COVID-19 Pseudovirus Service

RayBiotech's COVID-19 pseudovirus service enables the study of the SARS-CoV-2 virus in cell culture. This service is ideal for:

  • Screening patient serum for neutralizing antibodies
  • Validating inhibitors of the Spike-ACE2 interaction
  • COVID-19 vaccine development
Viral particle

Service Features

  • Complete. Send us your samples, we'll send you results!
  • Fast Turnaround. 4 weeks, with an option to expedite the service (additional fees apply).
  • Customized. Tailored to meet your needs.
  • Competitive Prices. The more samples you send for analysis, the more you save.

How It Works

How it works

In the presence of Spike-ACE2 inhibitors, the level of luminescence will decrease.

Service Description


Expresses the SARS-CoV-2 spike protein.

Sample types

Serum / Plasma / Peptides / Proteins / Purified antibodies / Small molecules

Sample amount to send

Undiluted serum or plasma (100 µL) / Peptides (≥ 200 µg) / Proteins (≥ 25 µg) / Purified antibodies (≥ 20 µg) / Small molecules (≥ 1 mg)

Sample minimum

No sample minimum. We charge our service based on how many 96-well plates are required. Therefore, regardless of whether 1 well is used or all 96 wells, the charge for the service will be the same.


We will perform 2 technical replicates unless otherwise requested.

Cell lines

You can choose between the ACE2-expressing cells, human A549 or monkey Vero. If you don't have a preference, we recommend the human A549 cell line.


Our service includes the following controls:

  • "Mock Infection" positive control (pseudovirus with a non-Spike glycoprotein with an ACE2-expressing cell line) at the same dilutions as your sample
  • "No Sample" positive control (cell culture media with ACE2-expressing cell line)
  • Negative control (no pseudovirus with an ACE2-expressing cell line)

Duplicate technical replicates will be performed for all controls unless otherwise requested.

Additional negative controls with cells that do not express the ACE2 receptor, mouse NIH3T3 or ovine OFTU cells, can be added to this service upon request (additional fees apply). If you don't have a preference, we recommend the mouse NIH3T3 cell line.


You will receive two files:

  1. An Excel-based report outlining the samples and their measured luminescence values. These values have already had background signal subtracted from them. The background signal is obtained from duplicate technical replicates of similar cells that have not had pseudovirus incubated with them. The Excel file will also include the inhibition rate(s) of the sample(s) at different dilutions compared to the "No Sample" positive control.
  2. A Word document summarizing the service background, controls, procedure, and references.


Figure 1
Figure. 1 Neutralization analysis by SARS-CoV-2-S-driven entry. Pseudoviruses expressing a non-Spike glycoprotein ("glycoprotein") or the SARS-CoV-2 Spike protein on the surface were incubated with A549 cells expressing the ACE2 receptor ("ACE2 cell") or NIH3T3 cells not expressing the ACE2 receptor ("Non-ACE2 cell"). Serum containing a neutralizing antibody was added at 400-, 200-, or 100-fold dilutions. Luminescence reflecting viral entry was measured, and the average luminescence across three independent experiments relative to the "no serum" sample data is shown. Error bars indicate standard deviations.
Figure 2
Figure 2. Western blot analyses reveal pseudovirus-specific glycoproteins. Pseudoviruses representing the vesicular stomatitis virus (VSV) (Lane 1) and SARS-CoV-2 (Lane 2) were analyzed on 10% or 8% SDS-PAGE gel, respectively, and transferred onto nitrocellulose membranes for 1 hour at 20 V. After blocking in 5% milk (w/v) in 1x phosphate-buffered saline (PBS) with 0.2% Tween-20 overnight at 4°C, the membranes were probed with primary antibodies targeting (A) the VSV non-Spike glycoprotein (G) (60 kDa) or (B) the SARS-CoV-2 Spike (S) protein (∼180 kDa) for 1 hour at room temperature (RT) at 1:2000 dilution in 5% milk + PBST. Both pseudoviruses are used in the RayBiotech's COVID-19 pseudovirus service; the VSV pseudovirus is used as a control. For (A), a mouse anti-VSV-G antibody (Kerafast, cat no. EB0010) was used. For (B), a mouse anti-SARS-CoV-2 S antibody (RayBIotech, cat no. 130-10808) was used. After washing the membranes three times for 5 minutes each, the secondary anti-mouse IgG antibody conjugated to horseradish peroxidase (HRP) diluted 1:5000 in 5% milk + PBST was added for 1 hour at RT.  The membranes were washed 5 times, 5 minutes each, in PBST. Finally, the HRP substrate was added and the chemiluminescence was detected using a compatible instrument.

Service FAQs

  • What is a pseudovirus?
  • Why use a pseudovirus to study COVID-19?
  • How does this pseudovirus work?
  • How can this pseudovirus be used to study SARS-CoV-2 neutralization?
  • Can I use this pseudovirus to screen for potential inhibitors of the Spike-ACE2 interaction?


  • Caohuy, Hung, et al. "Common cardiac medications potently inhibit ACE2 binding to the SARS-CoV-2 Spike, and block virus penetration and infectivity in human lung cells." Scientific Reports 11.1 (2021): 1-14. [view publication]
    Sample Type: Small molecules