The Walker laboratory focuses on mechanisms of immune control in HIV infection, focusing in particular on persons who control HIV infection spontaneously without the need for medication. Through an international collaboration now funded by the Gates Foundation, more than 1500 persons who control HIV infection to less than 2000 RNA Copies/ml without the need for antiviral medications have been recruited, and immunologic, virologic and host genetic mechanisms accounting for this remarkable phenotype are being investigated. Our results, recently published in Science, indicate that the major genetic determinants of HIV control affect the nature of the peptide-HLA binding. We are currently focusing our research efforts on this interaction and how it impacts the inductive and effector phases of the CD8 T cell response.

Other projects currently underway are building on a observation that the antiviral efficacy of CTL varies dramatically among different epitopes and different restricting HLA alleles, in an attempt to define the major antiviral effector functions and apply these to vaccine development. At the same time, efforts are underway to define the subset of CD8 T cell responses that exert the strongest antiviral effect, and to define those responses that are simply passengers and fail to contribute to immune control.

In addition to these efforts in Boston, a major effort is underway at our laboratory at the Nelson Mandela School of Medicine at the University of KwaZulu-Natal, South Africa, where a major population based effort is underway to define evolution of clade C virus infection under immune selection pressure, and to define predictable pathways to immune escape. We have established a mechanism for recruitment of persons with acute HIV infection by screening persons who test antibody negative at VCT (now HCT) sites in KZN. We anticipate an expanding collaboration with persons at the Ithembalebantu Clinic in Umlazi to accelerate these studies, which will include examination of tissue biopsies.

Persons interested in joining this lab should have a strong background in immunology and/or molecular biology, a strong interest in working on immune responses in humans, and an ability to work relatively independently. The lab is highly collaborative with other labs within the Ragon Institute and outside, and thus seeks people who are committed to scientific collaboration. Please visit the Training Programs page for information about how to apply.

Present Areas of Investigation:
		Define the relative antiviral efficacy of epitope-specific CTL responses in infected persons
		Define the predicatable pathways to immune escape in infected persons
		Define the mechanisms that underlie effective cell killing
		Define the mechanisms of spontaneous control of HIV infection using a genome wide association scan.
Important Accomplishments:
		Identification of strong circulating HIV-specific cytotoxic T lymphocytes in infected persons.
		Identification of HIV-specific CD4 T cells and their association with immune control of HIV.
		Identification of immunoregulatory pathways that turn HIV-specific immune responses off in vivo.
		Demonstration of the superior antiviral efficacy of Gag-specific CD8 T cell responses.
Publications of Interest:
	1.	Day CL, Kaufmann DE, Kiepiela P, Brown JA, Moodley ES, Reddy S, Mackey EW, Miller JD, Leslie AJ, DePierres C, Mncube Z, Duraiswamy J, Zhu B, Eichbaum Q, Altfeld M, Wherry EJ, Coovadia HM, Goulder PJ, Klenerman P, Ahmed R, Freeman GJ, Walker BD. 2006. PD-1 expression on HIV-specific T cells is associated with T-cell exhaustion and disease progression. Nature 443: 350-4
	2.	Kaufmann DE, Kavanagh DG, Pereyra F, Zaunders JJ, Mackey EW, Miura T, Palmer S, Brockman M, Rathod A, Piechocka-Trocha A, Baker B, Zhu B, Le Gall S, Waring MT, Ahern R, Moss K, Kelleher AD, Coffin JM, Freeman GJ, Rosenberg ES, Walker BD. 2007. Upregulation of CTLA-4 by HIV-specific CD4+ T cells correlates with disease progression and defines a reversible immune dysfunction. Nat Immunol 8: 1246-54
	3.	Chen H, Piechocka-Trocha A, Miura T, Brockman MA, Julg BD, Baker BM, Rothchild AC, Block BL, Schneidewind A, Koibuchi T, Pereyra F, Allen TM, Walker BD. 2009. Differential neutralization of human immunodeficiency virus (HIV) replication in autologous CD4 T cells by HIV-specific cytotoxic T lymphocytes. J Virol 83: 3138-49
	4.	Miura T, Brockman MA, Brumme ZL, Brumme CJ, Pereyra F, Trocha A, Block BL, Schneidewind A, Allen TM, Heckerman D, Walker BD. 2009. HLA-associated alterations in replication capacity of chimeric NL4-3 viruses carrying gag-protease from elite controllers of human immunodeficiency virus type 1. J Virol 83: 140-9
	5.	Kosmrlj A, Read EL, Qi Y, Allen TM, Altfeld M, Deeks SG, Pereyra F, Carrington M, Walker BD, Chakraborty AK. 2010. Effects of thymic selection of the T-cell repertoire on HLA class[thinsp]I-associated control of HIV infection. Nature 465: 350-4
	6.	The International HIV Controller Study. 2010. The major genetic determinants of HIV control affect HLA class I peptide binding. Science in press