Longitudinally profiling neutralizing antibody response to SARS coronavirus with pseudotypes.

Area of Science:

• Virology
• Immunology
• Infectious Diseases

Background:

• The severe acute respiratory syndrome-associated coronavirus (SARS-CoV) spike protein (S) is a key target for neutralizing antibodies.
• Developing sensitive and specific assays for SARS-CoV neutralizing antibodies is crucial for understanding immunity and vaccine efficacy.

Purpose of the Study:

• To develop and validate a novel in vitro microneutralization assay using retroviral SARS-CoV S pseudotypes.
• To assess the sensitivity and specificity of the pseudotype assay compared to traditional methods.
• To profile neutralizing antibody responses in SARS patients and evaluate the durability of immunity.

Main Methods:

• Construction of retroviral SARS-CoV S pseudotypes.
• Development of an in vitro microneutralization assay using these pseudotypes.
• Comparison of neutralization titers with an assay using replication-competent SARS-CoV.
• Analysis of sequential serum samples from 41 confirmed SARS patients.

Main Results:

• The pseudotype microneutralization assay is sensitive and specific for SARS-CoV neutralizing antibodies.
• Neutralization titers obtained by the pseudotype assay strongly correlate with those from replication-competent SARS-CoV assays.
• No cross-neutralization was observed with antibodies against common human coronaviruses (OC43, 229E).
• Most recovered SARS patients exhibited long-lasting neutralizing antibody responses against SARS-CoV S.

Conclusions:

• The SARS-CoV S pseudotype assay is a reliable and safe tool for measuring neutralizing antibody titers.
• This assay facilitates the study of natural infection immunity and preclinical vaccine evaluation without handling live SARS virus.
• The findings suggest robust and durable immunity in most individuals who recovered from SARS.