Pharmacokinetic and safety profile of tofacitinib in children with polyarticular course juvenile idiopathic arthritis: results of a phase 1, open-label, multicenter study.

BACKGROUND: Juvenile idiopathic arthritis (JIA) is the most common pediatric rheumatic disease and a leading cause of childhood disability. The objective of this study was to characterize the PK, safety, and taste acceptability of tofacitinib in patients with JIA. METHODS: This Phase 1, open-label, multiple-dose (twice daily [BID] for 5 days) study of tofacitinib in patients with active (≥ 5 joints) polyarticular course JIA was conducted from March 2013-December 2015. Patients were allocated to one of three age-based cohorts: Cohort 1, 12 to < 18 years; Cohort 2, 6 to < 12 years; and Cohort 3, 2 to < 6 years. Tofacitinib was administered according to age and body weight as tablets or oral solution (grape flavor). PK were assessed on Day 5; safety was assessed at screening, Day 1, and Day 5. Taste acceptability of the oral solution was evaluated. RESULTS: Twenty-six patients (age range 2-17 years) were enrolled: Cohort 1, N = 8; Cohort 2, N = 9; Cohort 3, N = 9; median tofacitinib doses were 5.0, 2.5, and 3.0 mg BID, respectively. The higher median tofacitinib dose in Cohort 3 versus Cohort 2 reflected implementation of an amended dosing scheme following an interim PK analysis after Cohort 2 recruitment. Geometric mean AUC at steady state (AUCtau) was 156.6 ng•h/mL in Cohort 1, 118.8 ng•h/mL in Cohort 2, and 142.5 ng•h/mL in Cohort 3; Cmax (ng/mL) was 47.0, 41.7, and 66.2, respectively. Ctrough, Cmin, and t1/2 were similar in Cohorts 2 and 3, but higher in Cohort 1. Median time to Cmax (Tmax) was similar between cohorts. Apparent clearance and volume of distribution decreased with decreasing age. Tofacitinib was well tolerated, with no serious adverse events or discontinuations due to adverse events reported. Taste acceptability was confirmed. CONCLUSIONS: PK findings from this study in children with polyarticular course JIA established dosing regimens and acceptable taste for use in subsequent studies within the tofacitinib pediatric development program. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01513902 .

Estimated medical expenditure and risk of job loss among rheumatoid arthritis patients undergoing tofacitinib treatment: post hoc analyses of two randomized clinical trials.

Objectives: RA causes high disability levels and reduces health-related quality of life, triggering increased costs and risk of unemployment. Tofacitinib is an oral Janus kinase inhibitor for the treatment of RA. These post hoc analyses of phase 3 data aimed to assess monthly medical expenditure (MME) and risk of job loss for tofacitinib treatment vs placebo. Methods: Data analysed were from two randomized phase 3 studies of RA patients (n = 1115) with inadequate response to MTX or TNF inhibitors (TNFi) receiving tofacitinib 5 or 10 mg twice daily, adalimumab (one study only) or placebo, in combination with MTX. Short Form 36 version 2 Health Survey physical and mental component summary scores were translated into predicted MME via an algorithm and concurrent inability to work and job loss risks at 6, 12 and 24 months, using Medical Outcomes Study data. Results: MME reduction by month 3 was $100 greater for tofacitinib- than placebo-treated TNFi inadequate responders (P < 0.001); >20 and 6% reductions from baseline, respectively. By month 3 of tofacitinib treatment, the odds of inability to work decreased ⩾16%, and risk of future job loss decreased ∼20% (P < 0.001 vs placebo). MME reduction by month 3 was $70 greater for tofacitinib- than placebo-treated MTX inadequate responders (P < 0.001); ⩾23 and 13% reductions from baseline, respectively. By month 3 of tofacitinib treatment, the odds of inability to work decreased ⩾31% and risk of future job loss decreased ⩾25% (P < 0.001 vs placebo). Conclusion: Tofacitinib treatment had a positive impact on estimated medical expenditure and risk of job loss for RA patients with inadequate response to MTX or TNFi.

Improved disease activity with fosdagrocorat (PF-04171327), a partial agonist of the glucocorticoid receptor, in patients with rheumatoid arthritis: a Phase 2 randomized study.

AIM: To assess efficacy and safety of fosdagrocorat (PF-04171327), a potential dissociated agonist of the glucocorticoid receptor, in rheumatoid arthritis (RA) patients. METHODS: This multicenter, double-blind, parallel-group, active- and placebo-controlled Phase 2 study (NCT00938587) randomized 86 patients (1 : 1 : 1 : 1) to receive fosdagrocorat 10 mg, fosdagrocorat 25 mg, prednisone 5 mg or placebo, all with stable background methotrexate therapy. The primary outcome was change from baseline in Disease Activity Score of 28 joints (DAS28-4[C-reactive protein (CRP)]) after 2 weeks of treatment. Secondary outcomes included American College of Rheumatology (ACR) response rates, change from baseline in ACR core components and Health Assessment Questionnaire Disability Index. RESULTS: At week 2, improvements from baseline in DAS28-4(CRP) with fosdagrocorat 10 and 25 mg, prednisone 5 mg and placebo were -1.69, -2.22, -1.17 and -0.96, respectively, and were statistically significantly greater for both fosdagrocorat doses versus placebo (P < 0.05) and for fosdagrocorat 25 mg versus prednisone 5 mg (P < 0.001). The effects of fosdagrocorat on secondary outcomes were generally consistent with those observed for the primary outcome. Adverse events (AEs) were reported for eight (38%), three (14%), four (19%) and 12 (55%) patients treated with fosdagrocorat 10 and 25 mg, prednisone 5 mg and placebo, respectively. Most AEs were mild in severity. Four patients discontinued treatment due to AEs (fosdagrocorat 10 mg, n = 2; placebo, n = 2). There were no serious AEs. CONCLUSION: Fosdagrocorat 10 and 25 mg demonstrated efficacy in improving signs and symptoms in RA patients, with manageable AEs. Additional studies are needed to assess the longer-term safety and efficacy of fosdagrocorat.

Efficacy and safety of tofacitinib in older and younger patients with rheumatoid arthritis.

OBJECTIVES: Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA). We evaluated the efficacy and safety of tofacitinib 5 or 10 mg twice daily (BID), in patients with moderate to severe RA, aged ≥65 and <65 years. METHODS: Data were pooled from five Phase 3 trials and, separately, from two open-label long-term extension (LTE) studies (data cut-off April, 2012). Patients received tofacitinib, or placebo (Phase 3 only), with/without conventional synthetic DMARDs (mainly methotrexate). Clinical efficacy outcomes from Phase 3 studies were evaluated at Month 3. Safety evaluations using pooled Phase 3 data (Month 12) and pooled LTE data (Month 24) compared exposure-adjusted incidence rates (IRs; with 95% confidence intervals [CIs]), in older versus younger patients. RESULTS: In Phase 3 and LTE studies, 15.3% (475/3111) and 16.1% (661/4102) of patients, respectively, were aged ≥65 years. Consequently, exposure to tofacitinib was lower in older versus younger patients in Phase 3 (259.2 vs. 1554.9 patient years [pt-yrs]) and LTE (962.1 vs. 5071.7 pt-yrs) studies. Probability ratios for ACR responses and HAQ-DI improvement from baseline ≥0.22 (Month 3) favoured tofacitinib and were similar in older and younger patients, with overlapping CIs. IRs for SAEs and discontinuations due to AEs were generally numerically higher in older versus younger patients, irrespective of treatment. CONCLUSIONS: Older patients receiving tofacitinib 5 or 10 mg BID had a similar probability of ACR20 or ACR50 response and, due to comorbidities, a numerically higher risk of SAEs and discontinuations due to AEs compared with younger patients.

Brief Report: Remission Rates With Tofacitinib Treatment in Rheumatoid Arthritis: A Comparison of Various Remission Criteria.

OBJECTIVE: Tofacitinib is an oral JAK inhibitor that is used for the treatment of rheumatoid arthritis (RA). In previous clinical trials of tofacitinib, a Disease Activity Score in 28 joints (DAS28)-based analysis was used to assess outcomes. In this study, remission rates according to various remission criteria were evaluated across 5 phase III randomized controlled studies. METHODS: In all 5 studies, tofacitinib was administered at a dosage of 5 mg twice daily or 10 mg twice daily, either as monotherapy or with background methotrexate or other conventional synthetic disease-modifying antirheumatic drugs. One of the studies included adalimumab 40 mg once every 2 weeks. In addition to the 4-variable DAS28 using the erythrocyte sedimentation rate (DAS28-4[ESR]), a primary efficacy variable used in the phase III studies, disease activity was assessed post hoc by the 4-variable DAS28 using the C-reactive protein level (DAS28-4[CRP]), the Clinical Disease Activity Index (CDAI), the Simplified Disease Activity Index (SDAI), and Boolean-based assessment. RESULTS: A total of 3,306 patients were analyzed (1,213 of these patients received tofacitinib 5 mg twice daily, 1,212 received tofacitinib 10 mg twice daily, 679 received placebo, and 202 received adalimumab 40 mg every 2 weeks). Remission rates varied according to the criteria used, with higher rates in the active-treatment groups for the DAS28-4(CRP) than for other scores. At month 3, remission rates with tofacitinib 5 mg twice daily were 18-22% using the DAS28-4(CRP), 5-10% using the DAS28-4(ESR), 4-7% using the SDAI, 5-6% using the CDAI, and 2-7% using the Boolean-based method. In contrast, the remission rates with placebo varied from 0% to 7%, with small differences between the DAS28-4(ESR) and the DAS28-4(CRP). CONCLUSION: Although tofacitinib at dosages of 5 mg twice daily and 10 mg twice daily was effective compared with placebo in achieving disease remission, regardless of the disease activity measure, remission rates were substantially higher when the DAS28-4(CRP) was used. The presence or absence and type of acute-phase reactants in remission criteria were significant contributors to remission rates across treatment groups. This finding has important consequences for trial design and clinical practice.

Tofacitinib, an oral Janus kinase inhibitor, for the treatment of chronic plaque psoriasis: Long-term efficacy and safety results from 2 randomized phase-III studies and 1 open-label long-term extension study.

BACKGROUND: Tofacitinib is an oral Janus kinase inhibitor being investigated for psoriasis. OBJECTIVES: We sought to report longer-term tofacitinib efficacy and safety in patients with moderate to severe psoriasis. METHODS: Data from 2 identical phase-III studies, Oral-treatment Psoriasis Trial Pivotal 1 and 2, were pooled with data from these patients in an ongoing open-label long-term extension study. Patients (n = 1861) were randomized 2:2:1 to tofacitinib 5 mg, 10 mg, or placebo twice daily (BID). At week 16, placebo patients were rerandomized to tofacitinib. Pivotal study participants could enroll into the long-term extension where they received tofacitinib at 10 mg BID for 3 months, after which dosing could be 5 or 10 mg BID. RESULTS: At week 28, the proportions of patients randomized to tofacitinib 5 and 10 mg BID achieving 75% or greater reduction in Psoriasis Area and Severity Index score from baseline were 55.6% and 68.8%, and achieving Physician Global Assessment of clear or almost clear were 54.7% and 65.9%. Efficacy was maintained in most patients through 24 months. Serious adverse events and discontinuations because of adverse events were reported in less than 11% of patients over 33 months of tofacitinib exposure. LIMITATIONS: There was no dose comparison beyond week 52. CONCLUSIONS: Oral tofacitinib demonstrated sustained efficacy in patients with psoriasis through 2 years, with 10 mg BID providing greater efficacy than 5 mg BID. No unexpected safety findings were observed.

Efficacy and safety of tofacitinib in US and non-US rheumatoid arthritis patients: pooled analyses of phase II and III.

OBJECTIVES: Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis. This post-hoc pooled analysis assessed commonalities and differences in tofacitinib efficacy and safety for US versus rest of the world (ROW) populations. METHODS: Pooled phase (P) III data from patients receiving tofacitinib 5 or 10 mg twice daily (BID) or placebo were assessed for efficacy at Month 3 and for safety outcomes over 12 months. For adverse events of special interest, data on tofacitinib 5 or 10 mg BID or placebo were pooled from six PII and five PIII randomised studies. RESULTS: PIII data were available for 664 vs. 2447 and PII/PIII data for 943 vs. 3567 US vs. ROW patients, respectively. The US population had a higher proportion of Caucasians (81.5% vs. 54.4%), lower proportion of Asians (1.0% vs. 34.6%), and higher mean body weight (85.7 vs. 66.2 kg) and body mass index (31.5 vs. 25.6 kg/m2) compared with ROW. At Month 3, PIII efficacy was similar between US and ROW as assessed by ACR 20/50/70 response rates, remission rates (DAS 28-4[ESR]<2.6), and HAQ-DI scores. Diarrhoea, peripheral oedema, and upper respiratory tract infection occurred in >5% of PIII patients in the US population. Incidence rates for adverse events of special interest were similar between the US and ROW PII/PIII populations. CONCLUSIONS: Patients in the US achieved similar efficacy and safety with tofacitinib 5 and 10 mg BID compared with patients in ROW.

The effect of tofacitinib on pneumococcal and influenza vaccine responses in rheumatoid arthritis.

OBJECTIVE: To evaluate tofacitinib's effect upon pneumococcal and influenza vaccine immunogenicity. METHODS: We conducted two studies in patients with rheumatoid arthritis using the 23-valent pneumococcal polysaccharide vaccine (PPSV-23) and the 2011-2012 trivalent influenza vaccine. In study A, tofacitinib-naive patients were randomised to tofacitinib 10 mg twice daily or placebo, stratified by background methotrexate and vaccinated 4 weeks later. In study B, patients already receiving tofacitinib 10 mg twice daily (with or without methotrexate) were randomised into two groups: those continuing ('continuous') or interrupting ('withdrawn') tofacitinib for 2 weeks, and then vaccinated 1 week after randomisation. In both studies, titres were measured 35 days after vaccination. Primary endpoints were the proportion of patients achieving a satisfactory response to pneumococcus (twofold or more titre increase against six or more of 12 pneumococcal serotypes) and influenza (fourfold or more titre increase against two or more of three influenza antigens). RESULTS: In study A (N=200), fewer tofacitinib patients (45.1%) developed satisfactory pneumococcal responses versus placebo (68.4%), and pneumococcal titres were lower with tofacitinib (particularly with methotrexate). Similar proportions of tofacitinib-treated and placebo-treated patients developed satisfactory influenza responses (56.9% and 62.2%, respectively), although fewer tofacitinib patients (76.5%) developed protective influenza titres (≥1:40 in two or more of three antigens) versus placebo (91.8%). In study B (N=183), similar proportions of continuous and withdrawn patients had satisfactory responses to PPSV-23 (75.0% and 84.6%, respectively) and influenza (66.3% and 63.7%, respectively). CONCLUSIONS: Among patients starting tofacitinib, diminished responsiveness to PPSV-23, but not influenza, was observed, particularly in those taking concomitant methotrexate. Among existing tofacitinib users, temporary drug discontinuation had limited effect upon influenza or PPSV-23 vaccine responses. TRIAL REGISTRATION NUMBERS: NCT01359150, NCT00413699.

Tofacitinib with methotrexate in third-line treatment of patients with active rheumatoid arthritis: patient-reported outcomes from a phase III trial.

OBJECTIVE: To assess patient-reported outcomes (PROs) for tofacitinib, an oral JAK inhibitor for the treatment of rheumatoid arthritis (RA), in a 6-month, phase III, randomized controlled trial. METHODS: Patients ages ≥18 years with active RA with an inadequate response to ≥1 tumor necrosis factor inhibitor (TNFi) and receiving stable background methotrexate were randomized 2:2:1:1 to tofacitinib 5 mg or 10 mg twice daily, or placebo advanced to tofacitinib 5 mg or 10 mg twice daily at month 3. PROs measured at month 3 included patient global assessment of disease activity (PtGA), pain, Health Assessment Questionnaire (HAQ) disability index (DI), Medical Outcomes Study (MOS) Short Form 36 Health Survey version 2 (SF-36v2; acute), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), and MOS Sleep Scale. RESULTS: Patients received tofacitinib 5 mg (n = 133) or 10 mg (n = 134) or placebo advanced to tofacitinib 5 mg (n = 66) or 10 mg (n = 66). HAQ DI (reported previously), PtGA (P < 0.0001), and SF-36v2 physical and mental component summary (P < 0.05) scores were improved for both tofacitinib doses versus placebo. Furthermore, improvements greater than or equal to the minimum clinically important difference were more frequently reported by tofacitinib-treated patients versus placebo for PtGA (P < 0.05), pain (P < 0.0001), HAQ DI (P < 0.05), SF-36v2 physical and mental component summary scores (P < 0.05), and FACIT-F (P < 0.001 for 5 mg twice daily). No statistical differences were observed in the MOS Sleep Scale. CONCLUSION: Tofacitinib treatment resulted in significant, clinically meaningful improvements in multiple PROs versus placebo over 3 months of treatment in patients with active RA and a previous inadequate response to TNFi.

Tofacitinib (CP-690,550) in combination with methotrexate in patients with active rheumatoid arthritis with an inadequate response to tumour necrosis factor inhibitors: a randomised phase 3 trial.

BACKGROUND: Rheumatoid arthritis is a heterogeneous chronic disease, and no therapeutic agent has been identified which is universally and persistently effective in all patients. We investigated the effectiveness of tofacitinib (CP-690,550), a novel oral Janus kinase inhibitor, as a targeted immunomodulator and disease-modifying therapy for rheumatoid arthritis. METHODS: We did a 6-month, double-blind, parallel-group phase 3 study at 82 centres in 13 countries, including North America, Europe, and Latin America. 399 patients aged 18 years or older with moderate-to-severe rheumatoid arthritis and inadequate response to tumour necrosis factor inhibitors (TNFi) were randomly assigned in a 2:2:1:1 ratio with an automated internet or telephone system to receive twice a day treatment with: tofacitinib 5 mg (n=133); tofacitinib 10 mg (n=134); or placebo (n=132), all with methotrexate. At month 3, patients given placebo advanced to either tofacitinib 5 mg twice a day (n=66) or 10 mg twice a day (n=66). Primary endpoints included American College of Rheumatology (ACR)20 response rate, mean change from baseline in Health Assessment Questionnaire-Disability Index (HAQ-DI), and rates of disease activity score (DAS)28-4(ESR) less than 2·6 (referred to as DAS28<2·6), all at month 3. The full analysis set for the primary analysis included all randomised patients who received at least one dose of study medication and had at least one post-baseline assessment. This trial is registered with www.ClinicalTrials.gov, number NCT00960440. FINDINGS: At month 3, ACR20 response rates were 41·7% (55 of 132 [95% CI vs placebo 6·06-28·41]; p=0·0024) for tofacitinib 5 mg twice a day and 48·1% (64 of 133; [12·45-34·92]; p<0·0001) for tofacitinib 10 mg twice a day versus 24·4% (32 of 131) for placebo. Improvements from baseline in HAQ-DI were -0·43 ([-0·36 to -0·15]; p<0·0001) for 5 mg twice a day and -0·46 ([-0·38 to -0·17]; p<0·0001) for 10 mg twice a day tofacitinib versus -0·18 for placebo; DAS28<2·6 rates were 6·7% (eight of 119; [0-10·10]; p=0·0496) for 5 mg twice a day tofacitinib and 8·8% (11 of 125 [1·66-12·60]; p=0·0105) for 10 mg twice a day tofacitinib versus 1·7% (two of 120) for placebo. Safety was consistent with phase 2 and 3 studies. The most common adverse events in months 0-3 were diarrhoea (13 of 267; 4·9%), nasopharyngitis (11 of 267; 4·1%), headache (11 of 267; 4·1%), and urinary tract infection (eight of 267; 3·0%) across tofacitinib groups, and nausea (nine of 132; 6·8%) in the placebo group. INTERPRETATION: In this treatment-refractory population, tofacitinib with methotrexate had rapid and clinically meaningful improvements in signs and symptoms of rheumatoid arthritis and physical function over 6 months with manageable safety. Tofacitinib could provide an effective treatment option in patients with an inadequate response to TNFi. FUNDING: Pfizer.

Rinderpest eradication: appropriate technology and social innovations.

Rinderpest is only the second infectious disease to have been globally eradicated. In the final stages of eradication, the virus was entrenched in pastoral areas of the Greater Horn of Africa, a region with weak governance, poor security, and little infrastructure that presented profound challenges to conventional control methods. Although the eradication process was a development activity rather than scientific research, its success owed much to several seminal research efforts in vaccine development and epidemiology and showed what scientific decision-making and management could accomplish with limited resources. The keys to success were the development of a thermostable vaccine and the application of participatory epidemiological techniques that allowed veterinary personnel to interact at a grassroots level with cattle herders to more effectively target control measures.

Efficacy and safety of CE-224,535, an antagonist of P2X7 receptor, in treatment of patients with rheumatoid arthritis inadequately controlled by methotrexate.

OBJECTIVE: To evaluate efficacy and safety of CE-224,535, a selective P2X(7) receptor antagonist, versus placebo, in patients with active rheumatoid arthritis (RA) and inadequate response to methotrexate (MTX). METHODS: In our phase IIA study (ClinicalTrials.gov no. NCT00628095; A6341009), patients aged ≥ 18 years with active RA were randomized to receive either CE-224,535 (500 mg bid) or placebo for 12 weeks; all patients continued a stable background dose of ≥ 7.5 mg MTX. RESULTS: The American College of Rheumatology 20% (ACR20) response rate (primary efficacy endpoint) was not significantly different from placebo for CE-224,535 (34.0% vs 36.2%; p = 0.591) at Week 12, or at any timepoint over the 12-week treatment period. There was no significant difference at Week 12 for the ACR20 response rate following subgroup analyses by age, sex, baseline disease activity, baseline duration of disease, geographic region, or concomitant use of steroids. ACR50/ACR70 response rates and change from baseline in Disease Activity Score 28-joint C-reactive protein (DAS28-3-CRP) and Health Assessment Questionnaire-Disability Index for CE-224,535 were not significant at Week 12 versus placebo. Treatment-emergent adverse events (AE) were reported by 62.3% (CE-224,535) and 55.3% (placebo) of patients; the most common AE were nausea (11.3%, CE-224,535; 4.3%, placebo) and diarrhea (7.5%, CE-224,535; 4.3%, placebo). The proportion of patients discontinuing due to an AE was 9.4% (CE-224,535) and 6.4% (placebo); no deaths were reported. Serious AE occurred in 3.8% (CE-224,535) and 2.1% (placebo) of patients; none was considered treatment-related. CONCLUSION: CE-224,535 was not efficacious, compared with placebo, for the treatment of RA in patients with an inadequate response to MTX. CE-224,535 demonstrated an acceptable safety and tolerability profile.

Maraviroc, a chemokine receptor-5 antagonist, fails to demonstrate efficacy in the treatment of patients with rheumatoid arthritis in a randomized, double-blind placebo-controlled trial.

INTRODUCTION: The purpose of this study was to determine whether maraviroc, a human CC chemokine receptor 5 (CCR5) antagonist, is safe and effective in the treatment of active rheumatoid arthritis (RA) in patients on background methotrexate (MTX). METHODS: This phase IIa study comprised two distinct components: an open-label safety study of the pharmacokinetics (PK) of MTX in the presence of maraviroc, and a randomized, double-blind, placebo-controlled, proof-of-concept (POC) component. In the PK component, patients were randomized 1:1 to receive maraviroc 150 or 300 mg twice daily (BID) for four weeks. In the POC component, patients were randomized 2:1 to receive maraviroc 300 mg BID or placebo for 12 weeks. Patients were not eligible for inclusion in both components. RESULTS: Sixteen patients were treated in the safety/PK component. Maraviroc was well tolerated and there was no evidence of drug-drug interaction with MTX. One hundred ten patients were treated in the POC component. The study was terminated after the planned interim futility analysis due to lack of efficacy, at which time 59 patients (38 maraviroc; 21 placebo) had completed their week 12 visit. There was no significant difference in the number of ACR20 responders between the maraviroc (23.7%) and placebo (23.8%) groups (treatment difference -0.13%; 90% CI -20.45, 17.70; P = 0.504). The most common all-causality treatment-emergent adverse events in the maraviroc group were constipation (7.8%), nausea (5.2%), and fatigue (3.9%). CONCLUSIONS: Maraviroc was generally well tolerated over 12 weeks; however, selective antagonism of CCR5 with maraviroc 300 mg BID failed to improve signs and symptoms in patients with active RA on background MTX. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00427934.

Foot-and-mouth disease in North American bison (Bison bison) and elk (Cervus elaphus nelsoni): susceptibility, intra- and interspecies transmission, clinical signs, and lesions.

There is limited information about the pathogenesis and epidemiology of foot-and-mouth disease (FMD) in North American bison (Bison bison) or elk (Cervus elaphus nelsoni). In these two experimental infection studies, we compared the susceptibilities of bison and elk to FMD virus (FMDV), respectively, with that of cattle; determined whether intra- and interspecies transmission could occur in bison and cattle, and elk and cattle; determined suitability of conventional available laboratory tests to detect FMDV infection in bison and elk; and investigated whether bison or elk are efficient long-term carriers of FMDV. In both studies, after a period of acclimation to the containment at Plum Island Animal Disease Center, animals were infected by intraepithelial tongue inoculation with 10,000 bovine tongue infective doses of FMDV, strain O1 Manisa. Inoculated animals were kept with contact animals; subsequently, inoculated and/or exposed contact animals were placed in rooms with unexposed animals. All bison developed oral mucosal and foot lesions similar to those of cattle. Bison developed fever, lameness, inappetence, and ptyalism. Physical examinations on bison revealed numerous small vesicles and erosions affecting tongue, gingiva, muzzle, hard and soft palates, coronary bands, and interdigital skin. Inoculated elk developed transient fever and mild focal tongue and foot lesions. Contact elk developed neither clinical signs nor gross pathologic lesions of FMD. At necropsy, lesions in bison included numerous extensive vesicles, erosions, and/or ulcers in the oral cavities, feet, and rumen pillars depending on the stage of disease. Less extensive oral, foot, and rumen lesions were present in the inoculated elk. All bison and inoculated elk developed antibodies to FMDV and were positive for FMDV by reverse transcription-polymerase chain reaction (RT-PCR). Transmission occurred between cattle and bison, and bison and bison. It did not occur between elk and cattle. Elk-to-elk transmission studies resulted in only one contact elk developing serologic evidence of a subclinical infection. Other exposed elk developed neither clinical, pathologic, virologic, nor serologic evidence of disease. FMDV was not isolated from animals past 28 days postinfection.