CONSTRUCTION OF RECOMBINANT AVIAN INFECTIOUS LARYNGOTRACHEITIS VIRUS EXPRESSING THE BETA-GALACTOSIDASE GENE AND DNA-SEQUENCING OF THE INSERTION REGION

Avian infectious laryngotracheitis virus (ILTV), a herpesvirus, is a h ighly contagious pathogen that causes an upper respiratory tract infec tion in chickens. It is one of the major problems in the poultry indus try worldwide. Current vaccines are not satisfactory due to the induct ion of latent infection. Here we describe a system for the constructio n of recombinant ILTV. A 4-kbp ILTV EcoRI DNA fragment was cloned into plasmid pUC13 and sequenced. Computer prediction revealed two potenti al open reading frames with 216 and 259 amino acid residues, respectiv ely. The 259-residue polypeptide was serine-rich. The beta-galactosida se (beta-gal) gene of E. coli was cloned into the Xhol/Bg/ll site of t his DNA fragment, integrated into the ILTV genome via homologous recom bination, expressed under the control of the immediate-early cytomegal ovirus promoter, and caused the formation of blue plaques in the prese nce of X-gal. The insertion of a foreign gene into the ILTV genome and the successful expression of the incorporated gene demonstrated the p otential for the construction of attenuated recombinant ILTV vaccines and the development of ILTV as vectors for polyvalent vaccines against avian upper respiratory tract infections, (C) 1994 Academic Press, In c.