ABCD. The Research and Development of Enterisol Ileitis. The European Licensure of Enterisol Ileitis. Mike Roof. Jeremy Kroll

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1 European Enterisol Ileitis Symposium October 13 15, 2005 Barcelona Mike Roof The Research and Development of Enterisol Ileitis Jeremy Kroll The European Licensure of Enterisol Ileitis Mike Roof Phd Jeremy Kroll Enterisol Ileitis Project Leader Biological R&D Boehringer Ingelheim Vetmedica, Inc. ABCD

2 1. The Research and Development of Enterisol Ileitis (Mike Roof) During the early 1990 s the US swine market began an aggressive phase of consolidation and integration. During this change in the swine industry, 3 site productions became increasingly common and high health status herds was achieved. These changes in pig management appeared to eliminate or reduce the clinical significance of some pathogens. However, by late 1993 it became apparent that in these high-health-herds clinical symptoms such as hose pipe or garden hose gut and acute gilt death due to hemorrhagic diarrhoea was becoming increasingly common. There was also an increased awareness about the widening of pig weight distributions in the finishers and the problems this caused in an all-in/all-out 3 site production system. At this same time, there were reports of a bacterium commonly associated with these clinical signs and associated with enterocyte proliferation and crypt cell hyperplasia. At the time the organism was referred to as CLO (Campylobacterlike-organism) based on its morphology or Ileal-symbiont intracellularis. In February 1994, Boehringer Ingelheim (BI) scientists began a focused effort to investigate and learn about the disease and the etiological agent we now know as Lawsonia intracellularis. Based on publications by Gordon Lawson and Steve McOrist, it was known that Lawsonia was an extremely unique bacterium: Microaerophilic/anaerobic Required hydrogen Obligate intracellular pathogen (requires eukaryotic host like a virus) These 3 characteristics made research on the organism extremely difficult. First of all isolation of the bacterium from an intestinal sample full of other bacteria on conventional media was not possible. The isolation therefore had to be done on a cell culture system, like virus isolation. The challenge was getting Lawsonia into the eukaryotic cells without destroying the eukaryotic cell monolayer with millions of other normal flora. The first 3 4 months of effort led to only frustration and failure. Cultures would either be established and not grow or we would see cultures with Lawsonia, but they would be contaminated with other bacterial flora and kills the cell culture systems. At the same time, Steve McOrist was on sabbatical at Iowa State University and working with Hank Harris to also investigate this clinical disease and improve diagnostics for some global breeding companies. This was a natural collaboration and soon we were jointly working together. Steve and the University of Edinburgh had developed some very nice monoclonal antibodies which were tremendous diagnostic reagents and proved to be a very valuable tool for detecting/monitoring bacterial isolation and growth in vitro. Steve worked with the BI team and with his technical guidance we were able to establish isolation techniques and obtain 3 pure culture isolates. This was as much art as science and this took about 18 months from start to finish which was a huge amount of time, effort, and resources. Upon completion of this first major milestone, we were then able to move forward to begin addressing the next 3 critical items: (1) Challenge model development (2) Vaccine Prototypes (3) Production of a vaccine The challenge model using a pure culture system had been established in Edinburgh and was confirmed and duplicated by BI scientist using both EU and USA challenge isolates. The use of the pure culture model instead of the previously reported gut homogenate insured that our vaccine trials measured the effects of ONLY L. intracellularis challenge and not other confounding agents. The completion of this challenge model allowed BI to then move into the next phase of potential vaccine development. In order to consider a vaccine to control ileitis caused by L. intracellularis, it is important to first consider the disease. We have an etiological agent that is transferred by faecal-oral routes, causes disease at the surface of the intestine and is an obligate intracellular pathogen. This type of disease would likely require a mucosal response to block attachment and a cell-mediated immune response to inactivate an intracellular 1 Boehringer Ingelheim European Enterisol Ileitis Symposium

3 pathogen. Because there is not a systemic component to the disease, a systemic humoral response (IgG) would not be predicted to provide significant levels of protection. If you consider generic vaccine approaches, there are several options with various attributes relative to immunity (Table 1.1). of these isolates along with PCR amplified DNA from clinical samples across the globe indicated that Lawsonia is Lawsonia and very conserved at the antigenic level (Table 1.2). This allowed BI to focus on an isolate based on safety and efficacy and soon various attenuated live vaccine candidates were available and tested. Table 1.1: Potential immune induction by various vaccine types Vaccine Mucosal Cell mediated Humoral/systemic Type immunity immunity immunity Killed Bacterin No No/limited Yes (IM) Oral Attenuated Yes Yes Yes Live Sub-unit No No/limited Yes (assuming a single Protein (IM) antigen can be protective against a complex disease) When you consider the disease, an oral vaccine would have the potential to stimulate a mucosal immune response and potentially stimulating the production of Lawsonia-blocking IgA antibodies. This would theoretically assist in blocking attachment and the invasion process of this intracellular pathogen. An oral vaccine that was an attenuated live would also have the possibility to be taken up by local gut associated lymphoid cells and induce a cell mediated response required to stop an intracellular pathogen. The other advantage of an attenuated live vaccine is that you would have a broad range of antigens processed by the immune system including KEY antigens ONLY induced under in vivo conditions! Early investigations looking at killed bacterin prototypes confirmed this hypothesis that killed vaccines provided no protective response against clinical disease or the colonization of the gut. Because of this, our efforts focused on the attenuated live approach. The other key issue that needed to be addressed before vaccine development was the source of a potential vaccine isolate. Were there strains or differences between isolates that needed to be considered to develop an effective vaccine? To answer this question, BI scientists used the pure culture isolates, isolates from Steve McOrist, and isolates from Connie Gebhart to investigate the relevance of strain differentiation in L. intracellularis. These represented swine isolates from the US (various locations), Scotland, and Denmark. Analysis Table 1.2: Comparison of L. intracellularis isolates recovered from swine Parameter Analyzed Result SDS Page of Outer Membrane Proteins (Lawson, McOrist and Gebhart) Reactivity by 16s PCR (Jones et al.) Reactivity Monoclonal VPM 53 (McOrist) Growth requirements (Knittel, Gebhart, Lawson, McOrist) Sequence of OMP H gene (Vaughn/Klinge) 100% homology Sequence of FliC gene (Vaughn/Klinge) 100% homology Sequence of HylA gene (Vaughn/Klinge) 100% homology Sequence of Sulfite reductace gene (Vaughn/Klinge) 100% homology Sequence of Hepto/glycosyltransferase (Vaughn/Klinge) 100% homology The final and most difficult challenge associated with this project was how to overcome the incredible technical challenges associated with growth so that this product could be commercially viable and produced at a cost acceptable to the market place. Based on publications, growth of Lawsonia was known to occur in static, anchorage-dependent cell culture systems (monolayers). Production of a vaccine in this format was not commercially viable. We also had the challenge that growth required hydrogen, which had some serious safety issues. In the late 90 s BI scientists (Roof, Knittel and Kroll) developed a proprietary and patented system of growth that allowed Lawsonia vaccine cultures to be grown in large (>300 liter) reactor vessels in a suspension system. This system allowed significant changes in the media and gas requirements, improved yields, and ultimately a vaccine that now had Fermentation-vessel in use for costs that were acceptable to production of Enterisol Ileitis. the industry. It was at this point European Enterisol Ileitis Symposium Boehringer Ingelheim 2

4 that we were confident we had a safe, efficacious, and costeffective vaccine that we could bring to the industry to help solve both the clinical and subclinical porcine proliferative enteropathy issues. The vaccine project then left the research phase and entered the development pathway with subsequent testing for all regulatory and government requirements. Research facility of Boehringer Ingelheim in St. Joseph, Minnesota, USA. 2. The European Licensure of Enterisol Ileitis Jeremy Kroll Enterisol Ileitis, the world s first vaccine against Proliferative Enteropathy (PE) was developed to provide consistent herd immunity and offer significant protection against L. intracellularis-associated disease. European licensure of this vaccine was successfully completed through the Mutual Recognition Procedure in which Germany positioned itself as the reference member state to assist BI in achieving marketing authorization in 17 additional European countries. The task of licensing the first attenuated live, orally administered, L. intracellularis vaccine for pigs in several of these countries was a considered a ground breaking task. A dynamic Lawsonia project team consisting of various disciplines including Research & Development, production, Quality Control/Quality Assurance, regulatory affairs and world renowned PE experts was assembled to design, develop and provide support through the registration process. The target product profile served as the primary focus for the final development and registration of this vaccine; for active immunisation of weaned pigs from three weeks of age and older to reduce intestinal lesions caused by Lawsonia intracellularis infection and to reduce growth variability and loss of weight gain associated with the disease. Several clinical trials following Good Clinical Practices (GCP) were conducted to demonstrate vaccine efficacy against all clinical forms of PE. Highlights from these trials are listed in Table 2.1 below. Presence of clinical symptoms such as diarrhea and anorexia as well as poor growth performance has been directly correlated to lesion development in PE affected pigs. Therefore, the primary parameters for determining vaccine efficacy were the prevalence and severity of gross and microscopic (IHC) lesions. Secondary parameters including average daily weight gain, clinical symptoms (diarrhea, behaviour and body condition), serology (IFAT) and fecal shedding (PCR) were monitored for use in support of vaccine efficacy in these trials. The pure culture L. intracellularis challenge model was chosen as the preferred method to evaluate efficacy of Enterisol Ileitis because the challenge material contained only the causative agent of PE (no extraneous viral, bacterial or fungal pathogens). Additionally, virulent pure culture challenge material can easily be quantified using conventional tissue culture assays and reproduction of Lawsoniaspecific ileitis is more consistent. Vaccine efficacy was initially demonstrated with a proof of concept study in which vaccinates had significantly (p<0.05) reduced gross and microscopic (IHC) lesion development caused by L. intracellularis and fecal excretion of L. intracellularis while increasing their average daily weight gain (ADG) equal to or better than pigs that did not receive a vaccine or virulent challenge treatment. Data from the route of administration study provided confidence in that an attenuated live L. intracellularis isolate can be delivered to pigs via the drinking water and will remain viable within a 4 hour time period. Results from this study revealed that vaccinated pigs in both the water-delivered and oral drench groups had significantly (p<0.05) reduced gross and microscopic lesions in the ileum and marked reductions in the colon compared to non-vaccinated, control pigs (Table 2.2). Vaccinated animals shed significantly (p<0.05) less L. intracellularis two and three weeks after virulent challenge exposure than non-vaccinated, control animals (Table 2.3). Trends in ADG were higher in vaccinated pigs with those in the water-delivered vaccine group having statistically (p<0.05) higher ADG than control pigs (Table 2.4). Thus, water delivery provides ease in administration of this vaccine to pigs, and minimizes human-to-animal contact and reduces administration costs. Field efficacy evaluations confirmed the positive aspects vaccine efficacy initially dem- European Enterisol Ileitis Symposium Boehringer Ingelheim 3

5 onstrated in controlled laboratory trials mentioned above. The primary focus for vaccine efficacy in the field is growth performance more so than differences in lesion development. This is because pigs can develop and resolve PE-specific lesions intermittently throughout their life span making comparisons in lesion development extremely difficult in a field setting. The efficacy of Enterisol Ileitis has been successfully demonstrated against virulent exposure in natural and experimental studies involving isolates from different geographical origins; USA, Europe, Australia, Japan, Mexico and Canada. Additionally, safety evaluations have consistently shown that an attenuated live L. intracellularis is safe and does not cause lesions typical of PE in pigs, see Table 2.1. A reversion to virulence trial was conducted to demonstrate that pigs receiving a high dose of actively growing vaccine master seed can not develop Lawsonia-specific gross and microscopic lesions. Other evaluations included the successful demonstration of vaccine safety in 1 day of age pigs as well as pigs receiving a repeated dose of vaccine, a 10x overdose and a 25x overdose. A study was conducted to demonstrate that detection of the vaccine isolate in pigs recently vaccinated with a high dose of Enterisol Ileitis was up to 3 days post inoculation only. No evidence of vaccine transmission was observed in among pen mates by IFAT and PCR in this study indicating that re-vaccination or shedding of an attenuated L. intracellularis to pigs via the feces is extremely low. Thus administration of feces containing the vaccine isolate is not a sufficient mechanism for vaccination against PE. Non-target safety evaluations were performed in mice, rats, guinea pigs, hamsters and horses of which no adverse effects or L. intracellularis infections were observed. In conclusion, Enterisol Ileitis is a safe and efficacious vaccine for use in weaned pigs 3 weeks of age and older to control and prevent PE caused by L. intracellularis. Significant reductions in Lawsonia-specific lesion development, colonization and fecal shedding were evident in pigs receiving a vaccine treatment compared to the non-vaccinated controls. Vaccinated pigs improved overall growth performance and uniform weight gains without the use of antibiotics. Administration of Enterisol Ileitis is easy, safe and improves pork quality due to needle-less inoculations, reductions in handling of animals thereby reducing stress and injury to animals and personnel. Table 2.1: Summary of vaccine efficacy and safety trials Clinical Parameters Average Daily Weight Gains Gross lesion prevalence & severity Microscopic lesion prevalence & severity Fecal shedding (post-challenge) Safety in repeat dose, overdose, reversion to virulence and 1 week of age vaccine administration studies Seroconversion* (pre-challenge) Onset of immunity Duration of immunity Delivery methods Antibiotic & disinfectant avoidance Administration period Storage conditions Recommended to neutralize chlorine in pig s drinking water prior to vaccination * Seronegative pigs are protected against subsequent virulent challenge Enterisol Ileitis Improved ADWG Reduced lesions Significant reduction Reduced shedding Yes Minimal 3 4 weeks 17 weeks Drinking water or oral drench Required 4 hours 2 8 C until use Yes Table 2.2: The prevalence and severity of microscopic lesions detected in the bioequivalence of oral vaccine administration study Treatment Group ILEUM COLON Group Identification Average Microscopic Average Microscopic (IHC) Lesion Scores (IHC) Lesion Scores 1 Water Delivery 0.30 a 0.15 a 2 Oral Drench 0.65 a 0.25 a,b 3 Challenge Controls 2.32 b 0.70 b 4 Strict Controls 0 a 0 a a, b like letters denote no significant difference among treatment groups (p<0.05) Note: strict controls not statistically analyzed. Table 2.3: Summary of Lawsonia intracellularis fecal shedding among treatment groups as measured by fecal PCR testing (positive/group total) in the bioequivalence of oral administration study Treatment Group Days 0 21 Day 28 Day 35 Day 42 Group Identification f-pcr f-pcr f-pcr f-pcr positive positive positive positive 1 Water Delivery 0/20 a 1/20 a 2/20 b 2/20 b 2 Oral Drench 0/20 a 1/20 a 6/20 b 4/20 b 3 Challenge Controls 0/20 a 4/20 a 14/20 b 14/19 b a Group comparisons are not significantly (p<0.05) different by Chi-square test b Group comparisons are significantly (p<0.05) different by Chi-square test Note: strict controls not statistically analyzed Table 2.4: Average Daily Weight Gains (ADWG) among treatment groups in the bioequivalence of oral administration study Treatment Group ADWG ADWG Group Identification Pre-challenge (g) Post-challenge (g) 1 Water Delivery a a 2 Oral Drench a a,b 3 Challenge Controls a b a, b Like letters denote no significant (p<0.05) differences between treatment groups in average daily weight gains compared to the challenge controls Note: strict controls not statistically analyzed European Enterisol Ileitis Symposium Boehringer Ingelheim 4

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