A novel vaccine with beta(2)-microglobulin linked to a viral epitope stimulates a CTL response and provides immunity to the virus

Designing a vaccine that can elicit a strong cytotoxic T-lymphocytes (CTL) response will be an important component of vaccines against many viruses, but in particular against HIV. CTL stimulation occurs through the recognition of epitopes presented in the context of the class-1 major histocompatibility complex (MHC-I). As a way to achieve this, the physical coupling of a viral epitope to the N-terminus of β₂-microglobulin (β ₂m) via a flexible linker has been explored. With the stimulation of CTLs against the Sendai virus as a model, both the effect of linker size on the vaccine and the ability of the β₂m-viral epitope fusion vaccine to trigger a primary immune response, as either a recombinant protein expressed in E. coli or as part of a mammalian expression vector are presented in this work. Here we show that as a DNA vaccine, β ₂m-linked to the immunodominant Sendai NP_(324–332) epitope, administered intramuscularly (IM) with or without a plasmid encoding for the cytokine IL-12, can cause the proliferation of viral specific splenocytes. However, when the vaccine was administered IM or subcutaneously as recombinant protein, no response was observed. We also show that a construct with a 21 amino acid (AA) linker stimulates more viral specific splenocytes than constructs with either a 10 AA or a 15 AA linker. Further, DNA vaccine dosages of 100 μg and 200 μg generate more viral specific splenocytes than dosages of 400 μg or 800 μg. We suggest that the reason for this might be high-localized concentrations of (β₂m. Finally, we show that in response to a sub-lethal challenge with the Sendai virus, mice primed with both the (β₂m-Sendai epitope DNA vaccine and the IL-12 plasmid can trigger the early arrival of viral specific CD8+ memory cells in the lungs.