A study on immune responses in mice against polyacrylamide nanoparticles trapped monophosphoryl lipid A as Toll like receptor 4 ligand and inactivated peste des petits ruminants virus
Abstract
Modern delivery systems are being developed with aims of improving traditional vaccines, prolonging duration of host immunity, designing mucosal vaccines, etc. This study presents the synthesis of polyacrylamide nanoparticle (PAA-NPs) and exploring their utility as the delivery system for peste des petits ruminants virus antigens (PPRV-Ags) and monophosphoryl lipid A (MPL) adjuvant. Size, charge and polydispersity of PAA-NPs before and after adsorption of the PPRV-Ags and MPL were examined by DLS and TEM. PAA-NPs with adsorbed PPRV-Ags & MPL were of 269 nm size by DLS (80 nm - 200 nm by TEM), -31.8 ± 6.48 mV charge and 0.437 polydispersity index. The kinetics of antibody response in different groups (11 in all, n=7/group) of Swiss albino mice inoculated with the experimental vaccine and controls were examined. Each mouse was inoculated twice at 4-week interval and the serum samples were collected bi-weekly up to 42 days. IgG levels in serum samples from
each group were determined by indirect ELISA. Statistically significant increase in IgG levels was observed in NP + MPL + PPRV (NMV) group on day 42 as compared to those in other groups (p<0.01). This observation indicated that PAA-NPs adsorbed with the inactivated PPRV antigens and MPL elicit a robust humoral immune response. For study of innate immune stimulation, the serum samples were collected 90 minutes after single intramuscular injection in the PAA-NPs-MPL and three controls groups of Swiss albino mice (n=7/group). TNF-α levels were measured by sandwich ELISA, using anti-TNF-α monoclonal antibodies. TNF-α levels in PAA-NPs-MPL group were significantly higher than those in MPL group and the negative controls (p<0.01). This study concluded that PAA-NPs adsorbed PPRV-Ags and MPL induced strong innate as well as IgG immune responses, and suggested that PAA-NPs could be developed as a delivery platform for vaccinal Ags and adjuvants.