Viability of eggs, filariform larvae and adults of <i>Strongyloides venezuelensis</i> (Nematoda: Strongyloidea) maintained in vitro

, Baek, B K; , Islam, M K; , Matsuda, K

doi:1998.36.2.99

Korean J Parasito > Volume 36(2):1998 > Article

Original Article


Korean J Parasitol. 1998 Jun;36(2):99-107. English. Published online Jun 20, 1998. http://dx.doi.org/10.3347/kjp.1998.36.2.99
Copyright © 1998 by The Korean Society for Parasitology


Viability of eggs, filariform larvae and adults of Strongyloides venezuelensis (Nematoda: Strongyloidea) maintained in vitro
B K Baek,^*M K Islam and K Matsuda
Biosafety Research Institute, Chonbuk National University, Chonju 561-756, Korea.

Received January 23, 1998; Accepted April 28, 1998.
Abstract
The present study was performed to check the viability of eggs, filariform larvae and adults of Strongyloides venezuelensis exposed to various conditions for an in vitro maintenance. The eggs in the feces remained viable for about 25 days at 4℃ and 15 days at room temperature. However, the isolated eggs in sterile saline lost their viability within 24 hr at 4℃. The eggs in morula stage were very sensitive to air drying and rapidly lost their viability (≤ or = 12 hr). Filariform larvae survived for a maximum period of 45 days in fecal suspension and 28 days in 0.12% nutrient broth in polyvinyl culture bags maintained at 20℃. On the other hand, those isolated from nutrient broth cultures survived for a maximum period of 32 days in tap water and 22 days in sterile saline at 20℃. The mature adult worms obtained from experimentally infected rats survived maximally for 9 days in serum supplemented (10% rat-serum) 0.12% nutrient broth and 4 days in serum free nutrient broth at 37℃ while the culture media were changed at an alternate day. The adult female worms deposited fertile eggs in serum supplemented and serum free nutrient broth cultures, however, the hatched larvae (L₁) were not able to develop to the filariform stage in the culture media and found to die within 24 hr of maintenance. The present findings on an in vitro maintenance of different stages of S. venezuelensis may provide useful information for biological and biochemical studies with Strongyloides species.

Figures

Figs. 1-9
Fig. 1. Eggs of S. venezuelensis (arrow) in the primary stage of development in the ovary of a parasitic female (×600). Fig. 2. Eggs (arrow) in different development stages in the uterus of a parasitic female (×300). Fig. 3. An egg-strand isolated from mucosal scrapings (×300). Fig. 4. An egg collected from freshly passed feces. Bar = 10 µm. Fig. 5. An embryonated egg. Bar = 10 µm. Fig. 6. A newly hatched larva of S. venezuelensis. Bar = 10 µm. Fig. 7. A free-living filariform larva recovered from the polyvinyl culture bag after death. Bar = 10 µm. Fig. 8. A free-living filariform larva recovered from the polyvinyl culture bag before death (fixed in 10% formalin). Bar = 50 µm. Fig. 9. A mature parasitic female maintained in serum supplemented nutrient broth at 37℃. Note the eggs in the uterus (arrow). Bar = 200 µm.

Tables


	Table 1 Viability of S. venezuelensis eggs exposed to different temperatures and air drying at room temperature


	Table 2 Viability of filariform larvae of S. venezuelensis maintained in various culture media at different temperatures


	Table 3 Viability of S. venezuelensis adult worms in nutrient broth and fecal suspension maintained at different temperatures

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