Molecular characterization and genetic diversity of the infectious laryngotracheitis virus strains circulating in Egypt during the outbreaks of 2018 and 2019

  • 32 Accesses


Infectious laryngotracheitis (ILT) is a respiratory disease that causes significant economic losses in the poultry industry worldwide. In this study, ILT outbreaks were reported on 30 farms located in eight Egyptian governorates between January 2018 and May 2019. Gross examination of diseased chickens revealed congestion and hemorrhage of laryngeal and tracheal mucosa with fibrinohemorrhagic casts and/or caseous material in the lumens. Histopathological examination showed epithelial sloughing, syncytium formation, heterophilic exudation, and development of eosinophilic intranuclear inclusion bodies. Infectious laryngotracheitis virus (ILTV) antigen was detected in the tracheal epithelium, infiltrated inflammatory cells, and syncytial cells, using immunohistochemistry. PCR targeting a portion of the thymidine kinase gene was further utilized to confirm the presence of ILTV DNA. The complete coding sequences of three envelope glycoprotein genes, gG, gD, and gJ, and a partial sequence of the infected cell polypeptide 4 (ICP4) gene from samples representing all of the farms and disease outbreaks were determined. Five prototype strains with unique sequences were chosen for detailed molecular characterization. Sequence comparisons and phylogenetic analysis of the partial ICP4 gene revealed that two strains were chicken embryo origin (CEO)-vaccine-like strains, and three were tissue culture origin (TCO)-vaccine-like strains. Analysis of the gJ gene sequence indicated that all of the strains were CEO vaccine-like strains. It was predicted that the latter three strains were recombinants of CEO- and TCO-vaccine-like strains. In conclusion, immunohistochemistry coupled with multi-genomic PCR sequencing proved to be efficient for identification and typing of ILTV strains during disease outbreaks. Both CEO-vaccine-like and recombinant virus strains were circulating in Egypt during the 2018 and 2019 outbreaks.

This is a preview of subscription content, log in to check access.

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA

Subscribe to journal

Immediate online access to all issues from 2019. Subscription will auto renew annually.

US$ 199

This is the net price. Taxes to be calculated in checkout.

Fig. 1
Fig. 2
Fig. 3
Fig. 4


  1. 1.

    Preis IS, Braga JFV, Couto RM et al (2013) Outbreak of infectious laryngotracheitis in large multi-age egg layer chicken flocks in Minas Gerais, Brazil. Pesqui Vet Bras 33:591–596.

  2. 2.

    García M (2008) Laryngotracheitis. In: Saif YM, Fadly AM, Glisson JR, McDougald LR, Nolan LK, Swayne DE (eds) Diseases of poultry, 12th edn. Blackwell Publishing, Oxford, pp 137–152

  3. 3.

    Crespo R, Woolcock PR, Chin RP et al (2007) Comparison of diagnostics techniques in an outbreak of infectious laryngotracheitis from meat chickens. Avian Dis 51:858–862.

  4. 4.

    Bagust T, Jones R, Guy J (2000) Avian infectious laryngotracheitis Aetiological agent. Rev Sci Tech 19:483–492

  5. 5.

    Coppo MJC, Noormohammadi AH, Browning GF, Devlin JM (2013) Challenges and recent advancements in infectious laryngotracheitis virus vaccines. Avian Pathol 42:195–205.

  6. 6.

    Menendez KR, García M, Spatz S, Tablante NL (2014) Molecular epidemiology of infectious laryngotracheitis: a review. Avian Pathol 43:108–117.

  7. 7.

    Kotiw M, Wilks CR, May JT (1995) The effect of serial in vivo passage on the expression of virulence and DNA stability of an infectious laryngotracheitis virus strain of low virulence. Vet Microbiol 45:71–80.

  8. 8.

    Guy JS, Barnes HJ, Smith L (1990) Increased virulence of modified-live infectious laryngotracheitis vaccine virus following bird-to-bird passage. Avian Dis 35:348.

  9. 9.

    Hughes CS, Williams RA, Gaskell RM et al (1991) Latency and reactivation of infectious laryngotracheitis vaccine virus. Arch Virol 121:213–218

  10. 10.

    Williams RA, Bennett M, Bradbury JM et al (1992) Demonstration of sites of latency of infectious laryngotracheitis virus using the polymerase chain reaction. J Gen Virol 73:2415–2420

  11. 11.

    Oldoni I, García M (2007) Characterization of infectious laryngotracheitis virus isolates from the US by polymerase chain reaction and restriction fragment length polymorphism of multiple genome regions. Avian Pathol 36:167–176.

  12. 12.

    Blacker HP, Kirkpatrick NC, Rubite A et al (2011) Epidemiology of recent outbreaks of infectious laryngotracheitis in poultry in Australia. Aust Vet J 89:89–94.

  13. 13.

    Ojkic D, Swinton J, Vallieres M et al (2006) Characterization of field isolates of infectious laryngotracheitis virus from Ontario. Avian Pathol 35:286–292.

  14. 14.

    Tantawy HH, El Batrawy AM, Bastami MA et al (1983) Avian infectious laryngo-tracheitis in Egypt. Epidemiology, virus isolation and infection. Vet Res Commun 6:281–287

  15. 15.

    Shehata AA, Halami MY, Sultan HH et al (2013) Chicken embryo origin-like strains are responsible for infectious laryngotracheitis virus outbreaks in Egyptian cross-bred broiler chickens. Virus Genes 46:423–430.

  16. 16.

    Abdel-Moneim AA, Shimaa MM, Mahmoud HM et al (2014) Molecular characterization of thymidine kinase and glycoprotein G genes from a possible vaccine induced infectious laryngotracheitis outbreaks in Egypt. Pak Vet J 34:381–385

  17. 17.

    Guy Bagust TJ (2003) Laryngotracheitis. In: Saif YM, Barnes HJ, Glisson JR, Fadley AM, McDougald LR, Swayne DE (eds) Diseases of poultry, 11th edn. Iowa State Press, Ames, pp 121–134

  18. 18.

    Lee S, Markham PF, Coppo MJC et al (2012) Attenuated vaccines can recombine to form virulent field viruses. Science 80–:337

  19. 19.

    Agnew-crumpton R, Vaz PK, Devlin JM et al (2016) Spread of the newly emerging infectious laryngotracheitis viruses in Australia. Infect Genet Evol 43:67–73.

  20. 20.

    Chang P, Lee Y, Shien J, Shieh HK (1997) Rapid differentiation of vaccine strains and field isolates of infectious 1, aryngotracheitis virus by restriction fragment length polymorphism of PCR products. J Virol Methods 66:179–186

  21. 21.

    Kirkpatrick NC, Mahmoudian A, O’Rourke D, Noormohammadi AH (2006) Differentiation of infectious laryngotracheitis virus isolates by restriction fragment length polymorphic analysis of polymerase chain reaction products amplified from multiple genes. Avian Dis 50:28–33.

  22. 22.

    Chacón JL, Ferreira AJP (2009) Differentiation of field isolates and vaccine strains of infectious laryngotracheitis virus by DNA sequencing. Vaccine 27:6731–6738.

  23. 23.

    Craig MI, Rojas MF, van der Ploeg CA et al (2017) Molecular characterization and cluster analysis of field isolates of avian infectious laryngotracheitis virus from Argentina. Front Vet Sci 4:1–7.

  24. 24.

    Yavuz O, Özdemir Ö, Aras Z, Terzi F (2018) Immunohistochemical studies on infectious laryngotracheitis in the respiratory tract lesions in naturally infected laying hens. Kafkas Univ Vet Fak Derg 24:257–264.

  25. 25.

    García M, Volkening J, Riblet S, Spatz S (2013) Genomic sequence analysis of the United States infectious laryngotracheitis vaccine strains chicken embryo origin (CEO) and tissue culture origin (TCO). Virology 440:64–74.

  26. 26.

    Preis I, Fiúza A, Silva C et al (2014) Pathological, immunohistochemical, and molecular findings in commercial laying hens and in backyard chickens naturally infected with the infectious laryngotracheitis virus. Braz J Poult Sci 16:359–366

  27. 27.

    Reddy VRAP, Steukers L, Li Y et al (2014) Replication characteristics of infectious laryngotracheitis virus in the respiratory and conjunctival mucosa. Avian Pathol 43:450–457.

  28. 28.

    Fuchs W, Veits J, Helferich D et al (2007) Molecular biology of avian infectious laryngotracheitis virus. Vet Res 20:261–279

  29. 29.

    Helferich D, Veits J, Teifke JP et al (2007) The UL47 gene of avian infectious laryngotracheitis virus is not essential for in vitro replication but is relevant for virulence in chickens. J Gen Virol 88:732–742.

  30. 30.

    Lee SW, Devlin JM, Markham JF et al (2013) Phylogenetic and molecular epidemiological studies reveal evidence of multiple past recombination events between infectious laryngotracheitis viruses. PLoS One.

  31. 31.

    La TM, Choi EJ, Lee JB et al (2019) Comparative genome analysis of Korean field strains of infectious laryngotracheitis virus. PLoS One 14:1–12.

  32. 32.

    Zhao W, Spatz S, Zhang Z et al (2014) Newcastle disease virus (NDV) recombinants expressing infectious laryngotracheitis virus (ILTV) glycoproteins gB and gD protect chickens against ILTV and NDV challenges. J Virol 88:8397–8406.

Download references


We would like to thank all colleagues and co-workers in the Virology and Pathology departments of the Faculty of Veterinary Medicine, Cairo University, Egypt, for their technical support.

Author information

Conceptualization: ME-M, EES and HA. Methodology: MB and ME-S. Formal analysis and investigation: HA, MB, EES, and ME-M. Writing – original draft preparation: MB and ME-S. Writing – review and editing: HA, MB, EES, and ME-M. Resources: ME-S and MB. Supervision: MB, EES, and ME-M.

Correspondence to Mahmoud Bayoumi.

Ethics declarations

Conflict of interest

The authors declare that they have no conflicting interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Handling Editor: Akbar Dastjerdi.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Bayoumi, M., El-Saied, M., Amer, H. et al. Molecular characterization and genetic diversity of the infectious laryngotracheitis virus strains circulating in Egypt during the outbreaks of 2018 and 2019. Arch Virol (2020) doi:10.1007/s00705-019-04522-4

Download citation