Rapid and sensitive point-of-care detection of Orthopoxviruses by ABICAP immunofiltration

Table 1 Validation of the OPV ABICAP assay with clinical samples

Sample Source	Diagnosed as	qPCR [C_T]^a	Tested Dilution	ABICAP^b [A_525nm]	Result^c
Cat, homogenized crust	Cowpox^d	17.4 (1.6 × 10⁹ GE/mL)	1:50/1:250	2.398/1.033	++/++
Cat, homogenized skin biopsy	Cowpox^d	27.5 (1.4 × 10⁶ GE/mL)	1:50/1:250	0.390/0.249	±/-
Human, homogenized crust	Cowpox^d	11.7 (8.2 × 10¹⁰ GE/mL)	1:50/1:250	1.428/0.446	++/+
Human, swab of crust	Cowpox^d	19.6 (3.4 × 10⁸ GE/mL)	1:10/1:50	1.912/0.987	++/+
Human, homogenized crust	Unknown (OPV + PPV PCR negative)	n.a.	1:50	0.334 ± 0.049	-
Rat, homogenized crust	Unknown (OPV PCR negative)	n.a.	1:50	0.245 ± 0.007	-
Rabbit, homogenized crust	Myxomavirus	n.a.	1:50	0.305 ± 0.092	-
Human, swab of rash	Varizella zoster	29.5	1:50	0.285 ± 0.007	-
Cell culture	Parapox virus	-	1:10 (2.5 × 10⁵TCID₅₀/ ml)	0.275 ± 0.022	-
Cell culture	Herpes simplex virus	-	1:10 (6.9 × 10⁷ PFU/ ml)	0.235 ± 0.065	-

^aIn parentheses: estimation of genome equivalents in undiluted samples. For negative controls (Parapox virus and herpes simplex virus cell culture supernatant): titer of tested 1:10 dilutions
^b,dFor scarce sample material, tested in two dilutions (1:10 and 1:50). Anywhere else, duplicate measurements (mean ± standard deviation of n = 2)
^cA_525nm < 0.417 (cutoff): - (negative), 0.417 < A_525nm < 1.0: + (positive), 1.0 < A_525nm :++ (highly positive). ±: borderline positive, see text

ISSN: 1743-422X