EN
Turkey rhinotracheitis (TRT) is an acute infectious and contagious avian disease found all over the world. It is caused by avian pneumovirus (APV), which has two superficial glicoproteins: G and F, that are the main antigen determinants. Examinations of the nucleotide sequence in the G protein coding gene found in TRT virus isolates allowed to distinguish two subgroups - A and B. Both viral subgroups have direct tropism to the ciliated epithelium of the respiratory tract, but serotype A seems to be more pathogenic. Both serotype A and В provide enough immunity against all TRT virus isolates. The highest level of immunity is obtained from vaccination in the form of aerosole.