Induction of Specific IgG antibodies and B-Cell Mediated Immunity by Glycoprotein 5 Peptides in Porcine Reproductive and Respiratory Syndrome virus Infected Swine

We analyze the humoral and B-cell mediated immunogenic response induced by GP5 lineal epitopes from porcine reproductive and respiratory syndrome virus (PRRSV) to explore the role of this protein in the protective response. For inoculation, pigs aged twenty-one days were allocated into six groups (seven pigs per group): control (PBS), vehicle (carrier), vaccinated (Ingelvac-PRRSV, MLV®), non-vaccinated and naturally infected, GP5-B and GP5-B3. Subsequently blood samples were collected and analyzed. Cytokine were measured by ProcartaPlex kit. Peptide-specific IgGs and cross-reactivity against peptides were analyzed by ELISA and B-cell subpopulations were analyzed by flow cytometry. At 2 days post-immunization (dpi), the GP5-B3 peptide increased the serum concentrations of cytokines associated to activate adaptive cellular immunity (IL-1β and IL-12). The concentration of IgGs anti-GP5-B increased in both cases at 21 and 42 dpi, while IgGs anti-GP5-B3 increased at 21 dpi and remained at the same level until 42 dpi. Also, antibody-forming/Plasma B cells (CD2+/CD21-) and primed B cells (CD2-/CD21+) from immunized pigs showed an increase at 42 dpi. Conversely the naïve B cells from immunized pigs decreased compared with the controls. Importantly, Both GP5-B and GP5-B3 peptides exhibited immunoreactivity against serum antibodies from vaccinated group, as well as non-vaccinated and naturally infected group. In conclusion, GP5-B and GP5-B3 peptides elicited immunogenicity mediated by antigen specific IgG´s and B-cell activation.