Similar relative abundance of mRNA transcripts from guinea pig lungs following 28 days of infection with Δrel strain compared to wild-type. Data points indicate values from individual Δrel-infected animals. Error bars represent standard deviation. mutant = Δrel strain; WT = wild type (H37Rv) strain; ΔCT = cycle threshold (CT) on Day 28 – CT on Day 1. IFN-γ (p=.06), IL-1B (p=.20), MCP (p=.11), IL-8 (p=.88), TGF-β (p=.47), and TNF-α (p=.003).