Characterization of a new coronavirus strain of poultry infections bronchitis

Un coronavirus a été isolé chez des poules pondeuses présentant des signes cliniques sévères évoquant la bronchite infectieuse aviaire, maladie contre laquelle, elles avaient été immunisées avec un vaccin préparé à partir du sérotype dominant Massachusetts ; ce virus présente des dif férences antigéniques avec les sérotypes Massachusetts et Connecticut ainsi qu’avec les quatre sérotypes « variants » isolés par l’Institut de Doom aux Pays-Bas. La maladie a été reproduite chez le poulet et la poule : les symptômes respiratoires ont été sévères dans les deux cas et la chute de ponte a été intense et persistante chez les pondeuses. Le fait de développer une prophylaxie médicale adaptée est discuté.A coronavirus was isolated in an infectious bronchitis (IB) vaccinated (Massachusetts strain) layers flock showing severe IB-like clinical signs. The isolate is antigenically different from the Massachusetts and the Connecticut serotypes and from the four « variant » serotypes isolated by the Doom Institute in Holland. The disease was reproduced in chickens and layers. Respiratory signs were severe in both groups. In layers, egg drop was intense and long-lasting. The eventual need for a suitable medical prophylaxy is discussed

Glycoprotein gene truncation in avian metapneumovirus subtype C isolates from the United States

The length of the published glycoprotein (G) gene sequences of avian metapneumovirus subtype-C (aMPV-C) isolated from domestic turkeys and wild birds in the United States (1996–2003) remains controversial. To explore the G gene size variation in aMPV-C by the year of isolation and cell culture passage levels, we examined 21 turkey isolates of aMPV-C at different cell culture passages. The early domestic turkey isolates of aMPV-C (aMPV/CO/1996, aMPV/MN/1a-b, and 2a-b/97) had a G gene of 1,798 nucleotides (nt) that coded for a predicted protein of 585 amino acids (aa) and showed >97% nt similarity with that of aMPV-C isolated from Canada geese. This large G gene got truncated upon serial passages in Vero cell cultures by deletion of 1,015 nt near the end of the open reading frame. The recent domestic turkey isolates of aMPV-C lacked the large G gene but instead had a small G gene of 783 nt, irrespective of cell culture passage levels. In some cultures, both large and small genes were detected, indicating the existence of a mixed population of the virus. Apparently, serial passage of aMPV-C in cell cultures and natural passage in turkeys in the field led to truncation of the G gene, which may be a mechanism of virus evolution for survival in a new host or environment