Fig. 6. Depletion of free histidine levels in the host cellular milieu post infection.

a The levels of free histidine in B6 mice lungs infected with H37Rv and ΔhisD decline post 15 days of infection while these remain unchanged in infected B6 IFN-γ^−/− mice lungs (n = 5 measurements from independently acquired and processed lung samples; mean and SEM). b While the relative abundance of urocanate increases post infection in B6 mice lungs infected with H37Rv, it remains undetected in infected B6 IFN-γ^−/− mice lungs (n = 5 measurements from independently acquired and processed lung samples; mean only). c The levels of histamine in B6 mice lungs infected with H37Rv rise over the 4 weeks of infection, while there is a sharp decline in infected B6 IFN-γ^−/− mice lungs post 15 days of infection (n = 5 measurements from independently acquired and processed lung samples; mean only). d The post transnationally modified excretory by-product methyl-histidine accumulates over the course of infection in B6 mice lungs infected with H37Rv while its abundance in infected B6 IFN-γ^−/− mice lungs declines post 15 days of infection (n = 5 measurements from independently acquired and processed lung samples; mean only). e The levels of intracellular free tryptophan in B6 mice lungs sharply reduce 15 days post infection with H37Rv, while remaining nearly similar in infected B6 IFN-γ^−/− mice lungs (n = 5 measurements from independently acquired and processed lung samples; mean and SEM).