Correlation between In Vitro Neutralization Assay and Serological Tests for Protective Antibodies Detection

Area of Science:

• Immunology
• Virology
• Epidemiology

Background:

• Serological assays are crucial for understanding humoral immunity and the spread of protective immunity against SARS-CoV-2.
• The plaque reduction neutralization test (PRNT) is the gold standard for quantifying neutralizing antibodies but is labor-intensive and requires specialized facilities.
• There is a need for alternative, more accessible serological methods that correlate well with PRNT results.

Purpose of the Study:

• To evaluate and compare the performance of four different immunoassays against the PRNT for assessing SARS-CoV-2 neutralizing antibody titers.
• To determine the correlation between commercial immunoassays and the gold standard PRNT.
• To assess the diagnostic accuracy of these assays in identifying high levels of neutralizing antibodies.

Main Methods:

• Four immunoassays (Roche Elecsys®, Snibe MAGLUMI® x2, EUROIMMUN® NeutraLISA) were tested using serum samples from individuals recovered from SARS-CoV-2 infection.
• Linear regression modeling, Pearson’s and Spearman’s correlation coefficients were used to compare assay results with PRNT.
• Receiver operating characteristic (ROC) curve analysis, Cohen’s Kappa, and positive predictive agreement were employed to assess diagnostic performance.

Main Results:

• The EUROIMMUN® NeutraLISA assay demonstrated the highest correlation with PRNT results (Pearson's r=0.660, Spearman's rho=0.784).
• EUROIMMUN® NeutraLISA also exhibited the best performance in ROC curve analysis, with high accuracy (0.857), sensitivity (0.889), and specificity (0.829).
• Other evaluated immunoassays showed varying degrees of correlation and diagnostic accuracy.

Conclusions:

• The EUROIMMUN® NeutraLISA assay is a promising alternative to PRNT for reliable assessment of SARS-CoV-2 neutralizing antibodies.
• This assay offers a more practical approach for epidemiological studies investigating protective immunity against COVID-19.
• Further validation may support its broader use in clinical and public health settings.