Glycan analysis in cell culture-based influenza vaccine production: Influence of host cell line and virus strain on the glycosylation pattern of viral hemagglutinin

Mammalian cell culture processes are commonly used for production of recombinant glycoproteins, antibodies and viral vaccines. Since several years there is an increasing interest in cell culture-based influenza vaccine production to overcome limitations of egg-based production systems, to improve vaccine supply and to increase flexibility in vaccine manufacturing. With the switch of the production system several key questions concerning the possible impact of host cell lines on antigen quality, passage-dependent selection of certain viral phenotypes or changes in hemagglutinin (HA) conformation have to be addressed to guarantee safety and efficiency of vaccines. In contrast to the production of recombinant glycoproteins, comparatively little is known regarding glycosylation of HA, derived from mammalian cell cultures. Within this study, a capillary DNA-sequencer (based on CGE-LIF technology), was utilized for N-glycan analysis of three different influenza virus strains, which were replicated in six different cell lines. Detailed results concerning the influence of the host cell line on complexity and composition of the HA N-glycosylation pattern, are presented. Strong host cell but also virus type and subtype dependence of HA N-glycosylation was found. Clear differences were already observed, by N-glycan fingerprint comparison. Further structural investigations of the N-glycan pools revealed that host cell dependence of HA N-glycosylation was mainly related to minor variations of the (monomeric) constitution of single N-glycans. To some extent, shifts in the N-glycan pool composition regarding the proportion of different N-glycan types were observed. In contrast to this, a principal switch of the N-glycan type attached to HA was observed when comparing different virus types (A and B) and subtypes (H1N1 and H3N2).