The frequent outbreak of respiratory
infectious diseases such as
influenza and
pulmonary tuberculosis calls for new immunization strategies with high effectiveness. Nasal immunization is one of the most potential methods to prevent the diseases infected through the respiratory tract. In this study, we designed a water-soluble system based on
antigen/
N-trimethylaminoethylmethacrylate chitosan conjugates for nasal immunization.
N-trimethylaminoethylmethacrylate chitosan (TMC) was synthesized by
free radical polymerization of
chitosan and N-trimethylaminoethylmethacrylate
chloride and identified by (1)H NMR and FT-IR. Thiolated
ovalbumin (OVA) was covalently conjugated to
maleimide modified TMC with high conjugation efficiency. OVA conjugated TMC (OVA-TMC) significantly increased uptake of OVA by Raw 264.7 cells, which was 2.38 times higher than that of OVA/TMC physical mixture (OVA+TMC) at 4h. After
nasal administration, OVA-TMC showed higher transport efficiency to superficial and deep cervical lymph nodes than OVA+TMC or OVA alone. Balb/C mice were intranasally given with OVA-TMC three times at 2-week internals to evaluate the immunological effect. The serum
IgG,
IgG1 and
IgG2a levels of the OVA-TMC group were 17.9-87.9 times higher than that of the OVA+TMC group and comparable to that of the intramuscular group. The
secretory IgA levels in nasal wash and saliva of the OVA-TMC group were 5.2-7.1 times higher than that of the OVA+TMC group while the
secretory IgA levels of the intramuscular
alum-precipitated OVA group were not increased. After immunofluorescence staining of nasal cavity,
IgA antibody secreting cells were mainly observed in the lamina propria regions and glands of nasal mucosa. OVA-TMC showed little toxicity to the nasal epithelia or cilia of rats after
nasal administration for three consecutive days. These results demonstrated that
antigen conjugated TMC can induce both systemic and mucosal immune responses after
nasal administration and may serve as a convenient, safe and effective
vaccine for preventing respiratory
infectious diseases.