title: Measurement of brevetoxin levels by radioimmunoassay of blood collection cards after acute, long-term, and low-dose exposure in mice.
abstract: We developed a radioimmunoassay (RIA) using a sheep anti-brevetoxin antiserum to evaluate detection of brevetoxin on blood collection cards from mice treated with the brevetoxin congener PbTx-3. The RIA has high affinity for PbTx-3 [half-maximal effective concentration (EC(50)) +/- SE = 1.2 +/- 0.2 nM; n = 10] and recognizes both type 1 and type 2 brevetoxins, but not ciguatoxin. Direct comparison of the RIA with a radiolabeled [(3)H]-PbTx-3 receptor-binding assay (RBA) revealed excellent sensitivity, congener selectivity, and minimal interference from blood matrix. We first analyzed blood samples from an acute time course exposure, using a maximal nonlethal dose [180 microg/kg body weight (bw)] for 0.5, 1, 2, 4, and 24 hr. Mean blood brevetoxin levels were 36 nM at 30 min and stayed above 20 nM during the 1-4 hr time points. We next analyzed blood brevetoxin levels after longer exposure (0.5, 1, 2, 3, 4, or 7 days). Mean blood brevetoxin levels were 26.0 nM at 0.5 days, decreased to 8.2 nM at 1.0 day, and maintained a significant level (p < 0.05) of 1.3 nM at day 2. We next determined the lowest measurable dose using increasing concentrations of PbTx-3 (10-300 micro g/kg bw). Analysis of the blood samples at 60 min revealed a linear relationship between administered and internal doses (r(2) = 0.993). All doses of brevetoxin administered were detectable at 1 hr, with significant levels found for the lowest administered dose of 10 micro g/kg bw--a dose that was 10-fold lower than the lowest observable effect level. This RIA provides an optimal first-tier detection of brevetoxin from blood collection cards and, used in combination with the RBA and liquid chromatography-mass spectrometry, should provide a complete panel of methods to biomonitor brevetoxin exposure.
authors.affiliation: Marine Biotoxins Program, Center for Coastal Environmental Health and Biomolecular Research, National Oceanic and Atmospheric Administration, National Ocean Service, Charleston, South Carolina 29412, USA.
authors.forename: Ricky
authors.initials: R
authors.lastname: Woofter
authors.forename: M-Yasmine Bottein
authors.initials: MY
authors.lastname: Dechraoui
authors.forename: Ian
authors.initials: I
authors.lastname: Garthwaite
authors.forename: Neale R
authors.initials: NR
authors.lastname: Towers
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Gordon
authors.forename: José
authors.initials: J
authors.lastname: Córdova
authors.forename: John S
authors.initials: JS
authors.lastname: Ramsdell
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis; D002853:Chromatography, Liquid; D004781:Environmental Exposure; D005260:Female; D008387:Marine Toxins / Q000008:administration & dosage / Q000097:blood*; D013058:Mass Spectrometry; D051379:Mice; D008813:Mice, Inbred ICR; D035964:Oxocins / Q000008:administration & dosage / Q000097:blood*; D011863:Radioimmunoassay / Q000379:methods* / Q000662:veterinary; D012680:Sensitivity and Specificity; D012756:Sheep; D000095702:Polyether Toxins
chemical_list: D000906:Antibodies; D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins