OBJECTIVEAngiotensin-converting enzyme 2 (ACE-2) has been identified as a functional receptor of severe acute respiratory syndrome coronavirus (SARS-CoV), so its gene was cloned and eukaryotic expressed for further insight into mechanisms in SARS-CoV entry and pathogenesis, as well as development of a safe and reliable neutralization assay for SARS-CoV.

METHODSTotal RNA was extracted from right atrial tissue of a patient with right heart failure resected during a valvular replacement surgery by Trizol one-step method, and the full-length ACE-2 encoding gene was acquired by RT-nested-PCR. The ACE-2 encoding gene was then cloned into pcDNA4/HisMax-TOPO eukaryotic expression vector to construct the recombinant plasmid pcDNA4/ ACE-2, which was then transfected into 293 T cell and ACE-2 eukaryotic transient expression was detected by Western Blot. Syncytia inhibition assay was established to detect SARS-CoV neutralizing antibody, and compared parallelly with SARS pseudovirus neutralization assay.

RESULTSThe recombinant plasmid pcDNA4/ ACE-2 could express ACE-2 protein in eukaryotic cells and induce cell-cell fusion between S protein- and ACE2-expressing cells. This cell-cell fusion assay could be used to detect SARS-CoV neutralizing antibody.

CONCLUSIONSARS-CoV receptor ACE-2 gene was successfully cloned and eukaryotic expressed, and used to establish syncytia inhibition assay for SARS-CoV neutralizing antibody assay.