Detection of a coronavirus from turkey poults in Europe genetically related to infectious bronchitis virus of chickens

Intestinal contents of 13-day-old turkey poults in Great Britain were analy sed as the birds showed stunting, unevenness and lameness, with 4% mortalit y. At post mortem examination, the main gross features were fluid caecal an d intestinal contents. Histological examination of tissues was largely unre markable, apart from some sections that showed crypt dilation and flattened epithelia. Negative contrast electron microscopy of caecal contents reveal ed virus particles, which in size and morphology had the appearance of a co ronavirus. RNA was extracted (turkey/UK/412/00) and used in a number of rev erse transcription-polymerase chain reactions (RT-PCRs) with the oligonucle otides based on sequences derived from avian infectious bronchitis virus ( IBV), a coronavirus of domestic fowl. The RT-PCRs confirmed that turkey/UK/ 412/00 was a coronavirus and, moreover, showed that it had the same partial gene order (S-E-M-5-N-3' untranslated region) as IBV. This gene order is u nlike that of any known mammalian coronavirus, which does not have a gene a nalogous to the gene 5 of IBV. The gene 5 of the turkey virus had two open reading frames, 5a and 5b, as in IBV and the coronaviruses isolated from tu rkeys in North America. The turkey/UK/412/00 also resembled IBV, but not ma mmalian coronaviruses, in having three open reading frames in the gene enco ding E protein ( gene 3). The percentage differences between the nucleotide sequences of genes 3 and 5 and the 3' untranslated region of turkey/UK/412 /00 when compared with those of IBVs were similar to the differences observ ed when different strains of IBV were compared with each other. No sequence s unique to the turkey isolates were identified. These results demonstrate, for the first time, that a coronavirus was associated with disease in turk eys outside of North America and that it is a Group 3 coronavirus, like IBV .