Notably, infection by the Delta variant induced significantly higher levels of chemokine mRNAs such as CXCL9, CXCL10, CXCL11, and CCL2 than infection by the wild type and there was negligeable upregulation of cytokine and chemokine mRNA levels in mice infected with Omicron at 3 dpi. This evidence concerns the gene CXCL10 and infection.