Louis Picker, M.D.

Some T cells are the immune system's memory chips. Before the immune system can mount an effective attack on a disease-causing microorganism, they must form a subset of "memory" T cells specific for that organism. These "memory" T cells orchestrate immune elimination of the invader and remain in the blood and tissues so that the system can mount another counterattack should the foreign agent invade again. Memory T cell activity is also the key to explaining how vaccines work. Vaccines expose the immune system to weakened or noninfectious forms of pathogens, thus activating T cell memory and tricking the system into generating these critical disease-fighting cells.Researchers in Louis Picker's laboratory focus their studies on memory T cell biology in human and nonhuman primates. They investigate the physiology of T cell memory and effector responses, including mechanisms that control "selection" of the memory repertoire, the functional specialization of the memory population, and the elements involved in T cell homeostasis and regeneration.At the same time, these scientists are seeking to determine the basis of effective immunity to certain chronic human pathogens, particularly HIV/SIV and cytomegalovirus, and are working on prophylactic and/or therapeutic vaccines against these pathogens. Finally, they are studying how memory T cells are reconstituted after HIV-1 infection or bone marrow transplantation. Picker and his colleagues have developed special expertise in the quantification and functional characterization of antigen-specific memory T cells. They exploit these technologies in the examination of human subjects and rhesus macaque models of chronic viral infection.


Louis Picker graduated from UCLA with a B.S. in bacteriology in 1978 and took his M.D. degree at the University of California at San Francisco in 1982. After residency training in pathology at Beth Israel Hospital, Boston, and postdoctoral training in immunology at Stanford University Medical Center, he was appointed assistant professor and then associate professor of pathology at the University of Texas Southwestern Medical Center at Dallas. In 1999 he came to OHSU and ONPRC as professor of pathology/molecular microbiology and immunology in the OHSU School of Medicine and head of the Division of Pathobiology and Immunology.


  • Fukazawa Y, Lum R, Okoye AA, Park H, Matsuda K, Bae JY, Hagen SI, Shoemaker R, Deleage C, Lucero C, Morcock D, Swanson T, Legasse AW, Axthelm MK, Hesselgesser J, Geleziunas R, Hirsch VM, Edlefsen PT, Piatak M Jr, Estes JD, Lifson JD, Picker LJ. Nat Med. 2015 Jan 19. (doi: 10.1038/nm.3781.) [PMID: 25599132]
  • Picker LJ, Lifson JD. HIV: Seeking ultimate victory. Nature. 2015 Jan 7. doi: 10.1038/nature14194. PMID: 25561174
  • Yang OO, Ali A, Kasahara N, Faure-Kumar E, Bae JY, Picker LJ, Park H. Short Conserved Sequences of HIV-1 Are Highly Immunogenic and Shift Immunodominance. J Virol. 2015 Jan 15;89(2):1195-204. (doi: 10.1128/JVI.02370-14.) [PMID: 25378501] Epub 2014 Nov 5.
  • Barouch DH, Picker LJ. Novel vaccine vectors for HIV-1. Nat Rev Microbiol. 2014 Nov;12(11):765-71. (doi: 10.1038/nrmicro3360.) [PMID: 25296195, PMCID: PMC4237164] Epub 2014 Oct 8.
  • Picker LJ. Are effector memory T cells the key to an effective HIV/AIDS vaccine? EMBO Rep. 2014 Aug;15(8):820-1. (doi: 10.15252/embr.201439052.) [PMID: 24980866, PMCID: PMC4197036] Epub 2014 Jun 30.
  • Del Prete GQ, Park H, Fennessey CM, Reid C, Lipkey L, Newman L, Oswald K, Kahl C, Piatak M Jr, Quiñones OA, Alvord WG, Smedley J, Estes JD, Lifson JD, Picker LJ, Keele BF. Molecularly tagged simian immunodeficiency virus SIVmac239 synthetic swarm for tracking independent infection events. J Virol. 2014 Jul;88(14):8077-90. (doi: 10.1128/JVI.01026-14.) [PMID: 24807714, PMCID: PMC4097795] Epub 2014 May 7.
  • Malouli D, Hansen SG, Nakayasu ES, Marshall EE, Hughes CM, Ventura AB, Gilbride RM, Lewis MS, Xu G, Kreklywich C, Whizin N, Fischer M, Legasse AW, Viswanathan K, Siess D, Camp DG 2nd, Axthelm MK, Kahl C, DeFilippis VR, Smith RD, Streblow DN, Picker LJ, Früh K. Cytomegalovirus pp65 limits dissemination but is dispensable for persistence. J Clin Invest. 2014 May 1;124(5):1928-44. [PMID: 24691437, PMCID: PMC4002596] Epub 2014 Apr 1.
  • Li H, Margolick JB, Bream JH, Nilles TL, Langan S, Bui HT, Sylwester AW, Picker LJ, Leng SX. Heterogeneity of CD4+ and CD8+ T-cell responses to cytomegalovirus in HIV-infected and HIV-uninfected men who have sex with men. J Infect Dis. 2014 Aug 1;210(3):400-4. (doi: 10.1093/infdis/jiu093.) [PMID: 2453260, PMCID: PMC4110456] Epub 2014 Feb 14.
  • Picker LJ, Deeks SG. HIV: Antibodies advance the search for a cure. Nature. 2013 Nov 14;503(7475):207-8. (doi: 10.1038/nature12703.)
  • Hansen SG, Piatak M Jr, Ventura AB, Hughes CM, Gilbride RM, Ford JC, Oswald K, Shoemaker R, Li Y, Lewis MS, Gilliam AN, Xu G, Whizin N, Burwitz BJ, Planer SL, Turner JM, Legasse AW, Axthelm MK, Nelson JA, Früh K, Sacha JB, Estes JD, Keele BF, Edlefsen PT, Lifson JD, Picker LJ. Immune clearance of highly pathogenic SIV infection. Nature. 2013 Oct 3;502(7469):100-4. (doi: 10.1038/nature12519.) [PMID: 24025770, PMCID: PMC3849456] Epub 2013 Sep 11.
  • Okoye AA, Picker LJ. CD4(+) T-cell depletion in HIV infection: mechanisms of immunological failure. Immunol Rev. 2013 Jul;254(1):54-64. (doi: 10.1111/imr.12066.) [PMID: 23772614, PMCID: PMC3729334]
  • Park H, Adamson L, Ha T, Mullen K, Hagen SI, Nogueron A, Sylwester AW, Axthelm MK, Legasse A, Piatak M Jr, Lifson JD, McElrath JM, Picker LJ, Seder RA. Polyinosinic-polycytidylic acid is the most effective TLR adjuvant for SIV Gag protein-induced T cell responses in nonhuman primates. J Immunol. 2013 Apr 15;190(8):4103-15. (doi: 10.4049/jimmunol.1202958.) [PMID: 23509365, PMCID: PMC3622154] Epub 2013 Mar 15.
  • Fukazawa Y, Park H, Cameron MJ, Lefebvre F, Lum R, Coombes N, Mahyari E, Hagen SI, Bae JY, Reyes MD 3rd, Swanson T, Legasse AW, Sylwester A, Hansen SG, Smith AT, Stafova P, Shoemaker R, Li Y, Oswald K, Axthelm MK, McDermott A, Ferrari G, Montefiori DC, Edlefsen PT, Piatak M Jr, Lifson JD, Sékaly RP, Picker LJ. Lymph node T cell responses predict the efficacy of live attenuated SIV vaccines. Nat Med. 2012 Nov;18(11):1673-81. (doi: 10.1038/nm.2934.) [PMID: 22961108, PMCID: PMC3493820] Epub 2012 Sep 9.
  • Okoye AA, Rohankhedkar M, Abana C, Pattenn A, Reyes M, Pexton C, Lum R, Sylwester A, Planer SL, Legasse A, Park BS, Piatak M Jr, Lifson JD, Axthelm MK, Picker LJ. Naive T cells are dispensable for memory CD4+ T cell homeostasis in progressive simian immunodeficiency virus infection. J Exp Med. 2012 Apr 9;209(4):641-51. (doi: 10.1084/jem.20112071.) [PMID: 22451717, PMCID: PMC3328373] Epub 2012 Mar 26.
  • Cicin-Sain L, Sylwester AW, Hagen SI, Siess DC, Currier N, Legasse AW, Fischer MB, Koudelka CW, Axthelm MK, Nikolich-Zugich J, Picker LJ. Cytomegalovirus-specific T cell immunity is maintained in immunosenescent rhesus macaques. J Immunol. 2011 Aug 15;187(4):1722-32. (doi: 10.4049/jimmunol.1100560.) [PMID: 21765018, PMCID: PMC3151292] Epub 2011 Jul 15.
  • Picker LJ, Hansen SG, Lifson JD. New paradigms for HIV/AIDS vaccine development. Annu Rev Med. 2012;63:95-111. (doi: 10.1146/annurev-med-042010-085643.) [PMID: 21942424, PMCID: PMC3368276] Epub 2011 Sep 19.
  • Hansen SG, Powers CJ, Richards R, Ventura AB, Ford JC, Siess D, Axthelm MK, Nelson JA, Jarvis MA, Picker LJ, Früh K. Evasion of CD8+ T cells is critical for superinfection by cytomegalovirus. Science. 2010 Apr 2;328(5974):102-6. (doi: 10.1126/science.1185350.) [PMID: 20360110, PMCID: PMC2883175]
  • Okoye A, Park H, Rohankhedkar M, Coyne-Johnson L, Lum R, Walker JM, Planer SL, Legasse AW, Sylwester AW, Piatak M Jr, Lifson JD, Sodora DL, Villinger F, Axthelm MK, Schmitz JE, Picker LJ. Profound CD4+/CCR5+ T cell expansion is induced by CD8+ lymphocyte depletion but does not account for accelerated SIV pathogenesis. J Exp Med. 2009 Jul 6;206(7):1575-88. (doi: 10.1084/jem.20090356.) [PMID: 19546246, PMCID: PMC2715089] Epub 2009 Jun 22.
  • Cicin-Sain L, Messaoudi I, Park B, Currier N, Planer S, Fischer M, Tackitt S, Nikolich-Zugich D, Legasse A, Axthelm MK, Picker LJ, Mori M, Nikolich-Zugich J. Dramatic increase in naive T cell turnover is linked to loss of naive T cells from old primates. Proc Natl Acad Sci U S A. 2007 Dec 11;104(50):19960-5. [PMID: 18056811, PMCID: PMC2148405] Epub 2007 Dec 4.
  • Okoye A, Meier-Schellersheim M, Brenchley JM, Hagen SI, Walker JM, Rohankhedkar M, Lum R, Edgar JB, Planer SL, Legasse A, Sylwester AW, Piatak M Jr, Lifson JD, Maino VC, Sodora DL, Douek DC, Axthelm MK, Grossman Z, Picker LJ. Progressive CD4+ central memory T cell decline results in CD4+ effector memory insufficiency and overt disease in chronic SIV infection. J Exp Med. 2007 Sep 3;204(9):2171-85. [PMID: 17724130, PMCID: PMC2118701] Epub 2007 Aug 27.
  • Messaoudi I, Warner J, Fischer M, Park B, Hill B, Mattison J, Lane MA, Roth GS, Ingram DK, Picker LJ, Douek DC, Mori M, Nikolich-Zugich J. Delay of T cell senescence by caloric restriction in aged long-lived nonhuman primates. Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19448-53. [PMID: 17159149, PMCID: PMC1748246] Epub 2006 Dec 11.
  • Picker LJ. Immunopathogenesis of acute AIDS virus infection. Curr Opin Immunol. 2006 Aug;18(4):399-405. [PMID: 16753288] Epub 2006 Jun 5.
  • Picker LJ, Reed-Inderbitzin EF, Hagen SI, Edgar JB, Hansen SG, Legasse A, Planer S, Piatak M Jr, Lifson JD, Maino VC, Axthelm MK, Villinger F. IL-15 induces CD4 effector memory T cell production and tissue emigration in nonhuman primates. J Clin Invest. 2006 Jun;116(6):1514-24. [PMID: 16691294, PMCID: PMC1459071] Epub 2006 May 11.
  • Walker JM, Maecker HT, Maino VC, Picker LJ. Multicolor flow cytometric analysis in SIV-infected rhesus macaque. Methods Cell Biol. 2004;75:535-57. [PMID: 15603441]
  • Picker LJ, Hagen SI, Lum R, Reed-Inderbitzin EF, Daly LM, Sylwester AW, Walker JM, Siess DC, Piatak M Jr, Wang C, Allison DB, Maino VC, Lifson JD, Kodama T, Axthelm MK. Insufficient production and tissue delivery of CD4+ memory T cells in rapidly progressive simian immunodeficiency virus infection. J Exp Med. 2004 Nov 15;200(10):1299-314. [PMID: 15545355, PMCID: PMC2211921]
  • Bitmansour AD, Douek DC, Maino VC, Picker LJ. Direct ex vivo analysis of human CD4(+) memory T cell activation requirements at the single clonotype level. J Immunol. 2002 Aug 1;169(3):1207-18. [PMID: 12133941]
  • Pitcher CJ, Hagen SI, Walker JM, Lum R, Mitchell BL, Maino VC, Axthelm MK, Picker LJ. Development and homeostasis of T cell memory in rhesus macaque. J Immunol. 2002 Jan 1;168(1):29-43. [PMID: 11751943]