Neutralizing Activity of SARS-CoV-2 Antibodies in Patients with COVID-19 and Vaccinated Individuals

Scientific paper - Original scientific paper

• Author: Tatjana Vilibić-Čavlek
• Author: Vladimir Stevanović
• Author: Snježana Kovač
• Author: Ema Borko
• Author: Maja Bogdanić
• Author: Gorana Miletić
• Author: Željka Hruskar
• Author: Thomas Ferenc
• Author: Ivona Ćorić
• Author: Mateja Vujica Ferenc
• Author: Ljiljana Milasincic
• Author: Ljiljana Antolašić
• Author: Ljubo Barbić
• Author's institution: University of Zagreb; School of Medicine; (Department of Medical Microbiology and Parasitology)
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Clinical Medical Sciences; Medical Microbiology

Abstract (english)

Background: Serological diagnosis of COVID-19 is complex due to the emergence of different SARS-CoV-2 variants.

Methods: 164 serum samples from (I) patients who recovered from COVID-19 (n = 62) as well as (II) vaccinated individuals (n = 52) and (III) vaccinated individuals who were infected with different SARS-CoV-2 variants after vaccination (n = 50) were included. All samples were tested using EIA (binding antibodies) and a virus neutralization test (VNT) using the Wuhan strain (NT antibodies). Group III was further tested with a VNT using the Alpha/Delta/Omicron strains.

Results: The highest antibody index (AI) was observed in vaccinated individuals infected with COVID-19 (median AI = 50, IQR = 27-71) and the lowest in vaccinated individuals (median AI = 19, IQR = 8-48). Similarly, NT antibody titer was highest in vaccinated individuals infected with COVID-19 (median 128; IQR = 32-256) compared to vaccinated individuals (median 32, IQR = 4-128) and patients with COVID-19 (median 32, IQR = 8-64). The correlation between AI and NT titer was strongly positive in vaccinated individuals and moderately positive in patients with COVID-19. No significant correlation was observed in vaccinated individuals infected with COVID-19. In patients infected with Alpha and Delta, the lowest VNT positivity rate was for the Omicron variant (85.0%/83.3%). Patients infected with the Alpha variant showed the lowest NT titer for the Omicron variant (median titer 32) compared to the Wuhan/Delta variants (64/128). Patients infected with the Delta variant had the lowest NT titer to the Omicron variant (median 32), compared to the Wuhan/Alpha variants (64/128). Patients infected with the Omicron variant showed similar titers to the Delta/Wuhan variants (128) and higher to the Alpha variant (256).

Conclusions: The cross-immunity to SARS-CoV-2 is lowest for the Omicron variant compared to the Alpha/Delta variants.

• Keywords (english): COVID-19; EIA; SARS-CoV-2; cross-neutralization; variants of concern; virus neutralization test
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review
• Publication version: Published version
• Journal title: Antibodies
• Numbering: vol. 12, no. 4, 61
• e-ISSN: 2073-4468
• DOI: https://doi.org/10.3390/antib12040061
• URN:NBN: urn:nbn:hr:105:122245
• Publication: 2023-09-25
• Document URL: https://www.mdpi.com/2073-4468/12/4/61
• Type of resource: Text
• Access conditions: Open access
• Created on: 2024-05-17 07:33:29