HIV p24-Specific Helper T Cell Clones From Immunised Primates Recognize Highly Conserved Regions of HIV-l

We have investigated Th cell recognition of the HIV core protein p24 by using CD4+ T cell clones derived from cynomolgus macaques immunized with hybrid HIV p24:Ty virus-like particles (VLP). T cell lines from two immunized animals responded to p24:Ty-VLP, control Ty-VLP, purified p24, and whole inactivated HIV, indicating the presence of T cells specific for p24 as well as the Ty carrier protein. The HIV determinants recognized by the T cell lines were identified by using a series of overlapping peptides synthesized according to the sequence of p24. Both T cell lines recognized peptide 11 (amino acids 235-249) and peptide 14 (amino acids 265- 279). In addition, one T cell line also responded to peptide 9 (amino acids 215-229). Definitive identification of two T cell epitopes on p24 was confirmed at the clonal level: from a total of four T cell clones generated from one of the T cell lines, two respond specifically to peptide 11 and two to peptide 14. The T cell clones were CD4' and MHC class 11-restricted and secreted IL-2 in response to stimulation with purified p24, inactivated HIV or a single synthetic peptide. The specificityof the Th clones for variant peptides demonstrated cross-reactivity with two simian immunodeficiency virus isolates, but only limited responses to HIV-2 sequences. However, the Th cell epitopes identified on p24 are highly conserved between 12 HIV-1 isolates and were recognized by both of the immunized primates. These sequences may therefore be useful for priming a broadly reactive immune response to HIV-1

The “Putative” Leucine Zipper Region of Murine Leukemia Virus Transmembrane Protein (P15e) Is Essential for Viral Infectivity

AbstractIn order to determine the role of the putative leucine zipper region of murine leukemia virus (MLV) transmembrane protein p15E, nine mutations in this region were introduced by site-directed mutagenesis. None of these mutations affected the expression or transport of the envelope protein or incorporation into virions. The mutants were analyzed for their ability to infect NIH3T3 cells and to induce cell fusion in a rat XC cell fusion assay. Mutations removing the charge of the hydrophilic residues reduced infectivity in NIH3T3 cells but had either no effect or a minor effect on envelope-induced XC cell fusion. Six mutations of hydrophobic residues of the putative leucine zipper region were constructed; four completely abolished the ability to infect NIH3T3 cells and these mutant envelopes were also unable to induce cell fusion in the XC cell fusion assay. These data demonstrate the absolute requirement for the putative leucine zipper region for both fusion and infection of MLV

Murine leukemia virus-based Tat-inducible long terminal repeat replacement vectors: a new system for anti-human immunodeficiency virus gene therapy.

We have constructed new murine leukemia virus (MLV)-based vectors (TIN vectors) which, following integration, contain human immunodeficiency virus (HIV) type 1 U3 and R sequences in place of the MLV U3 and R regions. This provides, for the first time, single transcriptional unit retroviral vectors under the control of Tat. TIN vectors have several advantages for anti-HIV gene therapy applications