Virus-Like Particles (VLPs): An Expression & Display Platform for Recombinant and Membrane Proteins

Virus-like particles (VLPs) are self-assembling, nanoscale protein shells that mimic the size and surface architecture of a native virus but carry no viral genome, so they cannot replicate or infect a host cell. This combination of authentic, repetitive surface structure and inherent non-infectiousness has made the VLP a versatile platform for vaccine development, targeted drug delivery, and — increasingly — the expression and display of otherwise difficult recombinant and membrane proteins.

1. What Are Virus-Like Particles?

A VLP forms when one or more viral structural (capsid or envelope) proteins are expressed and spontaneously assemble into a particle that reproduces the geometry of the parent virus, typically 20–200 nm in diameter. Because the assembly reconstitutes native surface epitopes at high, ordered density, the immune system recognizes a VLP much as it would the real virus — yet without any packaged nucleic acid, the particle is replication-incompetent and non-infectious.

Rather than grouping VLPs loosely by their parent virus, it is more accurate to classify them by structure into two families:

• Non-enveloped VLPs — assembled purely from capsid protein(s), either a single protein (for example hepatitis B core or HPV L1) or several capsid layers. They are robust and comparatively simple to produce.
• Enveloped VLPs — a capsid or matrix scaffold wrapped in a host-derived lipid bilayer that carries membrane-anchored surface glycoproteins. They are structurally more complex but can present transmembrane antigens in a near-native lipid environment.

This enveloped/non-enveloped distinction, rather than the parent virus alone, is what determines which host system and downstream process are appropriate (Nooraei et al., 2021).

2. How Are VLPs Produced? A Comparison of Expression Systems

VLPs can be produced in bacterial, yeast, insect, mammalian, and plant hosts. The right VLP expression system depends on the structural class of the particle and, critically, on whether the target protein needs post-translational modifications (PTMs) such as glycosylation or a lipid membrane. Each host trades yield and cost against modification fidelity.

Two practical points follow from this table. First, no single host is "best" — E. coli is unbeatable on cost for simple capsids (Wei et al., 2014), yeast underpins the highest-volume licensed VLP vaccines (Srivastava et al., 2023), and plant systems offer rapid, low-cost surge manufacturing (Mardanova et al., 2024). Second, mammalian expression, though more expensive and lower-yielding, is often the only route that preserves the human-like glycosylation and lipid membrane that complex antigens and membrane proteins require.

3. VLPs as a Vaccine Platform

Vaccines remain the most established VLP application, and several products are licensed and in worldwide use — the strongest possible proof of the platform:

• Hepatitis B — yeast-expressed HBsAg self-assembles into non-enveloped VLPs; among the first recombinant VLP vaccines.
• Human papillomavirus (HPV) — L1 capsid VLPs; Gardasil is produced in yeast and Cervarix in insect cells, illustrating that the same antigen class can be made in different hosts (Srivastava et al., 2023).
• Hepatitis E — the p239 capsid fragment expressed in E. coli assembles into VLPs that retain virion-like neutralizing epitopes, licensed as Hecolin (Wei et al., 2014).

VLPs are strongly immunogenic because their surface presents antigen as a dense, repetitive array — a pattern that efficiently cross-links B-cell receptors and can engage both antibody- and T-cell–mediated responses (Nooraei et al., 2021). Chimeric VLPs extend this further: a foreign antigen is genetically fused to, or displayed on, the structural protein, so that a non-native immunogen is presented in the highly immunogenic VLP format.

4. VLPs for Recombinant Protein Expression and Display

Beyond whole-particle vaccines, VLPs are a general scaffold for presenting recombinant proteins. Their advantages for protein expression and display are structural rather than incidental:

• Multivalent, ordered display — many copies of the target are arrayed on one particle, raising avidity in binding assays and immune recognition.
• Native-like conformation — surface antigens sit in the spatial context they occupy on a real virion, preserving conformational epitopes that a soluble fragment would lose.
• Engineerability — antigens can be fused into the scaffold (chimeric VLPs) or captured post-assembly, allowing rapid design of new display constructs.
• Built-in safety — with no viral genome, the particle carries no replication or integration risk, simplifying handling and biosafety.

This is why VLPs are widely used to present viral envelope glycoproteins in trimeric, native form for antibody discovery and immunization studies (Iyer et al., 2016).

5. VLPs for Membrane and Transmembrane Protein Expression

Integral membrane proteins — G-protein-coupled receptors (GPCRs), ion channels, claudins, and other multi-pass targets — are among the hardest proteins to produce in a functional state. Their folding and activity depend on a lipid bilayer; detergent solubilization frequently strips away the conformation that antibodies and ligands actually recognize. This is where enveloped VLPs are especially valuable.

Because an enveloped VLP buds from the host-cell membrane, a co-expressed target membrane protein is incorporated into the particle within a native lipid bilayer, displayed at the surface in its correct, membrane-embedded conformation. Studies displaying membrane-anchored viral envelope glycoproteins on VLPs have shown that this format preserves native trimeric structure and conformational epitopes far better than soluble constructs (Iyer et al., 2016; Boix-Besora et al., 2023). For a research team, that translates into practical uses:

• Antibody discovery & immunization against GPCRs and other membrane targets, using an immunogen that presents native epitopes.
• Binding and functional assays — measuring ligand or antibody affinity against a membrane protein in a lipid context.
• Structural and mechanistic studies of receptors that are unstable once removed from the membrane.

eBioHippo's VLP Membrane Proteins catalog applies exactly this approach, offering active membrane targets displayed on VLPs — including high-value immuno-oncology antigens such as CD20 (MS4A1), Claudin-18.2, Claudin-6, CCR8, and the somatostatin receptor SSTR2 — expressed in mammalian cells to retain native conformation. These sit alongside the broader recombinant proteins & peptides range.

Frequently Asked Questions About Virus-Like Particles

What are virus-like particles (VLPs)?

Virus-like particles (VLPs) are self-assembling protein nanoparticles, typically 20–200 nm across, built from one or more viral structural proteins. VLPs reproduce a virus's outer structure but contain no viral genome, so they are non-infectious and cannot replicate.

Are virus-like particles safe, and can they replicate or infect cells?

Virus-like particles are considered highly biosafe: because a VLP carries no genetic material, it cannot replicate, integrate into the genome, or cause infection. This built-in safety is a main reason VLPs are used in licensed vaccines and as research reagents.

What are virus-like particles used for?

Virus-like particles are used for three main purposes: vaccine development (licensed hepatitis B, HPV, and hepatitis E vaccines are VLP-based), targeted drug and gene delivery, and the expression and display of recombinant and membrane proteins in a native-like conformation for antibody discovery and assays.

How are virus-like particles made?

Virus-like particles are made by expressing viral structural proteins in a host system — bacteria, yeast, insect, mammalian, or plant cells — where the proteins self-assemble into particles that are then purified. The host is chosen based on whether the VLP is enveloped and what post-translational modifications, such as glycosylation, the target requires.

How big are virus-like particles?

Virus-like particles are typically 20–200 nm in diameter. Non-enveloped capsid VLPs are usually about 20–60 nm, while enveloped VLPs are larger, around 80–200 nm.

Which expression system is best for membrane proteins on VLPs?

Mammalian expression systems such as HEK293 are generally best for membrane and transmembrane proteins on VLPs, because enveloped VLPs bud with a native lipid bilayer and human-like glycosylation that preserve the target's correctly folded, functional conformation.

What is the difference between a VLP and a viral vector?

A viral vector (such as AAV or lentivirus) packages nucleic acid to deliver genes into cells, whereas a virus-like particle contains no genome and is used to present antigens or proteins on its surface — not to deliver genetic cargo.

References

1. Nooraei S, et al. Virus-like particles: preparation, immunogenicity and their roles as nanovaccines and drug nanocarriers. J Nanobiotechnology. 2021;19(1):59. doi:10.1186/s12951-021-00806-7
2. Srivastava V, et al. Yeast-based virus-like particles as an emerging platform for vaccine development and delivery. Vaccines (Basel). 2023;11(2):479. doi:10.3390/vaccines11020479
3. Mardanova ES, et al. Virus-like particles produced in plants: a promising platform for recombinant vaccine development. Plants (Basel). 2024;13(24):3564. doi:10.3390/plants13243564
4. Wei M, et al. Bacteria expressed hepatitis E virus capsid proteins maintain virion-like epitopes. Vaccine. 2014;32(24):2859–2865. doi:10.1016/j.vaccine.2014.02.025
5. Iyer SS, et al. Virus-like particles displaying trimeric SIV envelope gp160 enhance vaccine-induced antibody responses in rhesus macaques. J Virol. 2016;90(19):8842–8854. doi:10.1128/JVI.01163-16
6. Boix-Besora A, et al. Gag virus-like particles functionalized with SARS-CoV-2 variants: generation, characterization and recognition by convalescent sera. Vaccines (Basel). 2023;11(11):1641. doi:10.3390/vaccines11111641