Towards successful implementation of public health research into practice: Experiences and lessons learned from EDUCATE.

Background: The English schools-based human papillomavirus (HPV) vaccination programme is routinely offered to all young people aged 12-13 years. The EDUCATE lesson was developed to overcome barriers to uptake related to unmet information needs by providing young people with information and answering questions they may have about the HPV vaccine. The resource comprises a PowerPoint presentation, interspersed with five short films and a guidance document for professionals delivering the lesson. Adopting public health research into practice is challenging and few papers describe the process. This paper reports the initial use of the EDUCATE resource in schools and the process involved in supporting wider implementation. Study design: Implementation and knowledge mobilisation. Methods: Five secondary schools supported implementation of the EDUCATE resource. Delivery took place during April and December 2022 and was observed in four schools, with feedback obtained from two school staff members and 15 young people. Alongside this, meetings were held with over 80 stakeholders with the aim of identifying possible policy levers to encourage use of the EDUCATE resource, and to enhance understanding of how wider scale and sustained impact can be achieved. Results: Overall, the resource was positively received by school staff and young people engaged well during the lesson. As a result of the stakeholder networking activities, the research team worked with the Personal, Social, Health and Economic (PSHE) Association to adapt the materials to meet their Quality Assessment and incorporate elements, such as more interactive activities, requested during the implementation study. Conclusion: The EDUCATE resource has the potential to change practice by enhancing information provision about the HPV vaccine in schools and supporting young people nationally to make informed decisions. Key learnings from the project include the importance of integrating input from target users at all stages of the research process, pragmatism in relation to evaluation research designs, and incentivising researchers to undertake translation activities through further funding and a greater focus on impact. Together, these can help facilitate the availability of public health resources and their adoption into 'real-world' practice.

Watch me grow integrated (WMG-I): protocol for a cluster randomised controlled trial of a web-based surveillance approach for developmental screening in primary care settings.

INTRODUCTION: The increasing prevalence of developmental disorders in early childhood poses a significant global health burden. Early detection of developmental problems is vital to ensure timely access to early intervention, and universal developmental surveillance is recommended best practice for identifying issues. Despite this, there is currently considerable variation in developmental surveillance and screening between Australian states and territories and low rates of developmental screening uptake by parents. This study aims to evaluate an innovative web-based developmental surveillance programme and a sustainable approach to referral and care pathways, linking primary care general practice (GP) services that fall under federal policy responsibility and state government-funded child health services. METHODS AND ANALYSIS: The proposed study describes a longitudinal cluster randomised controlled trial (c-RCT) comparing a 'Watch Me Grow Integrated' (WMG-I) approach for developmental screening, to Surveillance as Usual (SaU) in GPs. Forty practices will be recruited across New South Wales and Queensland, and randomly allocated into either the (1) WMG-I or (2) SaU group. A cohort of 2000 children will be recruited during their 18-month vaccination visit or opportunistic visit to GP. At the end of the c-RCT, a qualitative study using focus groups/interviews will evaluate parent and practitioner views of the WMG-I programme and inform national and state policy recommendations. ETHICS AND DISSEMINATION: The South Western Sydney Local Health District (2020/ETH01625), UNSW Sydney (2020/ETH01625) and University of Queensland (2021/HE000667) Human Research Ethics Committees independently reviewed and approved this study. Findings will be reported to the funding bodies, study institutes and partners; families and peer-reviewed conferences/publications. TRIAL REGISTRATION NUMBER: ANZCTR12621000680864.

Development of an educational package for the universal human papillomavirus (HPV) vaccination programme: a co-production study with young people and key informants.

BACKGROUND: The English schools-based human papillomavirus (HPV) vaccination programme is routinely offered to all young people aged 12-13 years, to prevent cancers affecting the cervix, vulva, vagina, penis, anus and mouth. Lower uptake among some population groups has been identified, in part, because of unmet information needs among young people. To address these unmet needs we report intervention planning and development processes to co-produce an educational package about the HPV vaccine. METHODS: We used co-production research methodologies and the 'person-based approach' involving the following iterative stages: (i) collating and analysing primary and secondary evidence, including HPV vaccine communication materials, interviews and workshops; (ii) developing guiding principles; (iii) undertaking a behavioural analysis informed by the Behaviour Change Wheel and the Behaviour Change Technique taxonomy; (iv) development of a preliminary logic model; (v) co-production of resources, and; (vi) refinement of resources informed by feedback from young people and key informants. RESULTS: We co-produced EDUCATE, a theory-based educational package, that is designed to be delivered to young people prior to being offered the HPV vaccine to support uptake. Young people and key informants identified the following key issues to include as content: (i) HPV-related information; (ii) how vaccines work; (iii) safety and side-effects of the HPV vaccine; (iii) eligibility for the HPV vaccination programme, and; (iv) preparation of young people to receive the HPV vaccine. A manual for professionals (e.g. immunisation nurses, school staff) delivering the intervention and a PowerPoint presentation, interspersed with five short films, were co-produced with young people and key informants. Following feedback, the content of the EDUCATE package was refined to increase acceptability, engagement, and persuasiveness to the target users. CONCLUSION: Engagement with young people and key informants was integral to the development of our rigorously developed, theory-based intervention to address young people's information needs about the HPV vaccination programme. The acceptability and persuasiveness of the package has been maximised by working closely with young people and key informants to develop the content. An implementation study to examine how the EDUCATE package is implemented in practice and the impact on uptake of the HPV vaccination programme is underway.

In England, young people are offered the human papillomavirus (HPV) vaccine in schools at age 12­13 years to prevent some types of cancer. Some young people have unanswered questions which may stop them getting vaccinated. We report how we developed a lesson about the HPV vaccine jointly with young people and professionals to improve how information about the HPV vaccine is given. First, we reviewed research studies and HPV vaccine information materials designed for young people. Then, we carried out interviews and workshops to ask about the best way to give a lesson and the most important information to include. We worked with creative designers to produce films and animations. Finally, we asked young people and professionals for feedback on the lesson materials. The lesson includes a PowerPoint presentation with five films and guidance for people leading the session. Key topics about the HPV vaccine to be covered were identified by young people. These included information about how vaccines work and ways to improve young people's experience of having the HPV vaccine at school. We made changes to the information in the lesson to ensure that it was relevant to young people. We are now carrying out a study to find out how well the lesson is given and whether it can help more young people get the HPV vaccine if they want it.

Design, Synthesis, and Characterization of I-BET567, a Pan-Bromodomain and Extra Terminal (BET) Bromodomain Oral Candidate.

Through regulation of the epigenome, the bromodomain and extra terminal (BET) family of proteins represent important therapeutic targets for the treatment of human disease. Through mimicking the endogenous N-acetyl-lysine group and disrupting the protein-protein interaction between histone tails and the bromodomain, several small molecule pan-BET inhibitors have progressed to oncology clinical trials. This work describes the medicinal chemistry strategy and execution to deliver an orally bioavailable tetrahydroquinoline (THQ) pan-BET candidate. Critical to the success of this endeavor was a potency agnostic analysis of a data set of 1999 THQ BET inhibitors within the GSK collection which enabled identification of appropriate lipophilicity space to deliver compounds with a higher probability of desired oral candidate quality properties. SAR knowledge was leveraged via Free-Wilson analysis within this design space to identify a small group of targets which ultimately delivered I-BET567 (27), a pan-BET candidate inhibitor that demonstrated efficacy in mouse models of oncology and inflammation.

Co-production of an educational package for the universal human papillomavirus (HPV) vaccination programme tailored for schools with low uptake: a participatory study protocol.

AIM: To co-produce with young people an educational package about the human papillomavirus (HPV) vaccine that is tailored to increase vaccine uptake in schools and populations with lower uptake. INTRODUCTION: Persistent infection with HPV can result in cancers affecting men and especially women. From September 2019, the English-schools-based HPV vaccination programme was expanded to include young men (in addition to young women) aged 12-13 years. Some young people attending schools with lower uptake of the vaccine have unmet information needs. We hypothesise that mechanisms to address information needs and increase young people's autonomy in consent procedures will result in higher uptake. METHODS AND ANALYSIS: The Medical Research Council's framework for development and evaluation of complex interventions will inform intervention development. Recruitment of young people aged 12-15 years and key stakeholders (National Health Service commissioners, school staff, immunisation nurses and youth workers/practitioners) will be facilitated through existing links with healthcare organisations, schools and youth organisations in areas with lower uptake of the HPV vaccination programme. The proposed research will comprise three phases: (1) a rapid review of adolescent immunisation materials and preliminary qualitative interviews with young people and key stakeholders, (2) theory development and co-production of HPV vaccine communication materials through an iterative process with young people and (iii) testing delivery mechanisms and acceptability of the educational package in four schools with lower uptake. ETHICS AND DISSEMINATION: The University of Bristol's Faculty of Health Sciences and London School of Hygiene and Tropical Medicine's Research Ethics Committees provided approvals for the study. A dissemination event for young people and key stakeholders and webinar with the National Immunisation Network will be organised. The study findings will be published in peer-reviewed journals and presented at conferences. Recommendations for a future larger scale study will be made.

Omalizumab reduces bronchial mucosal IgE and improves lung function in non-atopic asthma.

Omalizumab therapy of non-atopic asthmatics reduces bronchial mucosal IgE and inflammation and preserves/improves lung function when disease is destabilised by staged withdrawal of therapy.18 symptomatic, non-atopic asthmatics were randomised (1:1) to receive omalizumab or identical placebo treatment in addition to existing therapy for 20 weeks. Bronchial biopsies were collected before and after 12-14 weeks of treatment, then the patients destabilised by substantial, supervised reduction of their regular therapy. Primary outcome measures were changes in bronchial mucosal IgE+ cells at 12-14 weeks, prior to regular therapy reduction, and changes in lung function (forced expiratory volume in 1 s) after destabilisation at 20 weeks. Quality of life was also monitored.Omalizumab but not placebo therapy significantly reduced median total bronchial mucosal IgE+ cells (p<0.01) but did not significantly alter median total mast cells, plasma cells, B lymphocytes, eosinophils and plasmablasts, although the latter were difficult to enumerate, being distributed as disperse clusters. By 20 weeks, lung function declined in the placebo-treated patients but improved in the omalizumab treated patients, with significant differences in absolute (p=0.04) and % predicted forced expiratory volume in 1 s (p=0.015).Omalizumab therapy of non-atopic asthmatics reduces bronchial mucosal IgE+ mast cells and improves lung function despite withdrawal of conventional therapy.

Telehealth for patients at high risk of cardiovascular disease: pragmatic randomised controlled trial.

OBJECTIVE:  To assess whether non-clinical staff can effectively manage people at high risk of cardiovascular disease using digital health technologies. DESIGN:  Pragmatic, multicentre, randomised controlled trial. SETTING:  42 general practices in three areas of England. PARTICIPANTS:  Between 3 December 2012 and 23 July 2013 we recruited 641 adults aged 40 to 74 years with a 10 year cardiovascular disease risk of 20% or more, no previous cardiovascular event, at least one modifiable risk factor (systolic blood pressure ≥140 mm Hg, body mass index ≥30, current smoker), and access to a telephone, the internet, and email. Participants were individually allocated to intervention (n=325) or control (n=316) groups using automated randomisation stratified by site, minimised by practice and baseline risk score. INTERVENTIONS:  Intervention was the Healthlines service (alongside usual care), comprising regular telephone calls from trained lay health advisors following scripts generated by interactive software. Advisors facilitated self management by supporting participants to use online resources to reduce risk factors, and sought to optimise drug use, improve treatment adherence, and encourage healthier lifestyles. The control group comprised usual care alone. MAIN OUTCOME MEASURES:  The primary outcome was the proportion of participants responding to treatment, defined as maintaining or reducing their cardiovascular risk after 12 months. Outcomes were collected six and 12 months after randomisation and analysed masked. Participants were not masked. RESULTS:  50% (148/295) of participants in the intervention group responded to treatment compared with 43% (124/291) in the control group (adjusted odds ratio 1.3, 95% confidence interval 1.0 to 1.9; number needed to treat=13); a difference possibly due to chance (P=0.08). The intervention was associated with reductions in blood pressure (difference in mean systolic -2.7 mm Hg (95% confidence interval -4.7 to -0.6 mm Hg), mean diastolic -2.8 (-4.0 to -1.6 mm Hg); weight -1.0 kg (-1.8 to -0.3 kg), and body mass index -0.4 ( -0.6 to -0.1) but not cholesterol -0.1 (-0.2 to 0.0), smoking status (adjusted odds ratio 0.4, 0.2 to 1.0), or overall cardiovascular risk as a continuous measure (-0.4, -1.2 to 0.3)). The intervention was associated with improvements in diet, physical activity, drug adherence, and satisfaction with access to care, treatment received, and care coordination. One serious related adverse event occurred, when a participant was admitted to hospital with low blood pressure. CONCLUSIONS:  This evidence based telehealth approach was associated with small clinical benefits for a minority of people with high cardiovascular risk, and there was no overall improvement in average risk. The Healthlines service was, however, associated with improvements in some risk behaviours, and in perceptions of support and access to care.Trial registration Current Controlled Trials ISRCTN 27508731.

Human intrahepatic regulatory T cells are functional, require IL-2 from effector cells for survival, and are susceptible to Fas ligand-mediated apoptosis.

UNLABELLED: Regulatory T cells (Treg ) suppress T effector cell proliferation and maintain immune homeostasis. Autoimmune liver diseases persist despite high frequencies of Treg in the liver, suggesting that the local hepatic microenvironment might affect Treg stability, survival, and function. We hypothesized that interactions between Treg and endothelial cells during recruitment and then with epithelial cells within the liver affect Treg stability, survival, and function. To model this, we explored the function of Treg after migration through human hepatic sinusoidal-endothelium (postendothelial migrated Treg [PEM Treg ]) and the effect of subsequent interactions with cholangiocytes and local proinflammatory cytokines on survival and stability of Treg . Our findings suggest that the intrahepatic microenvironment is highly enriched with proinflammatory cytokines but deficient in the Treg survival cytokine interleukin (IL)-2. Migration through endothelium into a model mimicking the inflamed liver microenvironment did not affect Treg stability; however, functional capacity was reduced. Furthermore, the addition of exogenous IL-2 enhanced PEM Treg phosphorylated STAT5 signaling compared with PEMCD8. CD4 and CD8 T cells are the main source of IL-2 in the inflamed liver. Liver-infiltrating Treg reside close to bile ducts and coculture with cholangiocytes or their supernatants induced preferential apoptosis of Treg compared with CD8 effector cells. Treg from diseased livers expressed high levels of CD95, and their apoptosis was inhibited by IL-2 or blockade of CD95. CONCLUSION: Recruitment through endothelium does not impair Treg stability, but a proinflammatory microenvironment deficient in IL-2 leads to impaired function and increased susceptibility of Treg to epithelial cell-induced Fas-mediated apoptosis. These results provide a mechanism to explain Treg dysfunction in inflamed tissues and suggest that IL-2 supplementation, particularly if used in conjunction with Treg therapy, could restore immune homeostasis in inflammatory and autoimmune liver disease. (Hepatology 2016;64:138-150).

The effect of a decaffeinated green tea extract formula on fat oxidation, body composition and exercise performance.

BACKGROUND: The cardio-metabolic and antioxidant health benefits of caffeinated green tea (GT) relate to its catechin polyphenol content. Less is known about decaffeinated extracts, particularly in combination with exercise. The aim of this study was therefore to determine whether a decaffeinated green tea extract (dGTE) positively influenced fat oxidation, body composition and exercise performance in recreationally active participants. METHODS: Fourteen, recreationally active males participated in a double-blind, placebo-controlled, parallel design intervention (mean ± SE; age = 21.4 ± 0.3 yrs; weight = 76.37 ± 1.73 kg; body fat = 16.84 ± 0.97%, peak oxygen consumption [[Formula: see text]] = 3.00 ± 0.10 L·min(-1)). Participants were randomly assigned capsulated dGTE (571 mg·d(-1); n = 7) or placebo (PL; n = 7) for 4 weeks. Following body composition and resting cardiovascular measures, participants cycled for 1 hour at 50% [Formula: see text], followed by a 40 minute performance trial at week 0, 2 and 4. Fat and carbohydrate oxidation was assessed via indirect calorimetry. Pre-post exercise blood samples were collected for determination of total fatty acids (TFA). Distance covered (km) and average power output (W) were assessed as exercise performance criteria. RESULTS: Total fat oxidation rates increased by 24.9% from 0.241 ± 0.025 to 0.301 ± 0.009 g·min(-1) with dGTE (P = 0.05; ηp(2) = 0.45) by week 4, whereas substrate utilisation was unaltered with PL. Body fat significantly decreased with dGTE by 1.63 ± 0.16% in contrast to PL over the intervention period (P < 0.001; ηp(2) = 0.84). No significant changes for FFA or blood pressure between groups were observed. dGTE resulted in a 10.9% improvement in performance distance covered from 20.23 ± 0.54 km to 22.43 ± 0.40 km by week 4 (P < 0.001; ηp(2) = 0.85). CONCLUSIONS: A 4 week dGTE intervention favourably enhanced substrate utilisation and subsequent performance indices, but did not alter TFA concentrations in comparison to PL. The results support the use of catechin polyphenols from dGTE in combination with exercise training in recreationally active volunteers.

Suppression of Wnt signaling by Dkk1 attenuates PTH-mediated stromal cell response and new bone formation.

Parathyroid hormone (PTH) suppresses Dickkopf 1 (Dkk1) expression in osteoblasts. To determine whether this suppression is essential for PTH-mediated Wnt signaling and bone formation, we examined mice that overexpress Dkk1 in osteoblasts (Dkk1 mice). Dkk1 mice were osteopenic due to abnormal osteoblast and osteoclast activity. When fed a low-calcium diet, and in two other models of hyperparathyroidism, these mice failed to develop the peritrabecular stromal cell response ("osteitis fibrosis") and new bone formation seen in wild-type mice. Despite these effects of Dkk1 overexpression, PTH still activated Wnt signaling in Dkk1 mice and in osteoblastic cells cultured from these mice. In cultured MC3T3E1 preosteoblastic cells, PTH dramatically suppressed Dkk1 expression, induced PKA-mediated phosphorylation of beta-catenin, and significantly enhanced Lef1 expression. Our findings indicate that the full actions of PTH require intact Wnt signaling but that PTH can activate the Wnt pathway despite overexpression of Dkk1.

Gene transfer into rat brain using adenoviral vectors.

Viral vector-mediated gene delivery is an attractive procedure for introducing genes into the brain, both for purposes of basic neuroscience research and to develop gene therapy for neurological diseases. Replication-defective adenoviruses possess many features which make them ideal vectors for this purpose-efficiently transducing terminally differentiated cells such as neurons and glial cells, resulting in high levels of transgene expression in vivo. Also, in the absence of anti-adenovirus immunity, these vectors can sustain very long-term transgene expression within the brain parenchyma. This unit provides protocols for the stereotactic injection of adenoviral vectors into the brain, followed by protocols to detect transgene expression or infiltrates of immune cells by immunocytochemistry or immunofluorescence. ELISPOT and neutralizing antibody assay methodologies are provided to quantitate the levels of cellular and humoral immune responses against adenoviruses. Quantitation of adenoviral vector genomes within the rat brain using qPCR is also described.

Osteoprotegerin abrogated cortical porosity and bone marrow fibrosis in a mouse model of constitutive activation of the PTH/PTHrP receptor.

Intracortical porosities and marrow fibrosis are hallmarks of hyperparathyroidism and are present in bones of transgenic mice expressing constitutively active parathyroid hormone/parathyroid hormone-related protein receptors (PPR*Tg). Cortical porosity is the result of osteoclast activity; however, the etiology of marrow fibrosis is poorly understood. While osteoclast numbers and activity are regulated by osteoprotegerin (OPG), bisphosphonates suppress osteoclast activity but not osteoclast numbers. We therefore used OPG and bisphosphonates to evaluate the extent to which osteoclasts, as opposed to bone resorption, regulate marrow fibrosis in PPR*Tg mice after treatment of animals with vehicle, OPG, alendronate, or zoledronate. All three agents similarly increased trabecular bone volume in both PPR*Tg and control mice, suggesting that trabecular bone resorption was comparably suppressed by these agents. However, the number of trabecular osteoclasts was greatly decreased by OPG but not by either alendronate or zoledronate. Furthermore, intracortical porosity and marrow fibrosis were virtually abolished by OPG treatment, whereas alendronate and zoledronate only partially reduced these two parameters. The greater reductions in cortical porosity and increments in cortical bone mineral density with OPG in PPR*Tg mice were associated with greater improvements in bone strength. The differential effect of OPG versus bisphosphonates on marrow fibrosis, despite similar effects on trabecular bone volume, suggests that marrow fibrosis was related not only to bone resorption but also to the presence of osteoclasts.

Clinical outcomes of Queensland children with cystic fibrosis: a comparison between tertiary centre and outreach services.

OBJECTIVE: To evaluate and compare the clinical outcomes of children with cystic fibrosis (CF) managed primarily at a tertiary cystic fibrosis centre (CFC) with those treated at regional centres by local health care professionals and the cystic fibrosis outreach service (CFOS). DESIGN, SETTING AND PATIENTS: Retrospective study of 273 children with CF born between 19 October 1982 and 19 February 2002 and with clinical data available between 1 January 2000 and 31 December 2002. Patients were grouped into CFC (n = 131) or CFOS (n = 142), with CFOS then further categorised into three groups depending on the level of care they received. MAIN OUTCOME MEASURES: Pulmonary function, Pseudomonas aeruginosa status, height and weight z scores, and hospital admission rates. RESULTS: There were no significant differences in pulmonary function, P. aeruginosa status, or height and weight z scores between children managed by CFC or by CFOS. Children receiving more care at the CFC (level of care [LOC] 1 and 2) were more likely to have multiple hospital admissions than children receiving more care in regional areas (LOC 3 and 4) (P < 0.001). CONCLUSION: The CFOS model provides effective delivery of specialised multidisciplinary care to children and adolescents living in rural and regional Queensland.

In vivo mature immunological synapses forming SMACs mediate clearance of virally infected astrocytes from the brain.

The microanatomy of immune clearance of infected brain cells remains poorly understood. Immunological synapses are essential anatomical structures that channel information exchanges between T cell-antigen-presenting cells (APC) during the priming and effector phases of T cells' function, and during natural killer-target cell interactions. The hallmark of immunological synapses established by T cells is the formation of the supramolecular activation clusters (SMACs), in which adhesion molecules such as leukocyte function-associated antigen 1 segregate to the peripheral domain of the immunological synapse (p-SMAC), which surrounds the T cell receptor-rich or central SMAC (c-SMAC). The inability so far to detect SMAC formation in vivo has cast doubts on its functional relevance. Herein, we demonstrate that the in vivo formation of SMAC at immunological synapses between effector CD8+ T cells and target cells precedes and mediates clearance of virally infected brain astrocytes.

Quality-of-life in children and adolescents with cystic fibrosis managed in both regional outreach and cystic fibrosis center settings in Queensland.

OBJECTIVES: To assess the health-related quality-of-life (HRQOL) of children/adolescents with cystic fibrosis (CF) and compare HRQOL in children managed by cystic fibrosis outreach service (CFOS) with those treated in a cystic fibrosis center (CFC). To compare HRQOL of children with CF in Queensland with previously published HRQOL data from the United States and examine the relationship between HRQOL scores and pulmonary function. STUDY DESIGN: Participants were children/adolescents with CF and their parents managed by the Royal Children's Hospital Queensland at a CFC or CFOS. Two HRQOL surveys were used: PedsQL and Cystic Fibrosis Questionnaire (CFQ). RESULTS: There were 91 CFC and 71 CFOS participants with similar demographics. PedsQL total summary score was statistically higher in CFOS, P=.05. There was no significant difference in CFQ scores between groups. Queensland parents reported lower HRQOL for their children compared with US parents (P<.01) despite similar pulmonary function. Declining pulmonary function correlated with worse CFQ scores in adolescents, P<.05. CONCLUSIONS: Children living in regional Queensland reported as good as or slightly better HRQOL compared with children attending a CFC. Parent proxy HRQOL scores were generally low suggesting a reduced perception of HRQOL by parents for their children.

Immunological thresholds in neurological gene therapy: highly efficient elimination of transduced cells might be related to the specific formation of immunological synapses between T cells and virus-infected brain cells.

First-generation adenovirus can be engineered with powerful promoters to drive expression of therapeutic transgenes. Numerous clinical trials for glioblastoma multiforme using first generation adenoviral vectors have either been performed or are ongoing, including an ongoing, Phase III, multicenter trial in Europe and Israel (Ark Therapeutics, Inc.). Although in the absence of anti-adenovirus immune responses expression in the brain lasts 6-18 months, systemic infection with adenovirus induces immune responses that inhibit dramatically therapeutic transgene expression from first generation adenoviral vectors, thus, potentially compromising therapeutic efficacy. Here, we show evidence of an immunization threshold for the dose that generates an immune response strong enough to eliminate transgene expression from the CNS. For the systemic immunization to eliminate transgene expression from the brain, > or = 1 x 10(7) infectious units (iu) of adenovirus need to be used as immunogen. Furthermore, this immune response eliminates >90% of transgene expression from 1 x 10(7)-1 x 10(3) iu of vector injected into the striatum 60 days earlier. Importantly, elimination of transgene expression is independent of the nature of the promoter that drives transgene expression and is accompanied by brain infiltration of CD8(+) T cells and macrophages. In conclusion, once the threshold for systemic immunization (i.e. 1 x 10(7) iu) is crossed, the immune response eliminates transgene expression by >90% even from brains that receive as little as 1000 iu of adenoviral vectors, independently of the type of promoter that drives expression.