Ask A Scientist:
Should I Use CMV Antigens or CMV Peptides?

ask a scientist

ask a scientistCMV antigens and CMV peptides are both great tools for studying the implications of the human cytomegalovirus (CMV), which infects nearly 1/3 of children before the age of five and more than half of adults in the U.S.

Although CMV-infected individuals are often asymptomatic, the virus does pose a serious threat to individuals with weakened immune systems, infants, and the elderly. Researchers have linked CMV infections to learning disabilities in children, vascular disease, and some cancers. Continued research using CMV antigens and CMV peptides will help to further the understanding of the human immune system and the impacts of this infection.

CMV Antigens and CMV Peptides: What Are They?

CMV Antigens are lysates from CMV-infected human fibroblasts. The lysate is enriched for viral antigens and exposed to UV light to inactivate any virus that is present, rendering the lysate non-infectious.

CMV Peptides produced by Astarte are nine amino acids long and are targeted by the immune system in its mission to remove CMV-infected cells.

Use Cases for CMV Antigens

Because CMV is a latent infection that lives dormant inside the body, the immune system produces a large number of T cells to control the virus, making the in vitro T cell response to CMV extremely robust. We use CMV antigens to detect the T cell response to CMV and confirm our CMV-positive blood donors are in fact CMV positive.

You can use CMV antigens to study immune-oncology applications. The immune response is not able to remove CMV from the body, much like tumors that are not attacked by the immune system. Our CMV antigens and CMV-positive donors were used to show the activity of Opdivo (nivolumab) in this in vitro model system: Wang, et. al. In Vitro Characterization of the Anti-PD-1 Antibody Nivolumab, BMS-936558, and In Vivo Toxicology in Non-Human Primates. Cancer Immunology Research. 2014, 2:846.

CMV antigens are the right tool for stimulating proliferation and cytokine secretion by PBMC from CMV-positive donors. CMV peptides, on the other hand, only stimulate a very specific subset of CMV-reactive cells, so using CMV peptides with PBMC is not going to yield a quick response.

Use Cases for CMV Peptides

The number of T cells that react to any given protein sequence is small even in donors who have been immunized by vaccination or infection. In the best cases, only 1 in 100 T cells are specific for any given CMV peptide, so it can be difficult to detect CMV-reactive T cells in PBMC. If you have a donor who expresses the HLA-A*0201 or HLA-B*3501 alleles, for example, you may not be able to detect the corresponding T cells reactive to our CMV peptides in PBMC.

To help, we have developed short CMV peptides that are just nine amino acids long, the optimal length for binding to HLA class I molecules. We have CMV peptides that bind to HLA-A*0201 and HLA-B*3501, along with cultured T cell lines specific to each of these peptides, so you can be sure the T cells will recognize the peptide.

Related Protocols

Our Recall Antigen Testing protocol demonstrates how to use CMV antigens when testing PBMC for reactivity.

Our Antigen Specific T Cell Assay can be used to measure cytokine production or proliferation of CMV-specific T cells using the corresponding CMV peptide.

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