{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T12:29:09Z","timestamp":1786624149550,"version":"build-2736575974"},"reference-count":81,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T00:00:00Z","timestamp":1786579200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Viruses"],"abstract":"<jats:p>Highly pathogenic avian influenza (HPAI) virus H5N1of clade 2.3.4.4b has emerged as the predominant lineage circulating in poultry flocks worldwide, raising concerns regarding the protective efficacy of currently available commercial vaccines, particularly in domestic ducks, which play an important role in virus maintenance and transmission. Thus, this study evaluated the immunogenicity along with the protective efficacy of four inactivated H5 vaccines against a recently isolated local HPAI-H5N1 (Newvalley-3-H5N1-2024, clade 2.3.4.4b) strain in Pekin ducks in Egypt. A total of 150 seronegative ducks were divided into vaccinated and control groups (10 groups) and vaccinated at 10 days of age. At 31 days of age, the vaccinated and positive control groups were challenged using 106.5 EID50\/0.5 mL\/duck with the local isolate (Newvalley-3-H5N1-2024) via the oculo-nasal route. The vaccine efficacy was assessed through clinical signs, survival rate, hemagglutination inhibition (HI) antibody titer, tracheal and cloacal viral shedding quantified by real-time RT-PCR, and histopathological examination of trachea, lung, pancreas, and brain tissues. Generally, all ducks vaccinated with the ValleyVac Avian Flu H5 plus and MEFLUVACTM H5 PLUS 8 showed a significantly higher survival rate (100%) at 10 days post-vaccination (DPV) than those in the positive control (66.7% mortality rate). In contrast, ducks exhibited mortality rates ranging from 6.7% in the SERVAC Flu H5N1 group to 13.4% in the Sinder Fluvac group. The ValleyVac Avian Flu H5 plus and MEFLUVAC\u2122 H5 PLUS 8 vaccines induced the highest HI antibody titers at 7, 14, 21, and 28 DPV in both homologous and heterologous AIV antigens, resulting in a significant reduction in viral load among all vaccinated duck groups (p-value &lt; 0.05) comparable to the positive control group. Conversely, the SERVAC Flu H5N1 and Sinder Fluvac vaccines provided partial protection, suboptimal immunogenicity at different time points, and elevated viral shedding. Histopathological findings in ValleyVac Avian Flu H5 plus and MEFLUVAC\u2122 H5 PLUS 8 vaccines exhibited mild tissue alterations following AIV challenge. Marked pathological lesions were observed in the SERVAC Flu H5N1 and Sinder Fluvac vaccinated groups. Among tested vaccines, both ValleyVac Avian Flu H5 plus and MEFLUVACTM H5 PLUS 8 showed the highest level of protective efficacy against the circulating AIV strain compared with other commercial vaccines. This study highlights the need for continuous molecular surveillance, antigenic matching, and regular updating of vaccine seed strains to ensure efficient HPAI control in Egypt.<\/jats:p>","DOI":"10.3390\/v18080891","type":"journal-article","created":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T11:33:46Z","timestamp":1786620826000},"page":"891","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Protective Efficacy Evaluation of Various Inactivated Vaccines Against the Newly Circulated Highly Pathogenic Avian Influenza Virus H5N1 of Clade 2.3.4.4b in Pekin Ducks"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5862-3137","authenticated-orcid":false,"given":"Eman Abd El Menum","family":"Shosha","sequence":"first","affiliation":[{"name":"Virology Department, Faculty of Veterinary Medicine, New Valley University, El-Khargia 72511, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1750-1448","authenticated-orcid":false,"given":"Ibrahim","family":"Eldaghayes","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Parasitology, Faculty of Veterinary Medicine, University of Tripoli, Tripoli 1300, Libya"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ahmed Abd-Elsamie H.","family":"Ali","sequence":"additional","affiliation":[{"name":"Virology Department, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44519, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Waleed","family":"Senosy Ali","sequence":"additional","affiliation":[{"name":"Theriogenology Department, Faculty of Veterinary Medicine, New Valley University, El-Khargia 72511, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eman Hafez","family":"Elhayani","sequence":"additional","affiliation":[{"name":"Virology Department, Faculty of Veterinary Medicine, New Valley University, El-Khargia 72511, Egypt"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1186\/s12985-025-02718-6","article-title":"A Full-length S1 gene sequencing of a novel emerged GI-19 and GI-23 lineages of Infectious bronchitis virus currently circulating in chicken flocks in Upper Egypt reveals marked genetic diversity and recombination events","volume":"22","author":"Shosha","year":"2025","journal-title":"Virol. J."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Shosha, E.A.E., Abdelnaser, S., Zanaty, A.M., Elzanaty, A.E., Selim, K., and Eldaghayes, I. (2025). Successive Efficacy Evaluation of Various Commercial Live-Attenuated Avian coronavirus Vaccination Schedules Against a Local GI-23.3 Challenge in SPF Broilers. Vaccines, 13.","DOI":"10.3390\/vaccines13111132"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1186\/s12985-026-03257-4","article-title":"Full genome sequencing, evolutionary dynamics, and pathogenicity evaluation of chicken infectious anemia virus with emphasis on Upper Egypt reveals genetic variability linked to vaccinal strains","volume":"23","author":"Shosha","year":"2026","journal-title":"Virol. J."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"199779","DOI":"10.1016\/j.virusres.2026.199779","article-title":"Pathogenicity and molecular evolutionary analysis of novel Avian orthreovirus genotypes IV and V in Upper Egypt","volume":"371","author":"Ahmed","year":"2026","journal-title":"Virus Res."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1367","DOI":"10.3201\/eid2907.221149","article-title":"Highly Pathogenic Avian Influenza Virus (H5N1) Clade 2.3.4.4b Introduced by Wild Birds, China, 2021","volume":"29","author":"Tian","year":"2023","journal-title":"Emerg. Infect. Dis."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"109860","DOI":"10.1016\/j.virol.2023.109860","article-title":"H5N1 highly pathogenic avian influenza clade 2.3.4.4b in wild and domestic birds: Introductions into the United States and reassortments, December 2021\u2013April 2022","volume":"587","author":"Youk","year":"2023","journal-title":"Virology"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1842","DOI":"10.3201\/eid2909.230067","article-title":"Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus in Wild Birds, Chile","volume":"29","author":"Ariyama","year":"2023","journal-title":"Emerg. Infect. Dis. J."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"102591","DOI":"10.1016\/j.tmaid.2023.102591","article-title":"Multiple introductions of highly pathogenic avian influenza H5N1 clade 2.3.4.4b into South America","volume":"53","author":"Pujol","year":"2023","journal-title":"Travel. Med. Infect. Dis."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Mosaad, Z., Elhusseiny, M.H., Zanaty, A., Fathy, M.M., Hagag, N.M., Mady, W.H., Said, D., Elsayed, M.M., Erfan, A.M., and Rabie, N. (2023). Emergence of highly pathogenic avian influenza A virus (H5N1) of Clade 2.3.4.4b in Egypt, 2021\u20132022. Pathogens, 12.","DOI":"10.3390\/pathogens12010090"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"122","DOI":"10.12688\/gatesopenres.13171.1","article-title":"Are current avian influenza vaccines a solution for smallholder poultry farmers?","volume":"4","author":"Guyonnet","year":"2020","journal-title":"Gates Open Res."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Dey, P., Ahuja, A., Panwar, J., Choudhary, P., Rani, S., Kaur, M., Sharma, A., Kaur, J., Yadav, A.K., and Sood, V. (2023). Immune Control of Avian Influenza Virus Infection and Its Vaccine Development. Vaccines, 11.","DOI":"10.3390\/vaccines11030593"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/j.rvsc.2021.08.012","article-title":"Examination of the protective efficacy of two avian influenza H5 vaccines against clade 2.3.4.4b H5N8 highly pathogenic avian influenza virus in commercial broilers","volume":"140","author":"Awad","year":"2021","journal-title":"Res. Vet. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Hagag, N.M., Yehia, N., El-Husseiny, M.H., Adel, A., Shalaby, A.G., Rabie, N., Samy, M., Mohamed, M., El-Oksh, A.S.A., and Selim, A. (2022). Molecular Epidemiology and Evolutionary Analysis of Avian Influenza A(H5) Viruses Circulating in Egypt, 2019\u20132021. Viruses, 14.","DOI":"10.3390\/v14081758"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1016\/j.meegid.2016.02.023","article-title":"Introduction and enzootic of A\/H5N1 in Egypt: Virus evolution, pathogenicity and vaccine efficacy ten years on","volume":"40","author":"Abdelwhab","year":"2016","journal-title":"Infect. Genet. Evol."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Kim, S.H. (2018). Challenge for One Health: Co-Circulation of Zoonotic H5N1 and H9N2 Avian Influenza Viruses in Egypt. Viruses, 10.","DOI":"10.3390\/v10030121"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1194","DOI":"10.14202\/vetworld.2017.1194-1204","article-title":"Public health concerns of highly pathogenic avian influenza H5N1 endemicity in Africa","volume":"10","author":"Fasanmi","year":"2017","journal-title":"Vet. World"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Mahmoud, S.H., Khalil, A.A., Abo Shama, N.M., El Sayed, M.F., Soliman, R.A., Hagag, N.M., Yehia, N., Naguib, M.M., Arafa, A.S., and Ali, M.A. (2023). Immunogenicity and cross-protective efficacy induced by an inactivated recombinant avian influenza A\/H5N1 (clade 2.3.4.4b) vaccine against Co-circulating influenza A\/H5Nx viruses. Vaccines, 11.","DOI":"10.3390\/vaccines11091397"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e3255","DOI":"10.1111\/tbed.14551","article-title":"Emergence of clade 2.3. 4.4 b novel reassortant H5N1 high pathogenicity avian influenza virus in South Korea during late 2021","volume":"69","author":"Sagong","year":"2022","journal-title":"Transbound. Emerg. Dis."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"e0249921","DOI":"10.1128\/spectrum.02499-21","article-title":"Multiple Introductions of Reassorted Highly Pathogenic Avian Influenza H5Nx Viruses Clade 2.3. 4.4 b Causing Outbreaks in Wild Birds and Poultry in The Netherlands, 2020\u20132021","volume":"10","author":"Engelsma","year":"2022","journal-title":"Microbiol. Spectr."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Parvin, R., Helal, S.B., Uddin, M.M., Tasnim, S., Hossain, M.R., Shila, R.A., Begum, J.A., Nooruzzaman, M., Ahrens, A.K., and Harder, T. (2025). Emerging Highly Pathogenic Avian Influenza H5N1 Clade 2.3.4.4b Causes Neurological Disease and Mortality in Scavenging Ducks in Bangladesh. Vet. Sci., 12.","DOI":"10.3390\/vetsci12080689"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1455","DOI":"10.1007\/s00705-022-05442-6","article-title":"A new clade 2.3. 4.4 b H5N1 highly pathogenic avian influenza genotype detected in Europe in 2021","volume":"167","author":"Nagy","year":"2022","journal-title":"Arch. Virol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1693","DOI":"10.1080\/22221751.2022.2088407","article-title":"Global dissemination of H5N1 influenza viruses bearing the clade 2.3.4.4b HA gene and biologic analysis of the ones detected in China","volume":"11","author":"Cui","year":"2022","journal-title":"Emerg. Microbes Infect."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"101601","DOI":"10.1016\/j.cimid.2020.101601","article-title":"A single dose of inactivated oil-emulsion bivalent H5N8\/H5N1 vaccine protects chickens against the lethal challenge of both highly pathogenic avian influenza viruses","volume":"74","author":"Ibrahim","year":"2021","journal-title":"Comp. Immunol. Microbiol. Infect. Dis."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1080\/03079457.2018.1470606","article-title":"Characterization of highly pathogenic avian influenza H5N8 virus from Egyptian domestic waterfowl in 2017","volume":"47","author":"Anis","year":"2018","journal-title":"Avian Pathol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"6345","DOI":"10.1016\/j.vaccine.2017.04.042","article-title":"Homologous and heterologous antigenic matched vaccines containing different H5 hemagglutinins provide variable protection of chickens from the 2014 US H5N8 and H5N2 clade 2.3. 4.4 highly pathogenic avian influenza viruses","volume":"35","author":"Kapczynski","year":"2017","journal-title":"Vaccine"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"9697","DOI":"10.1038\/s41598-018-28057-x","article-title":"Efficacy of commercial vaccines against newly emerging avian influenza H5N8 virus in Egypt","volume":"8","author":"Kandeil","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_27","first-page":"3143189","article-title":"Efficacy of a recombinant Turkey herpesvirus AI (H5) vaccine in preventing transmission of heterologous highly pathogenic H5N8 clade 2.3.4.4b challenge virus in commercial broilers and layer pullets","volume":"21","author":"Palya","year":"2018","journal-title":"J. Immunol. Res."},{"key":"ref_28","first-page":"2131","article-title":"Discrepancies in the efficacy of H5 inactivated avian influenza vaccines in specific-pathogen-free chickens against challenge with the Egyptian H5N8 clade 2.3.4.4 Group B virus isolated in 2018","volume":"14","author":"Elsaied","year":"2021","journal-title":"Vet. World"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1038\/s44298-024-00035-3","article-title":"Transmission dynamics of avian influenza viruses in Egyptian poultry markets","volume":"2","author":"Mahmoud","year":"2024","journal-title":"npj Viruses"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1111\/irv.12634","article-title":"Surveillance for avian influenza viruses in wild birds at live bird markets, Egypt, 2014\u20132016","volume":"13","author":"Kayed","year":"2019","journal-title":"Influenza Other Respir. Viruses"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Kamel, M.N., Moatasim, Y., Aboulhoda, B.E., Gomaa, M., El Taweel, A., Kutkat, O., El Sayes, M., GabAllah, M., AbdAllah, H., and Gabre, R.M. (2025). Genetic Characterization and Pathogenesis of Highly Pathogenic Avian Influenza Virus A (H5N1) Isolated in Egypt During 2021\u20132023. Viruses, 17.","DOI":"10.3390\/v17101370"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"844","DOI":"10.1111\/tbed.13406","article-title":"Domestic ducks play a major role in the maintenance and spread of H5N8 highly pathogenic avian influenza viruses in South Korea","volume":"67","author":"Kwon","year":"2020","journal-title":"Transbound. Emerg. Dis."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"11729","DOI":"10.1038\/s41598-022-13447-z","article-title":"Transatlantic spread of highly pathogenic avian influenza H5N1 by wild birds from Europe to North America in 2021","volume":"12","author":"Caliendo","year":"2022","journal-title":"Sci. Rep."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"275","DOI":"10.20506\/rst.28.1.1881","article-title":"Efficacy of a commercial inactivated H5 influenza vaccine against highly pathogenic avian influenza H5N1 in waterfowl evaluated under field conditions","volume":"28","author":"Rudolf","year":"2009","journal-title":"Rev. Sci. Tech."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1186\/s12985-016-0477-7","article-title":"Phylodynamics of avian influenza clade 2.2.1 H5N1 viruses in Egypt","volume":"13","author":"Arafa","year":"2016","journal-title":"Virol. J."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"100932","DOI":"10.1016\/j.onehlt.2024.100932","article-title":"Transmission dynamics of highly pathogenic avian influenza virus at the wildlife-poultry-environmental interface: A case study","volume":"19","author":"Giacinti","year":"2024","journal-title":"One Health"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Mostafa, A., Kanrai, P., Petersen, H., Ibrahim, S., Rautenschlein, S., and Pleschka, S. (2015). Efficient Generation of Recombinant Influenza AViruses Employing a New Approach to Overcome the Genetic Instability of HA Segments. PLoS ONE, 10.","DOI":"10.1371\/journal.pone.0116917"},{"key":"ref_38","first-page":"153","article-title":"Development and application of avian influenza vaccines in China","volume":"333","author":"Chen","year":"2009","journal-title":"Curr. Top. Microbiol. Immunol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"e0026024","DOI":"10.1128\/mra.00260-24","article-title":"Detection and genomic characterization of an avian influenza virus A\/mute swan\/Mangystau\/1-S24R-2\/2024 (H5N1; clade 2.3.4.4b) strain isolated from the lung of a dead swan in Kazakhstan","volume":"13","author":"Tabynov","year":"2024","journal-title":"Microbiol. Resour. Announc."},{"key":"ref_40","first-page":"493","article-title":"A simple method of estimating fifty percent endpoints","volume":"27","author":"Reed","year":"1938","journal-title":"Am. J. Hyg."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"102952","DOI":"10.1016\/j.psj.2023.102952","article-title":"Evaluation of inactivated avian influenza virus and Newcastle disease virus bivalent vaccination program against newly circulated H5N8 and NDV strains","volume":"102","author":"Azab","year":"2023","journal-title":"Poult. Sci."},{"key":"ref_42","unstructured":"World Organisation for Animal Health (2021). Avian Influenza (Including Infection with High Pathogenicity Avian Influenza Viruses, Chapter 3.3.4. WOAH Terrestrial Manual 2021, WOAH. Available online: https:\/\/www.woah.org\/fileadmin\/Home\/eng\/Health_standards\/tahm\/3.03.04_AI.pdf."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Metwally, S., Viljoen, G., and El Idrissi, A. (2022). Veterinary Vaccines: Principles and Applications, John Wiley & Sons, Ltd.","DOI":"10.1002\/9781119506287"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"619","DOI":"10.1080\/03079450802499126","article-title":"Pathogenesis of highly pathogenic avian influenza A\/Turkey\/Turkey\/1\/2005 H5N1 in Pekin ducks (Anas platyrhynchos) infected experimentally","volume":"37","author":"Nunez","year":"2008","journal-title":"Avian Pathol."},{"key":"ref_45","unstructured":"Suvarna, K.S., Layton, C., and Bancroft, J.D. (2013). Bancroft\u2019s Theory and Practice of Histological Techniques, Churchill Livingstone. [7th ed.]."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1007","DOI":"10.1177\/0300985813485099","article-title":"Prin ciples for valid histopathologic scoring in research","volume":"50","author":"Olivier","year":"2013","journal-title":"Vet. Pathol."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Moatasim, Y., Kandeil, A., Aboulhoda, B.E., El-Shesheny, R., Alkhazindar, M., AbdElSalam, E.T., Kutkat, O., Kamel, M.N., El Taweel, A.N., and Mostafa, A. (2019). Comparative virological and pathogenic characteristics of avian influenza H5N8 viruses detected in wild birds and domestic poultry in Egypt during the winter of 2016\/2017. Viruses, 11.","DOI":"10.3390\/v11110990"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"158","DOI":"10.1016\/j.coviro.2016.02.005","article-title":"Emergence and dissemination of clade 2.3.4.4 H5Nx influenza viruses-how is the Asian HPAI H5 lineage maintained","volume":"16","author":"Claes","year":"2016","journal-title":"Curr. Opin. Virol."},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Shosha, E.A.E., Eldaghayes, I., Abdel-Rahaman, S.E.A., Hussein, A., El Naggar, H.M., Gamaleldin, M.A., Fotouh, A., and Radwan, A.A. (2026). Pathogenicity and Genotyping of Fowl Adenovirus-D Serotype 2\/11 Circulating in Commercial Broilers in Egypt. Viruses, 18.","DOI":"10.3390\/v18020252"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"veae027","DOI":"10.1093\/ve\/veae027","article-title":"High pathogenic avian influenza A(H5) viruses of clade 2.3.4.4b in Europe-Why trends of virus evolution are more difficult to predict","volume":"10","author":"Fusaro","year":"2024","journal-title":"Virus Evol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1139\/cjm-2025-0214","article-title":"Epidemiology and impact of high pathogenicity avian influenza in Europe 2020\u20132025","volume":"72","author":"Brown","year":"2026","journal-title":"Can. J. Microbiol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"3745","DOI":"10.14202\/vetworld.2025.3745-3760","article-title":"Genomic and evolu-tionary characterization of newly emerged highly pathogenic avian influenza H5N1 clade 2.3.4.4b viruses circulating in broiler flocks in Upper Egypt (2023\u20132025)","volume":"18","author":"Shosha","year":"2025","journal-title":"Vet. World"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"3756","DOI":"10.1016\/j.vaccine.2024.04.088","article-title":"Efficacy of live and inactivated recombinant Newcastle disease virus vaccines expressing clade 2.3.4.4b H5 hemagglutinin against H5N1 highly pathogenic avian influenza in SPF chickens, Broilers, and domestic ducks","volume":"42","author":"Kim","year":"2024","journal-title":"Vaccine"},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"2562046","DOI":"10.1080\/22221751.2025.2562046","article-title":"Genomic surveillance and evolution of co-circulating avian influenza H5N1 and H5N8 viruses in Egypt, 2022\u20132024","volume":"14","author":"Eid","year":"2025","journal-title":"Emerg. Microbes Infect."},{"key":"ref_55","doi-asserted-by":"crossref","unstructured":"Kilany, W.H., Safwat, M., Zain El-Abideen, M.A., Hisham, I., Moussa, Y., Ali, A., and Elkady, M.F. (2025). Multivalent Inactivated Vaccine Protects Chickens from Distinct Clades of Highly Pathogenic Avian Influenza Subtypes H5N1 and H5N8. Vaccines, 13.","DOI":"10.3390\/vaccines13020204"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"e0002125","DOI":"10.1128\/msphere.00021-25","article-title":"Comparative pathogenicity of three A(H5N1) clade 2.3.4.4b HPAI viruses in blue-winged teal and transmission to domestic poultry","volume":"10","author":"Alkie","year":"2025","journal-title":"mSphere"},{"key":"ref_57","doi-asserted-by":"crossref","unstructured":"Piesche, R., Cazaban, C., Frizzo DaSilva, L., Ram\u00edrez-Mart\u00ednez, L., Hufen, H., Beer, M., Harder, T., and Grund, C. (2025). Immunogenicity and Protective Efficacy of Five Vaccines Against Highly Pathogenic Avian InfluenzaVirus H5N1,Clade2.3.4.4b, in Fattening Geese. Vaccines, 13.","DOI":"10.20944\/preprints202503.0731.v1"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"e00720-20","DOI":"10.1128\/JVI.00720-20","article-title":"Cross-Protection by Inactivated H5 Prepandemic Vaccine Seed Strains against Diverse Goose\/Guangdong Lineage H5N1 Highly Pathogenic Avian Influenza Viruses","volume":"94","author":"Criado","year":"2020","journal-title":"J. Virol."},{"key":"ref_59","doi-asserted-by":"crossref","unstructured":"Graziosi, G., Lupini, C., Catelli, E., and Carnaccini, S. (2024). Highly Pathogenic Avian Influenza (HPAI) H5 Clade 2.3.4.4b Virus Infection in Birds and Mammals. Animals, 14.","DOI":"10.20944\/preprints202404.1123.v1"},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"2399970","DOI":"10.1080\/22221751.2024.2399970","article-title":"Experimental infection of chickens, Pekin ducks, Eurasian wigeons and Barnacle geese with two recent highly pathogenic avian influenza H5N1 clade 2.3.4.4b viruses","volume":"13","author":"Bordes","year":"2024","journal-title":"Emerg. Microbes Infect."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"5913","DOI":"10.1073\/pnas.1001755107","article-title":"Association of RIG-I with innate immunity of ducks to influenza","volume":"107","author":"Barber","year":"2010","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_62","doi-asserted-by":"crossref","unstructured":"EFSA Panel on Animal Health and Animal Welfare (AHAW), European Union Reference Laboratory for Avian Influenza, Nielsen, S.S., Alvarez, J., Bicout, D.J., Calistri, P., Canali, E., Drewe, J.A., Garin-Bastuji, B., and Gort\u00e1zar, C. (2024). Vaccination of poultry against highly pathogenic avian influenza\u2014Part 2. Surveillance and mitigation measures. EFSA J., 22, e8755.","DOI":"10.2903\/j.efsa.2024.8755"},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"109546","DOI":"10.1016\/j.vetmic.2022.109546","article-title":"Stress-induced immunosuppression affecting avian influenza virus vaccine immune response through miR-20a-5p\/NR4A3 pathway in chicken","volume":"273","author":"Tian","year":"2022","journal-title":"Vet. Microbiol."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"709","DOI":"10.1093\/ps\/84.5.709","article-title":"Stress response differences and disease susceptibility reflected by heterophil to lymphocyte ratio in turkeys selected for increased body weight","volume":"84","author":"Huff","year":"2005","journal-title":"Poult. Sci."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1007\/s10393-013-0861-3","article-title":"Success factors for avian influenza vaccine use in poultry and potential impact at the wild bird-agricultural interface","volume":"11","author":"Swayne","year":"2014","journal-title":"Ecohealth"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1177\/08828245261424908","article-title":"Cross-Reactive Antibody Responses to Emerging Bovine H5N1 Clade 2.3.4.4b Following Seasonal Influenza Vaccination: Implications for Pandemic Preparedness","volume":"39","author":"Li","year":"2026","journal-title":"Viral Immunol."},{"key":"ref_67","doi-asserted-by":"crossref","unstructured":"Kov\u00e1cs, L., Farkas, M., Dobra, P.F., Lennon, G., K\u00f6nyves, L.P., and Rusvai, M. (2025). Avian Influenza Clade 2.3.4.4b: Global Impact and Summary Analysis of Vaccine Trials. Vaccines, 13.","DOI":"10.3390\/vaccines13050453"},{"key":"ref_68","first-page":"1749","article-title":"An H5N1 clade 2.3.4.4b virus vaccine that elicits cross-protective antibodies against conserved domains of H5 and N1 glycoproteins","volume":"17","author":"Andrade","year":"2025","journal-title":"Nat. Commun."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"3794","DOI":"10.1016\/j.vaccine.2021.05.060","article-title":"Antigenic evolution of contemporary clade 2.3.4.4 HPAI H5 influenza A viruses and impact on vaccine use for mitigation and control","volume":"39","author":"Lewis","year":"2021","journal-title":"Vaccine"},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"269","DOI":"10.4142\/jvs.2017.18.S1.269","article-title":"Evolution, global spread, and pathogenicity of highly pathogenic avian influenza H5Nx clade 2.3.4.4","volume":"18","author":"Lee","year":"2017","journal-title":"J. Vet. Sci."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"582","DOI":"10.4161\/hv.23239","article-title":"Cross-protection against drifted influenza viruses: Options offered by adjuvanted and intradermal vaccines","volume":"9","author":"Orsi","year":"2013","journal-title":"Hum. Vaccin. Immunother."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"6195","DOI":"10.1016\/j.vaccine.2017.09.040","article-title":"Avian influenza H5N1 vaccination efficacy in Egyptian backyard poultry","volume":"35","author":"Kandeil","year":"2017","journal-title":"Vaccine"},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"10954","DOI":"10.1038\/s41467-025-66431-2","article-title":"Pre-existing cross-reactive immunity to highly pathogenic avian influenza 2.3.4.4b A(H5N1) virus in the United States","volume":"16","author":"Li","year":"2025","journal-title":"Nat. Commun."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"100","DOI":"10.1186\/s13567-024-01357-z","article-title":"Viral shedding and environmental dispersion of two clade 2.3.4.4b H5 high pathogenicity avian influenza viruses in experimentally infected mule ducks: Implications for environmental sampling","volume":"55","author":"Filaire","year":"2024","journal-title":"Vet. Res."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"110601","DOI":"10.1016\/j.virol.2025.110601","article-title":"Evaluation of commercial vaccines for efficacy and transmission control against the emergent H5N8 (clade 2.3.4.4b) avi-an influenza virus in Kazakhstan","volume":"610","author":"Tabynov","year":"2025","journal-title":"Virology"},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1186\/s13567-023-01219-0","article-title":"A systematic review of mechanistic models used to study avian influenza virus transmission and control","volume":"54","author":"Lambert","year":"2023","journal-title":"Vet. Res."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"805","DOI":"10.1038\/s41579-023-00945-8","article-title":"Co-evolution of immunity and seasonal influenza viruses","volume":"21","author":"Han","year":"2023","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_78","first-page":"263","article-title":"Pathogenicity of Highly Pathogenic Avian Influenza Virus (H5N1) in Different Duck Breeds","volume":"15","author":"Hussein","year":"2025","journal-title":"J. World Poult. Res."},{"key":"ref_79","doi-asserted-by":"crossref","unstructured":"Pantin-Jackwood, M.J., Spackman, E., Leyson, C., Youk, S., Lee, S.A., Moon, L.M., Torchetti, M.K., Killian, M.L., Lenoch, J.B., and Kapczynski, D.R. (2023). Pathogenicity in chickens and turkeys of a 2021 United States H5N1 highly pathogenic avian influenza clade 2.3.4.4b wild bird virus compared to two previous H5N8 clade 2.3.4.4 viruses. Viruses, 15.","DOI":"10.3390\/v15112273"},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"6289","DOI":"10.3382\/ps\/pez385","article-title":"Development of an effective contemporary trivalent avian influenza vaccine against circulating H5N1, H5N8, and H9N2 in Egypt","volume":"98","author":"Gomaa","year":"2019","journal-title":"Poult. Sci."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"1463","DOI":"10.1111\/tbed.13515","article-title":"Control of avian influenza in China: Strategies and lessons","volume":"67","author":"Liu","year":"2020","journal-title":"Transbound. Emerg. Dis."}],"container-title":["Viruses"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1999-4915\/18\/8\/891\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T11:38:22Z","timestamp":1786621102000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1999-4915\/18\/8\/891"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,13]]},"references-count":81,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["v18080891"],"URL":"https:\/\/doi.org\/10.3390\/v18080891","relation":{},"ISSN":["1999-4915"],"issn-type":[{"value":"1999-4915","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,13]]}}}