Stunting syndrome in turkey poults: isolation and identification of the etiologic agent

The aetiologic agent of stunting syndrome (SS)was investigated in day-old turkey poults orally inoculated with a SS-inducing inoculum. The intestinal epithelial cells (IECs) were isolated on the fourth day after inoculation. The IECs were lysed and filtered through 0.2-, 0.1-, and 0.02-µm filters. The cell lysate filtrate (0.1 µm) was subjected to density gradient ultracentrifugation. Intact IECs, filtrates from IECs (0.2, 0.1, and 0.02 µm), and IEC lysate fractions from gradients (FRG) were used as inocula to infect day-old turkey poults. The weight gain, jejunal maltase activity, and gross intestinal lesions were used as the test parameters. Weight gain and maltase activity were reduced (P ≤ 0.001) by the isolated IECs, 0.2 and 0.1 µm filtrates, and FRG when compared with corresponding controls. IEC lysate filtrate (0.1 µm) and FRG were examined under transmission electron microscope (EM). Enveloped, pleomorphic particles varying in size from 60 to 95 nm were identified and termed stunting syndrome agent (SSA). Primary cultures of turkey IECs were used to further isolate and propagate the SSA. Following the fifth passage in the turkey IECs, the cell lysate induced SS in day-old poults. SSA particles were detected under EM after the fifth passage. These results provide evidence that a viral agent has been isolated and identified from IECs of SS-infected poults and is the aetiologic agent of SS.