SARS-coronavirus replicates in mononuclear cells of peripheral blood (PBMCs) from SARS patients

Abstract

Background: The etiologic agent of severe acute respiratory syndrome (SARS) is a recently identified, positive single-stranded RNA (ssRNA) coronavirus (SARS-CoV). Little is known about the dynamic changes of the viral replicative form in SARS cases.

Objectives: Evaluate whether SARS-CoV can infect and replicate in peripheral blood mononuclear cells (PBMCs) of infected persons and reveal any dynamic changes to the virus during the course of the disease.

Study design: Peripheral blood mononuclear cells collected from SARS cases infected by the same infectious source were tested for both negative-stranded RNA (minus-RNA, "replicative intermediates") and positive-stranded RNA (genomic RNA) of SARS-CoV during the course of hospitalization by reverse transcription-polymerase chain reaction (RT-PCR).

Results: SARS-CoV minus-RNA was detected in PBMCs from SARS patients. The viral replicative forms in PBMCs were detectable during a period of 6 days post-onset of the disease, while the plus-RNA were detectable for a longer period (8-12 days post-onset).

Conclusions: SARS-coronavirus can infect and replicate within PBMCs of SARS patients, but viral replication in PBMCs seems subject to self-limitation.

Figures

Fig. 1

Electrophoresis results of RT/nested-PCR of samples collected from three SARS patients on day 1 (A, B), on day 2 (C) and on day 5 (D) following admission to hospital. (A) Detection of SARS-CoV genomic RNA using antisense primers in RT-reaction. (B–D) Detection of SARS-CoV replicative intermediate minus-RNA using sense primers in RT-reaction. M: 100 bp DNA ladder. Lanes 1 and 2: Patient 1. Lanes 3 and 4: Patient 2. Lanes 5 and 6: Patient 3. Lanes 7 and 8: normal control. Lanes with odd numbers are from plasma and lanes of even numbers from PBMCs. The expected size of plus- and minus-PCR products was 110 bp.

Fig. 2

Timeline of events and SARS-CoV RNA markers in the course of SARS cases.