Click on the 'Resources' tab to download the ePoster. 

Use of a SARS-CoV-2 Surrogate Virus Neutralization Test to predict a SARS-CoV-2 plaque reduction neutralization test value of ≥1:160 in convalescent plasma (CP) from Canadian blood donors

Steven J. Drews1,2*, Dana V. Devine3,4, Alyssia Robinson5, Janet McManus3, Emelissa Mendoza5, Kathy Manguiat5, Chantale Pambrun6, Michael Drebot5,7, Heidi Wood5,

1. Canadian Blood Services, Edmonton, AB, Canada, 2. Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada, 3. Canadian Blood Services, Vancouver, BC, Canada, 4. Centre for Blood Research and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada, 5. Zoonotic Diseases and Special Pathogens, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada, 6. Canadian Blood Services, Ottawa, ON, Canada, 7. Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB, Canada

Introduction: Canadian Blood Services utilizes a plaque reduction neutralization test (PRNT)50 titer of 1:160 to qualify SARS-CoV-2 CP. Although PRNT50 is the gold-standard for determining SARS-CoV-2 neutralizing antibody titers in CP, it is labor intensive and requires a biosafety level 3 (BSL3) laboratory. The GenScript SARS-CoV-2 Surrogate Virus Neutralization Test (sVNT) Kit (Piscataway, NJ) estimates the % neutralizing capacity of plasma more rapidly in a BSL-2. Aim: To identify the sVNT% cut-off (CO) most capable of identifying high-titer CP (i.e. PRNT50 ≥1:160).

Methods: In April 2020, plasma specimens were collected as part of an assay qualification process from individuals with either; a self-declared SARS-CoV-2–positive nucleic acid test (NAT), or risk factors and signs/symptoms of COVID-19 disease, ≥2 weeks after cessation of clinical symptoms. PRNT50 and sVNT were done at National Microbiology Laboratory (Winnipeg, MB, Canada. Data was stored (Microsoft Excel; Redmond, WA) and statistically analyzed (GraphPad Prism 5; San Diego, CA).

Results: 59 donors were recruited (30 NAT-positive, 29 no NAT). Donor specimens had; median PRNT50 (1:80), median sVNT% (50.1%). Only 42.4% (25/59) of specimens had a PRNT50 ≥1:160. There was an association between PRNT50 and sVNT% (Spearman r: 0.5474 p<0.0001). At a sVNT% CO of 60%, 25/59 (42.4%) specimens would be captured. Within this captured group, 6/25 (24.0%) had a PRNT50 ≤1:160 (%; n/specimens). Furthermore, a sVNT% CO of 60% captured 19/25 (76.0%) specimens that had a PRNT50 ≥1:160. Compared to other CO percentages, a sVNT% CO of 60% yielded less low titer specimens while capturing a reasonable number of specimens with a PRNT50 ≥1:160 (data presented in slides). xtagstartz/p>