title: Lack of peripheral memory B cell responses in recovered patients with severe acute respiratory syndrome: a six-year follow-up study.
abstract: 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.
authors.affiliation: State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, People's Republic of China.
authors.forename: Fang
authors.initials: F
authors.lastname: Tang
authors.forename: Yan
authors.initials: Y
authors.lastname: Quan
authors.forename: Zhong-Tao
authors.initials: ZT
authors.lastname: Xin
authors.forename: Jens
authors.initials: J
authors.lastname: Wrammert
authors.forename: Mai-Juan
authors.initials: MJ
authors.lastname: Ma
authors.forename: Hui
authors.initials: H
authors.lastname: Lv
authors.forename: Tian-Bao
authors.initials: TB
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.forename: Jan H
authors.initials: JH
authors.lastname: Richardus
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Wu-Chun
authors.initials: WC
authors.lastname: Cao
mesh_terms: D000328:Adult; D000956:Antigens, Viral / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology*; D016022:Case-Control Studies; D004196:Disease Outbreaks; D058501:Enzyme-Linked Immunospot Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007111:Immunity, Cellular; D056724:Immunity, Humoral; D007156:Immunologic Memory / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D045473:Severe acute respiratory syndrome-related coronavirus / Q000276:immunology; D045169:Severe Acute Respiratory Syndrome / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000956:Antigens, Viral