Viruses are nanoscale pathogens capable of infecting humans, animals, plants, and bacteria. Lacking independent metabolism, they rely entirely on host cells for replication. They exist either within host cells or as independent virions, consisting of genetic material encased in a protein shell called a capsid. Some viruses, such as SARS-CoV-2 and HIV, also have a lipid bilayer envelope derived from their host cells.
VLPs are engineered structures designed to mimic viral architecture while lacking genetic material, rendering them non-infectious. This makes them particularly suitable for safe therapeutic applications like vaccines. Their sizes vary:

• Influenza virus: 80–120 nm
• SARS-CoV-2: 60–140 nm
• Small viruses (e.g., Circoviridae): 15–30 nm
• Large viruses (e.g., giant viruses): 400–500 nm

Both viruses and VLPs are integral to virology research, therapeutics, and vaccine development.

Viruses and VLPs can be categorized based on their structure and intended use:

Enveloped types: Contain a lipid bilayer, such as influenza and SARS-CoV-2.

Non-enveloped types: Composed solely of protein shells, like adenoviruses and HPV.

Hybrid VLPs: Custom-engineered for applications in drug delivery and gene therapy.

The study of viruses and VLPs presents unique
challenges due to their small size, structural complexity, and heterogeneity.
Isolation and characterization are often difficult due to contaminants like
proteins, lipoproteins, and cellular debris. Additionally, their tendency to
aggregate complicates accurate measurement and may impact functionality.

Identifying subpopulations within viral
particle samples is critical for both research and therapeutic applications.
Fluorescence-based techniques such as Nanoparticle Tracking Analysis (F-NTA)
enable precise detection of specific viral markers, enhancing analytical
accuracy.

Sophisticated analytical tools are essential for measuring size, concentration, and stability of viral particles with high precision. NTA is a gold-standard technique that provides unparalleled insights into their behavior and properties.

Our ZetaView® PMX-230 TWIN and PMX-420 QUATT systems offer high-resolution measurements of particle size, concentration, and zeta potential. Fluorescence detection and colocalization capabilities enable accurate quantification of subpopulations by tagging viral markers such as capsid proteins or envelope glycoproteins.