Effect of multiple freeze–thaw cycles on the detection of anti-SARS-CoV-2 IgG antibodies. Issue 8 (6th August 2021)

• Record Type: Journal Article
• Authors: Shurrab, Farah M.; Al-Sadeq, Duaa W.; Amanullah, Fathima; Younes, Salma N.; Al-Jighefee, Hadeel; Younes, Nadin; Dargham, Soha R.; Yassine, Hadi M.; Abu Raddad, Laith J.; Nasrallah, Gheyath K.
• Is Part Of: Journal of medical microbiology. Volume 70:Issue 8(2021)
• Publication Date: 2021-08-06
• Subjects: antibodies -- detection -- COVID-19 -- SARS-CoV-2 -- IgG -- freeze -- thaw; Medical microbiology -- Periodicals; 616.9041
• DOI: 10.1099/jmm.0.001402
• Languages: English
• ISSNs: 0022-2615

Abstract

Abstract : Several studies have investigated the effect of repeated freeze–thaw (F/T) cycles on RNA detection for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, no data are available regarding the effect of repeated F/T cycles on SARS-CoV-2 antibody detection in serum. We investigated the effect of multiple F/T cycles on anti-SARS-CoV-2 IgG detection using an ELISA test targeting the nucleocapsid antibodies. Ten positive and 1 negative SARS-CoV-2 IgG sera from 11 participants, in replicates of 5, were subjected to a total of 16 F/T cycles and stored at 4 °C until tested by ELISA. Statistical analysis was performed to test for F/T cycle effect. None of the 10 positive sera became negative after 16 F/T cycles. There was no significant difference in the OD average reading between the first and last F/T cycles, except for one serum with a minimal decline in the OD. The random effect linear regression of log (OD) on the number of cycles showed no significant trend, with a slope consistent with zero (B=−0.0001; 95 % CI −0.0008; 0.0006; P -value=0.781). These results suggest that multiple F/T cycles had no effect on the ability of the ELISA assay to detect SARS-CoV-2 IgG antibodies.