A Method for Isolating Pure, Viable Schistosome Eggs from Host Tissues

Browne, Harry G.; Thomas, John I.

doi:10.2307/3275800

Cited by 43 publications

(15 citation statements)

References 5 publications

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“…In brief, the procedure was as follows: SEA was prepared from isolated S. mansoni eggs according to the technique described by Browne and Thomas (1953). After homogenization and centrifugation (25,000 g, 45 min) of the eggs, the SEA-containing supernatant was dialyzed against distilled water (4°C) overnight.…”

Section: Animalsmentioning

confidence: 99%

Expression of intercellular adhesion molecule-1 and lymphocytefunction-associated antigen-1 in experimental Schistosoma mansoni infection and in synchronous periparticular hepatic granulomas in mice: immunohistochemistry, confocal laser scanning microscopy, and immunoelectron microscopy

Jacobs¹,

Bogers²,

Deelder

et al. 1997

Parasitology Research

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Adhesion molecules play an important role in inflammatory and immunological responses. We assessed the expression pattern of intercellular adhesion molecule-1 (ICAM-1) and lymphocytefunction-associated antigen-1 (LFA-1) in the livers of mice experimentally infected with Schistosoma mansoni and in synchronous hepatic granulomas induced by injection of soluble egg antigen (SEA)-coupled Sepharose beads in a mesenteric vein of mice. By immunohistochemistry, confocal laser scanning microscopy, and immunoelectron microscopy, ICAM-1 was localized on endothelial cells, sinusoidal-lining cells (Kupffer cells and sinusoidal endothelium), the hepatocyte cell membrane facing Disse's space, and inflammatory cells in the granuloma. LFA-1 was visualized on the inflammatory cells of the granuloma and on phagocytic sinusoidal-lining cells, most likely Kupffer cells. ICAM-1- and LFA-1-immunoreactive cells were present in the granuloma as early as at 3 days after injection of SEA-coupled beads and persisted with time. As granulomas became older, nonimmunoreactive granuloma cells appeared. We conclude that adhesion molecules play an important role in the genesis of the schistosomal granuloma.

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Section: Animalsmentioning

confidence: 99%

Expression of intercellular adhesion molecule-1 and lymphocytefunction-associated antigen-1 in experimental Schistosoma mansoni infection and in synchronous periparticular hepatic granulomas in mice: immunohistochemistry, confocal laser scanning microscopy, and immunoelectron microscopy

Jacobs¹,

Bogers²,

Deelder

et al. 1997

Parasitology Research

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“…Further experiments (Hamburger J, unpublished data) showed that a nylon screen can be used instead of the polycarbonate filter for diminishing the risk of clogging in case filtration of turbid water is to be done. Since the same filtration apparatus is regularly used for collecting schistosome eggs from very turbid tissue digests, 20 we expect it should be useful for filtration of cercariae in turbid water too, if proper presieving is used. Also, since dismantling and reassembly of the filtration device is very easy, changing filters/sieves when filtration of turbid water is carried out is not expected to present a problem.…”

Section: Discussionmentioning

confidence: 99%

“…As expected from the results with different number of cercariae examined directly ( Figure 5), a direct relationship was also found between the number of cercariae in water filtrates and the banding pattern of PCR products. Different numbers of cercariae (1,5,10,20, and 30) were added into five liters of water. After filtration and confirmation of the number of the cercariae on the filter, the DNA was extracted and 1 l was amplified by PCR.…”

Section: Detection Of Single Cercariae Samples In Filtratesmentioning

confidence: 99%

Development and laboratory evaluation of a polymerase chain reaction for monitoring Schistosoma mansoni infestation of water.

Hamburger¹,

Xu²,

Ramzy³

et al. 1998

The American Journal of Tropical Medicine and Hygiene

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Abstract. A sensitive and specific detection of cercariae of human schistosomes is required for better definition of risk of infection. In the present study, we have developed a polymerase chain reaction (PCR) assay for the detection of cercariae of Schistosoma mansoni in water. A simple DNA preparation was adapted for this purpose, and PCR primers were designed based on the 121-basepair highly repeated sequence we previously identified in the genome of S. mansoni. The PCR assay detected as little as 10 Ϫ6 ng of S. mansoni DNA, and the high sensitivity enabled the detection of a single cercaria. For trapping of cercariae we adapted a filtration apparatus previously used for separating schistosome eggs from turbid enzymatic digests of tissues. A single cercaria could be detected in repeated tests of water filtrates. Since the target DNA is tandemly arranged, a ladder pattern of the PCR products was demonstrated. A direct relationship was demonstrated between the number of ladder bands of the amplification products, and DNA concentration or number of cercariae. The feasibility of semiquantitation of schistosome larvae in natural water was thus suggested. The potential of the procedures described here for epidemiologic studies is discussed.Schistosomiasis, a water-borne disease caused by blood flukes, continues to plague many developing countries in the tropics, 1 with an estimated 200 million people infected worldwide by Schistosoma mansoni, S. haematobium, and S. japonicum, the main schistosome species of humans. Humans become infected by contact with water infested with schistosome infective larvae, the cercariae, which are capable of actively penetrating the skin. Cercariae are released into the water by certain aquatic snails, intermediate hosts of schistosomes, in which the parasite undergoes asexual larval multiplication. Snails, in turn, become infected by miracidia, larvae released from schistosome eggs reaching water with human excreta.Human infection by schistosomes frequently occurs in stable foci, 2,3 and is dependent on snail infection and contact patterns of humans with water infested with cercariae. 4 The risk of infection in these transmission sites may be routinely estimated by detecting infected snails capable of shedding cercariae. 5 However, since seasonal fluctuations exist in snail population densities, infection rates, and cercarial output, 2,6,7 information on both snail infection and presence and distribution of cercariae is required for evaluating the risk of infection. 4,8 Information on presence of cercariae in water is particularly important when only one of many snails is infected yet capable of shedding enough cercariae to maintain high endemicity. 9 Such a situation may occur in the case of residual transmission following intensive control, or during the initial stages of emerging transmission in newly contaminated water bodies.Schistosome cercariae are difficult to recover for identification in natural water bodies. The use of sentinel mice for this purpose 4,8 is inaccurate, time-...

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“…They were then cultured for 24 -48 h in Basch Schistosoma culture medium 169 with 10% fetal calf serum and penicillin/streptomycin to produce schistosomula. Eggs were collected from three hamster livers and harvested as previously described (18) in which livers were homogenized in 2ϫ saline solution and the eggs were cleared of mammalian tissue. Miracidia were hatched from the eggs by slowly removing the saline solution and replacing it with hypotonic solution.…”

Section: Methodsmentioning

confidence: 99%