Immune Response to Conjugates of Fragments of the Type K9 Capsular Polysaccharide of Acinetobacter baumannii with Carrier Proteins

Abstract

Immunization by glycoconjugates with A. baumannii type K9 CPS fragments induced a high level of antibodies (predominantly IgG) in sera, which reacted specifically with the CPS of A. baumannii type K9, as well as a long immunological memory. The sera of immunized animals efficiently opsonized A. baumannii type K9.

Protective Capacity of Monoclonal Antibodies against Acinetobacter baumannii K9 Capsular Polysaccharide

“…To obtain monoclonal antibodies, we immunized mice with a conjugate synthesized by squaric-acid chemistry which included bovine serum albumin (BSA) and a fragment of two oligosaccharide repeats (K-units) of A. baumannii type K9 CPS. As shown earlier, immunization with this conjugate provides a high titer of specific antibodies in blood serum ( 6 ), indicating the formation of a sufficient pool of plasma cells to obtain hybridoma cell lines which stably produce MAbs. Splenocytes and cells of the popliteal lymph nodes were used as a source of lymphocytes for hybridomas secreting MAbs against the K9 CPS according to the methods of Kоller and Milstein ( 8 ).…”

“…Previously, the authors have shown that immunization with conjugates of CPS fragments via protein carriers stimulates and induces protective immune reactions and protects model laboratory animals against infection by A. baumannii ( 6 ). In this work, MAbs against the K9 capsular polysaccharide of A. baumannii were prepared by immunization with a glycoconjugate that contained a K9 CPS fragment.…”

“…Strain K9 often appears as a cause of bacterial infections ( 7 ). Its structure remained stable over a long period of observation ( 6 ).…”

Subunit vaccines for Acinetobacter baumannii

“…Immunizing mice with the conjugate induced high levels of IgG antibodies in serum and stimulated the production of IL-10, IL-17A, and TNF-α. Mice immunized with the conjugate together with Freund’s adjuvant and calcium phosphate adjuvant, had 100% and 70% survival after stimulation with A. baumannii , respectively ( 50 ). Li et al.…”

“…Freund’s adjuvant is a water-in-oil emulsion that can cause granulomas and have other adverse effects after injection, so it cannot be used in the manufacture of human vaccines ( 148 ). Freund’s adjuvant is still widely used in animal experiments because of its strong adjuvant effect and affordable cost ( 27 , 50 , 149 ). MF59 and AS03 are oil-in-water adjuvants that overcome the shortcomings of Freund’s adjuvant and are effective adjuvants in many vaccines.…”