Monophosphoryl lipid A as adjuvant for recombinant influenza nucleoprotein vaccine in mice

CARGNELUTTI D.E.; SANCHEZ, VICTORIA; MACKERN OBERTI, JUAN; BOADO, LORENA; ALVAREZ, PAULA; MATTION, NORA; SCODELLER, EDUARDO

Buenos Aires

Congreso; First French-Argentine Immunology Congress; 2010

French Society of Immunology and Argentine Society of Immunology

Background: Influenza is one of the most important respiratory pathogens worldwide. Vaccination is the best way to control influenza. Lipopolysaccharides (LPS) trigger innate immune response through activation of Toll-like receptor 4 (TLR4). Such responses may be exploited for the development of adjuvants and in particular monophosphoryl lipid A (MPLA) obtained by controlled hydrolysis of LPS of Salmonella minnesota. The use of influenza A virus recombinant nucleoprotein (rNP) as a vaccine antigen, stems from the fact that NP show less antigenic variation than the influenza virus surface glycoproteins, haemagglutinin and neuraminidase. The object of this work is to describe the production and immunogenicity of rNP from influenza A virus formulated with MPLA as a vaccine. Method: Homologous prime and boost subcutaneous vaccination of BALB/c mice with 10ug of the rNP (control group) and 10ug of rNP formulated with 25ug of MPLA (experimental group) were administered 3 weeks apart. On day 60 post prime, serum samples were collected to evaluate the specific titre of total IgG, IgG1 and IgG2a isotypes. At the same time, culture supernatants of spleen cells were collected, after antigen stimulation to test the presence of IFN-g by ELISA. Result: Subcutaneous injection of rNP with MPLA into BALB/c mice elicited both humoral and cellular immune responses. Animals injected with rNP/MPLA developed NP-specific antibodies, with total IgG titers of 11200 and increase the ratio IgG2a/IgG1 from 0,045 to 0,96. In addition, the rNP/MPLA vaccine induced a significant different on the production of IFN-g, within control group and experimental group. Conclusion: This study demonstrates that the formulation of rNPr with MPLA induces a strong specific Th1 type immune response, humoral as well as cellular. This is a first step to demonstrate that MPLA can be use as an adjuvant in the formulation of a recombinant NP influenza vaccine.