Comparison of a direct radioimmunoassay with virus isolation in cell culture for detection of pseudorabies virus in tissues of infected swine

A direct radioimmunoassay (DRIA) was developed for detection of pseudorabies virus (PRV) in tissue of pigs with clinical disease. Homogenates of tissues prepared from 289 swine were tested for PRV with the DRIA and virus-isolation technique (VIT). The virus was detected in 53 (18%) of the homogenates by both DRIA and VIT. Fifteen (5%) others were positive for PTV by VIT, but negative by DRIA. There were no samples negative by VIT and positive by DRIA. A total of 211 (77%) pigs with clinical PRV infection were negative in both DRIA and VIT. Although the VIT is more sensitive than DRIA, the DRIA possesses certain advantages which include reduced requirements for aseptic procedures and cell cultures, rapidity, and increased objectivity. Moreover, high levels of confidence could be attributed to DRIA-positive results, since DRIA-positive/VIT-negative results were not obtained.