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Objectives: To validate and recalibrate the CURB-65 and pneumonia severity index (PSI) in predicting 30-day mortality and critical care intervention (CCI) in a multiethnic population with COVID-19, along with evaluating both models in predicting CCI. Methods: Retrospective data was collected for 1181 patients admitted to the largest hospital in Qatar with COVID-19 pneumonia. The area under the curve (AUC), calibration curves, and other metrics were bootstrapped to examine the performance of the models. Variables constituting the CURB-65 and PSI scores underwent further analysis using the Least Absolute Shrinkage and Selection Operator (LASSO) along with logistic regression to develop a model predicting CCI. Complex machine learning models were built for comparative analysis. Results: The PSI performed better than CURB-65 in predicting 30-day mortality (AUC 0.83, 0.78 respectively), while CURB-65 outperformed PSI in predicting CCI (AUC 0.78, 0.70 respectively). The modified PSI/CURB-65 model (respiratory rate, oxygen saturation, hematocrit, age, sodium, and glucose) predicting CCI had excellent accuracy (AUC 0.823) and good calibration. Conclusions: Our study recalibrated, externally validated the PSI and CURB-65 for predicting 30-day mortality and CCI, and developed a model for predicting CCI. Our tool can potentially guide clinicians in Qatar to stratify patients with COVID-19 pneumonia.

هـدفت الدراسة الراهنة إلى التعرف على واقع أداء العاملين في المؤسسات الإصلاحية، وقد استندت الدراسة إلى المنهج الوصفي التحليلي، وتم استخدام أداة المقابلة لجمع البيانات. وتكوّن مجتمع الدراسة من العاملين في المؤسسات الإصلاحية في كل من الرياض ومكة المكرمة وجدة والدمام، وكانت عينة الدراسة عينة قصديّة من العاملين الذكور والإناث في كل من الإصلاحيات قيد الدراسة، وقد بلغ عددهم 86 أخصائيًّا نفسيًّا واجتماعيًّا. ومن أهم ما توصلت إليه الدراسة من نتائج اتفاق أفراد عينة الدراسة حول طريقة استقبال النزيل؛ حيث يتم تعبئة استمارة أولية تحتوي على معلومات أولية للتأكد من صحة النزيل العضوية والنفسية، ومدى احتياجه إلى أدوية معينة. وكذلك اتفاق أفراد عينة الدراسة حول عملية توزيع النزلاء على الأخصائيين الاجتماعيين والنفسيين على أنها تتم بالتساوي دون أي معايير أخرى. وكذلك اتفاق أفراد عينة الدراسة على أن هناك مجموعة من المعوقات التي تحول دون قيامهم بأداء أعمالهم بالشكل المطلوب، ومن أهمها قلة عدد الأخصائيين الاجتماعيين والنفسيين مقارنة بأعداد النزلاء في إصلاحيات الذكور. وبناءً على هذه النتائج كانت أهم التوصيات: ضرورة استخدام الاستمارات الرسمية المعتمدة، والاهتمام بتصنيف النزلاء وفق معايير عملية تهدف إلى الوقاية من تعلم النزلاء السلوك الإجرامي، ورفع معدل الاستفادة من برامج التأهيل والإصلاح، والاهتمام بالبرامج التأهيلية، وتفعيل برامج الرعاية اللاحقة للنزلاء.

IntroductionProgress in the knowledge of metabolic interactions between cancer and its microenvironment is ongoing and may lead to novel therapeutic approaches. Until recently, melanoma was considered a glycolytic tumour due to mutations in mitochondrial-DNA, however, these malignant cells can regain OXPHOS capacity via the transfer of mitochondrial-DNA, a process that supports their proliferation in-vitro and in-vivo. Here we study how melanoma cells acquire mitochondria and how this process is facilitated from the tumour microenvironment.MethodsPrimary melanoma cells, and MSCs derived from patients were obtained. Genes’ expression and DNA quantification was analysed using Real-time PCR. MSC migration, melanoma proliferation and tumour volume, in a xenograft subcutaneous mouse model, were monitored through bioluminescent live animal imaging.ResultsHuman melanoma cells attract bone marrow-derived stromal cells (MSCs) to the primary tumour site where they stimulate mitochondrial biogenesis in the MSCs through upregulation of PGC1a. Mitochondria are transferred to the melanoma cells via direct contact with the MSCs. Moreover, inhibition of MSC-derived PGC1a was able to prevent mitochondrial transfer and improve NSG melanoma mouse tumour burden.ConclusionMSC mitochondrial biogenesis stimulated by melanoma cells is prerequisite for mitochondrial transfer and subsequent tumour growth, where targeting this pathway may provide an effective novel therapeutic approach in melanoma.

T he current research aimed at identifying the degree of importance the requirements of implementing school accreditation in development schools for girls in Tabuk from the viewpoints of principals of development schools and the supervisors of development and quality, and to determine the differences of the statistically significant differences between the mean scores of the importance degree of the requirements of implementing school accreditation in development schools for girls in Tabuk from principals of development schools and quality and development supervisors point of view according to the nature of work and years of experience. The descriptive survey method was utilized, participants were (30) principals of the development schools and (17) supervisors of Development& Quality in Tabuk. Findings revealed that the participants' response to all dimensions was high with a general mean: (2,83), (2,76), (2,71), (2,67), (2,50) respectively. Findings revealed no statistically significant difference for the responses related to the variables: nature of work and years of experience.

Fungi have been shown to be a good source for lead molecules in drug discovery and development. However, many compounds derived from fungi were not evaluated for their bioactivity against economic pests. In this study, twelve fungal secondary metabolites (1-12) were evaluated for herbicidal activity against Silybum marianum, fungicidal activity against Alternaria solani and Fusarium oxysporum, insecticidal activity against Culex pipiens larvae, and antifeedant activity against Spodoptera littoralis larvae. Among the tested metabolites, brefeldin A (6) and 6-eopxy-4-hydroxy-3-methoxy-5-methyl-cyclohex-2-en-1-one (11) showed potent herbicidal activity against S. marianum with complete inhibition of seed germination at 500 mg/l. Compound 6 revealed an exceptional herbicidal activity as it caused complete inhibition of root growth and strong reduction in shoot growth (I = 74.5%) and germination (10.0%) at 25 mg/l. In addition, anthracobic acid A (7) showed the highest antifungal activity against F. oxysporum (EC50 = 8.21 mg/l) and 19-(α-D-glucopyranosyloxy)isopimara-7,15-dien-3β-ol (2) was the most potent compound against A. solani (EC50 = 140.8 mg/l). Furthermore, dehydroaustin (9), phomaxanthone A (4) and deacetylphomaxanthone A (5) displayed a potent toxicity against fourth larval instar of C. pipiens with LC50 values of 3.27, 57.03 and 63.5 mg/l, respectively. Among the tested metabolites, four compounds (4, 5, 7 and 11) showed antifeedant activity against third-instar larvae of S. littoralis at 1000 mg/l. The results presented in this study should be useful for developing brefeldin A (6) and dehydroaustin (9) as natural herbicide and insecticide, respectively.

The first conceptualised class of dual-binding guanine quadruplex binders has been designed, synthesised and biophysically studied. These compounds combine diaromatic guanidinium systems and neutral tetra-phenylporphyrins (classical binding moiety for guanine quadruplexes) by means of a semi-rigid linker. An extensive screening of a variety of guanine quadruplex structures and double stranded DNA via UV-vis, FRET and CD experiments revealed the preference of the conjugates towards guanine quadruplexes. Additionally, docking studies indicate the potential dual mode of binding.

Background β-thalassemia major is a hereditary disorder of hemoglobin (Hb) that results in defective Hb synthesis, leading to severe chronic anemia. The mainstay of its treatment is lifelong regular packed red cell transfusions associated with iron-chelating therapy. Globally, there is a gap between blood donation and the actual needs of the patients who depend on transfusion. Patients with β-thalassemia major are no exception and have limited access to regular and safe blood transfusions. This study aimed to assess the gap between the demand and supply of blood for transfusion-dependent patients with β-thalassemia major treated at the Hereditary Blood Diseases Center, Al Ahsa, Eastern Saudi Arabia. Methodology This was a retrospective, cross-sectional study conducted at the Hereditary Blood Disease Center, Al Ahsa, Saudi Arabia, including patient data from January 2017 to December 2019. We used Excel 365 from Microsoft Office 2016, version 1706. Results A total of 158 patients were on chronic transfusion. Of the total patients, 65% were adults, while the remaining 35% comprised the pediatric population. The total number of units requested and received during the three-year period was 14,509 and 9,530, respectively, indicating a gap of 4,979 (34%) units. The age of most of the units received was more than 14 days: 36% of those in 2017, 49.9% in 2018, and 61.5% in 2019. Rare blood groups and alloimmunization accounted for

Progress in the knowledge of metabolic interactions between cancer and its microenvironment is ongoing and may lead to novel therapeutic approaches. Until recently, melanoma was considered a glycolytic tumour due to mutations in mitochondrial-DNA, however, these malignant cells can regain OXPHOS capacity via the transfer of mitochondrial-DNA, a process that supports their proliferation in-vitro and in-vivo. Here we study how melanoma cells acquire mitochondria and how this process is facilitated from the tumour microenvironment.Primary melanoma cells, and MSCs derived from patients were obtained. Genes' expression and DNA quantification was analysed using Real-time PCR. MSC migration, melanoma proliferation and tumour volume, in a xenograft subcutaneous mouse model, were monitored through bioluminescent live animal imaging.Human melanoma cells attract bone marrow-derived stromal cells (MSCs) to the primary tumour site where they stimulate mitochondrial biogenesis in the MSCs through upregulation of PGC1a. Mitochondria are transferred to the melanoma cells via direct contact with the MSCs. Moreover, inhibition of MSC-derived PGC1a was able to prevent mitochondrial transfer and improve NSG melanoma mouse tumour burden.MSC mitochondrial biogenesis stimulated by melanoma cells is prerequisite for mitochondrial transfer and subsequent tumour growth, where targeting this pathway may provide an effective novel therapeutic approach in melanoma.

Bone tissue engineering is an advanced field for treatment of fractured bones to restore/regulate biological functions. Biopolymeric/bioceramic-based hybrid nanocomposite scaffolds are potential biomaterials for bone tissue because of biodegradable and biocompatible characteristics. We report synthesis of nanocomposite based on acrylic acid (AAc)/guar gum (GG), nano-hydroxyapatite (HAp NPs), titanium nanoparticles (TiO2 NPs), and optimum graphene oxide (GO) amount via free radical polymerization method. Porous scaffolds were fabricated through freeze-drying technique and coated with silver sulphadiazine. Different techniques were used to investigate functional group, crystal structural properties, morphology/elemental properties, porosity, and mechanical properties of fabricated scaffolds. Results show that increasing amount of TiO2 in combination with optimized GO has improved physicochemical and microstructural properties, mechanical properties (compressive strength (2.96 to 13.31 MPa) and Young’s modulus (39.56 to 300.81 MPa)), and porous properties (pore size (256.11 to 107.42 μm) and porosity (79.97 to 44.32%)). After 150 min, silver sulfadiazine release was found to be ~94.1%. In vitro assay of scaffolds also exhibited promising results against mouse pre-osteoblast (MC3T3-E1) cell lines. Hence, these fabricated scaffolds would be potential biomaterials for bone tissue engineering in biomedical engineering.

Importance Obesity is associated with increased prevalence of gastroesophageal reflux disease (GERD); with recent reports suggesting improvement in GERD symptoms and weight loss following bariatric surgical intervention. However, the exact impact of the type of bariatric surgery on the evolution of GERD symptoms have remained unexamined. Objective To characterize the exact evolution of GERD symptoms, post bariatric surgery.Data sources We systematically searched electronic databases (PubMed, EMBASE, Web of Science, and the Cochrane Library from inception to December 2018) for eligible studies that satisfy pre-specified inclusion criteria. Study selection We included clinical trials of all designs (prospective and retrospective) that reported on GERD outcomes following Laparoscopic Sleeve Gastrectomy (LSG) or laparoscopic Roux-en-Y gastric bypass (LRYGB).Data extraction and synthesis Two independent reviewers extracted relevant data based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Data were pooled using a random-effects model.Main outcomes Symptomatic improvement in GERD symptoms following bariatric surgery Results A total of 39 studies were analyzed and a robust-error meta-regression model was used to conduct a Dose-Response Meta-Analysis (DRMA) synthesizing data on 39 studies that reported GERD outcomes after bariatric surgery. Out of 43,994 patients who underwent either LSG (N = 9,547 patients) or LRYGB (N = 34,447 patients), 32.4% experienced improvement in symptoms (95% CI 20.62 to 45.45); The DRMA demonstrated a window period of two years for sustained improvement after which symptoms began to recur in those that were asymptomatic. Conclusion and relevance Bariatric surgery may improve GERD symptoms in obese patients who underwent LSG, however, the most favorable effect is likely to be found after Roux-en-Y gastric bypass surgery. The effects were not sustained and returned to baseline within 4 years.

Aim: The purpose of this study is to evaluate the anti-biofilm capacity of Diode laser 980 nm, triple antibiotic mixture and calcium hydroxide.Methods: Eighty five single-rooted teeth with mature apices were prepared using Protaper Universal rotary nickel titanium system till size # F4 then contaminated with E.faecalis. Irrigation done using 2.5% sodium hypochlorite followed by 17% EDTA. Samples were divided into 4 groups (n= 20) according to the irrigant activation method. Laser group,TAP group, Ca(OH)2group and the control group. Residual bacteria were plated onto Brain Heart Infusion media and determined as colony-forming units (CFU mL-1). Data were analyzed using one way ANOVA followed by performance of Tukey post hoc tests. Significance was set at p < 0.05.Results: There was a statistically significant reduction in the mean numbers of colony-forming units among all groups. However, none of the activation methods was able to kill E. faecalis biofilm completely. The Laser group behaved most effectively among all groups.Conclusion: The adjunctive use of 980nm laser is an effective method for bacterial reduction after chemo-mechanical instrumentation of the root canal.

Aim: The purpose of this study is to evaluate the antibacterial effect of Diode laser 980 nm, EndoVac and passive ultrasonic irrigation ex vivo. Methods: One hundred and five maxillary central incisors were standardized to 15mm in length. All samples were prepared using Protaper Universal rotary nickel titanium system till size # F4 then contaminated with E. faecalis. The irrigation protocol used was 2.5% sodium hypochlorite followed by 17% EDTA. Samples were randomly divided into 5 groups (n= 20) according to the irrigant activation method. LAI group, Diode laser 980nm. API group, EndoVac system. PUI group, passive ultrasonic activation. The positive control group, in which the irrigating solution was not activated and the negative control group in which the samples were not subjected to irrigation or activation. Residual bacteria were collected with sterile paper point, plated onto BHI media and incubated (37 °C, 48 h) to determine the colony-forming units (CFU mL-1). Data were analyzed using one-way ANOVA followed by performance of Tukey post hoc tests. Significance was set at p < 0.05. Scanning electron microscopy was used to investigate the changes in biofilm. Results: There was a statistically significant reduction in the mean numbers of colony-forming units among all groups. However, none of the activation methods was able to kill E. faecalis biofilm completely. The LAI group behaved most effectively among all groups.Conclusion: The adjunctive use of 980nm laser is an effective method for bacterial reduction after chemo-mechanical instrumentation of the root canal.

Background: Mechanically ventilated patients experience many stressors related to their physiological conditions, treatments, and the Intensive Care Unit (ICU) environment itself. As patients are recovered from the respiratory problems, they can be weaned from mechanical ventilation (MV). Weaning represents a major challenge in critically ill patients' management. Weaning from MV imposes more stress on the patients as it leads to feeling of helplessness. Excessive and inappropriate use of sedatives can result in cardiovascular instability, prolongation of MV and ventilator associated pneumonia. Critical care nurses have an important role in alleviating stress manifestations and helping patients’ holistic healing. Non-pharmacological approach is recommended to be used prior to or in conjunction with sedatives use. Listening to Holy Quran Recitation (HQR) is a kind of spiritual support for Muslim patients. Spiritual care has been recommended as it can affect patient’s comfort. Accordingly, spiritual support strategies including HQR have been recently proposed to achieve better outcomes of critically ill patients which is the aim of the current study. Methods: A quasi experimental research design was used in this study. Physiological and psychological parameters were measured before and after HQR in the study group. Results: All differences between physiological and psychological parameters of the study group before and after HQR were statistically significant (P= 0.00). All differences between initial and the final measurement values of physiological and psychological parameters of the control group were statistically not significant. The mean values of heart rate, respiratory rate, mean arterial blood pressure, and shortness of breath of the study group after HQR were lower than that in the control group. Conclusion: HQR is an effective non-pharmacological strategy to improve vital signs, SpO2, shortness of breath and anxiety level for mechanically ventilated Muslim patients undergoing weaning. In addition, it can increase spontaneous breathing trial (SBT) duration for patients undergoing weaning from MV.

International audience; G-quadruplexes (G4) are non-canonical DNA and/or RNA secondary structures formed in guanine-rich regions. Given their over-representation in specific regions in the genome such as promoters and telomeres, they are likely to play important roles in key processes such as transcription, replication or RNA maturation. Putative G4-forming sequences (G4FS) have been reported in humans, yeast, bacteria, viruses and many organisms. Here we present the first mapping of G-quadruplex sequences in Dictyostelium discoideum, the social amoeba. ‘Dicty’ is an ameboid protozoan with a small (34 Mb) and extremely AT rich genome (78%). As a consequence, very few G4-prone motifs are expected. An in silico analysis of the Dictyostelium genome with the G4Hunter software detected 249–1055 G4-prone motifs, depending on G4Hunter chosen threshold. Interestingly, despite an even lower GC content (as compared to the whole Dicty genome), the density of G4 motifs in Dictyostelium promoters and introns is significantly higher than in the rest of the genome. Fourteen selected sequences located in important genes were characterized by a combination of biophysical and biochemical techniques. Our data show that these sequences form highly stable G4 structures under physiological conditions. Five Dictyostelium genes containing G4-prone motifs in their promoters were studied for the effect of a new G4-binding porphyrin derivative on their expression. Our results demonstrated that the new ligand significantly decreased their expression. Overall, our results constitute the first step to adopt Dictyostelium discoideum as a ‘G4-poor’ model for studies on G-quadruplexes.

Water-pipe (WP) smoking is the most common method of tobacco consumption in the Middle-East and is rapidly spreading on a global scale. Although, water-pipe smoking is linked to various diseases, such as emphysema and various types of cancers, its effect on testosterone levels has yet to be investigated. This study explores the effect of water-pipe smoking on serum testosterone levels in males in Qatar. In this cross-sectional sample within a cohort study, we retrieved data for a total of 1000 male volunteers from the Qatar BioBank (QBB) project. A self-reported questionnaire was used to determine the water-pipe smoking status of participants. Moreover, participants were stratified based on the frequency of smoking. Total testosterone and sex hormone binding globulin (SHBG) were measured clinically, whereas free testosterone and bioavailable testosterone were calculated using Vermeulen's equation. Hormone values of 541 males (277 water-pipe smokers and 264 non-smokers) were compared using multiple regression analysis based on water-pipe smoking status after adjusting for confounding factors. No statistically significant difference was observed between WP smokers and non-water-pipe smokers in the likelihood of having lower or higher total testosterone, after adjustment for confounding factors. Similar results were found in free testosterone, bioavailable testosterone, and sex hormone binding globulin (all p>0.05). When compared with the reference group, both light and heavy water-pipe smokers had a similar likelihood of circulating low total testosterone levels (OR=0.83, 95% CI: 0.46-1.49; and OR=0.80, 95% CI: 0.43-1.49; respectively). Our results reveal, for the first time, that there is no significant change in total testosterone, free testosterone, bioavailable testosterone and sex hormone binding globulin in waterpipe smokers compared to non-water-pipe smokers. Therefore, we believe that further studies are needed to confirm the effect of water-pipe smoking on testosterone in different populations. This work was supported by the College of Medicine of Qatar University and grant QUST-2-CMED-2018-1 from Qatar University.

Background: Efforts have been made to define professionalism across the professions, yet little attention has been paid to the concept in mental health services, where patients’ needs differ to that in other healthcare specialties. Aims: To derive a definition of professionalism for mental health services using the existing literature. Method: A rapid, systematic review was conducted to identify empirical and non-empirical records that described professionalism in a mental health service context from 2006 to 2017. Studies were synthesised narratively using thematic analysis. Results: Seventy records were included in the review. Professionalism was described on two levels; at a societal level, a dynamic social contract between professions and society, and; at an individual level, having intrapersonal, interpersonal, and working professionalism. Utilising emerging themes, an operationalised definition of professionalism, suitable for a mental health service context was derived. Conclusions: Within mental health services, emphasis is placed on the interpersonal aspects of practice such as communication skills, maintaining boundaries and humanity. Themes relating to the vulnerability of patients and the challenge of supporting autonomy and choice whilst maintaining safety and acting in a client’s best interest are also evident. ‘Practical wisdom’ and a flexible approach to working are needed to manage these challenging situations.

We investigated whether spinalized animals can produce inspiratory rhythm. We recorded spinal inspiratory phrenic (PNA) and cranial inspiratory hypoglossal (HNA) nerve activity in the perfused brainstem preparation of rat. Complete transverse transections were performed at 1.5 (pyramidal decussation) or 2 mm (first cervical spinal segment) caudal to obex. Excitatory drive was enhanced by either extracellular potassium, hypercapnia or by stimulating arterial chemoreceptors. Caudal transections immediately eliminated descending network drive for PNA, while the cranial inspiratory HNA remained unaffected. After transection, PNA bursting remained sporadic even during enhanced excitatory drive. This implies, cervical spinal circuits lack intrinsic rhythmogenic capacity. Rostral transections also abolished PNA immediately. However, HNA also progressively lost its amplitude and rhythm. Chemoreceptor activation only triggered tonic, non-rhythmic HNA. Thus the integrity of ponto-medullary circuitry was maintained. Our results suggest that an area overlapping the caudal nucleus retroambiguus provides critical ascending input to the ponto-medullary respiratory network for inspiratory rhythm generation.

The immunity profile against H5N1 highly pathogenic avian influenza (HPAI) in the commercial poultry value chain network in Egypt was modeled with the use of different vaccination scenarios. The model estimated the vaccination coverage, the protective seroconversion level, and the duration of immunity for each node of the network and vaccination scenario. Partial budget analysis was used to compare the benefit-cost of the different vaccination scenarios. The model predicted that targeting day-old chick avian influenza (AI) vaccination in industrial and large hatcheries would increase immunity levels in the overall poultry population in Egypt and especially in small commercial poultry farms (from 60%). This strategy was shown to be more efficient than the current strategy of using inactivated vaccines. Improving HPAI control in the commercial poultry sector in Egypt would have a positive impact to improve disease control.

Background and objectives: Pseudomonas aeruginosa possesses a variety of virulence factors that may contribute to its pathogenicity. P. aeruginosa also has a large number of virulence factors such as exotoxin A, exoenzyme S, nan 1 and Las genes. The aim of this study was to evaluate oprI, oprL as reliable factors for rapid identification of P. aeruginosa and to detect toxA, exo S, nan1 and LasB genes by Polymerase Chain Reaction (PCR). Materials and methods: In this study 30 isolates of P. aeruginosa were recovered from burn, pulmonary tract and blood infections. Results and conclusions: The oprI and oprL genes were detected in all of 30 P. aeruginosa isolates collected. The presence of toxA gene in isolates from burn and pulmonary tract was significantly higher than that from blood. All tested isolates harbored LasB gene. However, difference between exoS prevalence in isolates from pulmonary tract and burn isolates was statistically significant higher than that from blood. The prevalence of nan1 gene was significantly higher in isolates of pulmonary tract and burn specimens than isolates from blood. Molecular methods have been reported to be superior to the phenotypic methods for identification of P. aeruginosa by designing a multiplex PCR assay based on oprI and oprL genes for molecular detection of P. aeruginosa Determination of different virulence genes of P. aeruginosa isolates suggests that they are associated with different levels of intrinsic virulence and pathogenicity. Significant correlations between some virulence genes and source of infections indicates implementation of infection control measures will help in controlling the dissemination of virulence genes among P. aeruginosa isolates.

The effectiveness of recombinant turkey herpesvirus avian influenza (A/swan/Hungary/4999/2006(H5N1)) clade 2.2 virus (rHVT-H5) vaccine was evaluated in two layer chicken breeds (White Bovans [WB] and Brown Shaver [BS]). One dose of rHVT-H5 vaccine was administered at day 1 and birds were monitored serologically (haemagglutination inhibition test) and virologically for 19 weeks. Maternally-derived antibody and post-vaccination H5 antibody titres were measured using the Chinese (A/Goose/Guangdong/1/96(H5N1)) HA and the Egyptian (A/chicken/Egypt/128s/2012(H5N1)) HA as antigens. The challenge was conducted at 19 weeks of age and on six experimental groups: Groups I (WB) and II (BS), both vaccinated and challenged; Groups III (WB) and IV (BS), both vaccinated but not challenged; Groups V and VI, unvaccinated specific pathogen free chickens, serving respectively as positive and negative controls. The challenge virus was the clade 2.2.1 highly pathogenic avian influenza H5N1 A/chicken/Egypt/128s/2012 at a dose of 10(6) median embryo infective dose. For both breeds, complete maternally-derived antibody waning occurred at the age of 4 weeks. The immune response to rHVT-H5 vaccination was detected from the sixth week. The seroconversion rates for both breeds reached 85.7 to 100% in the eighth week of age. Protection levels of 73.3%, 60% and 0% were respectively recorded in Groups I, II and V. No mortalities occurred in the unchallenged groups. Group I showed superior results for all measured post-challenge parameters. In conclusion, a single rHVT-H5 hatchery vaccination conferred a high level of protection for a relatively extended period. This vaccine could be an important tool for future A/H5N1 prevention/control in endemic countries. Further studies on persistence of immunity beyond 19 weeks, need for booster with inactivated vaccines, breed susceptibility and vaccinal response, and transmissibility are recommended.