Detection of chlamydial antibody by fetal serology - an aid to the diagnosis of ovine abortion

Two serological tests (indirect immunofluorescence and enzyme-linked immuno sorbent assay) were developed for the detection of fetal antibody to Chlamy dia psittaci. Fetal blood and thoracic fluid from 126 field cases of suspec ted ovine chlamydial abortion were examined using both tests. Placenta and fetal tissues (lung, liver, and kidney) from the same animals were also exa mined by the following conventional diagnostic methods: isolation in McCoy cells, detection of chlamydial lipopolysaccharide (LPS), modified Ziehl-Nie lsen staining, and direct fluorescent antibody staining of chlamydia in fro zen cryostat sections. Seventy cases were positive by fetal serology, and o f these, 68 were also positive by isolation and/or LPS detection. The remai ning 56 cases had negative fetal serology, and of these, 39 were positive b y isolation and/or LPS detection. Results indicate that fetal serology, alt hough less sensitive than either isolation in McCoy cells or detection of c hlamydial LPS antigen, may be of particular use when placenta is not availa ble.