Effect of vaccination of cattle with the low virulence Nc-Spain 1H isolate of Neospora caninum against a heterologous challenge in early and mid-gestation

Table 3 Detection of parasite DNA and histopathological changes in tissue samples from foetuses, calves and heifers from immunised and non-immunised groups following challenge infection at mid-gestation

Group	Time of foetal death (dpc)^a	Serology in progeny (IFAT)^b	Tissues from foetus/calf								Maternal placenta
			Brain			Liver			Heart		Maternal placenta
			HP^c	DNA^d	MS^e	HP^c	DNA^d	MS^e	HP^c	DNA^d	HP^c	DNA^d	MS^e
	25	-	*	2/3	Nc-1	++	2/3	na	+	0/3	++	1/3	na
4 (Immunised/135-challenged)	Alive	-	-	0/12	-	-	0/3	-	-	0/3	-	1/3	-
	Alive	1:100	-	0/12	-	-	0/3	-	-	0/3	-	0/3	-
	Alive	1:200	-	0/12	-	-	0/3	-	-	0/3	-	0/3	-
	Alive	1:200	-	0/12	-	-	0/3	-	-	0/3	-	0/3	-
5 (Non-immunised/135-challenged)	47	1:16	++	1/3	na	++	0/3	-	++	0/3	++	2/3	na
	Alive	1:800	-	0/12	-	-	0/3	-	-	0/3	-	0/3	-
	Alive	1:1600	-	0/12	-	-	0/3	-	-	0/3	-	0/3	-
	Alive	1:1600	-	0/12	-	-	0/3	-	-	0/3	-	0/3	-

^a Day post-challenge when foetal death was detected by transrectal ultrasonography. The remaining foetuses lived until the end of the experiment.
^b Mean IFAT IgG antibody titres in foetal body fluids and in pre-colostral serum collected after birth in calves born alive.
^c Histopathological lesion severity: none detected (-), consistent with (+), and characteristic of (++) N. caninum infection; * Autolysed.
^d Fractions represent number of samples positive by nested PCR/number of samples examined.
^e Microsatellite analysis was performed using one sample per nested-PCR-positive tissue. Microsatellite markers could not be amplified from all of the PCR-positive tissues analysed (na). The microsatellite profiles of the tissues from which the microsatellite markers could be amplified corresponded to that of the challenge isolate (Nc-1).

ISSN: 1297-9716