Figure 1. The virulence of the human Shigella strain ZD02 using the Sereny test and the HeLa cell invasiveness test.

(A) Sereny test. Guinea pigs were infected with Shigella strain ZD02 via the cornea and conjunctiva. Corneal and conjunctiva inflammation were seen in infected eyes at 18 h post-inoculation (A1). Corneas and conjunctiva is normal in uninfected control eyes (A2). (B) HeLa cells infected with the Shigella strain ZD02. Transmission electron microscopy was used to detect the internalized bacteria within HeLa cells. Representative pictures are shown. The internalized bacteria (arrowheads) were detected at 2 h post-inoculation (B1). Control HeLa cells without infection (B2). Scale bars = 1 µm.