Schistosomiasis vaccines

Hagan, Paul; Sharaf, Osama

doi:10.1517/eobt.3.8.1271.21288

Cited by 10 publications

(9 citation statements)

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“…The annual mortality rate in Africa is estimated to be as high as 280,000 (van der Werf et al 1980). Due to unavailability of schistosomiasis vaccine (Bergquist and Colley 1998;Katz 1999;Bergquist et al 2002;Hagan and Sharaf 2003), the current strategy for the control of schistosomiasis depends only on a drug namely praziquantel, which is used in the treatment of three major species of schistosomes infecting humans (Fenwick et al 2006;Doenhoff et al 2009). However, drug resistance has been a challenging issue (Doenhoff et al 2002;Sangster 2001) and therefore, development of a vaccine against S. mansoni could provide a powerful tool to prevent and cure the disease.…”

Section: Introductionmentioning

confidence: 99%

Transmission electron microscopic observations on ultrastructural alterations in Schistosoma mansoni adult worms recovered from C57BL/6 mice treated with radiation-attenuated vaccine and/or praziquantel in addition to passive immunization with normal and vaccinated rabbit sera against infection

et al. 2015

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Although the current treatment of schistosomiasis relies largely on praziquantel (PZQ), it has not been successful in significantly reducing the overall rate of disease cases, one of the suggested reasons being the inevitable resistance to PZQ. Previous studies showed that radiation-attenuated vaccine provides protection against Schistosoma mansoni in a host of various species. In the present study, we evaluated the effect of various vaccination strategies in C57BL/6 mice, including single or multiple vaccination strategy, subcurative dose (20 mg/kg) of PZQ, and a combination of single vaccination with subcurative dose of PZQ. Treatment either with subcurative dose of PZQ or with a single vaccination of attenuated cercariae (500 per mouse), caused significant reduction in total worm burden, hepatic, and intestinal ova counts of 43.03, 73.2, and 59.5 and 37.97, 52.02, and 26.3%, respectively. Furthermore, tegumental changes were observed. In multiple vaccinated group, there was an extensive lysis in tegumental layers. High deformations in gastrodermis, testis cells, vitelline cells, and oocytes were recorded. Also, this study is to explore the role of humoral immunity using highly resistant rabbits that had been exposed to three immunizations with ultraviolet (UV)-irradiated cercariae (8000 per rabbit in each immunization), and their sera were tested for their ability to transfer protection. The reduction in challenge worm burden had reached 32.76-43.64% when compared with recipients of normal serum or no serum. The reduction in hepatic and intestinal ova counts reached to 74.4 and 71.08% in group immunized with vaccinated rabbit sera. Swelling and extensive lysis of tegumental layers, gastrodermis lumen, spermatocytes, and deformation of oocytes were recorded with more severity than that recorded in normal rabbit sera group. Our findings recorded that multiple vaccination strategy is the most effective strategy then passive transfer of vaccinated rabbit. This gives guiding in the design the appropriate therapeutic strategy.

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Section: Introductionmentioning

confidence: 99%

Transmission electron microscopic observations on ultrastructural alterations in Schistosoma mansoni adult worms recovered from C57BL/6 mice treated with radiation-attenuated vaccine and/or praziquantel in addition to passive immunization with normal and vaccinated rabbit sera against infection

et al. 2015

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“…However, it was revealed that the global burden of schistosomiasis and its consequences had been under-estimated, and hence, needs to be revised (King et al 2005). Due to the unavailability of schistosomiasis vaccine (Bergquist and Colley 1998;Capron 1998;Katz 1999;Bergquist et al 2002;Hagan and Sharaf 2003), the current strategy for the control of schistosomiasis is reducing morbidity at both individual and community levels using safe and effective schistosomicidal drugs (WHO Expert Committee 2002). Mass chemotherapy with praziquantel has emerged as the major tool for the control of schistosomiasis but concerns are raised about the development of resistance/tolerance due to the intensive and prolonged selective pressures that are now occurring with tens of millions of people receiving annual treatment with praziquantel (Fenwick and Webster 2006;Botros and Bennett 2007).…”

Section: Introductionmentioning

confidence: 99%

Experimentally promising antischistosomal drugs: a review of some drug candidates not reaching the clinical use

2009

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Schistosomiasis is a chronic parasitic disease affecting about 207 million people in the world. It still represents a major health problem in many tropical and sub-tropical countries as well as for travelers from developed countries. Control of the disease depends mainly on chemotherapy, with praziquantel becoming the exclusive drug. Extensive use of praziquantel with concerns about the possibility of drug resistance development, unavailability of an applicable vaccine, and the absence of a reasonable alternative to praziquantel all represent a real challenge. One of the suggested solutions is to exploit the advantages of compounds that proved efficacious at the experimental level with a good safety profile. These may undergo further investigations for the sake of developing their antischistosomal properties or to incorporate them in combination therapies. Chemotherapy literature is redundant with a huge number of compounds screened for their schistosomicidal properties. However, only a few of these may act as drug leads that could be promising in the development of a therapeutic reserve for schistosomiasis. The present paper reviews previous studies carried out on some of these compounds.

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“…Due to unavailability of schistosomiasis vaccine (Bergquist and Colley 1998;Katz 1999;Bergquist et al 2002;Hagan and Sharaf 2003), the current strategy for the control of schistosomiasis depends only on a drug namely praziquantel (PZQ), which is used in the treatment of three major species of schistosomes infecting humans (Fenwick et al 2003;Doenhoff et al 2009). However, drug resistance has been a challenging issue (Bergquist 2002;Doenhoff et al 2002;Sangster 2001).…”

Section: Introductionmentioning

confidence: 99%

Structural changes of Schistosoma mansoni adult worms recovered from C57BL/6 mice treated with radiation-attenuated vaccine and/or praziquantel against infection

et al. 2011

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Although the current treatment of schistosomiasis relies largely on praziquantel (PZQ), it has not significantly reduced the overall number of disease cases, perhaps due to inevitable resistance to PZQ. Previous studies showed that radiation-attenuated vaccine gives protection levels for Schistosoma mansoni in host various species. In the present study, we evaluated the effect of various vaccination strategies in C57BL/6 mice, including single or multiple vaccination strategy, subcurative dose (20 mg/kg) of PZQ, and a combination of single vaccination with subcurative dose of PZQ. Groups of five mice were sacrificed postinfection in 42 days and schistosomes were collected by perfusion and examined by scanning electron microscopy. Treatment either with subcurative dose of PZQ or with a single vaccination of attenuated cercariae (500 per mouse), caused significant reduction in total worm burden, hepatic and intestinal ova counts 43.03%, 73.2%, 59.5% and 37.97%, 52.02%, 26.3%, respectively. Furthermore, tegumental changes were observed, including severe swelling, fusion of tegumental folds, vesicle formation, and loss or shortening of the spines on the tubercles. However, multiple vaccination strategy resulted in much higher reduction in total worm burden, hepatic and intestinal ova count. However, multiple vaccination strategy resulted in high reduction of worm burden, hepatic and intestinal ova counts 72.5%, 90.7%, 65.79%, respectively, and further causing swollen, disruption of tubercles teguments and erosion, extensive peeling, fusion of tegumental folds. Our findings suggest that multiple vaccination strategy is the most effective strategy to clear schistosomal infection, indicating its potential in guiding the design of appropriate therapeutic strategy against schistosomes.

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Schistosomiasis vaccines

Cited by 10 publications

References 0 publications

Transmission electron microscopic observations on ultrastructural alterations in Schistosoma mansoni adult worms recovered from C57BL/6 mice treated with radiation-attenuated vaccine and/or praziquantel in addition to passive immunization with normal and vaccinated rabbit sera against infection

Transmission electron microscopic observations on ultrastructural alterations in Schistosoma mansoni adult worms recovered from C57BL/6 mice treated with radiation-attenuated vaccine and/or praziquantel in addition to passive immunization with normal and vaccinated rabbit sera against infection

Experimentally promising antischistosomal drugs: a review of some drug candidates not reaching the clinical use

Structural changes of Schistosoma mansoni adult worms recovered from C57BL/6 mice treated with radiation-attenuated vaccine and/or praziquantel against infection

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