New European IBV strains show antigenic correlation

摘要

Preliminary results show an antigenic correlation between the Fa-6881/97 or AZ-27/98 serotype of IBV, isolated in 1997-'98 in Italy and the so-called "lt-02" isolates found in Western Europe. The "lt-02" demonstrated to be serological similar if not identical but antigenically different from most serotypes known worldwide. In Italy researchers regularly report the isolation of ever-new serotypes or variants of avian infectious bronchitis virus (IBV). Isolates as from 1997 have been characterised andsummarized in Avian Disease, 2003. Particular attention was given to the antigenically closely related Fa-6881/97 and AZ-27/98 isolates, derived respectively from a flock of 32-day-old broilers with severe nephritic lesions and from a flock of 20-week-old pullets showing only malaise and respiratory symptoms. These outbreaks were followed by repeated isolations of over 20 antigenic similar IBV strains at different times and in far-off places of our country, from chickens that also showed respiratory andenteric symptoms or/and kidney lesions, Such strains that were antigenically different from the most well-known serotypes reported in the past both in Europe and worldwide, could be considered as a new serotype or variant. In more recent years, over 100isolates of IBV strains were considered to be related to the Italian isolate Fo-4682/99. Some researchers reported during the International Symposium of Avian Coronavirus, in Germany, 2004, that also "It -02" isolates have been found in other countriesof the EU such as Italy, the United Kingdom, the Netherlands, France, Germany and Spain. The question however is whether there is an antigenic correlation between "lt-02" and the fixed Fa-6881/97 or AZ-27/98 serotype that have been isolated in 1997-98 in Italy.