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AIDS VACCINE RESEARCH LABORATORYDavid Watkins, P.I. |
Tetramer/Protein Core
Nancy Wilson Schlei, Ph.D. – Associate Scientist, leads the tetramer core, along with the Protein group in the Watkins lab. Tetramers are used to enumerate T cells responding to SIV epitopes (in this case) presented by an MHC molecule. The MHC-peptide – T cell receptor interaction is the central interaction for the cellular immune response. Theoretically, T cells responding to SIV (simian immunodeficiency virus) could be stained for flow cytometry using MHC Class I and cognate peptide, linked to a fluorophore. However, since this interaction, while highly specific, is of very low affinity and has a very short half life, we need to make a higher order complex, such as a tetramer, so that the avidity is sufficient to permit staining for flow cytometry.
Tetramers are available as a service for primate researchers, please contact nwilson@primate.wisc.edu and/or check out our ordering website at: www.gls-ent.us/tetdb. All tetramer requests must be approved by David Watkins and may be subject to a nominal fee to cover reagents and labor for production.
We have identified several MHC class I alleles that are present at high frequency in the Indian rhesus macaque population (Mamu-A*01 (Allen 1998; Sidney 2000; Allen 2001), Mamu-A*02 (Vogel 2002; Loffredo 2004) and Mamu-B*17 (Mothe 2002)) and determined which SIV-derived epitopes are bound by these alleles. We are working to produce tetramers to all of the identified epitopes for these alleles, so that we can use tetramers to follow as many immune responses as possible in MHC-defined macaques. As alleles are uncovered that are useful for the rhesus macaque model for SIV, we will continue to develop tetramers for these new alleles. In addition, we will develop MHC Class II tetramers, so that the critical CD4+ subset that recognizes SIV epitopes can be visualized as well.
MHC molecules are produced in a variety of ways, since one allele may express better in one system or another. These methods include production of fully folded MHC Class I alleles with beta2microglobulin and peptide is exchanged in, as well as production of inclusion bodies in bacteria which are subsequently re-folded with peptide according to the method of David Price and Emma Gostick. We have developed a working tetramer protocol (link). We currently produce tetramers for four different MHC class I alleles and are developing tetramers MHC class II alleles in the near future so that HTL responses can also be followed.