Seroprevalence of Coxiella burnetii in Washington State domestic goat herds.

A caprine herd seroprevalence of Coxiella burnetii infection was determined by passive surveillance of domestic goat herds in Washington State. Serum samples (n=1794) from 105 herds in 31 counties were analyzed for C. burnetii antibodies using a commercially available Q fever antibody enzyme-linked immunosorbent assay (ELISA) test kit. The sera were submitted to the Washington Animal Disease Diagnostic Laboratory for routine serologic screening over an approximate 1-year period from November, 2010, through November, 2011. To avoid bias introduced by testing samples from ill animals, only accessions for routine screening of nonclinical animals were included in the study. A standard cluster sampling approach to investigate seroprevalence at the herd level was used to determine optimal study sample size. The results identified C. burnetii antibodies in 8.0% of samples tested (144/1794), 8.6% of goat herds tested (9/105), and 25.8% of counties tested (8/31). Within-herd seroprevalence in positive counties ranged from 2.9% to 75.8%. Counties with seropositive goats were represented in the western, eastern, southeastern, and Columbia basin agricultural districts of the state. To our knowledge this is the first county-specific, statewide study of C. burnetii seroprevalence in Washington State goat herds. The findings provide baseline information for future epidemiologic, herd management and public health investigations of Q fever.

Neospora caninum: antibodies directed against tachyzoite surface protein NcSRS2 inhibit parasite attachment and invasion of placental trophoblasts in vitro.

Polyclonal and monoclonal antibodies to native Neospora caninum tachyzoite surface protein NcSRS2 were generated and tested in vitro for their ability to neutralize tachyzoite attachment to and invasion of host cells. Host cells included Vero cells and a newly cloned, immortalized ovine trophoblast cell line obtained from primary cultures of ovine placenta. The ovine trophoblasts had morphology consistent with fetal trophoblasts and expressed mRNA for interferon-tau, a marker for trophoblasts. Native NcSRS2 was used to immunize mice to obtain monospecific anti-NcSRS2 polyclonal serum and anti-NcSRS2 monoclonal antibodies. Compared to irrelevant antibodies, monospecific anti-NcSRS2 serum and two anti-NcSRS2 monoclonal antibodies, 100.2.4.4 and 119.4.9.10, significantly blocked invasion of tachyzoites into both trophoblasts and Vero cells. Parasite attachment, assessed by IFA, was significantly reduced by anti-NcSRS2 mAb 100.2.4.4 and monospecific serum. The findings provide rationale to investigate a role for antibodies to NcSRS2 in prevention of N. caninum transplacental transmission in vivo.