Characterization of Mce4A protein of Mycobacterium tuberculosis: role in invasion and survival

BMC Microbiology

Table 2 Survival of recombinant E. coli within THP-1 cells

Recombinant E. coli used to infect THP-1 cells	Colony forming units at different time points (% survival)
	t₀	t₃	t₂₄
Vector only	1426 ± 112	376 ± 37.74 (26.3 ± 1.8)	6.6 ± 1.45 (0.46 ± 0.12)
pET28a/mce4A	3157 ± 37.17	1493 ± 90.07 (47.2 ± 2.7^φφ)	556 ± 60.80 (18.3 ± 2.17^θθ)
pET28a/mce1A	3596 ± 106.4	2209 ± 146.3 (61.5 ± 4.59**)	770.7 ± 59.05 (21.33 ± 1.09***)

Survival was assayed as colony forming units per milliliter of lysate following lysis of the infected cells. Time points considered were as follows: t₀ - 1 hour, t₃ - 3 hours and t₂₄ - 24 hours, post-infection. All values were normalised to t₀ value taken as 100%. The significance was calculated using t test. Recombinant E. coli expressing Mce4A or Mce1A survived inside THP-1 cells at a significantly high CFU as compared to recombinant E. coli with vector alone.
^φφ, p < 0.005; **, p < 0.005; when t test applied to compare percentage survival of E. coli (pET28a) with percentage survival of E. coli (pET28a/mce4A) and E. coli (pET28a/mce1A) respectively at 3 h of incubation.
^θθ, p < 0.005; ***, p < 0.0005; t test applied to compare percentage survival of E. coli (pET28a) with percentage survival of E. coli (pET28a/mce4A) and E. coli (pET28a/mce1A) respectively at 24 h of incubation.

ISSN: 1471-2180