Schistosoma mansoni threatens hundreds of millions of people in >50 countries. Schistosomulae migrate through the lung and adult worms reside in blood vessels adjacent to the intestinal mucosa. Current candidate vaccines aren’t designed to elicit a mucosal response. We have repurposed an attenuated Salmonella enterica Typhimurium strain (YS1646) to produce such a vaccine targeting Cathepsin B (CatB), a digestive enzyme important for parasite survival. Promoter-Type 3 secretory signal pairs were screened for protein expression in vitro and transfected into YS1646 to generate candidate vaccine strains. Two strains were selected for in vivo evaluation (nirB_SspH1 and SspH1_SspH1). Female C57BL/6 mice were immunized twice, 3 weeks apart, using six strategies: i) saline gavage (control), ii) the ‘empty’ YS1646 vector orally (PO) followed by intramuscular (IM) recombinant CatB (20μg IM rCatB), iii) two doses of IM rCatB, iv) two PO doses of YS1646-CatB, v) IM rCatB then PO YS1646-CatB and vi) PO YS1646-CatB then IM rCatB. Serum IgG responses to CatB were monitored by ELISA. Three weeks after the second dose, mice were challenged with 150 cercariae and sacrificed 7 weeks later to assess adult worm and egg burden (liver and intestine), granuloma size and egg morphology. CatB-specific IgG antibodies were low/absent in the control and PO only groups but rose substantially in other groups (5898-6766ng/mL). The highest response was in animals that received nirB_SspH1 YS1646 PO then IM rCatB. In this group, reductions in worm and intestine/liver egg burden (vs. control) were 93.1% and 79.5%/90.3% respectively (all P < .0001). Granuloma size was reduced in all vaccinated groups (range 32.9–52.8 x103μm2) and most significantly in the nirB_SspH1 + CatB IM group (34.7±3.4 x103μm2vs. 62.2±6.1 x103μm2: vs. control P < .01). Many eggs in the vaccinated animals had abnormal morphology. Targeting CatB using a multi-modality approach can provide almost complete protection against S. mansoni challenge.
A vaccine against schistosomiasis would contribute to a long-lasting decrease in disease spectrum and transmission. Our previous protection studies in mice using Schistosoma mansoni Cathepsin B (Sm-Cathepsin B) resulted in 59 and 60% worm burden reduction with CpG oligodeoxynucleotides and Montanide ISA720 VG as adjuvants, respectively. While both formulations resulted in significant protection in a mouse model of schistosomiasis, the elicited immune responses differed. Therefore, in this study, we aimed to decipher the mechanisms involved in Sm-Cathepsin B vaccine-mediated protection. We performed in vitro killing assays using schistosomula stage parasites as targets for lung-derived leukocytes and serum obtained from mice immunized with Sm-Cathepsin B adjuvanted with either Montanide ISA 720 VG or CpG and from non-vaccinated controls. Lung cells and immune sera from the Sm-Cathepsin B + Montanide group induced the highest killing (63%) suggesting the importance of antibodies in cell-mediated parasite killing. By contrast, incubation with lung cells from Sm-Cathepsin B + CpG immunized animals induced significant parasite killing (53%) independent of the addition of immune serum. Significant parasite killing was also observed in the animals immunized with Sm-Cathepsin B alone (41%). For the Sm-Cathepsin B + Montanide group, the high level killing effect was lost after the depletion of CD4+ T cells or natural killer (NK) cells from the lung cell preparation. For the Sm-Cathepsin B + CpG group, high parasite killing was lost after CD8+ T cell depletion, and a reduction to 39% was observed upon depletion of NK cells. Finally, the parasite killing in the Sm-Cathepsin B alone group was lost after the depletion of CD4+ T cells. Our results demonstrate how the different Sm-Cathepsin B formulations influence the immune mechanisms involved in parasite killing and protection against schistosomiasis.
e18656 Background: Medical oncology (MEDONC) requires a combination of skills in collaboration, communication, and professionalism, ultimately delivering technical and clinical knowledge in practice. Standard assessment tools (e.g. written examination, OSCE) are not effective in evaluating competencies beyond technical skills and fail to define the cancer care experience holistically. This explorative, descriptive study aims to identify the potential of unstructured, unsolicited, open access online patient reviews (OPRs) as a tool to assess physician competency. Methods: University-affiliated MEDONCs in Ontario (Canada) were selected. All OPRs were identified on RateMD using every name permutation; physician names and institutional affiliations were removed from comments. A descriptive analysis of the cohort was completed. The CanMEDS Framework, defining physician standards, was used with its hierarchy of roles, concepts, and competencies. Two reviewers, a communication studies researcher and a healthcare professional, independently assessed comments and identified common themes. Competency-level assessments were evaluated using kappa with linear weights. Results: 473 OPRs were identified for 49 MEDONCs (71% male, 29% female). Of these, 23% were written by care providers. Competencies defining roles of Medical Expert, Communicator, and Professional were most prevalent (64%, 38%, and 27% respectively). Agreement levels were high in all roles (wK = 0.71 - 1.00). Themes identified were similar in positive and negative evaluations. Most commonly discussed positive themes were knowledge translation and compassionate interpersonal skills. Most common negative themes centered on lack of humility, compassion, and communication skills. 38% of comments were marked helpful, indicating engagement with other OPRs as a key characteristic of rating tools. In addition to the physician in question, 21% of OPRs reported on healthcare delivery by staff. Conclusions: OPRs emphasize experiential competencies related to interpersonal skills and suggest an alternative format to evaluating such aspects of MEDONC competencies.[Table: see text]
24Schistosoma mansoni threatens hundreds of millions of people in >50 countries. Schistosomulae 25 migrate through the lung and adult worms reside adjacent to the intestinal mucosa. None of the 26 candidate vaccines in current development is designed to elicit a mucosal response. We have 27 repurposed an attenuated Salmonella enterica Typhimurium strain (YS1646) to produce such a 28 vaccine targeting Cathepsin B (CatB), a digestive enzyme important for parasite survival. 29 Promoter-Type 3 secretory signal pairs were screened for protein expression in vitro and 30 transfected into YS1646 to generate candidate vaccine strains. Two strains were selected for in 31 vivo evaluation (nirB_SspH1 and SspH1_SspH1). Female C57BL/6 mice were immunized twice, 32 3 weeks apart, using six strategies: i) saline gavage (control), ii) the 'empty' YS1646 vector orally 33 (PO) followed by intramuscular recombinant CatB (20g IM rCatB), iii) two doses of IM rCatB, 34 iv) two PO doses of YS1646-CatB, v) IM rCatB then PO YS1646-CatB and vi) PO YS1646-CatB 35 then IM rCatB. Serum IgG responses to CatB were monitored by ELISA. Three weeks after the 36 second dose, mice were challenged with 150 cercariae and sacrificed 7 weeks later to assess adult 37 worm and egg burden (liver and intestine), granuloma size and egg morphology. CatB-specific 38 IgG antibodies were low/absent in the control and PO only groups but rose substantially in other 39 groups (5898-6766ng/mL). The highest response was in animals that received nirB_SspH1 40 YS1646 PO then IM rCatB. In this group, reductions in worm and intestine/liver egg burden (vs. 41 control) were 93.1% and 79.5%/90.3% respectively (all P<.0001). Granuloma size was reduced in 42 all vaccinated groups (range 32.86-52.83 x10 3 m 2 ) and most significantly in the nirB_SspH1 + 43 CatB IM group (34.74±3.35 x10 3 m 2 vs. 62.22±6.08 x10 3 m 2 : vs. control P<.01). Many eggs in 44 the vaccinated animals had abnormal morphology. Targeting CatB using a multi-modality 45 approach can provide almost complete protection against S. mansoni challenge. 46 Author Summary 47 Schistosomiasis is a parasitic disease that affects over 250 million people worldwide and over 800 48 million are at risk of infection. Of the three main species, Schistosoma mansoni is the most widely 49 distributed and is endemic in the Caribbean, South America, Africa, and the Middle East. It causes 50 a chronic disease with severe negative effects on quality of life. Mass drug administration of 51 praziquantel is the only available course of action due to a current lack of vaccines. However, 52 praziquantel does not protect from reinfection. Therefore, a vaccine would be beneficial as a long-53 term solution to reduce morbidity and transmission of the disease. Our group has repurposed the 54 attenuated YS1646 strain of Salmonella Typhimurium as an oral vaccine vector for the digestive 55 enzyme Cathepsin B of S. mansoni. Oral vaccination followed by an intramuscular dose of 56 recombinant Cathepsin B lead to significant reduction...
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