Preparation And Evaluation Of A Recent Infectious Laryngotracheitis (Ilt) Vaccine From A Local Field Isolate

Infectious laryngotracheitis (ILT) is a respiratory tract disease affecting chickens worldwide. The disease leads to severe production losses due to increased mortality, decreased egg production, and delayed body weight gain, causing enormous economic losses to the poultry industry. ILT is controlled through vaccination with live-modified attenuated vaccines of chicken embryo origin (CEO) and/or the tissue-culture origin (TCO). This study was conducted to develop Specific Pathogenic Free (SPF) egg-adapted live attenuated ILT vaccine from the field strain Fayoum_2018 isolated from broilers in Fayoum Province, Egypt in 2018. The isolate Fayoum_2018 with accession number (MN082684) was characterized molecularly as a TCO vaccine related strain. Measurement of immunity in vaccinated chicks employing the potency test revealed that chicks vaccinated with 0.5 ml of prepared ILT vaccine exhibited ELISA with 1905 antibody titer at 2nd-week post-vaccination, which was considered an ILT adequate immune response and increased till reach 3497 antibody titer at 6th-week post-vaccination. The current work revealed that Fayoum_2018 ILTV egg adapted live attenuated vaccine produced a satisfactory antibodies titer that was efficient in controlling the ILT field infection in Egypt.