Ticks as potential vectors of Mycobacterium leprae: Use of tick cell lines to culture the bacilli and generate transgenic strains
Fig 7
Mycobacterium leprae is able to grow in tick cell cultures.
Tick cell lines AVL/CTVM17, HAE/CTVM8 and IDE8 were infected with M. leprae; the initial inoculum (24h) and the bacillary load after 10 and 20 days of incubation at 30°C were determined by cell lysis and counting of total acid-fast bacilli. In (A) AVL/CTVM17 and (B) HAE/CTVM8 cells there was a slight, non-significant increase in bacteria over the first 10 days followed by a decrease, whereas in (C) IDE8 cells there was a significant increase in bacterial numbers over the 20-day period. Each bar represents the mean of nine independent cultures performed using three different M. leprae preparations. (D) Viable M. leprae titer in human monocyte THP-1 cells and tick cell lines after 20 days of infection. Levels of 16S rRNA (viable bacillus marker) and 16S rDNA (M. leprae genome normalizer) were determined by qPCR. Through generation of qPCR standard curves by titration of known numbers of live M. leprae bacilli in different cell cultures, values were converted into number of genomes (viable M. leprae, y-axis). Combined results from three independent experiments, in which none of the negative control samples showed detectable signal; ** = p <0.0001 by Dunn’s multiple comparisons test.