Journal of Clinical Virology
Volume 35, Issue 2 , Pages 179-184, February 2006

Anti-SARS-CoV IgG response in relation to disease severity of severe acute respiratory syndrome

  • Nelson Lee

      Affiliations

    • Department of Medicine and Therapeutics, Prince of Wales Hospital, Faculty of Medicine, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
  • ,
  • P.K.S. Chan

      Affiliations

    • Department of Microbiology and School of Public Health, Faculty of Medicine, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
  • ,
  • Margaret Ip

      Affiliations

    • Department of Microbiology and School of Public Health, Faculty of Medicine, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
  • ,
  • Eric Wong

      Affiliations

    • Centre for Epidemiology and Biostatistics, School of Public Health, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
  • ,
  • Jenny Ho

      Affiliations

    • Department of Medicine and Therapeutics, Prince of Wales Hospital, Faculty of Medicine, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
  • ,
  • Catherine Ho

      Affiliations

    • Department of Medicine and Therapeutics, Prince of Wales Hospital, Faculty of Medicine, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
  • ,
  • C.S. Cockram

      Affiliations

    • Department of Medicine and Therapeutics, Prince of Wales Hospital, Faculty of Medicine, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
  • ,
  • David S. Hui

      Affiliations

    • Department of Medicine and Therapeutics, Prince of Wales Hospital, Faculty of Medicine, The Chinese University of Hong Kong, 30-32 Ngan Shing Street, Shatin, NT, Hong Kong, P.R. China
    • Corresponding Author InformationCorresponding author. Tel.: +852 26322195; fax: +852 26489957.

Received 9 May 2005; received in revised form 7 July 2005; accepted 12 July 2005. published online 22 August 2005.

Abstract 

Background

The association between a robust or depressed antibody response and clinical severity of SARS remains unknown.

Objectives

To study seroconversion and the magnitude of IgG responses in a SARS cohort with different disease severities.

Study design and method

A retrospective analysis of all acute and convalescent-phase sera collected from a cohort of laboratory-confirmed SARS cases. Anti-SARS-CoV IgG antibody was detected using indirect immunofluorescence technique and quantified by two-fold serial dilutions. Characteristics of patients who seroconverted “early” (<median interval) were compared to those documented to remain sero-negative during the same time interval. Median IgG levels in convalescent-phase sera (collected within 30 days) were compared among patients with different disease severities. Correlations between IgG levels and important laboratory parameters were assessed.

Results

A total of 325 laboratory-confirmed SARS cases were analyzed; of which 301 (92.6%) had anti-SARS-CoV IgG detected in their sera at the time of sampling. IgG was first detected on day 4 of illness; seroconversion occurred at a median of 16 days (range 4–35 days), and IgG peak levels were reached in the fourth week. Early seroconversion (<day 16) occurred more frequently among patients who required ICU-admission (χ2; p=0.011). Higher IgG levels were detected in patients who required supplemental oxygen (Mann–Whitney; p=0.002), ICU-admission (p=0.001), had negative pre-discharge fecal RT-PCR results (p=0.004), and lymphopenia at presentation (p=0.028). Peak IgG titres also correlated positively with peak LDH levels (Spearman's r=+0.360; p<0.001) among survivors.

Conclusions

Severe SARS is associated with a more robust IgG response.

Keywords: Anti-SARS-CoV IgG, Seroconversion, SARS, Disease severity

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PII: S1386-6532(05)00197-6

doi:10.1016/j.jcv.2005.07.005

Journal of Clinical Virology
Volume 35, Issue 2 , Pages 179-184, February 2006