Določitev referenčnih vrednosti za serumsko koncentracijo protiteles proti SARS-CoV-2 po cepljenju

Lombergar, Leon (author), Jerin, Aleš (mentor), Marc, Janja (co-mentor)

Pandemija COVID-19 je svet nenadoma potisnila v izolacijo. Zaradi izjemno visoke hitrosti širjenja virusa je imunost pred virusom ključnega pomena za obvladovanje negativnih socialnih in ekonomskih posledic pandemije. Najbolj varen način za pridobitev imunosti pred virusom je cepljenje, s čimer v telo vnesemo informacije za proizvodnjo proteinov – antigenov, ki izzovejo imunski odziv. Po izpostavitvi antigenu se limfociti B diferencirajo v plazmatke, ki so specializirane celice za proizvodnjo protiteles. Glavna naloga protiteles je nevtralizacija virusa v telesu, s čimer se prepreči replikacija virusa, kar lahko prepreči oziroma ublaži okužbo. Za nevtralizacijo so najbolj učinkovita protitelesa proti proteinu S (virusni bodici), ki jo virus uporablja za vstop v celico. Vendar pa koncentracija protiteles v telesnih tekočinah skozi čas upada, kar posledično zmanjšuje tudi zaščito, ki jo protitelesa omogočajo. Namen magistrske naloge je bil preučevanje koncentracij protiteles proti proteinu S SARS-CoV-2 v obdobju 1, 3, 6 in 9 mesecev po cepljenju z mRNA- ali vektorskim cepivom. Udeleženci v raziskavi so bili zaposleni na UKC Ljubljana, ki smo jih razdelili glede na prejeto cepivo in jim izmerili koncentracijo protiteles s pomočjo dvojne (antigen) sendvič elektrokemiluminiscenčne metode. Uspešno smo določili orientacijske referenčne vrednosti za protitelesa proti SARS-CoV-2 po uporabi različnih cepiv, za različna obdobja po cepljenju, dodatno pa smo posameznike razdelili še glede na predhodno prebolevnost COVID-19. Koncentracije protiteles smo primerjali v venski in kapilarni krvi in ugotovili, da je za potrebe spremljanja koncentracije protiteles kapilarna kri enako zanesljiv vzorec kot venska. Podrobno smo preučili tudi vpliv časa na upad koncentracije protiteles in primerjali različne modele, ki napovedujejo odvisnost koncentracije protiteles od časa. Za najbolj ustreznega se je izkazal model drugega reda kinetike, ki kljub slabši teoretični podlagi številsko najbolje napoveduje upad izmerjene koncentracije protiteles. Preverili smo še vpliv vrste cepiva in drugih dejavnikov na koncentracijo in hitrost upada protiteles. Koncentracije protiteles so bile konstantno višje po uporabi mRNA-cepiva (še posebej kot tretja imunizacija) in pri posameznikih, ki so predhodno preboleli COVID-19, medtem ko vpliva na hitrost upada ni bilo. Potrdili smo tudi vpliv starosti na koncentracijo in hitrost padanja protiteles, medtem ko spol ni imel vpliva. Na koncu smo preverili še vpliv koncentracije protiteles po celjenju na možnost okužbe s SARS-CoV-2 in presenetljivo ugotovili, da ni statistično značilnega vpliva.

• Language: Slovenian
• Keywords: COVID-19, SARS-CoV-2, cepljenje, koncentracija protiteles, referenčne vrednosti
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2022
• PID: 20.500.12556/RUL-141561
• Publication date in RUL: 01.10.2022

Secondary language

• Language: English
• Title: Determination of reference values for anti-SARS-CoV-2 antibodies serum concentration following vaccination

Abstract

The COVID-19 pandemic suddenly pushed the world into isolation. Due to the extremely rapid spread of the virus, immunity to the virus is critical to managing the negative social and economic consequences of the pandemic. The safest way to gain immunity to the virus is through vaccination, which introduces biological information for protein (antigen) synthesis, in turn inducing an immune response. After exposure to the antigen, B-cells differentiate into plasma cells, specialized for antibody production. The main function of antibodies is to neutralise virions, preventing replication of the virus, which can prevent or attenuate the infection. Antibodies to the SARS-CoV-2 spike (S) protein, which the virus uses to enter cells, are particularly important for neutralisation. However, the concentration of antibodies in body fluids decreases over time, which in turn reduces antibody protection. The objective of the master's thesis was to investigate the concentrations of antibodies to the SARS-CoV-2 spike protein 1, 3, 6 and 9 months after vaccination with an mRNA or vector vaccine. The research participants were employees of the University Medical Centre Ljubljana, who were classified according to the vaccine they received. Their antibody concentrations were measured using a double antigen sandwich electrochemiluminescence immunoassay. We have successfully determined reference values for antibodies to SARS-CoV-2 after the use of different vaccines, for different periods after vaccination, with additional classification of individuals based on previous contraction of COVID-19. Antibody concentrations were compared in venous and capillary blood, and capillary blood was found as reliable a sample for the monitoring of antibody concentrations as venous blood. We investigated in detail the effect of time on the decline in antibody concentration and compared different models for predicting the time-dependency of antibody concentration. The second-order kinetic model proved to be the most appropriate, best predicting the decline in measured antibody concentrations despite a poor theoretical basis. We also investigated the influence of vaccine type and other factors on the concentration and rate of antibody decline. Antibody concentrations were consistently higher after use of the mRNA vaccine (especially as a third immunization) and in individuals who had previously recovered from COVID-19, whereas there was no effect on the rate of decline. There was also an effect of age on antibody concentration and rate of decline, whereas sex had no effect. Finally, we also examined the effect of antibody concentration on the likelihood of infection with SARS-CoV-2 and surprisingly found that there was no statistically significant effect.

• Keywords: COVID-19, SARS-CoV-2, vaccination, antibody concentration, reference intervals