LIBRARIES OF HUMAN RHINOVIRUS-BASED HIV VACCINES GENERATED USING RANDOM SYSTEMATIC MUTAGENESIS

Human rhinovirus (HRV), an immunogenic and relatively nonpathogenic vi rus, has been engineered to display HIV-1 immunogens with the intent o f developing a vaccine against AIDS. HIV immunogens from the V3 loop h ave been placed into the neutralizing immunogenic (NIm) sites on the s urface of HRV14 naturally recognized by the immune system. To increase the likelihood of recovering viable chimeras displaying the transplan ted HIV-1 V3 loop sequences in conformations that mimic that of HIV, w e have used random systematic mutagenesis to produce libraries of chim eric HRV14 in which the transplanted epitope from HIV-1 is flanked by one or more randomized amino acid residues. This allows the HIV epitop e to be accommodated into the HRV coat proteins in many conformations, some of which should result in the production of viable, immunogenic hybrids. Using this approach, a library containing the sequence XXIGPG RAXX, where X could be any of the 20 amino acids, was generated. A non random distribution of residues was found at the randomized positions, which may be a reflection of the structural requirements for viabilit y. A subset of chimeras was identified that reacted with neutralizing anti-HIV-1 V3 loop antibody preparations, indicating that the antigeni city of the epitopes had been transplanted. Another chimeric virus lib rary was designed to reflect the natural diversity of the V3 loop by i ncorporating amino acids at frequencies similar to those found among n aturally occurring isolates of HIV-1. Powerful selection techniques ut ilizing anti-HIV-1 V3 loop neutralizing antibodies are being employed to isolate efficiently antigenic chimeras that could serve as potentia l vaccine candidates.