Iscom is an efficient mucosal delivery system for Mycoplasma mycoides subsp. mycoides (MmmSC) antigens inducing high mucosal and systemic antibody responses

Abstract

The purpose of this study was to explore the iscom as a mucosal delivery system for Mycoplasma mycoides subsp. mycoides small colony (MmmSC) antigens. BALB c female mice were immunised intranasally (i.n.) twice, 8 weeks apart with three different doses (3, 10 and 20 μg) or subcutaneously (s.c.) with 3 μg of M. mycoides antigens incorporated into iscoms. Mycoplasma cells were administered s.c. twice, 8 weeks apart at a dose of 3 μg or i.n. at 10 μg as for iscoms. Both i.n. and s.c. modes of immunisation with iscoms induced prominent primary serum antibody responses in a dose-dependent manner, which were efficiently boosted. Compared to whole mycoplasma cells, iscoms enhanced the total Ig and IgG subclass (IgG1, IgG2a and IgG2b) responses in serum and in lungs greatly, and this enhancement was more prominent after i.n. than after s.c. immunisation. By the i.n. mode of immunisation iscoms containing mycoplasma antigens induced a 60-fold higher IgA response in lungs than the whole cell antigen. Iscoms also induced substantially higher total Ig and IgG subclass responses in the lungs. By Western blot a reduced number of bands (7) were detected in lung secretion after both i.n. and s.c. immunisations with iscoms compared to a high number of bands (more than 30) detected by serum antibodies. Interestingly i.n. immunisation with iscoms induced antibodies in lungs as well as in serum to mycoplasma cell antigens which differed from those induced by s.c. immunisation as revealed by the Western blot patterns.