Altering the competitive environment of B cell epitopes significantly extends the duration of antibody production

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 IgG production, namely amino acid sequences, protein carriers, and immunization programs. We show that anti-peptide IgG 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 IgG 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 coimmunized with PPR live-attenuated vaccine and BSA-Pi, the induced anti-Pi IgG 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.