Table 3.
The limit of detection (LOD) of VHH-based DAS-ELISAs. Various authentic particles (AP), VLPs, or their 12S particles prepared by heating were titrated in ELISA in triplicate.
| VHH a | FMDV Strain | Capsid Type | LOD (ng/mL) b | Ratio 12S/Intact Capsid d | |
|---|---|---|---|---|---|
| Intact Capsid | 12S | ||||
| M691F | A/TUR/14/98 | AP | 97 | >2000 c | 21 |
| M691F | A/GDMM/CHA/2013 | AP | 21 | >2000 | 95 |
| M691F | A/GDMM/CHA/2013 | VLP | >2000 | >2000 | NA e |
| M702F | A/TUR/14/98 | AP | 41 | >2000 | 49 |
| M702F | A/GDMM/CHA/2013 | AP | 17 | >2000 | 119 |
| M702F | A/GDMM/CHA/2013 | VLP | 162 | >2000 | 12 |
| M652F | C1/Detmold/FRG/60 | AP | 76 | >2000 | 27 |
| M652F | A/GDMM/CHA/2013 | AP | 23 | >2000 | 86 |
| M661F | Asia1/Shamir/ISR/89 | AP | 341 | >2000 | 5.9 |
a VHHs that bind specifically to 146S of serotype A strains are colored green or purple by their CDR3 group. b The LOD was calculated based on the average absorbance value of background plus three times the standard deviation. c >2000 indicates LOD not reached at the highest FMDV particle concentration used (2 μg/mL). d The ratio 12S/Intact capsid (146S specificity) was determined by LOD of 12S/LOD of capsid. e NA, Not applicable.