A serological survey on neutralizing antibody titer of SARS convalescent sera

Abstract

A seroepidemiologic study was conducted in North China in 2003 to determine the neutralizing antibody titer of severe acute respiratory syndrome (SARS) convalescent sera. A total of 99 SARS convalescent serum samples were collected from patients from the Inner Mongolia Autonomous Region, Hebei Province, and Beijing 35-180 days after the onset of symptoms. The anti-SARS antibodies were detected by enzyme-linked immunosorbent assay (ELISA), neutralization assay, and Western blot. Eighty-seven serum samples were confirmed to be positive for SARS antibodies. The neutralizing antibody titer of the 87 positive sera was analyzed quantitatively by neutralization assay. The geometric mean titer (GMT) of the 87 convalescent sera was 1:61. The Kolmogorov-Smirnov test showed that the neutralizing antibody titers conform to normal distribution, which suggests that the average anti-SARS antibody level in this study was representative of the convalescent antibody level of the SARS population. This result could be useful for the development and quality control of SARS vaccines.

A Double-Inactivated Severe Acute Respiratory Syndrome Coronavirus Vaccine Provides Incomplete Protection in Mice and Induces Increased Eosinophilic Proinflammatory Pulmonary Response upon Challenge

“…SARS-CoV-targeted neutralizing antibodies are sufficient to provide complete immunity against lethal SARS challenges in multiple animal models and show evidence of controlling disease severity in human infections (4,5,11,15,44,64,67). Spike-specific antibodies are both neutralizing and protective up to 1 year postvaccination in mice, while anti-nucleocapsid antibodies are neither neutralizing nor protective and, further, appear to be detrimental to the longevity of protective antibodies (11,61).…”

The convalescent sera option for containing COVID-19

“…Passive antibody therapy has a storied history going back to the 1890s and was the only means of treating certain infectious diseases prior to the development of antimicrobial therapy in the 1940s (1,2). Experience from prior outbreaks with other coronaviruses, such as SARS-CoV-1, shows that such convalescent sera contain neutralizing antibodies to the relevant virus (3).…”

A chimeric multi-epitope DNA vaccine elicited specific antibody response against severe acute respiratory syndrome-associated coronavirus which attenuated the virulence of SARS-CoV in vitro

“…Although lot of efforts have been made to understand the roles of various immune effectors in protective immunity and identifying protective antigens recognized by these effector cells, no conclusive information is available on the immune correlates of protection to SARS. However, the convalescent sera were reported very efficient to neutralize SARS-CoV infection [2], and spike-mediated infection could be inhibited by sera from SARS patients [3], SARS patients derived antibodies to S and M proteins efficiently neutralized SARS-CoV infectivity [4], indicating neutralizing antibodies as one of the important protective immune effectors. The SARS-CoV encodes four major structural proteins, known as nucleocapsid (N) protein, envelope (E) protein, membrane (M) protein and spike (S) protein [5].…”