The grafting of universal T-helper epitopes enhances immunogenicity of HIV-1 Tat concurrently improving its safety profile

PLoS One. 2014 Dec 22;9(12):e114155. doi: 10.1371/journal.pone.0114155. eCollection 2014.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AIDS Vaccines / adverse effects
  • AIDS Vaccines / immunology
  • Animals
  • Antibodies, Viral / immunology
  • Cell Line
  • Engineering
  • Epitopes, B-Lymphocyte / immunology
  • Epitopes, T-Lymphocyte / immunology*
  • Extracellular Space / metabolism
  • Female
  • Genetic Vectors / genetics
  • HIV-1 / immunology*
  • Immunization
  • Mice
  • Protein Structure, Tertiary
  • Safety*
  • T-Lymphocytes, Helper-Inducer / immunology*
  • Th1 Cells / immunology
  • Th2 Cells / immunology
  • Transcriptional Activation / immunology
  • tat Gene Products, Human Immunodeficiency Virus / chemistry
  • tat Gene Products, Human Immunodeficiency Virus / genetics
  • tat Gene Products, Human Immunodeficiency Virus / immunology*
  • tat Gene Products, Human Immunodeficiency Virus / metabolism

Substances

  • AIDS Vaccines
  • Antibodies, Viral
  • Epitopes, B-Lymphocyte
  • Epitopes, T-Lymphocyte
  • tat Gene Products, Human Immunodeficiency Virus

Grants and funding

This study was supported by grants from the Indian Council of Medical Research, India (HIV/50/114/09-ECDII, IRIS No. 2008-06300) and intramural grants from Jawaharlal Nehru Center for Advanced Scientific Research to Udaykumar Ranga. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.