ENVIRONMENT, HEALTH, AND BEHAVIOR Gastric Gross and Microscopic Lesions Caused by the UNAM-97 Variant Strain of Infectious Bronchitis Virus after the Eighth Passage in Specific Pathogen-Free Chicken Embryos

ABSTRACT Herein we report a description of gross and microscopic lesions found in specific pathogen-free chicken embryos caused by UNAM-97 infectious bronchi-tis virus (IBV) variant strain after the eighth passage. Embryos were divided into three groups and were inocu-lated in the chorioallantoic sac with 0.2 mL of UNAM-97, Mass 41 IBV (positive control), or sterile PBS (negative control). Forty-eight hours later the allatoic fluid was taken and used to start a cycle of eight passages through 9-d-old embryos. Seven days after the last passage, embryos were harvested and macroscopic lesions in all organs were recorded. Proventriculus and gizzard samples were obtained from all embryos and routinely processed for microscopic and ultrastructural examinations. The UNAM-97 IBV variant strain caused two macroscopi