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Korean J Parasitol > Volume 21(2):1983 > Article

Original Article
Korean J Parasitol. 1983 Dec;21(2):234-240. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1983.21.2.234
Copyright © 1983 by The Korean Society for Parasitology
Changes in the pathogenicity of Naegleria fowleri by several brain passage in mice
Deung-Ki Lee,Keun-Tae Lee and Kyung-Il Im*
Department of Parasitology, College of Medicine, Yonsei University, Korea.
*Department of Parasitology, College of Medicine, Hanyang University, Korea.

The pathogenicity of free-living amoeba, Naegleria fowleri, is influenced according to the strain, cultural condition and host (Culbertson et al., 1968; Carter, 1970; Wong et al., 1975). Phillips (1973) demonstrated that Entamoeba histolytica became avirulent after more than 2 year maintenance in axenic culture in vitro. This study was carried out to compare the difference in pathogenicity between two strains of N. fowleri, one of a prolonged maintenance in axenic medium and the other one obtained by serial brain passage in mice.

The 0 strain was that N. fowleri had cultivated axenically more than 7 years in CGVS medium. The 2-1 strain was obtained from the brain of mouse inoculated intranasally with a strain, which was from the mouse brain infected with 0 strain, and cultured for 15 weeks until the beginning of this experiment. White male mice weighing 18-22 g were used. Mice were anesthetized by an intraperitoneal injection of about 1 mg secobarbital, and inoculated intranasally with 10 × 104 live N. fowleri trophozoites in a 5 µl cell suspension.

Sluggish behaviour, nervousness, rotation and leg paralysis were developed earlier and more frequently in the 2-1 experimental group than the control 0 group. Pathological changes such as inflammatory and necrotic lesion were observed in the olfactory and anterior portion of brain, and these changes were more extensive in the 2-1 group. The edematous and inflammatory changes in lung were demonstrated in mice died after 13th day post-inoculation. The experimental mice of 2-1 group began to die suddenly from 7th day post-inoculation, and the survival time in 2-1 group mice was shorter than 0 group mice.

The typical primary amoebic meningoencephalitis was developed in the mice inoculated intranasally with N. fowleri. The prolonged maintenance of N. fowleri amoebae in axenic CGVS medium was observed to have lost their original pathogenicity for mice, but their pathogenicity was restored by serial brain passage in mice.


Fig. 1
Fate of mice infected with Naegleria fowleri intranasally. The experimental group received strain 2-1, while the control group received strain 0.

Fig. 2
Naegleria fowleri trophozoites demonstrated in mouse brain tissue with severe inflammatory cells infiltration. (×500)

Figs. 2-3
Naegleria fowleri trophozoites observed in mouse lung tissue with severe inflammatory cells infiltration (×1,000)

Fig. 4
Naegleria fowleri trophozoites shown in the nasal cavity of mouse. (×500)


Table 1
Naegleria fowleri used in this study

Table 2
Symptoms observed in each postinfection day

1. Butt CG, Baro C, Knorr RW. Naegleria (sp.) identified in amebic encephalitis. Am J Clin Pathol 1968;50(5):568–574.
2. Carter RF. Primary amoebic meningo-encephalitis: clinical, pathological and epidemiological features of six fatal cases. J Pathol Bacteriol 1968;96(1):1–25.
3. Carter RF. Description of a Naegleria sp. isolated from two cases of primary amoebic meningo-encephalitis, and of the experimental pathological changes induced by it. J Pathol 1970;100(4):217–244.
4. Culbertson CG, Ensminger PW, Overton WM. Hartmannella (acanthamoeba). Experimental chronic, granulomatous brain infections produced by new isolates of low virulence. Am J Clin Pathol 1966;46(3):305–314.
5. Culbertson CG, Ensminger PW, Overton WM. Pathogenic Naegleria sp.--study of a strain isolated from human cerebrospinal fluid. J Protozool 1968;15(2):353–363.
6. Dunnebacke TH, Schuster FL. Infectious agent from a free-living soil amoeba, Naegleria gruberi. Science 1971;174(8):516–518.
7. Hwang HK, et al. Yonsei J Med Sci 1976;9:183–194.
8. Jadin JB. Path Biol 1974;22:81–87.
9. Maitra SC, Krishna Prasad BN, Das SR, Agarwala SC. Ultrastructural differences of Hartmannella culbertsoni Singh and Das, 1970, in mouse brain and under different cultural conditions. Trans R Soc Trop Med Hyg 1974;68(3):229–235.
10. Martinez J, Duma RJ, Nelson EC, Moretta FL. Experimental naegleria meningoencephalitis in mice. Penetration of the olfactory mucosal epithelium by Naegleria and pathologic changes produced: a light and electron microscope study. Lab Invest 1973;29(2):121–133.
11. Neal RA, Vincent P. Strain variation in Entamoeba histolytica. II. The effect of serial liver passage on the virulence. Parasitology 1956;46(1-2):173–182.
12. Patras D, Andujar JJ. Meningoencephalitis due to Hartmannella (Acanthamoeba). Am J Clin Pathol 1966;46(2):226–233.
13. Phillips BP. Entamoeba histolytica: concurrent irreversible loss of infectivity-pathogenicity and encystment potential after prolonged maintenance in axenic culture in vitro. Exp Parasitol 1973;34(2):163–167.
14. Phillips BP, Diamond LS, Bartgis IL, Stuppler SA. Results of intracecal inoculation of germfree and conventional guinea pigs and germfree rats with axenically cultivated Entamoeba histolytica. J Protozool 1972;19(3):498–499.
15. Visvesvara GS, Callaway CS. Light and electron microsopic observations on the pathogenesis of Naegleria fowleri in mouse brain and tissue culture. J Protozool 1974;21(2):239–250.
16. Wittner M, Rosenbaum RM. Role of bacteria in modifying virulence of Entamoeba histolytica. Studies of amebae from axenic cultures. Am J Trop Med Hyg 1970;19(5):755–761.
17. Wong MM, Karr SL Jr, Balamuth WB. Experimental infections with pathogenic free-living amebae in laboratory primate hosts: I (A) A study on susceptibility to Naegleria fowleri. J Parasitol 1975;61(2):199–208.
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