To verify that the maintained activity of recombinant HA-49K is similar to that of nascent E3/49K produced during viral infection, we collected cell supernatants from the A549-based expression systems and from infected cells and incubated them with Jurkat T cell and Ramos B cell lines, which either express CD45 or do not (CD45-/-). This evidence concerns the gene PTPRC and viral infectious disease.