A183 VARIATION IN HEALTH SERVICES UTILIZATION AND RISK OF SURGERY ACROSS CHILDREN WITH INFLAMMATORY BOWEL DISEASE: A MULTIPROVINCE COHORT STUDY

Background

Marked variation in access to care and health services utilization is a marker of variation in quality of care. With the rising incidence of pediatric inflammatory bowel disease (IBD), we must understand variation in access to and outcomes of care to improve quality.

Purpose

Describe variation in care for pediatric IBD treated in 4 Canadian provinces.

Method

Incident cases of IBD diagnosed in children <16y were identified from health administrative data in Alberta (AB), Manitoba, Nova Scotia, and Ontario (ON) using validated algorithms. Children were assigned to one of 8 centres of care using a hierarchical assessment of health services use within 6 months of diagnosis. Children treated by adult gastroenterologists or community-based pediatric gastroenterologists were excluded due to small sample size. Outcomes included IBD-related hospitalizations, emergency department (ED) visits (AB/ON only), and IBD-related abdominal surgery. Hospitalizations and ED visits were counted cumulatively from 6-60 months after diagnosis. The risk of first surgery was defined during the same 6-60 month period. Mixed-effects meta-analysis was used to pool results across centres. Heterogeneity among centres was quantified using I² (variation in pooled event rates between centres) and τ (standard deviation of the true event rates). R² quantified the residual heterogeneity in outcomes not attributable to among-province variation.

Result(s)

We identified 3777 incident cases of pediatric IBD, 2936 (78%) of which were treated at 8 pediatric centres. The number of hospitalizations was 0.67 (95% CI 0.56-0.79) per person with high between-centre heterogeneity (I² 84%, τ 0.1556). Provincial differences accounted for 93% of heterogeneity across centres (residual heterogeneity: I² 29%, τ 0.0412). Hospitalizations were less frequent in AB than other provinces (0.43 vs. 0.72-0.78). Children averaged 1.94 IBD-related ED visits, with significant heterogeneity (I² 99%, τ 1.33) with 99.7% of heterogeneity attributable to among-province differences (residual heterogeneity: I² 32%; τ 0.074). Mean ED visits were 1.1 visits in ON (I² 39%) and 3.7 in AB (I² 0%). Intestinal resection was required by 12% (95% CI 0.08-0.15) of Crohn’s patients with high among-centre heterogeneity (I² 81%, τ 0.042), and low (19%) heterogeneity due to provincial differences (residual heterogeneity: I² 76%; τ 0.039). Colectomy was required by 12% (95% CI 10-14) of children with ulcerative colitis (UC) with no between-centre heterogeneity (I² 0%, τ 0).

Conclusion(s)

There is a high degree of between-province (but not between-centre, within province) variability in health services utilization among children with IBD. There was significant between-centre variability in surgery rates for Crohn’s, but not colectomy for UC. Differences in patient characteristics or provincial health systems may be more important predictors of variation in care. Surgery for Crohn’s disease may be a target for inter-centre quality improvement efforts.

Please acknowledge all funding agencies by checking the applicable boxes below

CCC

Disclosure of Interest

None Declared

A189 EMERGENCY DEPARTMENT UTILIZATION AND RISK OF INTESTINAL RESECTION IS LOWER AMONG CHILDREN DIAGNOSED WITH INFLAMMATORY BOWEL DISEASE BEFORE 10 YEARS OF AGE: A MULTIPROVINCE POPULATION-BASED COHORT STUDY

Background

In Canada, the incidence of inflammatory bowel disease (IBD) is increasing faster among those <10 years (y) of age than in any other age group. Understanding the health services burden of IBD in this population is important for health system planning.

Purpose

To compare healthcare utilization and risk of surgery among children diagnosed with IBD across age groups defined by the Paris Classification (A1a: <10y; A1b: 10 to <16y) across 5 Canadian provinces.

Method

Children diagnosed with IBD <16 years of age were identified from health administrative data using validated algorithms in Alberta, Manitoba, Nova Scotia, Ontario, and Québec. Negative binomial regression models were used to compare (1) the pre-diagnosis frequency of health services utilization (outpatient, emergency department (ED), and hospitalization) using diagnostic codes suggestive of future IBD and (2) the annual post-diagnosis frequency of IBD-specific and IBD-related (signs, symptoms, and extra-intestinal manifestations of IBD) visits among children diagnosed <10y (A1a) and 10 to <16y (A1b). Cox proportional hazard models compared the risk of surgery (identified with validated procedure codes) across age groups. All regression models were adjusted for sex, rural/urban residence, and mean neighbourhood income quintile. Province-specific event counts (all ages combined) and models (comparing age groups; reference: A1b [10 to <16y]) were pooled using random-effects meta-analysis.

Result(s)

Among 5124 children with IBD (1165 [23%] were <10y at diagnosis), the mean number of pre-diagnosis healthcare encounters was 1.0 (95% CI 0.38 to 1.68, I²=99.6%). The mean annual post-diagnosis number of IBD-specific outpatient visits was 3.2 (95% CI 1.9-4.4, I²=99.6%); hospitalizations, 0.19 (95% CI 0.17-0.21, I²=74%); ED visits, 0.17 (95% CI 0.19-0.39, I²=99%). The mean annual post-diagnosis number of IBD-related outpatient visits was 3.9 (95% CI 2.3-5.5, I²=99.7%); hospitalizations, 0.21 (95% CI 0.19-0.23, I²=79%); ED visits, 0.29 (95% CI 0.19-0.39, I²=97%). Intestinal resection or colectomy within 5y of diagnosis occurred in 13% (95%CI 8-22, I²=93%) with Crohn’s disease (CD) and 16% (95% CI 14-18, I²=40%) with ulcerative colitis. IBD-specific ED visits (RR 0.70, 95% CI 0.50-0.97, I²=80) and the risk of intestinal resection in CD (HR 0.49, 95% CI 0.26-0.92, I²=40%) were significantly lower among children diagnosed <10y. There were no age-related differences in pre-diagnosis health services utilization or other post-diagnosis outcomes, including frequency of outpatient visits to a gastroenterologist.

Conclusion(s)

Health services utilization was generally similar for children diagnosed with IBD at <10y and between 10 and <16y, except for lower rates of IBD-specific ED visits and intestinal resection in children with CD. Further exploration of between-province differences, represented by the high statistical heterogeneity (I²) in the meta-analyses, is needed to understand sources of variation in care.

Please acknowledge all funding agencies by checking the applicable boxes below

CCC

Disclosure of Interest

E. Kuenzig: None Declared, H. Singh Consultant of: Amgen Canada, Bristol-Myers Squibb Canada, Sandoz Canada, Roche Canada, Takeda Canada and Guardant Health, A. Bitton: None Declared, G. Kaplan Grant / Research support from: Ferring, Consultant of: AbbVie, Janssen, Pfizer, Amgen, Sandoz, Pendophram, and Takeda, Speakers bureau of: AbbVie, Janssen, Pfizer, Amgen, Sandoz, Pendophram, and Takeda, M. Carroll: None Declared, A. Otley Grant / Research support from: Research support: AbbVie Global. Research site: AbbVie, Pfizer, Eli-Lily, Janssen, Consultant of: AbbVie Canada, T. Stukel: None Declared, S. Spruin: None Declared, A. Griffiths Grant / Research support from: Abbvie, Consultant of: Abbvie, Amgen, BristolMyersSquibb, Janssen, Lilly, Takeda, Speakers bureau of: Abbvie, Janssen, Takeda, D. Mack: None Declared, K. Jacobson Grant / Research support from: Abbvie Canada and Janssen Canada, Consultant of: Abbvie Canada, Janssen Canada, Merck Canada and Mylan Pharmaceuticals, Speakers bureau of: Abbvie Canada and Janssen Canada, G. Nguyen: None Declared, L. Targownik Grant / Research support from: Janssen Canada, Consultant of: AbbVie Canada, Sandoz Canada, Takeda Canada, Merck Canada, Pfizer Canada, Janssen Canada, and Roche Canada, W. El-Matary Consultant of: Abbvie and MERCK, Speakers bureau of: Abbvie and MERCK, E. Benchimol Consultant of: McKesson Canada, Dairy Farmers of Ontario (unrelated to medications used to treat inflammatory bowel disease)

A47 MICROBIAL FUNCTIONS AS BIOMARKERS OF PRO-INFLAMMATORY RESPONSE TO SELECT DIETARY FIBERS IN IBD

Background

Dietary fibers are not digested in the bowel; they are fermented by microbes, typically promoting gut health. However, IBD patients experience sensitivity to consumption of fibers. Our previous findings offered the first mechanistic evidence demonstrating that unfermented dietary β-fructans (inulin and FOS) can induce pro-inflammatory cytokines in a subset of pediatric IBD colonic biopsies cultured ex vivo, and in the SYNERGY-1 (β-fructan) clinical study of adult remission UC patients. Incubating FOS with whole-microbiota intestinal washes from non-IBD or remission IBD patients improved fermentation and reduced pro-inflammatory responses, but not from patients with active disease. Fibre-induced immune responses correlated with microbe functions, luminal metabolites, and fibre avoidance.

Aims

Here we aimed to expand on our findings and define the role of microbial functions in mediating host response to β-fructans.

Methods

Colonic biopsies cultured ex vivo and cell lines in vitro were incubated with FOS (5g/L), or fermentation supernatants (24hr anaerobic fermentation). Immune responses (cytokine secretion [ELISA/MSD] and expression [qPCR]) were assessed. Taxonomic classification of microbial fermentation cultures was conducted with Kraken2 and metabolic profiling by HUMAnN2. HPLC and gas chromatography volatile fatty acid (CG-VFA) analysis were used to identify concentrations of remaining fibre and SCFAs following anaerobic fermentation.

Results

7 microbial enzymes were identified to be predictive of cytokine (IL-1β, IL23, IL-5, IL-8, MIP-1α) secretion in ex vivo colonic biopsies from pediatric Crohn disease (CD; n=38), ulcerative colitis (UC; n=20), and non-IBD (n=21) patients, in response to β-fructans; their use as biomarkers of response was determined in patient stool from the SYNERGY-1 clinical study cohort. Fermentation of FOS by whole-microbe intestinal washes from only non-IBD or remission IBD patients reduced cytokine secretion, and our findings demonstrate that this was due to a combination of reduction of β-fructan present and production of a precise combination of anti-inflammatory SCFAs.

Conclusions

Our findings suggest that intolerance and avoidance of fibers in select IBD patients is associated with the inability to ferment these fibers, mediated by altered microbial functions (enzymes), leading to worsened inflammation. Data indicate that gut microbial function, not composition, predicts patient pro-inflammatory response to β-fructans, supporting our hypothesis that overall community function impacts fibre fermentation and affects associated pro-inflammatory effects. Our work highlights select disease state scenarios in which administration of fermentable fibers should be avoided and tailored dietary interventions considered.

Funding Agencies

CIHRWeston Foundation, Mitacs

The Phenotypic Spectrum of New-onset IBD in Canadian Children of South Asian Ethnicity: A Prospective Multi-Centre Comparative Study

BACKGROUND

Canadian-born children of South Asian [SA] ethnicity develop inflammatory bowel disease [IBD] at similar rates to those among Caucasian children. We evaluated the variation in phenotypic spectrum of IBD in SA and Caucasian children in a national paediatric inception cohort of new-onset IBD.

METHODS

Patients aged <17 years, enrolled in a Canadian nationwide inception cohort study, were included. Baseline demographic and IBD phenotypic features were compared between SA and Caucasian children. Longitudinal outcomes through 18 months of follow-up were compared matched by propensity scores.

RESULTS

Of 1156 children enrolled over 2014 to 2019, 623 were Caucasian [98% and 88% parents Canadian born] and 114 SA [79% Canadian born, 87% parents SA born]. Fewer SAs have a first-degree relative with IBD, 6% vs 19% in Caucasians, p = 0.002. SAs present at a younger age, median age 11.4 years (interquartile range [IQR] 9.2-14.3) vs 13 years [IQR 10.9-15 years], p = 0.03 and more commonly with a UC/IBD-U [ulcerative colitis/IBD-unclassified] subtype [ratio of UC/IBD-U to CD 1.2:1 vs 1:1.8 for Caucasians, p <0.001]. Additionally, a greater proportion of SA CD patients present with colonic-only disease [colonic-only CD/UC/IBD-U in SAs 67% vs 57% for Caucasians, p = 0.001], and among those with CD, colonic CD in SAs 31% vs 23% in Caucasians, p = 0.20]. Perianal fistulising disease was also numerically more common in SAs (14 [27%] vs 64 [18%], p = 0.06]. Adjusting for differences in phenotypic presentation, anti-tumour necrosis factor [TNF] exposure, and time to initiation was similar, and two-thirds of children, whether anti-TNF exposed or naïve, were in corticosteroid-free clinical remission at 18 months irrespective of ethnicity.

CONCLUSIONS

The phenotypic spectrum of new-onset IBD in SA children differs from that of Caucasian children, but treatment and clinical course are similar within phenotypic subgroups.

A33 MEALTIME SUPPORT: A PILOT COHORT STUDY OF AN EFFECTIVE, COST-SAVING OUTPATIENT HUNGER-BASED FEEDING PROGRAM FOR TUBE DEPENDENCY

Background

Tube dependency is an under recognized complication of long-term enteral feeding in young children. Many children struggle to progress to full oral feeds even with sufficient oral motor skills and swallowing ability. Tube dependency greatly impacts the quality of life of children and families and is a significant burden to the health care system. Economic challenges, increased burden of care and psychosocial issues all reinforce the need for timely tube removal.

Aims

We aimed to examine the efficacy of a multidisciplinary child-led, hunger-based approach called “Mealtime Support” at the Stollery Children’s Hospital in Edmonton. Nutritional outcomes, parental satisfaction and cost implications were evaluated. As a secondary aim we sought to determine the rates of gastrostomy tube insertions in the pediatric age range across Canada as a potential indicator of increasing need for long term tube feeding, hence the need for cost effective tube weaning programs to be developed in Canada.

Methods

The ambulatory program was delivered 2–3 times a day, for 2 weeks, by an occupational therapist and dietitian, under medical supervision. Hunger was promoted by reducing tube fed calories by 80% prior to commencement. Top-up tube feeds were given immediately after feeding sessions if needed. Caregivers completed 12-question subjective surveys pre and post intervention. Micro-costing methods compared costs between the program and ongoing tube feeding. The number of pediatric hospital admissions and gastrostomy tube insertions from 2008–2019, per province, was collected from the Canadian Institute for Health Information (CIHI).

Results

From 2016 - 2017, 6 children who had been tube fed from 7 to 21 months in total were enrolled and 5 completed the program. At 1-month post intervention, 4/5 of the children were 100% orally fed. Parents reported improvement in mealtime struggles (p-value = 0.005), reduction in worry about their child’s eating (p-value = 0.005) and improvement in their child’s appetite/variety foods eaten (p-value = 0.004). Over a year the potential cost savings were estimated at $42,471.24. By 6-months, all feeding tubes were removed. Based on the CIHI data, the number of gastrostomy tubes inserted per 100,000 children varied significantly between provinces, but highest in Nova Scotia, Saskatchewan and Alberta with increases seen from 2008–2018.

Conclusions

The transition from tube feeding to oral feeding is difficult for children who are tube dependent and poses several economic and psychosocial challenges. Mealtime Support was safe and successful in reducing tube dependency and cost-effective compared to no intervention or hospital based programs. There is a need to develop and fund Canadian outpatient feeding programs.

Funding Agencies

The Stollery Children’s Foundation

A41 LINKING THE APPENDIX MICROBIOME WITH INFLAMMATORY BOWEL DISEASES

Background

The appendix has been shown to be associated with the pathogenesis and health outcomes in inflammatory bowel diseases (IBD). Specifically, post appendectomy patients are found to be protective for development of ulcerative colitis (UC); however, mechanisms of appendix involvement remain unclear.

Aims

Our aim is to examine the microbes associated with the appendix of IBD patients by identifying changes in microbe abundance and interactions with the host in patient cecum luminal washes, collected from close to the neck of the appendix during colonoscopy. We hypothesize that microbes originating in the appendix of IBD patients, through interactions with host-cells in a disrupted microenvironment in the appendix, could contribute to the pathogenesis of UC.

Methods

Shotgun metagenomics was performed on cecum luminal washes of IBD patients and non-IBD controls. Guided by the metagenomic results, we performed gentamicin protection assays to determine virulence of microbes of interest using Caco2 intestinal epithelial cells. Co-culturing them with human host cells in vitro will identify relevant disease-related factors secreted by microbes and/or host cells using disease models and multiomic approaches.

Results

Shotgun metagenomics results showed that among numerous microbes, several bacterial taxa demonstrated differences in abundance between IBD and non-IBD patients: Flavonifractor, Bacteroide fragilis, and Alistipes represented 8%, 10%, and 21% abundance respectively in non-IBD patients, while in IBD patients they were present below 0.1%. In contrast, Bacteroide vulgatus and Escherichia coli were about 9% and 69% respectively, in IBD patients, whilst they were present at 1.7% and 1.2% in non-IBD patients, respectively. Following our recent method for validating pathobionts (Armstrong, 2019), we used the gentamicin protection assays to assess the ability of these bacteria to invade Caco2 cells, demonstrating a correlation between invasive potential of these microbes and cecal abundance. Mechanistic experiments, aimed at identifying factors impacting invasion, are in progress.

Conclusions

These results provide preliminary, but promising findings suggesting mechanisms by which microbiota possibly originating in the appendix may show altered virulence, which may be related to changes in the appendix microenvironment in IBD. With plans in place to increase our patient cohort we will validate these findings. Identifying and profiling these microbes in IBD patients can help improve the understanding of mechanisms underlying microenvironment changes within the appendix and the gut, which could shed light on the role of the appendix in IBD pathogenesis and clarify how microbes drive inflammation in IBD.

Funding Agencies

CIHR

A31 COMPLEX ROLE OF DIETARY FIBERS IN IBD: MICROBES MEDIATE FIBER-INDUCED INFLAMMATION

Background

Dietary fibers pass through the bowel undigested and are fermented within the intestine by microbes, typically promoting gut health. However, many IBD patients describe experiencing sensitivity to fibers. β-glucan, found on the surface of fungal cells during fungal infection, has been shown to bind to fiber receptors, such as Dectin-1, on host immune cells, resulting in a pro-inflammatory response. These fungal fibres share properties with dietary fibers.

Aims

As an altered gut microbial composition has been associated with IBD, we hypothesized that the loss of fiber-fermenting microbes populating the gut in IBD could lead to dietary fibers not being efficiently broken down into their beneficial biproducts (e.g. short chain fatty acids; SCFA), resulting in binding of intact fibers to pro-inflammatory host cell receptors.

Methods

Immune and epithelial cell lines and colonic biopsies cultured ex vivo were incubated with oligofructose or inulin (5g/L), or pre-fermented fibers (24hr anaerobic fermentation). Immune responses were measured by cytokine secretion (ELISA), and expression (qPCR). Barrier integrity was measured by transepithelial resistance (TEER). Food frequency questionnaire (FFQ) data of patient fiber consumption were correlated with gut microbes (shotgun sequencing) and immune responses to fiber in patient biopsies.

Results

Unfermented oligofructose induced IL-1β secretion in leukocytes (macrophage, T cell, neutrophil) and in colon biopsies from pediatric Crohn disease (CD; n=38) and ulcerative colitis (UC; n=20) patients cultured ex vivo, but not in non-IBD patients (n=21). IL-1β secretion was greater in patients with more severe disease. Pre-fermentation of oligofructose by whole-microbe intestinal washes from non-IBD patients or remission patients reduced secretion of IL-1β, while whole microbe intestinal washes from severe IBD patients were unable to ferment oligofructose or reduce cytokine secretion. Fiber effects on IL-1β secretion in biopsies positively correlated with effects on barrier integrity in T84 cells. Fiber-associated immune responses in patient biopsies cultured ex vivo (ELISA) correlated with fiber avoidance (FFQ) and gut microbiome (sequencing) in matching patient samples.

Conclusions

Our findings demonstrate that intolerance and avoidance of prebiotic fibers in select IBD patients is associated with the inability to ferment these fibers, leading to pro-inflammatory immune responses and intestinal barrier disruption. This highlights select disease state scenarios, in which administration of fermentable fibers should be avoided and tailored dietary interventions should be considered in IBD patients.

Funding Agencies

CIHRWeston Foundation

Characterisation of the T-cell response to Ebola virus glycoprotein amongst survivors of the 2013-16 West Africa epidemic

Zaire ebolavirus (EBOV) is a highly pathogenic filovirus which can result in Ebola virus disease (EVD); a serious medical condition that presents as flu like symptoms but then often leads to more serious or fatal outcomes. The 2013-16 West Africa epidemic saw an unparalleled number of cases. Here we show characterisation and identification of T cell epitopes in surviving patients from Guinea to the EBOV glycoprotein. We perform interferon gamma (IFNγ) ELISpot using a glycoprotein peptide library to identify T cell epitopes and determine the CD4+ or CD8+ T cell component response. Additionally, we generate data on the T cell phenotype and measure polyfunctional cytokine secretion by these antigen specific cells. We show candidate peptides able to elicit a T cell response in EBOV survivors and provide inferred human leukocyte antigen (HLA) allele restriction. This data informs on the long-term T cell response to Ebola virus disease and highlights potentially important immunodominant peptides.

A26 PEDIATRIC-ONSET INFLAMMATORY BOWEL DISEASE INCREASES THE RISK OF VENOUS THROMBOEMBOLISM: A CANGIEC POPULATION-BASED STUDY

Background

Inflammatory bowel disease (IBD) increases the risk of venous thromboembolism (VTE) in patients of all ages but the risk of VTE among Canadian children with IBD has not previously been investigated.

Aims

Report the incidence of VTE and subtypes pulmonary embolism (PE) and deep vein thrombosis (DVT) in children with and without IBD.

Methods

Children diagnosed with IBD &lt;16y were identified from health administrative data in Ontario (2002–2014), Alberta (2007–2015), and Nova Scotia (2002–2012) using validated algorithms and matched by age and sex to children without IBD (1:5 ratio). Validated ICD-10 codes identified hospitalizations for incident VTE (DVT, PE, and sinovenous thrombosis). Province-specific 5-year cumulative incidence per 1000 person-years (PY) of VTEs were pooled using fixed-effects generalized linear mixed models with a Freeman-Tukey double arcsine transformation. Incidence rate ratios (IRR) within 5 years of diagnosis were pooled using fixed-effects generalized linear mixed models to compare children with and without IBD, and children with Crohn’s disease (CD) and ulcerative colitis (UC).

Results

3127 children with IBD (1826 CD; 1045 UC) were matched to 15,635 children without IBD. The cumulative incidence of VTE within 5 years of IBD diagnosis was 2.8 (95% CI 2.1–3.8) per 1000 PYs compared to 0.13 (95% CI 0.07–0.24) per 1000 PYs in children without IBD (Table). The 5-year cumulative incidences of VTE, DVT, and PE were significantly higher in children with IBD than in children without IBD (VTE: IRR 21.44, 95% CI 10.73–42.82; DVT: IRR 25.15, 95% CI 11.12–56.89; PE: IRR 4.01, 95% CI 1.22–13.18). Compared to UC patients, children with CD were at lower risk of VTE (IRR 0.53, 95% CI 0.29–0.96) and numerically, but not statistically, lower risk of DVT (IRR 0.59, 95% CI 0.30–1.14).

Conclusions

Although VTEs are relatively rare among children with IBD, these children are at much greater risk than children without IBD. Gastroenterologists caring for these patients should be cognizant of VTE risk and provide appropriate prophylaxis to those at high risk of VTE.

Funding Agencies

CCC

A217 DEFINING THE RELATIONSHIP BETWEEN DIETARY FIBERS AND INFLAMMATORY RESPONSE IN PEDIATRIC INFLAMMATORY BOWEL DISEASES

Background

The incidence rates of inflammatory bowel diseases (IBD), Crohn disease (CD) and ulcerative colitis (UC) are increasing in children. Although the etiology of IBD is poorly understood, factors such as urban lifestyle, diet, increased hygiene, and reduced microbial biodiversity have been implicated as risk factors. Compositional changes and reduced microbial biodiversity have been linked to therapy failure in pediatric IBD. Non-digestible dietary carbohydrates, such as fiber, must undergo fermentation by gut microbiota within the large bowel, producing short chain fatty acids (SCFAs). Animal studies have shown that dietary fibers can inhibit IBD-associated inflammation, and clinical trials have demonstrated that SCFAs can prevent intestinal atrophy and allow for tissue recovery in IBD patients. In disease settings with altered gut microbes, fermentation of dietary fibers may be greatly affected. Unfermented fibers interact with receptors on host immune cells and can induce proinflammatory immune response, production of oxygen species and inflammation, or an inhibition of proinflammatory receptors.

Aims

Based on this rationale, we hypothesize that dysbiosis in the IBD gut leads to decreased fiber fermenting microbes, resulting in reduced SCFA production. This contributes to increased inflammatory responses both in in vitro cell lines, as well as ex vivo patient biopsies. Because intact fibers can bind to host cell receptors, this promotes inflammatory response and continued dysbiosis.

Methods

To assess effects of intact fiber on immune cells, macrophage and T-cell in vitro cultures were used to measure cytokine response to inulin (5mg/mL) and oligofructose (5mg/mL) through ELISAs/qPCR. These cell lines and ex vivo patient biopsies were treated with whole fibers and IL-1β secretion was measured. Fibers were also pre-fermented with microbes of interest or whole microbe patient intestinal washes and used to treat cell lines and patient biopsies.

Results

Whole fibers induced a pro-inflammatory response in macrophage cells but not T-cells, and this pro-inflammatory response was mitigated by pre-fermenting the fibers. Intestinal washes from severe IBD patients were unable to successfully ferment oligofructose or reduce fiber-associated inflammation in macrophage cell lines, whereas washes from remission or non-IBD samples reduced IL-1β. Oligofructose was found to increase IL-1β secretion in UC and CD patient biopsies, but not in non-IBD specimens. This increase was also correlated with disease severity.

Conclusions

These results indicate that a lack of fiber-fermenting microbes and presence of whole fibers can lead to pro-inflammatory responses, both in cell lines and patient biopsies. However, the presence of appropriate fermenting microbes can reduce fiber-associated inflammation.

Funding Agencies

CCCWCHRI, Weston Foundation

A64 HOSPITALIZATION IN INFLAMMATORY BOWEL DISEASE: A POPULATION-BASED COMPARISON OF DEFINITIONS

Background

Most administrative studies of hospitalization in inflammatory bowel disease (IBD) use two definitions: IBD in any diagnostic position (IBD-ANY), and IBD as the most responsible diagnostic (IBD-MRD). There is a third less commonly used definition: total hospitalization; this definition captures all hospitalizations of prevalent IBD patients and therefore it can give a more realistic picture of the burden of IBD.

Aims

To compare differing definitions (total, IBD-ANY, and IBD-MRD) of hospitalizations.

Methods

A previously defined population-based IBD prevalent cohort for Alberta (n=30,698) was used to pull all hospital admissions from the Discharge Administrative Database (DAD; 2002–2015). Three hospitalization definitions were used: i. Total (all hospitalizations of prevalent cohort independent of presence of code for IBD); ii. IBD-ANY (code for IBD [K50.x; K51.x] contained in any diagnosis field); and, iii. IBD-MRD (most responsible diagnosis was IBD). Age- and sex- standardized rates (2015 Canadian population) were calculated using the prevalent population. Log-linear regression was performed to calculate Average Annual Percentage Change (AAPC) with associated 95% confidence intervals (CI) of each type of hospitalization. We assessed the top five most common most-responsible diagnosis codes for hospitalizations that were contained in the total hospitalizations but not an IBD-ANY hospitalization.

Results

From 2002 to 2015, 63.5% of IBD prevalent patients in AB had ≥1 hospitalization; 44.2% had ≥1 IBD-ANY hospitalization; 28.6% had ≥1 IBD-MRD hospitalization; and, 40.6% had a hospitalization that did not contain a code for IBD. All hospitalization rates decreased significantly over time. Of the top five most common most responsible diagnosis, contained in admissions that were not IBD-ANY, three were gastroenterological: i. K52.9 (non-infective gastroenteritis); ii. A09.9 (diarrhea and gastroenteritis of presumed infectious origin); and, iii. Z43.2 (attention to ileostomy).

Conclusions

Total hospitalizations is an important measure to report since accounting for all hospitalizations of IBD patients is necessary in order to allocate healthcare resources appropriately. To be able to ensure these patients receive the care they need we need to be able to accurately assess the true burden of IBD.

Funding Agencies

CIHR

A15 MICROBES MEDIATE FIBER-INDUCED INFLAMMATION IN IBD

Background

The etiology of inflammatory bowel diseases (IBD) remains unknown, although gut microorganisms and diet have been implicated. Dietary fibers pass through the bowel undigested and are fermented within the intestine by microbes, promoting gut health. However, many IBD patients describe experiencing sensitivity to fibres. Interestingly, fiber receptors on immune cells are able to interact with fibers typically found on the surface of fungal cells (which share properties with dietary fibers), for example, resulting in a paradoxical pro-inflammatory response.

Aims

As an altered microbial composition is a hallmark of IBD, we hypothesized that the loss of fiber fermenting-microbes populating the IBD gut could lead to dietary fibers not being efficiently broken down into their beneficial biproducts, resulting in binding of intact fibers to pro-inflammatory host cell receptors. This can ultimately drive pro-inflammatory responses and a microenvironment that promotes continued dysbiosis and increased pathogenicity of select microbes, as observed in IBD.

Methods

Fiber receptor expression gut was examined using immunohistochemistry and flow cytometry and demonstrated elevated receptor expression due to increased presence of immune cells in IBD patient biopsies. Cytokine secretion, in response to fiber (5mg/mL) or pre-fermented fibers, cultured with microbes of interest, was measured by ELISAs in cell lines in vitro and biopsy tissues cultured ex vivo.

Results

Whole-fibers induced pro-inflammatory cytokine production in macrophage, monocytes, and neutrophils. Specific microbes were capable of fermenting fiber, measured by gas chromatography. Pre-fermentation of fibers by these microbes reduced inflammatory cytokine production. The fiber oligofructose increased IL-1β in pediatric CD (n=44) and UC (n=29) biopsies cultured ex vivo but not in non-IBD (n=25). The increase was greater in patients with more severe disease. Pre-fermentation of oligofructose by bacteria reduced this secretion of IL-1β. Whole-microbe intestinal washes from severe IBD patients were unable to ferment oligofructose or reduce fiber-associated inflammation in macrophage cells compared to remission or non-IBD children. Statistical analysis of food frequency questionnaire (FFQ) data on fiber consumption demonstrated that fiber-associated inflammation in patient biopsies cultured ex vivo (ELISA and qPCR) correlated with fiber avoidance (FFQ).

Conclusions

Comparing in vitro findings to our patient FFQs, intestinal washes (microbe abundance), and detailed patient history will better define the relationship between microbes, dietary fibers, and gut inflammation in IBD. This will allow for tailored dietary intervention through dietary recommendations, prebiotic, and/or probiotic therapies.

Funding Agencies

CCCWeston Foundation, WCHRI

Metagenomic sequencing at the epicenter of the Nigeria 2018 Lassa fever outbreak

The 2018 Nigerian Lassa fever season saw the largest ever recorded upsurge of cases, raising concerns over the emergence of a strain with increased transmission rate. To understand the molecular epidemiology of this upsurge, we performed, for the first time at the epicenter of an unfolding outbreak, metagenomic nanopore sequencing directly from patient samples, an approach dictated by the highly variable genome of the target pathogen. Genomic data and phylogenetic reconstructions were communicated immediately to Nigerian authorities and the World Health Organization to inform the public health response. Real-time analysis of 36 genomes and subsequent confirmation using all 120 samples sequenced in the country of origin revealed extensive diversity and phylogenetic intermingling with strains from previous years, suggesting independent zoonotic transmission events and thus allaying concerns of an emergent strain or extensive human-to-human transmission.

A Crimean-Congo hemorrhagic fever (CCHF) viral vaccine expressing nucleoprotein is immunogenic but fails to confer protection against lethal disease

Crimean-Congo Hemorrhagic Fever (CCHF) is a severe tick-borne disease, endemic in many countries in Africa, the Middle East, Eastern Europe and Asia. Between 15–70% of reported cases are fatal with no approved vaccine available. In the present study, the attenuated poxvirus vector, Modified Vaccinia virus Ankara, was used to develop a recombinant candidate vaccine expressing the CCHF virus nucleoprotein. Cellular and humoral immunogenicity was confirmed in 2 mouse strains, including type I interferon receptor knockout mice, which are susceptible to CCHF disease. Despite the immune responses generated post-immunisation, the vaccine failed to protect animals from lethal disease in a challenge model.

The continued emergence of hantaviruses: isolation of a Seoul virus implicated in human disease, United Kingdom, October 2012

Following a suspected case of hantavirus in a patientsuffering from acute kidney injury, rodents fromthe patient’s property in Yorkshire and the Humber,United Kingdom (UK) were screened for hantaviruses.Hantavirus RNA was detected via RT-PCR in two Rattusnorvegicus. Complete sequencing and phylogeneticanalysis established the virus as a Seoul hantavirus,which we have provisionally designated as strainHumber. This is the first hantavirus isolated from wildrodents in the UK and confirms the presence of a pathogenicSeoul virus in Europe.

The continued emergence of hantaviruses: isolation of a Seoul virus implicated in human disease, United Kingdom, October 2012

Binary file ES_Abstracts_Final_ECDC.txt matches

Frequency of adverse reactions to first- and second-line anti-tuberculosis chemotherapy in a Korean cohort

OBJECTIVE

To determine the frequency of and risk factors for major adverse drug reactions (MADRs) associated with anti-tuberculosis treatment at a tuberculosis (TB) referral hospital in the Republic of Korea.

METHODS

Data from an ongoing natural history cohort study were analyzed for permanent regimen changes due to adverse drug reactions and confirmed by chart review.

RESULTS

Among 655 subjects, there were 132 MADRs in 112 (17%) subjects. The most common MADRs were gastrointestinal (n = 53), musculoskeletal (n = 22), psychiatric (n = 10), visual (n = 9) and peripheral neuropathic (n = 8). MADRs were more frequent in subjects being treated with second-line regimens (16%) compared to first-line regimens (2.5%). Drugs frequently associated with MADRs were amikacin (3/10, 30%), linezolid (8/29, 28%), para-aminosalicylic acid (47/192, 24%), pyrazinamide (31/528, 5.8%), macrolides (2/44, 4.5%) and cycloserine (12/272, 4.4%). Fluoroquinolones accounted for a single MADR (1/377, 0.003%), despite widespread usage. In multivariate analysis, infection with multi- or extensively drug-resistant disease and previous history of anti-tuberculosis treatment were risk factors for MADR, with adjusted hazard ratios of respectively 2.2 (P = 0.02) and 1.6 (P = 0.04).

CONCLUSION

MADRs are common during anti-tuberculosis chemotherapy in this population, occurring in more than one in six subjects. New and less toxic agents to treat drug-resistant TB are urgently needed.

Survival and predictors of outcomes in non-HIV-infected patients with extensively drug-resistant tuberculosis

SETTING

A tuberculosis (TB) referral hospital in South Korea.

OBJECTIVE

To evaluate predictors of treatment outcomes and survival among non-human immunodeficiency virus (HIV) infected patients with extensively drug-resistant TB (XDR-TB).

DESIGN

Patients who were diagnosed with XDR-TB at the National Masan Tuberculosis Hospital from January 2001 to December 2005 were included in this study. We conducted a retrospective review of their medical records and mortality data.

RESULTS

A total of 176 non-HIV-infected patients with XDR-TB were included. TB-related mortality was 48% (84/176), and the median survival time from the diagnosis date of XDR-TB was 51 months (range 0-127, 95%CI 32.53-69.47). Cure and treatment completion were classified as favourable outcome and treatment failure, death during treatment and default as poor outcome. Previous TB treatment with second-line drugs (aOR 2.76, 95%CI 1.02-7.44) and cavitary disease (aOR 3.01, 95%CI 1.12-8.08) were independent risk factors for poor outcome. Use of linezolid (aOR 0.10, 95%CI 0.01-0.69) and surgical resection (aOR 0.18, 95%CI 0.04-0.78) were associated with favourable outcome.

CONCLUSION

There was high mortality in non-HIV-infected patients with XDR-TB at a TB referral hospital in South Korea. Adjunctive surgical treatment and linezolid improved the outcome for selected patients with XDR-TB.

Generation of recombinant vaccinia viruses

This unit first describes how to infect cells with vaccinia virus and then transfect them with a plasmid-transfer vector to generate a recombinant virus. Methods are also presented for purifying vaccinia virus and for isolating viral DNA, which can be used during transfection. Also presented are selection and screening methods used to isolate recombinant viruses and a method for the amplification of recombinant viruses. Finally, a method for live immunostaining that has been used primarily for detection of recombinant modified vaccinia virus Ankara (MVA) is presented.

Generation of recombinant vaccinia viruses

This unit first describes how to infect cells with vaccinia virus and then transfect them with a plasmid-transfer vector to generate a recombinant virus. Methods are also presented for purifying vaccinia virus and for isolating viral DNA, which can be used during transfection. Also presented are selection and screening methods used to isolate recombinant viruses and a method for the amplification of recombinant viruses. Finally, a method for live immunostaining that has been used primarily for detection of recombinant modified vaccinia virus Ankara (MVA) is presented.

Preparation of cell cultures and vaccinia virus stocks

This unit describes the maintenance of cell lines used with vaccinia virus, both in monolayer cultures and in suspension. The suspended cell culture is then used in the preparation of vaccinia virus stocks. The preparation of chick embryo fibroblasts (CEF) is also presented for use in the production of the highly attenuated and host range-restricted modified vaccinia virus Ankara (MVA) strain of vaccinia virus. Additionally, support protocols are presented for the titration of standard and MVA vaccinia virus stocks.

In vivo evaluation of an EIAV vector for the systemic genetic delivery of therapeutic antibodies

Lentiviral-based vectors hold great promise as gene delivery vehicles for the treatment of a wide variety of diseases. We have previously reported the development of a nonprimate lentiviral vector system based on the equine infectious anaemia virus (EIAV), which is able to efficiently transduce dividing and nondividing cells both in vitro and in vivo. Here, we report on the application of EIAV vectors for the systemic delivery of an antibody fusion protein designed for the treatment of cancer. The therapeutic potential of a single chain antibody against the tumour-associated antigen, 5T4, fused to immune enhancer moieties has been demonstrated in vitro and here we evaluate the genetic delivery of a 5T4 scFv fused to B7.1 (scFvB7) using an EIAV vector. The kinetics and concentration of protein produced following both intravenous (i.v.) and intramuscular (i.m.) administration was determined in immune competent adult mice. In addition, the immune response to the EIAV vector and the transgene were determined. Here, we show that a single injection of EIAV expressing scFv-B7 can give rise to concentrations of protein in the range of 1-5 microg/ml that persist in the sera for more than 50 days. After a second injection, concentrations of scFv-B7.1 rose as high as 20 microg/ml and levels greater than 2 microg/ml were present in the sera of all mice injected i.v. after 210 days despite the detection of antibodies against both the transgene and viral envelope for the duration of this study. These results demonstrate the potential of EIAV as a gene therapy vector for long-term production of therapeutic recombinant proteins.

Preparation of cell cultures and vaccinia virus stocks

This unit describes the maintenance of cell lines used with vaccinia virus, both in monolayer cultures and in suspension. The suspended cell culture is then used in the preparation of vaccinia virus stocks. The preparation of chick embryo fibroblasts (CEF) is also presented for use in the production of the highly attenuated and host range-restricted modified vaccinia virus Ankara (MVA) strain of vaccinia virus. Additionally, support protocols are presented for the titration of standard and MVA vaccinia virus stocks.

Isolation of a high affinity scFv from a monoclonal antibody recognising the oncofoetal antigen 5T4

The oncofoetal antigen 5T4 is a 72 kDa glycoprotein expressed at the cell surface. It is defined by a monoclonal antibody, mAb5T4, that recognises a conformational extracellular epitope in the molecule. Overexpression of 5T4 antigen by tumours of several types has been linked with disease progression and poor clinical outcome. Its restricted expression in non-malignant tissue makes 5T4 antigen a suitable target for the development of antibody directed therapies. The use of murine monoclonal antibodies for targeted therapy allows the tumour specific delivery of therapeutic agents. However, their use has several drawbacks, including a strong human anti-mouse immune (HAMA) response and limited tumour penetration due to the size of the molecules. The use of antibody fragments leads to improved targeting, pharmacokinetics and a reduced HAMA. A single chain antibody (scFv) comprising the variable regions of the mAb5T4 heavy and light chains has been expressed in Escherichia coli. The addition of a eukaryotic leader sequence allowed production in mammalian cells. The two 5T4 single chain antibodies, scFv5T4WT19 and LscFv5T4, described the same pattern of 5T4 antigen expression as mAb5T4 in normal human placenta and by FACS. Construction of a 5T4 extracellular domain-IgGFc fusion protein and its expression in COS-7 cells allowed the relative affinities of the antibodies to be compared by ELISA and measured in real time using a biosensor based assay. MAb5T4 has a high affinity, K(D)=1.8x10(-11) M, as did both single chain antibodies, scFv5T4WT19 K(D)=2.3x10(-9) M and LscFv5T4 K(D)=7.9x10(-10) M. The small size of this 5T4 specific scFv should allow construction of fusion proteins with a range of biological response modifiers to be prepared whilst retaining the improved pharmacokinetic properties of scFvs.

Vaccination with a recombinant vaccinia virus encoding a "self" antigen induces autoimmune vitiligo and tumor cell destruction in mice: requirement for CD4(+) T lymphocytes

Many human and mouse tumor antigens are normal, nonmutated tissue differentiation antigens. Consequently, immunization with these "self" antigens could induce autoimmunity. When we tried to induce immune responses to five mouse melanocyte differentiation antigens, gp100, MART-1, tyrosinase, and tyrosinase-related proteins (TRP) 1 and TRP-2, we observed striking depigmentation and melanocyte destruction only in the skin of mice inoculated with a vaccinia virus encoding mouse TRP-1. These mice rejected a lethal challenge of B16 melanoma, indicating the immune response against TRP-1 could destroy both normal and malignant melanocytes. Cytotoxic T lymphocytes specific for TRP-1 could not be detected in depigmented mice, but high titers of IgG anti-TRP-1 antibodies were present. Experiments with knockout mice revealed an absolute dependence on major histocompatibility complex class II, but not major histocompatibility complex class I, for the induction of both vitiligo and tumor protection. Together, these results suggest that the deliberate induction of self-reactivity using a recombinant viral vector can lead to tumor destruction, and that in this model, CD4(+) T lymphocytes are an integral part of this process. Vaccine strategies targeting tissue differentiation antigens may be valuable in cancers arising from nonessential cells and organs such as melanocytes, prostate, testis, breast, and ovary.

Construction and characterization of a triple-recombinant vaccinia virus encoding B7-1, interleukin 12, and a model tumor antigen

BACKGROUND

Construction of recombinant viruses that can serve as vaccines for the treatment of experimental murine tumors has recently been achieved. The cooperative effects of immune system modulators, including cytokines such as interleukin 12 (IL-12) and costimulatory molecules such as B7-1, may be necessary for activation of cytotoxic T lymphocytes. Thus, we have explored the feasibility and the efficacy of inclusion of these immunomodulatory molecules in recombinant virus vaccines in an experimental antitumor model in mice that uses Escherichia coli beta-galactosidase as a target antigen.

METHODS

We developed a "cassette" system in which three loci of the vaccinia virus genome were used for homologous recombination. A variety of recombinant vaccinia viruses were constructed, including one virus, vB7/beta/IL-12, that contains the following five transgenes: murine B7-1, murine IL-12 subunit p35, murine IL-12 subunit p40, E. coli lacZ (encodes beta-galactosidase, the model antigen), and E. coli gpt (xanthine-guanine phosphoribosyltransferase, a selection gene). The effects of the recombinant viruses on lung metastases and survival were tested in animals that had been given an intravenous injection of beta-galactosidase-expressing murine colon carcinoma cells 3 days before they received the recombinant virus by intravenous inoculation.

RESULTS

Expression of functional B7-1 and IL-12 by virally infected cells was demonstrated in vitro. Lung tumor nodules (i.e., metastases) were reduced in mice by more than 95% after treatment with the virus vB7/beta/IL-12; a further reduction in lung tumor nodules was observed when exogenous IL-12 was also given. Greatest survival of tumor-bearing mice was observed in those treated with viruses encoding beta-galactosidase and B7-1 plus exogenous IL-12.

CONCLUSION

This study shows the feasibility of constructing vaccinia viruses that express tumor antigens and multiple immune cofactors to create unique immunologic microenvironments that can modulate immune responses to cancer.

Marker rescue of the host range restriction defects of modified vaccinia virus Ankara

The severely attenuated and host range (HR) restricted modified vaccinia virus Ankara (MVA) was derived by >500 passages in chick embryo fibroblasts, during which multiple deletions and mutations occurred. To determine the basis of the HR defect, we prepared cosmids from the parental vaccinia virus Ankara genome and transfected them into nonpermissive monkey BS-C-1 cells that had been infected with MVA. Recombinant viruses that formed macroscopic plaques were detected after transfections with DNA segments that mapped near the left end of the viral genome. Plaque-forming viruses, generated by transfections with four individual cosmids and one pair of minimally overlapping cosmids, were purified, and their HRs were evaluated in BS-C-1 cells, rabbit RK-13 cells, and human HeLa, MRC-5, and A549 cells. The acquisition of the K1L and SPI-1 HR genes and the repair of large deletions were determined by polymerase chain reaction or pulse-field gel electrophoresis of NotI restriction enzyme digests of genomic DNA. The following results indicated the presence of previously unrecognized vaccinia virus HR genes: (1) the major mutations that restrict HR are within the left end of the MVA genome because the phenotypes of some recombinants approached that of the parental virus, (2) acquisition of the K1L gene correlated with the ability of recombinant viruses to propagate in RK-13 cells but did not enhance replication in human or monkey cell lines, (3) acquisition of the SPI-1 gene correlated with virus propagation in A549 cells but not with the extent of virus spread in monkey or other human cell lines, (4) there are at least two impaired HR genes because rescue occurred with nonoverlapping or minimally overlapping cosmids and recombinant viruses with intermediate HRs were isolated, and (5) at least one of the new HR genes did not map within any of the major deletions because the size of the left terminal NotI fragment was not appreciably altered in some recombinant viruses.

Recombinant modified vaccinia virus Ankara-simian immunodeficiency virus gag pol elicits cytotoxic T lymphocytes in rhesus monkeys detected by a major histocompatibility complex class I/peptide tetramer

The utility of modified vaccinia virus Ankara (MVA) as a vector for eliciting AIDS virus-specific cytotoxic T lymphocytes (CTL) was explored in the simian immunodeficiency virus (SIV)/rhesus monkey model. After two intramuscular immunizations with recombinant MVA-SIVSM gag pol, the monkeys developed a Gag epitope-specific CTL response readily detected in peripheral blood lymphocytes by using a functional killing assay. Moreover, those immunizations also elicited a population of CD8+ T lymphocytes in the peripheral blood that bound a specific major histocompatibility complex class I/peptide tetramer. These Gag epitope-specific CD8+ T lymphocytes also were demonstrated by using both functional and tetramer-binding assays in lymph nodes of the immunized monkeys. These observations suggest that MVA may prove a useful vector for an HIV-1 vaccine. They also suggest that tetramer staining may be a useful technology for monitoring CTL generation in vaccine trials in nonhuman primates and in humans.

gp100/pmel 17 is a murine tumor rejection antigen: induction of "self"-reactive, tumoricidal T cells using high-affinity, altered peptide ligand

Many tumor-associated antigens are nonmutated, poorly immunogenic tissue differentiation antigens. Their weak immunogenicity may be due to "self"-tolerance. To induce autoreactive T cells, we studied immune responses to gp100/pmel 17, an antigen naturally expressed by both normal melanocytes and melanoma cells. Although a recombinant vaccinia virus (rVV) encoding the mouse homologue of gp100 was nonimmunogenic, immunization of normal C57BL/6 mice with the rVV encoding the human gp100 elicited a specific CD8(+) T cell response. These lymphocytes were cross-reactive with mgp100 in vitro and treated established B16 melanoma upon adoptive transfer. To understand the mechanism of the greater immunogenicity of the human version of gp100, we characterized a 9-amino acid (AA) epitope, restricted by H-2Db, that was recognized by the T cells. The ability to induce specific T cells with human but not mouse gp100 resulted from differences within the major histocompatibility complex (MHC) class I-restricted epitope and not from differences elsewhere in the molecule, as was evidenced by experiments in which mice were immunized with rVV containing minigenes encoding these epitopes. Although the human (hgp10025-33) and mouse (mgp10025-33) epitopes were homologous, differences in the three NH2-terminal AAs resulted in a 2-log increase in the ability of the human peptide to stabilize "empty" Db on RMA-S cells and a 3-log increase in its ability to trigger interferon gamma release by T cells. Thus, the fortuitous existence of a peptide homologue with significantly greater avidity for MHC class I resulted in the generation of self-reactive T cells. High-affinity, altered peptide ligands might be useful in the rational design of recombinant and synthetic vaccines that target tissue differentiation antigens expressed by tumors.

Host range and cytopathogenicity of the highly attenuated MVA strain of vaccinia virus: propagation and generation of recombinant viruses in a nonhuman mammalian cell line

Modified vaccinia virus Ankara (MVA), attenuated by over 500 passages in primary chick embryo fibroblasts (CEF), is presently being used as a safe expression vector. We compared the host ranges of MVA and the parental Ankara strain in CEF and 15 permanent cell lines. The cells could be grouped into three categories: permissive, semipermissive, and nonpermissive. For MVA, the permissive category consisted of primary CEF, a quail cell line derived from QT6, and the Syrian hamster cell line BHK-21. Only in BHK-21 cells did the virus yield approach that occurring in primary CEF. The semipermissive category included two African green monkey cell lines: BS-C-1 and CV-1. The nonpermissive category for MVA consisted of three human cell lines HeLa, 293, and SW 839; one rhesus monkey cell line FRhK-4; two Chinese hamster cell lines CHO and CHL; one pig cell line PK(15); and three rabbit cell lines RK13, RAB-9, and SIRC. The grouping for MVA with a restored K1L host range gene was similar except for the inclusion of RK13 cells among permissive lines. The grouping for the Ankara strain, however, was quite different with more permissive and semipermissive cell lines. Nevertheless, in cells that were permissive for MVA, the virus replicated to higher levels than Ankara, consistent with both positive and negative growth elements associated with the adaptation of MVA. The cell lines were also characterized according to their susceptibility to MVA-induced cytopathic effects, expression of a late promoter regulated reporter gene by an MVA recombinant, and stage at which virion morphogenesis was blocked. Finally, the permissive BHK-21 cell line was shown to be competent for constructing and propagating recombinant MVA, providing an alternative to primary CEF.

Poxviruses as expression vectors

Poxviruses are widely used for the cytoplasmic expression of recombinant genes in mammalian cells. Recent improvements allow high expression and simplify the integration of multiple foreign genes. Vaccinia virus mutants and other poxviruses that undergo abortive infection in mammalian cells are receiving special attention because of their diminished cytopathic effects and increased safety. New replicating and 'non-replicating' vectors, encoding the bacteriophage T7 RNA polymerase for transcription of recombinant genes, have been engineered.

Addition of the MSA1 signal and anchor sequences to the malaria merozoite surface antigen 1 C-terminal region enhances immunogenicity when expressed by recombinant vaccinia virus

Genes encoding four different C-terminal fragments of a Plasmodium falciparum merozoite surface antigen were generated: MSA1C-(Si,A), containing signal and anchor regions of MSA1; MSA1C-(Si,nA), containing the signal but not the anchor; MSA1C-(nSi,A), containing the anchor but not the signal, and MSA1C-(nSi,nA) containing neither the signal nor the anchor region. Each gene was inserted into the thymidine kinase region of vaccinia virus, under the control of a synthetic strong early/ late promoter. When the plasmodial genes were expressed in cells infected by the recombinant vaccinia virus, the two proteins containing the signal region were transported to the surface of infected cells. Infection of mice and rabbits with the latter recombinant viruses stimulated C-terminal-specific antibody levels that were 10-80-fold higher than those induced by the two recombinant viruses without the signal region. The combination of the signal and anchor regions with the C-terminal MSA1 protein also generated the most effective neutralization in a P. falciparum invasion assay.

Antigen expression by dendritic cells correlates with the therapeutic effectiveness of a model recombinant poxvirus tumor vaccine

Recombinant poxviruses encoding tumor-associated antigens (TAA) are attractive as candidate cancer vaccines. Their effectiveness, however, will depend upon expression of the TAA in appropriate antigen-presenting cells. We have used a murine model in which the TAA is beta-galactosidase (beta-gal) and a panel of recombinant vaccinia viruses (rVV) in which beta-gal was expressed under early or late promoters at levels that varied over 500-fold during productive infections in tissue culture cells. Remarkably, only those rVV employing early promoters were capable of prolonging the survival of mice bearing established tumors expressing the model TAA. Late promoters were ineffective regardless of their determined promoter strength. The best results were obtained when beta-gal was regulated by a strong early promoter coupled to a strong late promoter. When a variety of cell types were infected with the panel of viruses in vitro, dendritic cells were found to express beta-gal only under the control of the early promoters even though late promoters were intrinsically more active in other cell types. Furthermore, in a functional assay, dendritic cells infected in vitro with rVV encoding beta-gal regulated by an early promoter activated beta-gal-specific cytotoxic T lymphocytes, whereas similar rVV with a late promoter-regulated gene did not. These data indicate that promoter strength per se is not the most critical quality of a recombinant poxvirus-based tumor vaccine and that the use of promoters capable of driving the production of TAA in "professional" antigen presenting cells may be crucial.

Highly attenuated modified vaccinia virus Ankara (MVA) as an effective recombinant vector: a murine tumor model

Modified vaccinia virus Ankara (MVA), a highly attenuated strain of vaccinia virus (VV) that is unable to replicate in most mammalian cells, was evaluated as an expression vector for a model tumor associated antigen (TAA) and as a potential anti-cancer vaccine. We employed an experimental murine model in which an adenocarcinoma tumor line, CT26.CL25, was stably transfected with a model TAA, beta-galactosidase (beta-gal). Mice injected intramuscularly with a recombinant MVA (rMVA) expressing beta-gal (MVA-LZ), were protected from a lethal intravenous (i.v.) challenge with CT26.CL25. In addition, splenocytes from mice primed with MVA-LZ were therapeutically effective upon adoptive transfer to mice bearing pulmonary metastases of the CT26.CL25 tumor established 3 days earlier. Most importantly, i.v. inoculation with MVA-LZ resulted in significantly prolonged survival of mice bearing three day old pulmonary metastases. This prolonged survival compared favorably to mice treated with a replication competent recombinant VV expressing beta-gal. These findings indicate that rMVA is an efficacious alternative to the more commonly used replication competent VV for the development of new recombinant anti-cancer vaccines.

Costimulation enhances the active immunotherapy effect of recombinant anticancer vaccines

Activation of T lymphocytes in the absence of a costimulatory signal can result in anergy or apoptotic cell death. Two molecules capable of providing a costimulatory signal, B7-1 (CD80) and B7-2 (CD86), have been shown to augment the immunogenicity of whole-tumor cell vaccines. To explore a potential role for costimulation in the design of recombinant anticancer vaccines, we used lacZ-transduced CT26 as an experimental tumor and beta-galactosidase (beta-gal) as the model tumor antigen. Attempts to augment the function of a recombinant vaccinia virus (rVV) expressing beta-gal by admixture with rVV expressing murine B7-1 were unsuccessful. However, a double recombinant vaccinia virus engineered to express both B7-1 and the model antigen beta-gal was capable of significantly reducing the number of pulmonary metastases when administered to mice bearing tumors established for 3 or 6 days. Most important, the double recombinant vaccinia virus prolonged the survival of tumor-bearing mice. These effects were antigen specific. The related costimulatory molecule B7-2 was found to have a similar, although less impressive enhancing effect on the function of a rVV expressing beta-gal. Thus, the addition of B7-1 and, to a lesser extent, B7-2 to a rVV encoding a model antigen significantly enhanced the therapeutic antitumor effects of these poxvirus-based, therapeutic anticancer vaccines.

Patterns of viral replication correlate with outcome in simian immunodeficiency virus (SIV)-infected macaques: effect of prior immunization with a trivalent SIV vaccine in modified vaccinia virus Ankara

The dynamics of plasma viremia were explored in a group of 12 simian immunodeficiency virus (SIV)-infected rhesus macaques (Macaca mulatta) that had received prior immunization with either nonrecombinant or trivalent (gag-pol, env) SIV-recombinant vaccinia viruses. Three distinct patterns of viral replication observed during and following primary viremia accounted for significant differences in survival times. High-level primary plasma viremia with subsequently increasing viremia was associated with rapid progression to AIDS (n = 2). A high-level primary plasma virus load with a transient decline and subsequent progressive increase in viremia in the post-acute phase of infection was associated with progression to AIDS within a year (n = 6). Low levels of primary plasma viremia followed by sustained restriction of virus replication were associated with maintenance of normal lymphocyte subsets and intact lymphoid architecture (n = 4), reminiscent of the profile observed in human immunodeficiency virus type 1-infected long-term nonprogressors. Three of four macaques that showed this pattern had been immunized with an SIV recombinant derived from the attenuated vaccinia virus, modified vaccinia virus Ankara. These data link the dynamics and extent of virus replication to disease course and suggest that sustained suppression of virus promotes long-term, asymptomatic survival of SIV-infected macaques. These findings also suggest that vaccine modulation of host immunity may have profound beneficial effects on the subsequent disease course, even if sterilizing immunity is not achieved.

IL-12 is an effective adjuvant to recombinant vaccinia virus-based tumor vaccines: enhancement by simultaneous B7-1 expression

A number of cytokines and costimulatory molecules involved in immune activation have recently been identified including IL-12, a heterodimeric cytokine that supports the development of cell-mediated immunity, and B7-1, a costimulatory molecule involved in the activation of T lymphocytes. We explored the use of these immunomodulants as molecularly defined adjuvants in the function of recombinant anticancer vaccines using a murine model adenocarcinoma, CT26, transduced with a model Ag, beta-galactosidase (beta-gal). Although IL-12 given alone to mice bearing tumors established for 3 days did not have consistent antitumor activity, a profound therapeutic effect was observed when IL-12 administration was combined with a recombinant vaccinia virus (rVV) encoding beta-gal called VJS6. On the basis of the reported synergistic effects of IL-12 and the costimulatory molecule B7-1 (CD80) in vitro, we immunized mice with a double recombinant vaccinia encoding both the model tumor Ag and the costimulatory molecule B7-1, designated B7-1 beta-gal rVV. The adjuvant administration of IL-12 after immunization with this virus significantly enhanced survival in tumor-bearing animals. T cell subset depletions demonstrated that the in vivo activity of IL-12 was largely independent of CD4+ T lymphocytes, whereas the in vivo activity of a B7-1 rVV required both CD4+ and CD8+ T cells to elicit maximal therapeutic effect. To our knowledge, this is the first description of B7-1 and IL-12 cooperation in vivo and represents a novel strategy to enhance the efficacy of recombinant anticancer vaccines.

IL-12 is an effective adjuvant to recombinant vaccinia virus-based tumor vaccines: enhancement by simultaneous B7-1 expression

A number of cytokines and costimulatory molecules involved in immune activation have recently been identified including IL-12, a heterodimeric cytokine that supports the development of cell-mediated immunity, and B7-1, a costimulatory molecule involved in the activation of T lymphocytes. We explored the use of these immunomodulants as molecularly defined adjuvants in the function of recombinant anticancer vaccines using a murine model adenocarcinoma, CT26, transduced with a model Ag, beta-galactosidase (beta-gal). Although IL-12 given alone to mice bearing tumors established for 3 days did not have consistent antitumor activity, a profound therapeutic effect was observed when IL-12 administration was combined with a recombinant vaccinia virus (rVV) encoding beta-gal called VJS6. On the basis of the reported synergistic effects of IL-12 and the costimulatory molecule B7-1 (CD80) in vitro, we immunized mice with a double recombinant vaccinia encoding both the model tumor Ag and the costimulatory molecule B7-1, designated B7-1 beta-gal rVV. The adjuvant administration of IL-12 after immunization with this virus significantly enhanced survival in tumor-bearing animals. T cell subset depletions demonstrated that the in vivo activity of IL-12 was largely independent of CD4+ T lymphocytes, whereas the in vivo activity of a B7-1 rVV required both CD4+ and CD8+ T cells to elicit maximal therapeutic effect. To our knowledge, this is the first description of B7-1 and IL-12 cooperation in vivo and represents a novel strategy to enhance the efficacy of recombinant anticancer vaccines.

Host range restricted, non-replicating vaccinia virus vectors as vaccine candidates

Three model systems were used to demonstrate the immunogenicity of highly attenuated and replication-defective recombinant MVA. (1) Intramuscular inoculation of MVA-IN-Fha/np induced humoral and cell-mediated immune responses in mice and protectively immunized them against a lethal respiratory challenge with influenza virus. Intranasal vaccination was also protective, although higher doses were needed. (2) In rhesus macaques, an immunization scheme involving intramuscular injections of MVA-SIVenv/gag/pol greatly reduced the severity of disease caused by an SIV challenge. (3) In a murine cancer model, immunization with MVA-beta gal prevented the establishment of tumor metastases and even prolonged life in animals with established tumors. These results, together with previous data on the safety of MVA in humans, suggest the potential usefulness of recombinant MVA for prophylactic vaccination and therapeutic treatment of infectious diseases and cancer.