Figure 8: Rv1988 is a mycobacterial virulence factor.
(a) Rv1988 gives survival advantage to M. smegmatis during infection in peritoneal macrophages. Rv1988-6XHis::M. smegmatis-, Rv1988R8A/R9A-6XHis::M. smegmatis- or pVV16::M. smegmatis-infected peritoneal macrophages cells were analysed for number of surviving internalized bacilli by CFU counting. (b,c) Survival advantage in infected mice. CFU counting was performed for various organs in BALB/c mice infected intravenously with Rv1988-6XHis::M. smegmatis (black bars) or control pVV16::M. smegmatis (white bars). A total of, 7 and 5 animals were used for each strain at the 7th (b) and 20th (c) day, respectively. (d) Rv1988-6XHis::M. smegmatis infection negatively influences the health of the infected mice. Body weights of infected mice measured at different time points as mentioned. n=11 for both the infected n=11 for both the infected groups till day 7. n=5 for both infected groups from day 8 to 20. n=3 for uninfected mice. Percentage of body weight for each animal was calculated with respect to their weight on the day of infection. (e) Splenomegaly in infected mice. Gross anatomy of Spleen in infected and uninfected mice as indicated. pVV16: infection with pVV16::M. smegmatis; Rv1988: infection with Rv1988-6XHis::M. smegmatis. Scale bar, ∼1 cm. (f) Deletion of Rv1988 from M. tuberculosis H37Rv reduces its survivability during infection in THP1 macrophages. M. tuberculosis H37Rv and ΔRv1988 mutant-infected THP1 macrophages were analysed for number of surviving internalized bacilli by CFU counting (n=3). THP1 cells were infected with M. tuberculosis H37Rv and ΔRv1988 strains at 1:10 MOI. The error bars represent s.d. Student’s t-test, *P<0.05, **P<0.001, ***P<0.0001.
