FIG. 2.
Northern blot analysis of MV RNA in lungs of Ifnartm and Ifnartm-CD46Ge mice intranasally inoculated with MV-P-CAT. Mice were sacrificed at the days p.i. indicated. Five micrograms of total lung RNA was separated on a 1% formaldehyde-agarose gel, blotted to a nylon membrane, and reacted with an antisense MV N RNA probe (top panel). The blot was stripped and rehybridized with an actin RNA probe (bottom panel). As a positive control, 6 ng of total RNA from MV-infected Vero cells was used (first lane) and, as a negative control, 10 μg of total RNA from mock-infected Vero cells (second lane) was used. As additional negative controls, total RNAs from two mock-infected mice (−) were examined. A synthetic MV N plus-strand standard RNA 851 bases in length (st 851) was added to the positive control. The positions of this standard RNA, the N mRNA (about 1.7 kb), and the actin mRNA are indicated on the right. About 30,000 copies of MV N mRNA are produced in MV-infected primate cells (first lane) (9). Considering that about 800 times less RNA from Vero cells than RNA from mouse lungs was loaded, the signal in the positive control corresponds to about 40 copies of N mRNA per cell, and the signals in the mouse lung tissues correspond to a few N mRNA copies per average cell.