Background

SSI Diagnostica manufactures polyclonal pneumococcus antisera, which is used by vaccine manufacturers in their QC. In this comparing assay we investigate the immunological differences between the monoclonal antibodies and polyclonal antisera using the IMMAGE 800 Immunochemistry System, Beckman Coulter.

Methods

Monoclonal and polyclonal antibodies against the 23-valent vaccine serotypes were evaluated in the routine Immunochemistry QC analysis (IMMAGE 800).

Affinity were analysed using specific polysaccharides from ATCC performing standard curves from 0.5 to 5µg/mL. Specificity were analysed using an antigen pool containing 50µg/mL of each of the 23 valent vaccine serotypes from ATCC.

Results

Monoclonal and Polyclonal antisera against serotype 1, 3, 5, 9V and 19A were evaluated undiluted and diluted. The monoclonal antibodies are overall lacking affinity (instrument response) compared with polyclonal antisera, which made it difficult to make an acceptable standard curve giving trouble passing the QC accept criteria set by vaccine manufactures.

Additional data for specificity and the last 18 antibodies will follow on the poster if abstracts is accepted.

Conclusions

The comparison between the pneumococcus monoclonal antibodies and polyclonal antisera, revealed that there is a detectable immunological difference and affinity between the polyclonal pneumococcal sera and the monoclonal pneumococcal sera analyzed in the immune nephelometric assays.

Background

Pneumococcal capsules are important in pathogenesis and vaccine development. Serotype 24F capsule consists of a hexasaccharide repeating unit with arabinitol (WO 2019/050815 AI). Here, we describe the discovery of a novel serotype (“24X”) within serogroup 24.

Methods

Serological properties of pneumococcal isolates were studied using Quellung. Serotypes 24F, 24A, 24B and 24X were subjected to whole genome sequencing (WGS). The capsular polysaccharide (CPS) structures were elucidated by NMR and GC-MS.

Results

Multiple pneumococcal isolates from several countries reacted with both factor sera 24d and 24e. Since this reaction pattern has not been reported and is unique, the isolates were provisionally labelled to be serotype “24X.” Genetic studies of cps loci could not distinguish 24X from 24F or 24B. Chemical structure studies of serogroup 24 members showed that 24B CPS is like 24F except for having ribitol instead of arabinitol, 24X CPS contains both repeat units of 24F and 24B. These findings could explain their reactivity with factor sera 24d and 24e.

Conclusions

The 24X capsule has a distinct serology and repeating unit structure, which qualify it as a new serotype. According to the Danish naming system, 24X was named serotype 24C. Correlation of cps loci with the capsule structure is under investigation.

Background

SSI Diagnostica manufactures polyclonal pneumococcus antisera, which is used by vaccine manufacturers in their QC. In this comparing assay we investigate the immunological differences between the monoclonal antibodies and polyclonal antisera using the IMMAGE 800 Immunochemistry System, Beckman Coulter.

Methods

Monoclonal and polyclonal antibodies against the 23-valent vaccine serotypes were evaluated in the routine Immunochemistry QC analysis (IMMAGE 800).

Affinity were analysed using specific polysaccharides from ATCC performing standard curves from 0.5 to 5µg/mL. Specificity were analysed using an antigen pool containing 50µg/mL of each of the 23 valent vaccine serotypes from ATCC.

Results

Monoclonal and Polyclonal antisera against serotype 1, 3, 5, 9V and 19A were evaluated undiluted and diluted. The monoclonal antibodies are overall lacking affinity (instrument response) compared with polyclonal antisera, which made it difficult to make an acceptable standard curve giving trouble passing the QC accept criteria set by vaccine manufactures.

Additional data for specificity and the last 18 antibodies will follow on the poster if abstracts is accepted.

Conclusions

The comparison between the pneumococcus monoclonal antibodies and polyclonal antisera, revealed that there is a detectable immunological difference and affinity between the polyclonal pneumococcal sera and the monoclonal pneumococcal sera analyzed in the immune nephelometric assays.