Background - COVID-19 convalescent plasma (CCP) is an experimental
treatment against SARS-CoV-2. Although there has so far been no evidence
of transmission through transfusion, pathogen reduction technologies (PRT)
have been applied to CCP to mitigate risk of infectious disease. This study
aims to assess the impact of methylene blue (MB) plus visible light PRT on the
virus-neutralising activity of the specific antibodies against SARS-CoV-2.
Material and methods - Thirty-five plasma doses collected by plasmapheresis
from COVID-19 convalescent donors were subjected to MB plus visible light
PRT. Anti-SARS-CoV-2 RBD S1 epitope IgGs antibodies were quantified by
ELISA. Titres of SARS-CoV-2 neutralising antibodies (NtAbs) were measured
before and after the PRT process. A Spearman's correlation was run to
determine the relationship between antibody neutralisation ability and
SARS-CoV-2 IgG ELISA ratio. Pre- and post-inactivation neutralising antibody
titres were evaluated using a Wilcoxon test.
Results - The plasma pathogen reduction procedure did not diminish NtAbS
titres and so did not cause a change in the viral neutralisation capacity of
CCP. There was a strong correlation between pre-and post-PRT NtAbs and
anti-SARS-CoV-2 IgGs titres.
Discussion - Our results showed PRT with MB did not impair the CCP passive
immunity preserving its potential therapeutic potency. Therefore, PRT of CCP
should be recommended to mitigate the risk for transmission of transfusionassociated
infectious disease. There is a good correlation between SARS-CoV-2
IgG titres determined by ELISA and the neutralising capacity. This allows blood
centres to select CCP donors based on IgG ELISA titres avoiding the much
more labour-intensive laboratory processes for determining neutralising
antibodies.Peer reviewe
