Detection and dissemination of Toxoplasma gondii in experimentally infected calves, a single test does not tell the whole story

Table 2 Mouse bioassay, qPCR on tissue homogenate, and MC-qPCR detection of T. gondii from pooled calf tissues by mouse bioassay (six weeks post-oral inoculation with 10⁶ M4 T. gondii oocysts). Figures in bold indicate a strong positive ELISA or real-time PCR (qPCR) result

Calf pool	Tissue	Mouse 1				Mouse 2				Tissue homogenate	Calf tissues
		Mouse No.	Cull date (dpi)	ELISA result (%SP)	qPCR (Cq)	Mouse No.	Cull date (dpi)	ELISA result (%SP)	qPCR (Cq)	qPCR (Cq)	MC-qPCR (Cq)
Pool 1 = ×2 animals (112, 120)	Liver	44-1	42	neg	neg	44-3	42	neg	neg	neg	neg
	Masseter	44-10	42	neg	neg	44-30	42	neg	neg	neg	neg
	Tongue	45-1	8	No sample	neg	45-3	42	neg	neg	neg	neg
	Heart	45-10	42	neg	neg	45-30	42	neg	neg	neg	neg
	Brain	46-1	6	No sample	neg	46-30	3	neg	neg	neg	neg
	Diaphragm	46-10	42	neg	neg	46-30	42	neg	neg	neg	neg
	Left triceps femoralis (forelimb)	47-1	42	neg	neg	47-30	42	neg	neg	37.20^a,c	neg
	Left semitendinosus (hindlimb)	47-10	42	neg	neg	47-30	42	neg	neg	neg	neg
	Psoas major (fillet)	48-1	42	neg	neg	48-3	42	neg	neg	neg	neg
	Longissimus dorsi (sirloin)	48-10	42	neg	neg	48-30	42	neg	neg	neg	neg
Pool 1 = ×3 animals (115, 111, 118)	Liver	53-1	42	neg	33.79	53-3^d	42	neg	33.83^a	neg	34.40
	Masseter	50-10	42	neg	neg	50-30	42	neg	neg	neg	35.54
	Tongue	50-1	12	24	19.66	50-3	12	neg	19.04	33.37	32.34
	Heart	49-10	42	neg	34.01^a	49-30	42	neg	33.53	neg	32.84
	Brain	51-1	12	12	21.56	51-3	12	13	21.70	neg	neg
	Diaphragm	49-1	12	8	23.09	49-3	12	16	21.47	29.04	34.16
	Left triceps femoralis (forelimb)	52-1^d	42	neg	33.60^a	52-3	42	neg	neg	neg	34.63
	Left semitendinosus (hindlimb)	52-10	42	285 ^b	18.43	52-30	42	230 ^b	19.87	33.92	32.54
	Psoas major (fillet)	53-10	42	neg	18.13	53-30^d	42	neg	19.90	neg	34.09
	Longissimus dorsi (sirloin)	51-10	42	neg	neg	51-30	42	neg	neg	neg	neg

Notes on tissue amounts: 50 g per calf (pool 1, as one calf was removed prior to the end of the experiment) and 33.3 g per calf (pool 2); each pool consisted of 100 g
^aA weak positive ELISA or real-time PCR result; ELISA results are expressed as sample to positive control ratios (%S/P); real-time PCR results are recorded as quantification cycle (Cq)
^bBetween day 10–14 post-inoculation mice showed signs of T. gondii infection
^cRepeated twice and on both occasions one duplicate was negative
^dMice positive by total T. gondii tachyzoite immunoblot (52–1, 53–30) or positive in p30 (TgSAG1) immunoblot (52–1, 53–3)
Abbreviation: neg, negative result

ISSN: 1756-3305