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Numerous investigators have postulated that one mechanism by which hepatitis C virus (HCV) may evade the immune system is through the formation of escape mutants. This hypothesis is based largely on the observed mutability of the viral genome resulting in evolution of diverse quasispecies over the course of infection. That such diversification is a product of viral RNA polymerase infidelity, immune-driven selection or a combination of the two processes has not been addressed. We have examined sequence variability in a specific segment of HCV RNA encoding a known immunodominant region of the viral helicase, amino acids 358-375 of the non-structural 3 protein. Using sequence-specific oligonucleotide probe hybridization and automated DNA sequencing, we report a high frequency of mutations, essentially all of which result in amino acid replacements. To assess the biological impact of such mutations, corresponding chemically synthesized peptides were compared to wild-type peptide in T cell proliferation assays. We observed that a sizeable fraction of such peptides stimulated attenuated or negligible levels of proliferation by peripheral T cells from a chronically infected patient. This observation is consistent with expectations for immune-mediated selection of escape variants at the epitope level. We postulate that such a mechanism may be important in the immunopathogenesis of HCV infections.

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A water-compatible molecularly imprinted polymer was prepared by Pickering emulsion polymerization using halloysite nanotubes as stabilized solid particles. During polymerization, we used 4-vinylpyridine as monomer, divinylbenzene as cross-linking agent, toluene as porogen, 2,2-azobisisobutyronitrile as initiator, 2,4-dichlorophenoxyacetic acid as template to form the oil phase, and Triton X-100 aqueous solution to form the water phase. The halloysite nanotubes molecularly imprinted polymer was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Kinetic and equilibrium bindings were also employed to evaluate the adsorption properties of the imprinted polymer. The imprinted polymer showed better selectivity, more rapid kinetic binding (60 min) for 2,4-dichlorophenoxyacetic acid in pure water compared with rebinding in toluene. The imprinted polymer was used as a sorbent to enrich and separate 2,4-dichlorophenoxyacetic acid from water, and was detected by high-performance liquid chromatography with UV detection.

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