IFNB1 and infection: Analysis of copy numbers of human IFN-β mRNA showed that rAMTV infection induced 2,467, 53,130, or 172,613 copies of human IFN-β mRNA in MRC-5 cells at 4, 8, or 16 hpi, which was 11, 110, or 625 times more than that of mock-infected cells, respectively.