SARS Coronavirus Spike Protein Expression in HL-CZ Human Promonocytic Cells: Monoclonal Antibody and Cellular Transcriptomic Analyses

Narasaraju, T.; Soong, P. L.; ter Meulen, J.; Goudsmit, J.; Chow, Vincent T. K.

The SARS coronavirus (CoV) spike protein is a target of intensive research, as it is a major virulence factor. Transfection of SARS-CoV spike into Vero E6, HEK293T and HL-CZ cells leads to strong expression of the glycosylated spike protein, as shown by Western blot analyses and immunofluorescent imaging using spike-specific human monoclonal antibodies, indicating the potential utility of these antigens and antibodies as diagnostic reagents. Furthermore, we employed cDNA microarray analysis to probe the changes in host gene transcription attributed to transfection of a codon-optimized spike construct into the HL-CZ cell line of monocyte lineage that is linked to immunological responses. A diverse representation of 100 genes displayed altered transcriptional patterns in response to SARS-CoV spike expression, with 61 upregulated and 39 downregulated genes. Genes involved in intracellular trafficking, signaling, modulation or transcription were generally upregulated. In contrast, genes involved in cell metabolism and cytoskeleton formation were notably downregulated. The transcripts of other functional categories exhibited varied responses to SARS-CoV spike transfection. Collectively, our analyses elucidate numerous and complex transcriptomic events that occur in response to spike protein expression and that contribute towards SARS-CoV pathogenesis.