Cassette-based presentation of SIV epitopes with recombinant gas vesicles from halophilic archaea.

In earlier studies we demonstrated recombinant gas vesicles from Halobacterium sp. NRC-1, expressing a model six amino acid insert, or native vesicles displaying chemically coupled TNP, each were immunogenic, and antigenic. Long-lived responses displaying immunologic memory were elicited without exogenous adjuvant. Here we report the generation and expression of cassettes containing SIV derived DNA. The results indicate a cassette-based display/delivery system derived from recombinant halobacterial gas vesicle genes is highly feasible. Data specifically support four conclusions: (i) Recombinants carrying up to 705 bp of SIV DNA inserted into the gvpC gene form functional gas vesicles; (ii) SIV peptides contained as part of the expressed recombinant, surface exposed GvpC protein are recognized by antibody elicited in monkeys exposed to native SIV in vivo; (iii) in the absence of adjuvant, mice immunized with the recombinant gas vesicle (r-GV) preparations mount a solid, titratable antibody response to the test SIV insert that is long lived and exhibits immunologic memory; (iv) recombinant organelles, created through the generation of cassettes encoding epitopes inserted into the gvpC DNA, can be used to construct a multiepitope display (MED) library, a potentially cost effective vehicle to express and deliver peptides of SIV, HIV or other pathogens.