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KSL Diagnostics and University at Buffalo Present at Congress of Clinical Rheumatology

Research Showing Correlation Between COVID-19 Antibody Levels and Virus Neutralization Led to KSL’s COVID-19 Immune Index™ Antibody Test That Measures Degree of Virus Immunity

KSL Diagnostics, Inc. (KSL), developers of novel diagnostic and therapeutic applications for immunology and oncology, and the University at Buffalo (UB) will present a poster paper on “Correlation of Antibody Levels with SARS-CoV-2 Virus Neutralization” at the Congress of Clinical Rheumatology May 11-15 in Destin, FL. The presentation highlights the results of a SARS-CoV-2 study conducted by KSL and researchers at UB’s Jacobs School of Medicine and Biomedical Sciences. The study was funded by a grant from the University at Buffalo Center for Advanced Technology in Big Data and Health Sciences (UB CAT).

The aim of the study was to compare the semi-quantitative titers of a laboratory-developed SARS-CoV-2 spike antibody assay against the industry-standard plaque reduction neutralization test (PRNT) to determine if a specific circulating antibody titer is needed for optimal virus deactivation. An additional consideration was developing a new assay suitable for high throughput testing that could be used to quickly assess immunity levels in a specific population to promote vaccine boosters as needed and inform healthcare policy.

Study results showed a correlation between COVID-19 antibody levels and virus neutralization with stratification of immunity:

  • IgG titers of 20 and above demonstrated 100% neutralization of SARS-CoV-2, suggesting adequate immunity

  • IgG levels from 10 – 20 reduced effective virus neutralization by 25%

  • Below IgG titers of 10, virus neutralization decreased considerably, suggesting inadequate immunity

  • Negative results for IgG indicated a lack of circulating antibodies that could represent a lack of immunity against COVID-19

The KSL/UB investigation led to the development of KSL’s COVID-19 Immune Index™ test, launched last month.

Immunity to COVID-19 is characterized by the production of antibodies that develop through vaccination or infection in response to viral antigens. Immunoglobulin IgG is the most abundant antibody type and provides longer-lasting immunity. Following a PCR-confirmed COVID-19 diagnosis, IgG titers remain stable for at least 4 to 6 months, allowing measurement over time.

Antibodies targeting the SARS-CoV-2 spike protein have shown the highest capacity to neutralize the virus. Neutralizing antibodies bind to antigens to block virus entry into susceptible host cells, providing at least partial resistance to subsequent infections. The presence of these antibodies is considered a functional correlate of immunity. However, due to previous indeterminate study results on the correlation between IgG and neutralizing antibodies in serological assays, it is important to validate new assays by comparison with standard virus-neutralizing tests, incorporating the significant COVID-19 virus strains to date.

The PRNT, often used as the reference standard for the evaluation of virus-neutralizing antibodies, can measure the immunological function of SARS-CoV-2-specific antibodies. Unfortunately, the assay is time-consuming, labor-intensive and requires high-level biosafety containment facilities to utilize, so it is not practical for large-scale community testing.

The KSL/University at Buffalo poster paper will be presented on Thursday May 12 at 4:30 pm EDT.

About KSL Diagnostics

KSL Diagnostics, Inc., a subsidiary of KSL Biomedical, Inc., is a national reference laboratory with headquarters near Buffalo, New York. Its rapidly expanding portfolio offers standard of care tests and novel assays developed at KSL and through partnership with innovative diagnostics companies. KSL Diagnostics owns and operates CAP and CLIA-certified clinical laboratories licensed throughout the U.S., including Beutner Laboratories and KSL Robert Guthrie Laboratory. KSL provides outstanding regulatory compliance, expert clinical consultation and industry-leading customer service. For more information, visit


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