I. Rahman et al., POTENTIAL VIRULENCE OF VIABLE BUT NONCULTURABLE SHIGELLA-DYSENTERIAE TYPE-1, Applied and environmental microbiology, 62(1), 1996, pp. 115-120
We examined a virulent strain of Shigella dysenteriae type 1 after ind
uction into the viable but nonculturable (VBNC) state for its ability
to (i) maintain the Shiga toxin (stx) gene; (ii) maintain biologically
active Shiga toxin (ShT); and (iii) adhere to intestinal epithelial c
ells (Henle 407 cell line). PCR was used to amplify the stx gene from
VBNC cells of S. dysenteriae type 1, thereby establishing its presence
even when cells are in the VBNC state. VBNC S. dysenteriae type 1 ShT
was monitored by the enzyme-linked immunosorbent assay with mouse mon
oclonal antibodies against the B subunit of ShT and affinity-purified
rabbit polyclonal antibodies against ShT. We used the Henle 407 cell l
ine to study the adhesive property of VBNC S. dysenteriae type 1 cells
in a series of tissue culture experiments. Results showed that VBNC S
. dysenteriae type 1 not only maintained the stx gene and biologically
active ShT but also remained capable of adhering to Henle 407 cells.
However, S. dysenteriae type 1 cells lost the ability to invade Henle
407 cells after entering the VBNC state. From results of the study, we
conclude that VBNC cells of S. dysenteriae type 1 retain several viru
lence factors and remain potentially virulent, posing a public health
problem.