Evaluation of probiotic Lactobacillus as adjuvants for nasal immunization with chimeric pneumococcal vaccine

LEONTIEVA G.F.; FILIMONOVA V.Y.; ALVAREZ SUSANA; GRABOVSKAYA K.B.; VILLENA JULIO; SUVOROV A.N.; KRAMSKAYA T.A.; LAIÑO JONATHAN; DANILENKO V.N.

Medical Immunology (Russia)

Russian Association of Allergologists and Clinical Immunologists, St. Petersburg Regional Branch

Año: 2016 vol. 18 p. 545 - 554

1563-0625

Vaccine protection against photogenic gram-positive bacteria including different species ofstreptococci is an important problem of contemporary molecular biology. Streptococcal infections are mostcommon bacterial infections surpassing by the economic losses all the infections excluding influenza. The gatesof streptococcal infection, oral cavity or vagina, are covered with immune and non-immune mucosal cells thatare the first line of defenses. Subcutaneous immunization not always stimulate the local immunity on mucosalsurfaces. On the other hand, mucosal vaccination can provide an appropriate local immune response togetherwith systemic protection. However, mucosal immunization often requires usage of special and effectiveadjuvants especially in case of vaccines based on recombinant proteins.For protection against Streptococcus pneumoniae infection, two chimeric recombinant proteins (PSPF andPSP) have been tested as vaccines. Recombinant proteins PSPF and PSP carry immunogenic epitopes fromthe respiratory pathogen including PspA, Spr1875 and PsaA. PSPF structure also carries a fraction of flagellin-FliC molecule in comparison with PSP, which does not have this fragment. This portion of PSPF was includedas internal adjuvant intended for the stimulation of Toll-like receptor 5.In this work, the adjuvant capacity of two probiotic strains, Lactobacillus rhamnosus CRL1505 andL. rhamnosus L32 was evaluated. It was demonstrated that both lactic acid bacteria strains were able to provideadjuvant effects by enhancing the mucosal and systemic immune responses after their co-administration withthe recombinant chimeric protein PSPF. The adjuvant effect of both Lactobacillus strains was significantlydecreased after their thermal inactivation. However, the cell walls of bacteria showed a marked adjuvant activity.An improved protection against several S. pneumoniae serotypes after mucosal immunization of infant micewith PSPF vaccine with probiotic strains or their cell walls was also demonstrated here.The recombinant chimeric protein PSPF administered with immunomodulatory probiotic strains or theirbacterial components would be a promising vaccine for immunization of humans against S. pneumoniae,particularly in children.