SEROLOGIC EVIDENCE OF INFECTIOUS BURSAL DISEASE VIRUS-INFECTION IN IOWA TURKEYS

Two infectious bursal disease viruses (IBDV), a cell-culture-adapted chicken strain designated Edgar strain and a recent isolate from turkeys in Missouri, were used to assay sera from 10 Iowa turkey flocks collected at 1-16 wk of age. The two viruses were serologically distinct in cross-neutralization tests. For all flocks, a similar serologic pattern was found consisting of low maternal antibody titers to turkey IBDV and occasionally to Edgar strain IBDV at 1-3 wk of age, a period of very low or no detectable toters at 3-8 wk of age and sharply rising high titers to turkey IBDV with low titers to Edgar IBBV beginning 5-8 wk of age. These findings indicate that infection with IBDV of the serotype represented in this study by the turkey isolate is common in Iowa turkey flocks, whereas infection with IBDV represented by the Edgar strain is uncommon. Infection occurred at 3-7 wk of age during the late brooding period or after birds had been moved to an intermediate growing facility. All flocks developed complicated respiratory disease with excessive mortality caused by Escherichia coli sepicemia, typically at 3-6 wk of age. Although there was a temporal relationship between IBDV infection and respiratory disease, the possible role of IBDV in the process is unknown.