Here, we report the construction, expression, and purification of a COVID-19 subunit vaccine, mutant phospholipase-D1 (mPLD1) fused to RBD (mPLD1-RBD), and study of its efficacy to raise antibody response in vivo as well as its neutralizing efficiency against COVID-19 viruses, Wuhan and Omicron variants, in conventional virus neutralization assay. The gene discussed is PLD1; the disease is COVID-19.