Glycoconjugate Vaccine: An Effective Way to Combat Infectious Diseases and Cancers

Glycoconjugate is a molecule of carbohydrate covalently linked to another compound. In glycoconjugate vaccine, carbohydrate antigen is linked to another molecule, particularly a protein carrier. Vaccines targeting capsular polysaccharides can prevent bacterial infection. However, capsular polysaccharide alone is weak immunogenic as it produces a B cell immune response independent of T lymphocyte. To increase the immunogenicity, the capsular polysaccharide can be covalently linked to a protein carrier that converts carbohydrate antigen from T lymphocyte independent to T lymphocyte dependent antigen. Several carrier proteins such as tetanus toxoid (TT), diphtheria toxin (DT), the outer membrane protein complex (OMPC) of N. meningitides serogroup B, and Haemophilus protein D are currently used in licensed conjugate vaccines. The protein carrier in the glycoconjugate vaccine engages with T cell dependent immune response and the carbohydrate part engages with T cell independent immune response. The involvement of T cells in the immune response against the glycoconjugate vaccine helps in B cell proliferation and differentiation into memory B cell which is utmost important for long-term immunity. Carbohydrate structures decorated on the surface of pathogens and malignant cells can be considered as a key target in developing safe and effective vaccines to combat cancer, bacterial infections, viral infections.