Separation of vaccinated and naturally infected individuals based on functional antibodies to pertussis toxin
Ahvenainen, Niina (2021-05-10)
Separation of vaccinated and naturally infected individuals based on functional antibodies to pertussis toxin
(10.05.2021)
Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
suljettu
Julkaisun pysyvä osoite on:
https://urn.fi/URN:NBN:fi-fe2021060835398
https://urn.fi/URN:NBN:fi-fe2021060835398
Tiivistelmä
Pertussis is a respiratory infection causing a high global burden. Despite high vaccination coverage, 16 million cases and 195 000 deaths were reported in 2008. Since the 1990s, outbreaks have been increasingly reported in vaccinated populations. Pertussis toxin (PT) is utilized in serology, which, in itself, does not provide separation between infection- and vaccination-induced antibodies. The aim of this thesis work was to study detailed characteristics of the antibodies to improve the reliability of pertussis diagnostics.
Avidity (the binding strength of antibodies) was tested with ELISA. The current assay was re-innovated to be concentration-independent. Five subunits of PT are slightly differentially expressed in vaccines due to chemical detoxification compared to natural infection. Specific antibody binding sites (epitopes) were studied through epitope mapping utilizing a blocking assay, which was changed from ELISA to a fluorescence-based assay.
Based on clinical samples, recently vaccinated individuals (N=143) had higher avidities than pertussis patients (N=134) (p<0.001). Also, based on 122 paired samples before and after vaccination avidity increased after booster vaccination (p<0.05) but was reduced in a year. The performance of the blocking assay was evaluated by studying the correlation of fluorescence assay and ELISA. A decent correlation was obtained across 37 samples (Spearman’s R=0.47). The fluorescence-based assay enables more extensive epitope mapping through reduced PT concentration and sample volume, and amplified signal levels. The results suggest the usability of avidity to separate vaccination- and infection-induced antibodies, whereas epitopes show promise to be utilized in future vaccine-design to obtain prolonged immunity.
Avidity (the binding strength of antibodies) was tested with ELISA. The current assay was re-innovated to be concentration-independent. Five subunits of PT are slightly differentially expressed in vaccines due to chemical detoxification compared to natural infection. Specific antibody binding sites (epitopes) were studied through epitope mapping utilizing a blocking assay, which was changed from ELISA to a fluorescence-based assay.
Based on clinical samples, recently vaccinated individuals (N=143) had higher avidities than pertussis patients (N=134) (p<0.001). Also, based on 122 paired samples before and after vaccination avidity increased after booster vaccination (p<0.05) but was reduced in a year. The performance of the blocking assay was evaluated by studying the correlation of fluorescence assay and ELISA. A decent correlation was obtained across 37 samples (Spearman’s R=0.47). The fluorescence-based assay enables more extensive epitope mapping through reduced PT concentration and sample volume, and amplified signal levels. The results suggest the usability of avidity to separate vaccination- and infection-induced antibodies, whereas epitopes show promise to be utilized in future vaccine-design to obtain prolonged immunity.