Chimeric Rhinoviruses as Tools for Vaccine Development and Characterization of Protein Epitopes

Abstract

Chimeric human rhinoviruses (HRVs) have the potential to serve as vaccines against a wide variety of diseases. Such vaccines can be developed optimally by generating libraries of chimeric HRVs displaying immunogens from dangerous pathogens or tumor cells in many different conformations. Extremely large numbers of conformationally defined presentations of foreign epitopes can be produced efficiently by flanking transplanted epitopes with linkers, or adapters, of small segments of randomized amino acids. In addition, the individual residues of the immunogenic sequences can be encoded in proportion to their prevalence in databases, generating composite immunogens that function as mimotopes. The diversity of sequences and conformations improves the likelihood of generating immunologically valuable vaccine candidates. Chimeric viruses thus generated can be propagated and purified to select for viruses whose growth and physical stability are like those of wild-type HRV. Viruses containing a foreign epitope in antigenically relevant conformations can then be captured by immunoselection with neutralizing antibodies directed against the foreign pathogen. Using this approach, we have been able to generate HRV chimeras that present V3 loop sequences of the human immunodeficiency virus type 1 (HIV-1) in immunologically relevant conformations. Antisera directed against such chimeras can neutralize multiple strains of HIV-1 in cell culture, suggesting that the HRV14:HIV-1 chimeras may be presenting their V3 loop sequences in manners that mimic those of multiple strains of HIV. Immunologically interesting chimeras can be examined using X-ray crystallography to yield detailed information about the structures of chimeras with immunogenic epitopes. This information may lead to a greater understanding of key functional and structural elements of immunogenicity. The chimeric HRV system allows one to present virtually any protein epitope or mimitope thereof, identify viruses with immunological characteristics that mimic those of the foreign pathogen, and examine the structures of these immunogenic sequences at the atomic level.

Mucosal delivery of human papillomavirus pseudovirus-encapsidated plasmids improves the potency of DNA vaccination

“…Gene-based vector delivery of vaccine antigens affords an option for eliciting immune responses against authentic antigenic structures while avoiding some of the liabilities of the native viral pathogen. However, there have been relatively few options for direct mucosal immunization with gene-based vaccine vectors described, and they have primarily been replication-competent vectors based on adenovirus (40), picornavirus (41), rhinovirus (42), or paramyxovirus (43, 44). Replication-defective poxvirus and adenovirus vectors have been delivered mucosally to humans, but with limited success (5, 6).…”

Therapeutic Use of Native and Recombinant Enteroviruses

“…Various strategies have been employed to express foreign genes from enterovirus vectors ( Figure 2 ). The vector design is based on the known principles governing picornavirus gene expression: Short inserts encoding antigenic epitopes have been placed within the capsid protein [ 26 , 27 , 28 , 29 ]. Viable recombinants can also be generated by placing inserts either in front of the VP4 gene or cloning the insert with flanking protease cleavage sites to the 3′-end of the VP1 structural protein gene or between the non-structural genes 2A and 3C ( Figure 1 C,D) [ 18 , 30 , 31 , 32 , 33 ].…”