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Abstract
Fighting Virus with Virus: Intracellular Immunization with H. saimiri-encoded Tip Inhibits the Functions of HIV-1 Tat.
Raymond A.1, Hasham M.1, Tsygankov A.1, Henderson E.2
1Temple University School of Medicine, Philadelphia, United States of America, 2Fels Molecular and Genetics Research Institute, Philadelphia, United States of America
Introduction: Herpesvirus saimiri (HVS), a simian oncogenic virus, transforms primate and human T-cells in vitro. T-lymphocytes retrovirally transduced to express Tyrosine-kinase interacting protein (Tip) exhibited significant restriction in the replication of HIV-1 X4 and R5 strains. Molecular mechanism(s) of these effects are unknown. Since, Tip interacts with signaling molecules within the T-cell receptor and cytokine (interferon-g (IFN-g)) cascades, binding and increasing the activity of Lymphocyte cell-specific kinase (Lck) and signal transducers and activators of transcription (STAT1 and STAT3), we examined the roles of these molecules in Tip restriction. HIV-1 infection in Tip+ T-cells with differential Lck expression were examined along with IFN-g induced genes (ISGs) – Protein Kinase RNA dependent (PKR) and 2´ -5´ oligoadenylate synthetase (2´ -5´ OAS).
Methods: HIV-based lentiviral vectors encoding Tip were prepared in 293T cells. MOLT4, Jurkat, JCaM1.6 (express kinase defective Lck), and JCaM-C1 (w/ tetratracycline repressible Lck expression) cells transduced and infected with HIV-1. Infections monitored using p24 capture ELISAs. Tat-mediated transcription investigated using LTR-CAT reporter constructs. Expression of ISGs in Tip+ transductants analyzed by SDS/PAGE and Western Blot analysis.
Results: Tip+ MOLT4 and Jurkat but not Tip+ JCaM1.6 and tetracycline-treated JCaM-C1 exhibited restricted HIV-1 replication. Tip significantly reduced HIV-1 Tat-mediated transcription in MOLT4, Jurkat, and JCaM1.6 independently of Lck. PKR and 2´ -5´ OAS expression levels were considerably increased by Tip.
Conclusions: Together these studies suggest that H. saimiri Tip is an antiviral gene that restricts HIV in infection on transcriptional and post-transcriptional levels. Additionally, the transcriptional restriction appears to be Lck independent while the post-transcriptional control is Lck dependent.
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