FIG. 4.

Random patterns of IE1 and IE2 transcription in latently infected lungs. For latently infected mice LM1 through LM5, poly(A)⁺ RNA was isolated piece by piece from pieces #1 through #9 derived from the three lobes (superior, middle, and inferior lobe) of the right lung and from pieces #12 through #18 derived from the left lung (ventral view). The postcaval lobes (shaded) were spent for determining the latent viral DNA load (recall Fig. 3). Aliquots (200 ng) of the poly(A)⁺ RNA, that is, ca. a tenth of the yield from each piece, were subjected to IE1- and IE2-specific RT-PCRs. (Left panels) Autoradiographs obtained after gel electrophoresis of the amplificates, Southern blotting, and hybridization with the γ-³²P-end-labeled oligonucleotide probes IE1-P and IE2-P, respectively. Faint signals (asterisks) are clearly visible on the original autoradiograph and were confirmed by testing of a further aliquot of the poly(A)⁺ RNA. (Right panels) Compilation of the data in topographical maps of the lungs. In accordance with the location of the ie1 and ie2 genes in the genetic map (recall Fig. 1), the left and right circles of the paired-circle (infinity) symbol correspond to IE1 and IE2 transcripts, respectively. The presence of transcripts is indicated by a closed circle, and the absence of transcripts is indicated by an open circle.