title: The grafting of universal T-helper epitopes enhances immunogenicity of HIV-1 Tat concurrently improving its safety profile.
abstract: Extracellular Tat (eTat) plays an important role in HIV-1 pathogenesis. The presence of anti-Tat antibodies is negatively correlated with disease progression, hence making Tat a potential vaccine candidate. The cytotoxicity and moderate immunogenicity of Tat however remain impediments for developing Tat-based vaccines. Here, we report a novel strategy to concurrently enhance the immunogenicity and safety profile of Tat. The grafting of universal helper T-lymphocyte (HTL) epitopes, Pan DR Epitope (PADRE) and Pol711 into the cysteine rich domain (CRD) and the basic domain (BD) abolished the transactivation potential of the Tat protein. The HTL-Tat proteins elicited a significantly higher titer of antibodies as compared to the wild-type Tat in BALB/c mice. While the N-terminal epitope remained immunodominant in HTL-Tat immunizations, an additional epitope in exon-2 was recognized with comparable magnitude suggesting a broader immune recognition. Additionally, the HTL-Tat proteins induced cross-reactive antibodies of high avidity that efficiently neutralized exogenous Tat, thus blocking the activation of a Tat-defective provirus. With advantages such as presentation of multiple B-cell epitopes, enhanced antibody response and importantly, transactivation-deficient Tat protein, this approach has potential application for the generation of Tat-based HIV/AIDS vaccines.
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India.
authors.forename: Venkatesh P
authors.initials: VP
authors.lastname: Kashi
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India; Cellular Immunology Group, International Center for Genetic Engineering and Biotechnology, Cape Town, South Africa.
authors.forename: Rajesh A
authors.initials: RA
authors.lastname: Jacob
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India; Laboratory of Molecular Gerontology, National Institute on Aging, Baltimore, Maryland, United States of America.
authors.forename: Raghavendra A
authors.initials: RA
authors.lastname: Shamanna
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India.
authors.forename: Malini
authors.initials: M
authors.lastname: Menon
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India.
authors.forename: Anangi
authors.initials: A
authors.lastname: Balasiddaiah
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India.
authors.forename: Rebu K
authors.initials: RK
authors.lastname: Varghese
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Bachu
authors.affiliation: HIV/AIDS laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, 560064, India.
authors.forename: Udaykumar
authors.initials: U
authors.lastname: Ranga
mesh_terms: D016915:AIDS Vaccines / Q000009:adverse effects / Q000276:immunology; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D002460:Cell Line; D004738:Engineering; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D005822:Genetic Vectors / Q000235:genetics; D015497:HIV-1 / Q000276:immunology*; D007114:Immunization; D051379:Mice; D017434:Protein Structure, Tertiary; D012449:Safety; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D015533:Transcriptional Activation / Q000276:immunology; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D016915:AIDS Vaccines; D000914:Antibodies, Viral; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D054322:tat Gene Products, Human Immunodeficiency Virus