ABSTRACT
Persistent immunoglobulin G (IgG) production (PIP) provides long-term vaccine protection. While variations in the duration of protection have been observed with vaccines prepared from different pathogens, little is known about the factors that determine PIP. Here, we investigated the impact of three parameters on the duration of anti-peptide IgGs production, namely amino acid sequences, protein carriers, and immunization programs. We show that anti-peptide IgGs production can be transformed from transient IgG production (TIP) to PIP, by placing short peptides (Pi) containing linear B cell epitopes in different competitive environments using bovine serum albumin (BSA) conjugates instead of the original viral particles. When goats were immunized with the peste des petits ruminants (PPR) live-attenuated vaccine (containing Pi as the constitutive component) and BSA-Pi conjugate, anti-Pi IgGs production exhibited TIP (duration <60 days) and PIP (duration >368 days), respectively. Further, this PIP was unaffected by subsequent immunization with the PPR live-attenuated vaccine in the same goat. When goats were co-immunized with PPR live-attenuated vaccine and BSA-Pi, the induced anti-Pi IgGs production showed a slightly extended TIP (from ~60 days to ~100 days). This discovery provides new perspectives for studying the fate of plasma cells in humoral immune responses and developing peptide vaccines related to linear neutralizing epitopes from various viruses.
ABSTRACT
Objective To elucidate the influences of epitope competition on the frequency and average intensity of specific T cell response.Methods C57BL/6 mice were immunized with either single epitope DNA vaccines (pSV-gag92 or pSV-env203) or fusion gene DNA vaccine (pSV-gag/env).Gag92and Env203 epitope-specific CD8 T cell responses were analyzed by intracellular cytokine staining assay.Results Gag92-specific IFN-γ+CD8 T cells that were induced by pSV-gag92 accounted for 0.415 00％ ±0.045 88％ of the total CD8 T cells,which was much more than that induced by pSV-gag/env of 0.058 67％ + 0.019 64％.Moreover,the mean fluorescence intensity of Gag92-specific TNF-α-IFN-γ+CD8 T cells (296.70+14.08) elicited by pSV-gag/env was significantly lower than that of Env203-specific TNF-α-IFN-γ+CD8 T cells (818.00+49.34).Conclusion Epitope competition could significantly decrease both the frequency and the average intensity of specific T cell response to subdominant epitopes.
