Measurement of brevetoxin levels by radioimmunoassay of blood collection cards after acute, long-term, and low-dose exposure in mice.
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.
Woofter
Ricky
R
Marine Biotoxins Program, Center for Coastal Environmental Health and Biomolecular Research, National Oceanic and Atmospheric Administration, National Ocean Service, Charleston, South Carolina 29412, USA.
Dechraoui
M-Yasmine Bottein
MY
Garthwaite
Ian
I
Towers
Neale R
NR
Gordon
Christopher J
CJ
Córdova
José
J
Ramsdell
John S
JS
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
D000906:Antibodies; D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins