Nasal immunization with Lactococcus lactis expressing the pneumococcal protective protein A induces protective immunity in mice

MEDINA MARCELA; VILLENA JULIO; VINTIÑI ELISA; HEBERT ELVIRA; RAYA RAUL; ALVAREZ SUSANA

INFECTION AND IMMUNITY

American Society for Microbiology

Lugar: Washington; Año: 2008 vol. 76 p. 2696 - 2705

0019-9567

The nisin controlled gene expression was used to develop a recombinant strain of L.lactis that is able to express the pneumococcal protective protein A (PppA) on its surface. Immunodetection assays confirmed that after the induction with nisin the PppA antigen was properly and efficiently displayed on the cell surface of the recombinant strain which was termed L. lactis PppA. The production of mucosal and systemic specific antibodies in adult and young mice was evaluated after nasal immunization with L. lactis PppA. IgM, IgG and IgA anti-PppA antibodies were detected in the serum and bronchoalveolar lavage (BAL) fluid of adult and young mice, which shows that PppA expressed in L. lactis was able to induce a strong mucosal and systemic immune response. Challenge-survival experiments demostrated that immunization with L. lactis PppA was able to increase resistance to the systemic and respiratory infection withdifferent pneumococcal serotypes and passive immunization assays in naïve young demonstrated a direct correlation between anti-PppA antibodies and protection. The results presented in this study demonstrate three major characteristics of the effectiveness of the nasal immunization with PppA expressed as a protein anchored to the cell wall of L. lactis: it elicited cross-protective immunity against different pneumococcal serotypes, afforded protection against both systemic and respiratorychallenges and induced protective immunity in mice of different ages.