Using glycan microarrays, the researchers characterized the carbohydrate binding activity of SARS-CoV neutralizing antibodies elicited by an inactivated SARS viral vaccine and found:
1.) An undesired autoantibody reactivity is present in SARS-CoV neutralization antibodies
2.) the autoimmune reactivity is directed toward the complex carbohydrate of an abundant human serum glycoprotein, ASOR (asialo-orosomucoid)
3.) lectin PHA-L is identified as a specific immunologic probe to detect this complex carbohydrate
4.) this lectin stains the SARS-CoV-infected cells specifically and intensively.
The authors said that based on these findings they "have sufficient immunologic evidence that a viral-expressed carbohydrate structure is responsible for the induction of the anti-ASOR autoimmunity in vaccinated animals. These observations raise concerns on human use of the whole virus-based SARS vaccine that is produced by the monkey Vero E6 cell."
They consider that it is too risky to introduce a whole-viral SARS vaccine to human subjects since its immunological property remains largely uncharacterized. They said: "It is necessary to eliminate the undesired autoimmunogenic activity of this preparation of inactivated SARS-CoV. It is possible to identify an alternative cell line or to genetically modify the Vero E6 cell line by altering its glycosylation pathway, thereby producing vaccines with enhanced efficacy without autoimmunogenic activity."
Wang and Lu note that the experimental approaches developed in their research are likely applicable for the immunologic characterization of other viral pathogens.