Study on the growth of Vibrio cholerae O139 within Acanthamoeba polyphaga and its survival in the cysts in low temperature / 中华流行病学杂志

<p><b>OBJECTIVE</b>To determine whether Acanthamoeba polyphaga could affect the survival and growth of Vibrio cholerae O139 in low temperature.</p><p><b>METHODS</b>V. cholerae O139 was co-cultured with the Acanthamoeba polyphaga to be examined on its intracellular growth and survival rate within cysts at low temperature, using methods as Gram-staining, electron microscope and passage culture.</p><p><b>RESULTS</b>V. cholerae O139 were observed to enter into the trophozoites and grow the within the vacuoles after 8 hour incubation with Acanthamoeba polyphaga. The germs survived in the vacuole and/or endo-layer of wall and could be re-isolated from the excystment of Acanthamoeba polyphaga. At 30 degrees C, V. cholerae O139 could survive for 120 days with the amoeba while less than 45 days in PAS. At 4 degrees C, the number of viable bacteria decreased and reached undetectable levels for both study and control groups after a 30-day incubation. V. cholerae O139 could be re-isolated from the 30-, 45-, 60- and 75-day's infected cysts after excystment. However the ability of excystment for 90-day's infected cysts decreased and V. cholerae O139 within the cyst could not be isolated again because the amoebae had lysed.</p><p><b>CONCLUSION</b>These findings indicated that V. cholerae O139 could grow within Acanthamoeba polyphaga and the survival time could be increased in the cysts at low temperature. It seemed that Acanthamoeba can provide an environmental reservoir for V. cholerae O139.</p>

Survival and growth of Vibrio cholerae O139 inside Acanthamoeba / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the survival and growth of Vibrio cholerae inside the Acanthamoeba polyphage.</p><p><b>METHODS</b>Survival and growth of Vibro cholerae O139, co-cultured with Acanthamoeba polyphaga, was observed inside the trophozoites and cysts, using Gram stain and electron microscope.</p><p><b>RESULTS</b>Viable O139 was observed inside the amoebal vacuoles in 24 hours. Vacuoles were filled with more bacteria along with the longer period of co-culture. The process of O139 infection with Amoebae would include uptake, formation of O139 vacuole, multiplication, trophozoites lysed and expel under electron microscopy. Some infected trophozoites could subsequently encyst and the surviving O139 could locate in the vesicles inside the cysts.</p><p><b>CONCLUSION</b>O139 might survive and multiply in the trophozoites and reside inside the cysts of Amoebae, suggesting that Acanthamoebae might serve as one of the environmental hosts of Vibro cholerae.</p>

The discovery of naked cluster particles of Parachlamydia and its developmental mechanism / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the survival and developmental morphology of Parachlamydia (BN9) within Acanthamoeba.</p><p><b>METHODS</b>The morphology of BN9 within Acanthamoeba was studied by inverted phase contrast microscope, electron microscope, Gimenez and AO-staining with amoebal co-culture.</p><p><b>RESULTS</b>The endosomal maturation-blocked were formed after the egress of BN9. Two developmental stages-elementary and reticulate bodies, were both observed within the vacuoles. The reticulate bodies, multiplicated by binary fission, were located mainly within the vacuoles, while the elementary bodies can also be located in the plasma individually. The naked cluster particles were observed after the trophozoites cytolysis with Gimenez-staining. The light infectious trophozoites could encyst, and elementary bodies could survive within the mature cysts.</p><p><b>CONCLUSION</b>The egress of BN9 could form the endosomal maturation-blocked, which was presented in two developmental stages-elementary and reticulate bodies. It exhibited the cytolysin activity that could lyse the infectious trophozoites and were expelled in the vesicles. A few light infected amoeba could encyst with survival elementary bodies in the plasma.</p>