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Abstract
Preliminary experimental evidence showed the potential for formation of a new isoform of the nef gene in HIV-1 by 1 ribosomal frameshifting. We have named this hypothetical nef transframe protein as nef-fs. Previous sequence analysis and molecular modeling data strongly support the possibility that this nef-fs may encode a chemokine-homologue. To prove this modeling result, we synthesized a series of peptides by solid phase synthesis. These peptides are located about one third of the way into the nef coding region, downstream of an internal methonine that is the beginning of a potential signal peptide of nef-fs. A calcium mobilizaion assay and a chemotaxis assay were performed in order to test these peptides chemotactic activity. The calcium mobilizaion assay showed that two of the peptides could induce calcium mobilization in a Jurkat cell at certain concentrations which indicated chemotacticity. The chemotaxis assay proved the two peptides can induce chemotactic movement of a Jurkat cell with a characteristic bell shape curve. The remaining peptides have little or none of this chemotactic ability. Both of these experiments proved that these peptides encoded by nef-fs are chemotactic peptides and support our modeling result that this peptide could be a chemokine homologue. Our results showed only two out of the five peptides having significant chemotactic ability and the remaining of peptides lack this property although much of the sequences is identical. This suggested that certain conformations maybe required for this nef-fs to be chemotactic in vivo.