Upon oxygen shift-down, Mycobacterium tuberculosis complex bacteria can induce a 
genetic program characterized by halted duplication, which is called 
Non-replicating persistence (NRP). During this phase, at least 48 genes, 
collectively named Dormancy survival regulator (DosR) regulon, are important for 
the long-term survival of bacilli under a non-respiring state, a condition that 
bacilli encounter inside granulomatous lesions. It remains unclear whether 
expression of NRP genes occurs within the tissue of Mycobacterium bovis 
naturally infected cattle. In order to start dissecting this question, total RNA 
from bovine lymph node tissues of sacrificed tuberculin reacting animals was 
isolated and transcription of genes required for in vivo duplication (esxB and 
fbpB) and in vitro NRP (hspX, pfkB, and mb2660c) were analyzed by RT-PCR 
approaches. Detection of transcripts was positive in bovine tissue samples for 
genes hspX, pfkB, and mb2660c in 84, 32, and 21%, respectively. NRP genes were 
upregulated even in animals with a negative IFN-γ in vitro test, and the 
expression of NRP genes occurred more often than expression of the esxB gene.