One-year trial evaluating the durability and antimicrobial efficacy of copper in public transportation systems

Surfaces on transit vehicles are frequently touched and could potentially act as reservoirs for micro-organism transmission. Regular cleaning and disinfection to minimize the spread of micro-organisms is operationally challenging due to the need to keep vehicles in circulation. The application of copper (Cu) alloys to high- touch surfaces could help reduce the risk of cross-contamination, however, little is known about the durability and efficacy of engineered copper surfaces after prolonged use. Three Cu products (decal, thermal fabrication, and alloy covers) were assessed over a 12-month period. These Cu products were randomly installed on 110 stanchions on three buses and four train (SkyTrain) cars in Vancouver and three buses, two subway cars, and two streetcars in Toronto with mirrored control surfaces directly opposite. Bacterial counts (Colony forming units, CFU) and ATP bioluminescence (ATPB) were measured every two months after peak morning routes. Durability of the Cu products were assessed monthly through visual inspection and colorimetry assays or by ex-situ microscopy. Cu products on stanchions reduced the mean colony forming units (CFU) of all vehicles by 42.7% in the mean CFU (0.573 (CI 95% 0.453-0.726), p-value < 0.001) compared to control surfaces. The three Cu products exhibited an overall 87.1% reduction in the mean ATPB readings (0.129 (CI 95% 0.059-0.285, p-value < 0.001) compared to controls. Surface Cu concentration for all three products was consistent throughout the 12-month period. Electron microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) cross-sectional analysis showed no change in thickness or dealloying of Cu products, however SEM top-down analysis revealed substantial carbon accumulation on all surfaces. Cu products installed on transit vehicles maintained antimicrobial efficacy and durability after 12 months of use.

A multimodality intervention to improve musculoskeletal health, function, metabolism, and well-being in spinal cord injury: study protocol for the FIT-SCI randomized controlled trial

BACKGROUND

A spinal cord injury (SCI) is a devastating, life-changing event that has profoundly deleterious effects on an individual's health and well-being. Dysregulation of neuromuscular, cardiometabolic, and endocrine organ systems following an SCI contribute to excess morbidity, mortality and a poor quality of life. As no effective treatments currently exist for SCI, the development of novel strategies to improve the functional and health status of individuals living with SCI are much needed. To address this knowledge gap, the current study will determine whether a Home-Based Multimodality Functional Recovery and Metabolic Health Enhancement Program that consists of functional electrical stimulation of the lower extremity during leg cycling (FES-LC) plus arm ergometry (AE) administered using behavioral motivational strategies, and testosterone therapy, is more efficacious than FES-LC plus AE and placebo in improving aerobic capacity, musculoskeletal health, function, metabolism, and wellbeing in SCI.

METHODS

This single-site, randomized, placebo-controlled, parallel group trial will enroll 88 community-dwelling men and women, 19 to 70 years of age, with cervical and thoracic level of SCI, ASIA Impairment Scale grade: A, B, C, or D, 6 months or later after an SCI. Participants randomized to the multimodality intervention will undergo 16 weeks of home-based FES-LC and AE training plus testosterone undecanoate. Testosterone undecanoate injections will be administered by study staff in clinic or by a visiting nurse in the participant's home. The control group will receive 16 weeks of home-based FES-LC and AE exercise plus placebo injections. The primary outcome of this trial is peak aerobic capacity, measured during an incremental exercise testing protocol. Secondary outcomes include whole body and regional lean and adipose tissue mass; muscle strength and power; insulin sensitivity, lipids, and inflammatory markers; SCI functional index and wellbeing (mood, anxiety, pain, life satisfaction and depressive symptoms); and safety.

DISCUSSION

We anticipate that a multimodality intervention that simultaneously addresses multiple physiological impairments in SCI will result in increased aerobic capacity and greater improvements in other musculoskeletal, metabolic, functional and patient-reported outcomes compared to the control intervention. The findings of this study will have important implications for improving the care of people living with an SCI.

TRIAL REGISTRATION

ClinicalTrials.gov :  ( NCT03576001 ). Prospectively registered: July 3, 2018.

Parallel Sequencing Reveals Campylobacter spp. in Commercial Meat Chickens Less than 8 Days Old

Campylobacter from contaminated poultry meat is a major source of human gastroenteritis worldwide. To date, attempts to control this zoonotic infection with on-farm biosecurity measures have been inconsistent in outcome. A cornerstone of these efforts has been the detection of chicken infection with microbiological culture, where Campylobacter is generally not detectable until birds are at least 21 days old. Using parallel sequence-based bacterial 16S profiling analysis and targeted sequencing of the porA gene, Campylobacter was identified at very low levels in all commercial flocks at less than 8 days old that were tested from the United Kingdom, Switzerland, and France. These young chicks exhibited a much greater diversity of porA types than older birds testing positive for Campylobacter by culture or quantitative PCR (qPCR). This suggests that as the bacteria multiply sufficiently to be detected by culture methods, one or two variants, as indicated by porA type, dominate the infection. The findings that (i) most young chicks carry some Campylobacter and (ii) not all flocks become Campylobacter positive by culture suggest that efforts to control infection, and therefore avoid contamination of poultry meat, should concentrate on how to limit Campylobacter to low levels by the prevention of the overgrowth of single strains. IMPORTANCE Our results demonstrate the presence of Campylobacter DNA among fecal samples from a range of commercially reared meat chicks that are less than 8 days of age, consistent across 3 European countries. The recently developed, sensitive detection method indicates that infection occurs on commercial farms much earlier and more widely than previously thought, which opens up new opportunities to control Campylobacter contamination at the start of the food chain and reduce the unacceptably high levels of human disease.

"It Runs in Your Blood": Reflections from Treatment Seeking Gamblers on Their Family History of Gambling

There are considerable gaps in our understanding of the familial transmission of gambling problems. This convergent mixed-methods study aimed to explore the: (1) sources of heterogeneity in the familial (paternal, maternal, and sibling) transmission of gambling problems; (2) degree to which family-of-origin characteristics are associated with family-of-origin problem gambling; and (3) beliefs of gamblers about the nature of the familial transmission of problem gambling. The sample consisted of 97 treatment-seeking gamblers in Australia. One-quarter (25.5%) of participants reported that at least one family member (16.5% father, 7.5% mother, 7.6% siblings) living with them when they were growing up had a gambling problem. Most participants reported that family members with a positive history of problem gambling were biological relatives, lived with them full-time, and experienced long-term difficulties with gambling. Participants with a family history of problem gambling were young (less than 12 years of age) at the onset of parental, but not sibling, problem gambling, were women, and reported difficulties with the same gambling activity as their family member. Participants raised in families with problem gambling were more likely to report parental separation (risk ratio [RR] = 2.32) and divorce (RR = 2.83), and extreme family financial hardship (RR = 1.80), as well as low levels of paternal authoritative parenting than participants raised in non-problem gambling families. Qualitatively, both social learning and genetics were perceived to play a central role in the familial transmission of gambling problems. These findings inform theories of the familial transmission of gambling problems and the design of targeted prevention and intervention strategies.

Interactions between structural remodeling and volumetric growth in right ventricle in response to pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) exerts substantial pressure overload on the right ventricle (RV). The associated RV free wall (RVFW) adaptation could consist of myocardial hypertrophy, augmented intrinsic contractility, collagen fibrosis, and structural remodeling in an attempt to cope with pressure overload. If RVFW adaptation cannot maintain the RV stroke volume, RV dilation will prevail as an exit mechanism which usually decompensates the RV function leading to RV failure. Our knowledge of the factors determining the transition from the upper limit of RVFW adaptation to RV decompensation and the role of fiber remodeling events in this transition remains very limited. Computational heart models that connect the growth and remodeling (G\&R) events at the fiber and tissue levels with alterations in the organ-level function are essential to predict the temporal order and the compensatory level of the underlying mechanisms. In this work, building upon our recent rodent heart models (RHM) of PAH, we integrated mathematical models that describe time-evolution volumetric growth of the RV and structural remodeling of the RVFW. Results suggest that augmentation of the intrinsic contractility of myofibers accompanied by an increase in passive stiffness of RVFW is among the first remodeling events through which the RV strives to maintain the cardiac output. Interestingly, we found that the observed reorientation of the myofibers towards the longitudinal (apex-to-base) direction was a maladaptive mechanism that impaired the contractile pattern of RVFW and advanced along with RV dilation at later stages of PAH development.

Treatment of primary Sjögren's syndrome with hydroxychloroquine: a retrospective, open-label study

Objectives

To determine whether patients with primary Sjögren's syndrome (SS), diagnosed according to San Diego criteria, had improvement in their laboratory or clinical features during treatment with hydroxychloroquine (6–7 mg/kg/day) for at least two years., Methods: The study population included 50 consecutive patients with primary SS who were diagnosed according to San Diego criteria, and in whom hydroxychloroquine was suggested as treatment. This group included 10 patients who were early dropouts (side effects or desire not to take antimalarial drugs) and 40 patients who received drugs for at least two years (range 24-48 months). In a subset of SS patients, values for ESR (westergren) and quantitative immunoglobulins were available for comparison. Improvement with therapy was defined as: (a) ≥20% improvement in variables of tear flow (Schirmer's test I) or corneal integrity (rose Bengal): (b) ≥20% salivary function (flow rate); and (c) improvement in at least two of the following measures: physicians assessment of global disease activity by ≥ 20%, patient assessment of improvement in pain or fatigue by ≥20%, and ESR improved by ≥20mm/ hr.

Results

In a retrospective study of SS patients who completed the trial, a significant improvement was noted in ocular symptoms (pain and dryness) in patients (55 and 57%) and improved corneal integrity (rose Bengal straining) in 53% of patients. The Schirmer's test was improved by ≥ 2 mm/5 minutes in 50% in patients. Improvement was noted in oral symptoms (pain and dryness) in patients (57 and 60%) and salivary flow rate was increased in 82% of patients. In a subset of SS patients evaluated, the ESR improved by ≥20mm/hr in 17/32 patients (53%) and quantitative IgG level by ≥20% in 8/13 patients (61%). Physician global assessment of overall patient status and patient assessment of overall status indicated improvement in over 62% of patients.

Conclusion

In a retrospective study of patients fulfilling San Diego Criteria for SS, we found: (a) sustained improvement of local symptoms (painful eyes, painful mouth) and improvement of systemic manifestations (arthralgias and myalgias) after treatment with hydroxychloroquine 6-7 mg/kg/day over mean three-year follow-up; (b) laboratory analysis showed a significant improvement in their ESR and their quantitative IgG levels; (c) no significant late toxicity was observed in this study cohort. A prospective study of hydroxychloroquine in patients fulfilling San Diego criteria for SS is indicated.

A 5-Enolpyruvylshikimate 3-Phosphate Synthase Functions as a Transcriptional Repressor in Populus

Long-lived perennial plants, with distinctive habits of inter-annual growth, defense, and physiology, are of great economic and ecological importance. However, some biological mechanisms resulting from genome duplication and functional divergence of genes in these systems remain poorly studied. Here, we discovered an association between a poplar (Populus trichocarpa) 5-enolpyruvylshikimate 3-phosphate synthase gene (PtrEPSP) and lignin biosynthesis. Functional characterization of PtrEPSP revealed that this isoform possesses a helix-turn-helix motif in the N terminus and can function as a transcriptional repressor that regulates expression of genes in the phenylpropanoid pathway in addition to performing its canonical biosynthesis function in the shikimate pathway. We demonstrated that this isoform can localize in the nucleus and specifically binds to the promoter and represses the expression of a SLEEPER-like transcriptional regulator, which itself specifically binds to the promoter and represses the expression of PtrMYB021 (known as MYB46 in Arabidopsis thaliana), a master regulator of the phenylpropanoid pathway and lignin biosynthesis. Analyses of overexpression and RNAi lines targeting PtrEPSP confirmed the predicted changes in PtrMYB021 expression patterns. These results demonstrate that PtrEPSP in its regulatory form and PtrhAT form a transcriptional hierarchy regulating phenylpropanoid pathway and lignin biosynthesis in Populus.

Epigenetic modulation of inflammation and synaptic plasticity promotes resilience against stress in mice

Major depressive disorder is associated with abnormalities in the brain and the immune system. Chronic stress in animals showed that epigenetic and inflammatory mechanisms play important roles in mediating resilience and susceptibility to depression. Here, through a high-throughput screening, we identify two phytochemicals, dihydrocaffeic acid (DHCA) and malvidin-3′-O-glucoside (Mal-gluc) that are effective in promoting resilience against stress by modulating brain synaptic plasticity and peripheral inflammation. DHCA/Mal-gluc also significantly reduces depression-like phenotypes in a mouse model of increased systemic inflammation induced by transplantation of hematopoietic progenitor cells from stress-susceptible mice. DHCA reduces pro-inflammatory interleukin 6 (IL-6) generations by inhibiting DNA methylation at the CpG-rich IL-6 sequences introns 1 and 3, while Mal-gluc modulates synaptic plasticity by increasing histone acetylation of the regulatory sequences of the Rac1 gene. Peripheral inflammation and synaptic maladaptation are in line with newly hypothesized clinical intervention targets for depression that are not addressed by currently available antidepressants.

Polyphenols have partial antidepressant effect without known mechanism. Here, the authors identify two phytochemicals from bioactive dietary polyphenols, show their antidepressant effect in a rodent model of depression, and that this effect is mediated by epigenetic and anti-inflammatory mechanisms.

The science of cocoa flavanols: bioavailability, emerging evidence, and proposed mechanisms

Over the past 20 y, evidence derived from in vitro experiments, animal models, observational studies, and clinical interventions have suggested that cacao (cocoa) flavonoids act through a variety of mechanisms to modify a number of risk factors associated with chronic conditions, including cardiovascular and neurodegenerative diseases. Recent studies have elucidated the synthesis of flavonoids by plants, making available for research specific flavonoids and their metabolites. The body of evidence suggesting that cocoa flavanols may play a role in reducing the risk of cardiovascular disease has been sufficient to generate several systematic reviews and meta-analyses. Studies are now being directed to identify the molecular pathways underlying the effect of cocoa flavanols, and clinical trials are being planned to test their impact on disease endpoints.

P5-02-04: Disruption of Endothelial Cells Barrier Integrity by Invasive Breast Cancer Cells

Despite its critical role in cancer metastasis the molecular mechanisms regulating breast cancer cells transendothelial migration are poorly understood, but clearly depend on the invasive capacity of tumor cells and their ability to breach the endothelial cell barrier. Vascular endothelial-cadherin (VE-cadherin) is found specifically in the endothelial cell adherens junction and has been implicated in playing a fundamental role in controlling the transport across the endothelial barrier. Tyrosine phosphorylation of VE-cadherin has been implicated in the disruption of endothelial cells adherens junctions and diapedesis of metastatic cancer cells. We tested this hypothesis that interaction of breast cancer cells with endothelial cells initiates the signal transductions that disrupt the endothelium barrier integrity. Our studies demonstrated that the attachment of MDA-MB-231 human breast cancer cells to Human Umbilical Vein Endothelial Cells (HUVECs) leads to tyrosine phosphorylation of VE-cadherin and the formation of gaps between endothelial cells. These were accompanied by activation of two tyrosine kinases, Src and proline rich tyrosine kinase (Pyk-2). In addition, immunoprecipitation studies indicated that the endothelial cells adherens junction structure was disrupted through MDA-MB-231-induced dissociation of VE-cadherin and β-catenin complex. Activation of RhoA and HRas by over expression of constitutively active forms of the genes leads to tyrosine phosphorylation of VE-cadherin and Pyk-2 in HUVECs. Over expression of dominant negative forms of RhoA, HRas, Raf and ERK2 but not Rac1 and Cdc42 attenuated breast cancer cell-induced tyrosine phosphorylation of VE-cadherin and Pyk-2 in HUVECs. Indicating that breast cancer cell-induced VE-cadherin tyrosine phosphorylation and disruption of adherens junction in endothelial cells is mediated by RhoA and HRas\Raf\MEK\ERK signaling cascade. Understanding the precise molecular mechanisms that facilitate breast cancer cells transendothelial migration could develop novel therapeutic strategies targeting cancer cell metastasis by improving the protective role of endothelial cells.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-02-04.

Myosin light chain phosphorylation facilitates monocyte transendothelial migration by dissociating endothelial adherens junctions

AIMS

Transendothelial migration (TEM) of monocytes is a crucial step in inflammatory processes such as atherogenesis. Tyrosine phosphorylation of vascular endothelial cadherin (VE-cad) has been implicated in the dissociation of adherens junctions and the increased paracellular permeability of endothelial cells (ECs) that occur during TEM of monocytes. However, the underlying molecular mechanism has not been determined. We tested the hypothesis that the phosphorylation of myosin light chain (MLC) in ECs is crucial for the dissociation of adherens junctions during TEM of monocytes.

METHODS AND RESULTS

Using a combination of biochemical and cellular techniques, we provide evidence for the signal transduction pathways that regulate tyrosine phosphorylation of VE-cad in ECs after the attachment of monocytes. Our findings indicate that after interaction of integrins on THP-1 cells with adhesion molecules on ECs, the induction of the HRas\Raf\MEK\ERK signalling cascade leads to the phosphorylation of MLC. This results in the recruitment of Src to the VE-cad complex and tyrosine phosphorylation of VE-cad, which leads to dissociation of β-catenin from the VE-cad complex, formation of gaps between ECs, and enhancement of THP-1 cell TEM.

CONCLUSION

Our studies suggest that monocyte-induced phosphorylation of MLC in ECs enhances TEM of monocytes through dissociation of EC adherens junctions.

Children and television watching: a qualitative study of New Zealand parents' perceptions and views

BACKGROUND

Television (TV) viewing is one of the most pervasive sedentary pursuits among children and adolescents. Research studies have shown that higher TV viewing hours are associated with a number of negative effects such as being overweight and obese, attention and behavioural problems, and impaired academic performance. Most interventions to reduce time spent watching TV have been school-based and little is known about the strategies that families use to control TV watching time.

METHODS

Six focus groups with Māori, Pacific and non-Māori non-Pacific parents were conducted to examine New Zealand parents' perceptions of their children's TV watching. Focus groups explored attitudes towards TV viewing, strategies used to reduce viewing, and opinion on two different electronic monitors that can be used to restrict TV viewing. Focus group discussions were transcribed and a content analysis was conducted.

RESULTS

Parents described TV as playing a dominant role in their family's lives, and highlighted several barriers to reducing children's TV viewing, such as parents not willing to reduce their own TV watching, a lack of safe alternatives to TV and the need to use TV as a babysitting tool. Limiting access to TV, making TV viewing a reward and finding alternative activities were current strategies parents employed to limit TV viewing; however, the barriers highlighted by parents make implementing such strategies difficult. Attitudes towards electronic monitor use to reduce TV viewing were mixed, but suggest further investigation of these devices is needed.

CONCLUSIONS

Electronic devices that restrict the amount and content of TV viewing have some potential to support interventions and merit further investigation. It is imperative for interventions aimed at reducing TV viewing to consider the role TV plays within a family context, ensuring parental perceptions around the benefits and barriers of reducing TV are accounted for.

Cytoplasmic Ig-domain proteins: cytoskeletal regulators with a role in human disease

Immunoglobulin domains are found in a wide variety of functionally diverse transmembrane proteins, and also in a smaller number of cytoplasmic proteins. Members of this latter group are usually associated with the actin cytoskeleton, and most of them bind directly to either actin or myosin, or both. Recently, studies of inherited human disorders have identified disease-causing mutations in five cytoplasmic Ig-domain proteins: myosin-binding protein C, titin, myotilin, palladin, and myopalladin. Together with results obtained from cultured cells and mouse models, these clinical studies have yielded novel insights into the unexpected roles of Ig domain proteins in mechanotransduction and signaling to the nucleus. An emerging theme in this field is that cytoskeleton-associated Ig domain proteins are more than structural elements of the cell, and may have evolved to fill different needs in different cellular compartments. Cell Motil. Cytoskeleton 2009. (c) 2009 Wiley-Liss, Inc.

Identification of a selective thieno[2,3-c]pyridine inhibitor of COT kinase and TNF-alpha production

COT (Tpl2 in mice) is a serine/threonine MAP3 kinase that regulates production of TNF-alpha and other pro-inflammatory cytokines such as IL-1beta via the ERK/MAP kinase pathway. As TNF-alpha and IL-1beta are clinically validated targets for therapeutic intervention in rheumatoid arthritis (RA), blocking COT provides a potential avenue for amelioration of disease. Herein we describe identification of a cellular active selective small molecule inhibitor of COT kinase.

STRIDE 1: effects of the selective ET(A) receptor antagonist, sitaxsentan sodium, in a patient population with pulmonary arterial hypertension that meets traditional inclusion criteria of previous pulmonary arterial hypertension trials

Sitaxsentan (SITAX; Thelin, Encysive Corporation, Bellaire, TX, U.S.A.) is a highly selective oral endothelin-A receptor antagonist. STRIDE-1, a 12-week randomized, doubleblind, placebo-controlled trial of sitaxsentan for pulmonary arterial hypertension showed significant benefit in 6-minute walk distance, functional class and hemodynamics. Pulmonary arterial hypertension clinical trials traditionally limit enrolment to class III/IV patients with idiopathic pulmonary arterial hypertension or pulmonary arterial hypertension related to connective tissue disease, who have a baseline 6-minute walk distance of < 450 m. In contrast, STRIDE-1 included milder cases: class II patients, no baseline 6- minute walk cut-off, and congenital heart disease patients. We now present the STRIDE-1 subset who would have qualified under traditional inclusion criteria. The results were: change for placebo (mean +/- SE) vs change for sitaxsentan (mean +/- SE) vs treatment effect (mean), all statistically significant: 6-minute walk (m): -26 +/- 13, 39 +/- 10, 65; mean right atrial pressure (mmHg): 2.1 +/- 0.8, -1.2 +/- 0.5, -3.3; mean pulmonary arterial pressure (mmHg): 0.4 +/- 1.5, -4.7 +/- 1.5, -5.1; cardiac index (L/min per m): -0.09 +/- 0.09, 0.38 +/- 0.06, 0.47; pulmonary vascular resistance (dyne.s.cm): 85 +/- 60, -274 +/- 47, -359. A 45% improvement in functional class was seen in sitaxsentan-treated patients (P = 0.0005). Thus, in the STRIDE-1 subpopulation that met enrolment criteria of previous pulmonary arterial hypertension trials, improvement in efficacy parameters with sitaxsentan therapy was even greater than seen in the entire STRIDE-1 population.

Discovery of thieno[2,3-c]pyridines as potent COT inhibitors

Evaluation of hit chemotypes from high throughput screening identified a novel series of 2,4-disubstituted thieno[2,3-c]pyridines as COT kinase inhibitors. Structural modifications exploring SAR at the 2- and 4-positions resulting in inhibitors with improved enzyme potency and cellular activity are disclosed.

The effect of surgical immunomodulation on liver inflammation and clearance of DHBV infection

The key to developing a therapeutic vaccine for chronic hepadnavirus infection lies in the characteristics of the host-immune response which leads to clearance of acute infection. Groups of 28-day-old ducks which had been surgically bursectomized (n = 10) or thymectomized (n = 13) on the day of hatch or were untreated (n = 21) were inoculated with 10(9) viral genome equivalents (vge) DHBV, then bled twice a week, and euthanased 40 days later. Serum and liver were tested for DHBV DNA and total leukocytes and peripheral blood mononuclear cells (PBMCs) counted. Liver and spleen sections were either stained with hematoxylin and eosin, and graded for inflammation or stained with peroxidase-labeled anti-human CD3 antibody and examined for T lymphocyte distribution. PBMC counts were similar in all groups. DHBV infection combined with bursectomy increased significantly, while thymectomy decreased significantly the total leukocyte count. The spleen and liver bursectomy increased T lymphocyte number while B cells were decreased. Converse changes were observed in thymectomized ducks. Histological evidence of hepatitis was present in infected control and bursectomized ducks but not in the uninfected control or infected thymectomized ducks. In control animals, DHBV challenge caused viremia in 17 and persistent infection in 11 (56%). Fewer thymectomized ducks (3/13, 23%) and significantly more (100%) bursectomized ducks remained persistently infected (P < 0.001). Unexpectedly, bursectomy led to persistence of infection while clearance of infection occurred normally in thymectomized ducks despite decreased T lymphocyte numbers. This suggests that clearance requires T and B lymphocyte collaboration.

Identification of T-cell epitopes associated with immunity within the surface protein of duck hepatitis B virus

Duck hepatitis is a convenient model of hepatitis B virus (HBV) infection, but the lack of immunological reagents hampers investigation of pathogenesis and vaccine development. The aim of this study was to define T-cell epitopes in the surface peptide recognized by vaccinated immune birds. Blastogenesis assays were used to test the proliferative response of spleen mononuclear cells to synthetic peptides spanning the pre-S/S region in 22 naïve and 13 immunized and challenged immune ducks. Roughly > or = 50% of the immune ducks responded to five immunodominant peptides eliciting a statistically greater proliferative response than in naïve birds. Fewer ducks responded to an additional six peptides. No statistically significant difference could be shown for the response to 11 peptides between the immune ducks and the naïve ducks. There was no clustering of the immunodominant peptides which were located throughout the surface antigen at sites of major swings in hydrophobicity. A number of peptides which induce lymphoblastogenesis in vaccinated immune ducks have been identified. Their role in spontaneous recovery from duck hepatitis B infection merits investigation.