Further studies on in vitro and in vivo assays of hemorrhagic enteritis virus (HEV).

Isolation of hemorrhagic enteritis virus (HEV) from spleens of infected turkeys in the MDTC-RP19 lymphoblastoid cell line was compared with detection of HEV antigen in the same spleens using the agar gel precipitation (AGP) test. A concordance of 80% was found between the two assays. Virus isolation had a sensitivity of 84% and a specificity of 88% compared with the AGP test. RP19 cells were also susceptible to infection with several other avian adenoviruses, but such infection was easily differentiated from that of HEV by a fluorescent-antibody (FA) test. Turkeys required 10(2) tissue-culture-infectious doses (TCID) to develop HE-specific lesions and 10(5) TCID to be killed. On the other hand, as little as 10 TCID of apathogenic HEV protected the poults against challenge with virulent HEV. The enzyme-linked immunosorbent assay (ELISA) for detection of HEV antibody was improved by using virus-infected RP19 cells as antigen. The ELISA appears to be more sensitive than the serum-neutralization test.