Gazzinelli, G.

Holanda, J. E.

Pellegrino, J.

English

Cadernos Espinosanos (E-Journal)

Rev. Inst. Med. trop. Sào Pa-iao 16(3):1$2-134, 111aio-.i1111ho, 19~'-J UDC 616.99,,.1:22 INFECTION OF MICE WITH C.ERCARIAE AND SCHISTOSOMULA OF SCHISTOSOMA MANSONI BY INTRAVE'NOUS AND SUBCUTANEOUS ROUTES J. e. HOLANDA (1 ), J. PELLEGRINO (2 ) and G. GAZZINELLI (3 ) SUMMARY Two groups of 10 mice were injected with 100 cercariae of Schistosoma mansoni per animal, by the intravenous route. A group of 10 mice, injected subcutaneously, with the sarne number of cercariae, served as control. All animais were sacrificed 7 weeks infection. The mean number of schistosomes recovered from mice infected intravenously was 9. 4 + 5. 5 and 9. 3 + 4. O, respectively. Mice infected suh.-cutaneously showed a mean burden of 23. 6 + 10. 9 schistosomes. These data show that S. mansoni cercariae are infective to mice when injected intravenously, although to a lesser extent than by the subcutaneous route. The infectivity oí schistosomula (S. mansoni) for mice was checked by injecting (intravenous and subcutaneous routes) 100 larvae, obtained in vitro, in two groups of 10 mice. The results obtained ( 44. O + 10. 1 and 40. 1 + 9. 8 schistosomes, respectively) showed that schistosomula are able do infect mice, with a great percentage of recovery, either by the intravenous or by the subcutaneous route. INTRODUCTION lt is well known the infective capacity of Schistosoma mansoni cercariae for mice when the animals are exposed via the skin or the cercariae are injected either by the sub-cutaneous or the intraperitoneal routes ( Cf. PELLEGRINO & KATZ 2 ). No reference was found in the literature on the infectivity of S. mansoni cercariae when injected intra-venously. The present paper reports the irioculation of mice with cercariae and schistosomula hy the intravenous and subcutaneous routes, in order to check the infective capacity of cer-cariae when injected intravenously and to verify whether schistosomula obtained in vi-tro, by a physical method, are able to infect mice. With regard to the infectivity of schisto-somula (S. mansoni), obtained in vitro, Sn-REWALT & UY s mentioned that these larvae produce infections in mice following intra-venous, but not intracutaneous or intraperi-toneal inoculation. (1) F•ellow from CNPq, Brazil MATERIAL AND METHODS Cercariae of S. mansoni - Cercariae were obtained by exposing Biomphalaria glabrata to light at the temperature of 28°C. The snails were reared and infected (L.E. strain) in the laboratory. (2) Schistosomiasis Research Unit, Institute of Biological Sciences, Federal University of Minas Ge-rais (3) Department of Biochemistry and Immunology, Institute of Biological Sci·ences Contribution no. 48 from the Schistosomiasis Research Unit 132 This work was supported, in part, by the "Conselho Nacional de Pesquisas" (MINIPLAN) Address · for reprints: Caixa Postal 1404 - 30000 Belo Horizonte, Brazil HOLANDA, J. C.; PELLEGRINO, J. & GAZZINELLI, G. - Infection of mice with cercariae and schis-tosomula of Schistosorna. rnansoni by intravenous and subcutaneous routes. Rev. Jnst. Med. trop. São Paulo 16:132-134, 1974. Schistosomula - Schistosomula were pre-pared according to the technique of GAZZI-NELLI et al. 1 as modified by RAMALHO-PINTO et al. 7 • Briefly, the method consists of three steps. First of aH, a cooled suspension of cercariae in 10 mi volume of Hank-BSS pH 7. 2-7. 4 was whorled in a Vortex mixer for 1 min (step one-tail loss). The tail-loss bo-dies separated hy gravity sedimentation were packed by 1 min low-speed centrifugation and incubated at 30ºC for 40 min (step two - secretion induction). Finally, the larvae from step two were suspended in inactivated guinea-pig serum and incubated under agi-tation at 37°C for 1 hour (step three - coat remova!). The larvae so obtained display the characteristics of schistosomula as esta-hlished by STIREWALT et al. 8 • Infection o/ a.nimals -- Cercariae and schistosomula were concentrated following the technique of PELLEGRINO & MACEDO 3 in order to obtain about 1,000 organisms per mi. A volume of O. 1 ml of the suspension was then injected into the dorso-lateral veins of the tail. Seven weeks after injection the animais were sacrificed and the liver and mesenteric veins perfused (PELLEGRINO & SIQUEIRA 5 ) for schistosome collection. Fragments from the small intestine were ta-ken for oogram studies (PELLEGRINO et al. '). RESUL TS AND COMMENTS Table I shows the results obtained after injection of a cercaria! suspension ( 100 orga-nisms per animal) in mice by intravenous and subcutaneous routes. Comparable re-sults were obtained in 2 experiments when the intravenous route was employed. Actual-ly, the mean worm burden was 9. 4 + 5. 5 and 9. 3 + 4. O schistosomes, respectively. ln the animais infected by the subcutaneous route a mean of 23. 6 + 10. 9 was observed. These results show that cercariae of S. man-soni are infective for mice when injected intravenously hut the percentage of worm recovery is very small. The results obtained after infection o.f mice with schistosomula using the intrave-nous or the subcutaneous routes wer~ very similar (Tahle II), the mean worm 1:ecover)' being about 40 % . TABLE I Recov·ery of adult Schistosorna rnansoni from mice injected intravenously and subcutaneously with 100 cercariae per animal Number Routes of inoculation and number· of schistosomes recovér•ed 1-----of mice 1 2 3 4 5 6 7 s 9 10 Total Mean ! Intrave-nous 18 13 12 3 4 5 19 9 5 6 94 9.4 ± 5.5 Intrave-nous 4 7 9 14 10 10 13 16 .3 7 93 9.3 ± 4.0 TABLE II Subcuta-neous (control) 34 21 15 7 31 44 15 28 12 29 236 23.6 ± 10.9 Recovery of adult Schistosorna ,nansoni from mice injected intravenously and subcutaneously with 100 schistosomula, obtained in vitro, per animal Number of mice 1 2 3 4 5 6 7 8 9 10 Total Mean Routes Qf inoculation and number of schistosomes recovered Intravenous 66 45 56 43 35 32 36 35 48 44 1 Subcutaneous 42 31 34 26 47 39 41 58 30 53 44.t: rn.:--,- 40.:º! 9.8 It is interesting to mention that the adult sc,histosomes recovered from mice infected either with cercariae or with schistosomula were of normal size and the female worms 133 HOLANDA, J. C.; PELLEGRINO, J. & GAZZINELLI, G. - Infection of mice with cercariae and schis-tosomula of Schistosoma mansoni by intravenous and subcutaneous routes. Rev. Inst. Med. trop. São Paulo 16:132-134, 1974. presented eggs of normal morphology. The oograms from rectal fragments showed viable eggs in all stages of maturation. According to STIREWALT & UY 9 , S. man-soni schistosomula produce infections follow-ing intravenous, but not intracutaneous or intraperitoneal inoculation. Our findings agree with those of PEREIRA 6 which studied the migratory capacity of schistosomula re-covered in vivo, but are in contrast with those repórted by STIREWALT & UY 9 in what con-cerns the. infection of mice after subcutaneous inoculation of larvae obtained in vitro. RESUMO Infecção do camundongo com cercárias e esquistossômulos do Schistosoma mansoni pe-las vias endovenosa e subcutânea Dois grupos de 10 camundongos foram injetados com 100 cercárias de Schistosoma mansoni pela via endovenosa. Um outro grupo de 10 camundongos, injetados com o mesmo número de cercárias, por via sub-cutânea, serviu como controle. Todos os ani-mais foram sacrificados 7 semanas depois da infecção. O número médio de esquistos-somos recuperados dos camundongos infec-tados por via endovenosa foi de 9,4 + 5,5 e 9,3 + 4,0, respectivamente. Os camundon-gos infectados por via subcutânea apresen-taram, em média, 23,6 + 10,9 esquistosso-mos. Esses dados mostram que a cercária do S. mansoni é infectante para o camundongo quando inoculada por via endovenosa, em-bora em menor grau do que pela via sub-cutânea. A infectividade do esquistossômulo (S. mansoni) para o camundongo foi testada pe-la injeção endovenosa e subcutânea de 100 larvas obtidas in vitro. Os resultados obti-dos ( 44,0 + 10,1 e 40,1 + 9,8 esquistos-somos) mostram que o esquistossômulo é ca-paz de infectar o camundongo, com grande percentagem de recuperação, tanto pela via endovenosa como pela via subcutânea. 134 REFERENCES 1. GAZZINELLI, G.; OLIVEIRA, C. c.; FI-GUEIREDO, E. A. & PELLEGRINO, J. -Schistosoma mansoni: Biochemical studies of the steps involved in the process of transfor-mation of cercariae into schistosomula. Exp. Parasitol. (In press), 1973. 2. PELLEGRINO, J. & KATZ, N. - Experi-mental chemotherapy of schistosomiasis man-soni. Advances Parasitology 6 :233-290, 1968. 3. PELLEGRINO, J. & MACEDO, D. G. - A simplified method for the concentration of cercariae. J. Parasitol. 41 :329-330, 1955. 4. PELLEGRINO, J .. ; OLIVEIRA, C. A.; FA-RIA, J. & CUNHA, A. S. -'- New approach to the screening of drugs in experimental schistosomiasis mansoni in mice. A mer. J. Trop. Med. & Hyg. 11:201-215, 1962. 5. PELLEGRINO, J. & SIQUEIRA, A. F. -Técnica d•e perfusão para colheita de Schis-tosoma mansoni em .cobaias experimentalmen-te infestadas. Rev. Brasil. Malariol. 8:589-597, 1956. 6. PEREIRA; L. H. - Capacidade de migração das larvas de Schistosoma mansoni Sambon, 1907, no canvundongo albino. Thesis. Insti-tute of Biological Sciences, Federal Universily of Minas Gerais, 1971, 38 pp. 7. RAMALHO-PINTO, F. J.; GAZZINELLI, G.; HOWELLS, R. E.; MOTA-SANTOS, T. A.; FIGUEIREDO, E. A. & PELLEGRINO, J. - Schistosoma mansoni: a defined system for the step-wise transformation of the cer-cariae to schistosomules in vitro. (Submitted for publication), 1973. 8. STIREWALT, M. A.; MINNICK, D. R. & FREGEAU, W. A. - Definition and collec-tion in quantity of schistosomules of Schis-tosomà mansoni. Trans. Royal Soe. Trop. Med. & Hyg. 60:352-360, 1966. 9. STIREWALT, M. A. & UY, A. - Schis-tosoma 1nansoni: Cercaria! p-enetration and schistosomule collection in an in vitro system. Exp. Parasito/. 26:17-28, 1969. Recebido para publicação em 23/10/1973. 

Infection of mice with cercariae and schistosomula of Schistosoma mansoni by intravenous and subcutaneous routes

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Infection of mice with cercariae and schistosomula of Schistosoma mansoni by intravenous and subcutaneous routes

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