11 amino acid peptide, on these VLPs enhances their utility in quantitative assays.

Applications

• Antibody Neutralization Studies: NiV-VLPs can be used to conduct virus neutralization assays in BSL-2 labs, crucial for developing and evaluating vaccines and therapeutics.
• Vaccine Development: These VLPs serve as a safe and effective platform for developing neutralizing antibodies and anti-virals.
• Basic Research: Facilitates studies into the immune response and pathogenesis of NiV without the need for high-level biosafety containment.

Advantages of the New VLPs

• Non-infectious: Lack of viral genetic material makes them safe to handle.
• Functional and Morphological Mimicry: These VLPs closely resemble the native virus in both structure and function.
• Reduced Biosafety Requirements: Can be handled in BSL-2 labs, greatly expanding the scope of research.

Virus-Like Particles (VLPs)

• Virus-like particles (VLPs) are molecular structures that resemble viruses but lack viral genetic material. This makes them non-infectious while retaining the ability to induce strong immune responses.
• Structure: VLPs typically consist of viral proteins that self-assemble into structures mimicking the morphology of actual viruses. They can be spherical, icosahedral, or filamentous in shape.

Composition and Formation

• Proteins: VLPs are composed mainly of viral capsid or envelope proteins. These proteins have the inherent ability to self-assemble into particles.
• Expression Systems: VLPs are produced using various expression systems, including:
  • Bacterial Systems: Often used for simple and cost-effective production.
  • Yeast Systems: Provide post-translational modifications.
  • Insect Cell Systems: Using baculovirus vectors for high-yield production.
  • Mammalian Cell Systems: Offer complex post-translational modifications and proper protein folding.
  • Plant Systems: Emerging as cost-effective and scalable platforms.

Applications of VLPs

• Vaccines:
  • Prophylactic Vaccines: VLPs can present viral antigens in their native conformation, making them effective for vaccine development. Examples include vaccines for HPV (Human Papillomavirus) and HBV (Hepatitis B Virus).
  • Therapeutic Vaccines: VLPs are being explored for cancer immunotherapy and chronic infections.
• Diagnostic Tools: VLPs can be used as antigens in diagnostic assays to detect antibodies against specific viruses.
• Nanotechnology and Drug Delivery: VLPs can be engineered to carry therapeutic agents or to serve as scaffolds in nanotechnology applications.

Advantages of VLPs

• Safety: As they lack genetic material, VLPs cannot replicate, ensuring safety.
• Immunogenicity: VLPs can elicit strong immune responses due to their size and repetitive surface structures.
• Versatility: Can be engineered to display epitopes from various pathogens.

Challenges and Limitations

• Production and Purification: The yield and purity of VLPs can vary depending on the expression system and production conditions.
• Stability: Maintaining the stability of VLPs during production, storage, and transport can be challenging.
• Cost: The cost of production, especially in mammalian systems, can be high.

Case Studies

• HPV Vaccines: The development of VLP-based vaccines like Gardasil and Cervarix has significantly reduced the incidence of HPV-related diseases.
• HBV Vaccines: VLP-based Hepatitis B vaccines have been instrumental in reducing global HBV infections.
• Emerging Infections: Research is ongoing for VLP-based vaccines for Zika, Chikungunya, and other emerging viral threats.

Sources:

Hindu