Mtb burden and killing in lymph nodes of cynomolgus and rhesus macaques.

A, B. Live Mtb burden (CFU) in thoracic LNs from cynomolgus (A) and rhesus (B) macaques at various time points post-infection (at necropsy). Lymph node CFU of cynomolgus macaques decreases over the course of infection while rhesus macaques do not. C, D. Total (live+dead, CEQ) Mtb burden in cynomolgus (C) and rhesus (D) macaque LNs. There was no difference in the level of CEQ in cynomolgus macaque LNs over the course of infection, while a decline in CEQ was found in rhesus macaque LNs at later time points post-infection. E, F. Mtb killing in thoracic lymph nodes, as calculated as the ratio of live (CFU) compared to total (CEQ) bacteria. Cynomolgus macaque LNs (E) exhibit poor Mtb killing at 4 weeks post infection but improve over the course of infection. Highest Mtb killing capacity was observed in monkeys with latent infection (34–54 weeks post infection). Little killing was observed in rhesus macaque LNs (F). The CFU was transformed by adding 1 to reflect sterile LNs with CEQ and/or granulomas either by gross or microscopic examination. For C-F, only LNs in which CEQ were detected were included. Each macaque is shown in a different color. Each data point is one lymph node. Open symbols are sterile lymph nodes (CFU-). The number of macaques per time point post-infection is as follows: a.) 4–6 weeks (Cynos n = 8, Rhesus n = 4); b.) 11–14 weeks (Cynos n = 9, Rhesus n = 7); c.) 16–29 weeks (Cynos n = 9, Rhesus n = 8); d.) 34–54 weeks (Cynos n = 6). The number of lymph nodes analyzed ranged from 4 to 13 per macaque. Dotted line represent the limit of detection of our qPCR assay. Statistics are Kruskal-Wallis with post-hoc Dunn’s multiple test comparisons; p values are shown on figure.