Lack of peripheral memory B cell responses in recovered patients with severe acute respiratory syndrome: a six-year follow-up study

J Immunol. 2011 Jun 15;186(12):7264-8. doi: 10.4049/jimmunol.0903490. Epub 2011 May 16.


Six years have passed since the outbreak of severe acute respiratory syndrome (SARS). Previous studies indicated that specific Abs to SARS-related coronavirus (SARS-CoV) waned over time in recovered SARS patients. It is critical to find out whether a potential anamnestic response, as seen with other viral infections, exists to protect a person from reinfection in case of another SARS outbreak. Recovered SARS patients were followed up to 6 y to estimate the longevity of specific Ab. The specific memory B cell and T cell responses to SARS-CoV Ags were measured by means of ELISPOT assay. Factors in relation to humoral and cellular immunity were investigated. Six years postinfection, specific IgG Ab to SARS-CoV became undetectable in 21 of the 23 former patients. No SARS-CoV Ag-specific memory B cell response was detected in either 23 former SARS patients or 22 close contacts of SARS patients. Memory T cell responses to a pool of SARS-CoV S peptides were identified in 14 of 23 (60.9%) recovered SARS patients, whereas there was no such specific response in either close contacts or healthy controls. Patients with more severe clinical manifestations seemed to present a higher level of Ag-specific memory T cell response. SARS-specific IgG Ab may eventually vanish and peripheral memory B cell responses are undetectable in recovered SARS patients. In contrast, specific T cell anamnestic responses can be maintained for at least 6 y. These findings have applications in preparation for the possible reemergence of SARS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens, Viral / analysis
  • B-Lymphocytes / immunology*
  • Case-Control Studies
  • Disease Outbreaks*
  • Enzyme-Linked Immunospot Assay
  • Female
  • Follow-Up Studies
  • Humans
  • Immunity, Cellular
  • Immunity, Humoral
  • Immunologic Memory / immunology*
  • Male
  • Middle Aged
  • Severe Acute Respiratory Syndrome / immunology*
  • Severe acute respiratory syndrome-related coronavirus / immunology
  • T-Lymphocytes / immunology


  • Antigens, Viral