Table 1.

Markers of PTV infection in gnotobiotic pigs

Pig no.	Route	dpi	Nervous signs	Diarrhoea	Encephalomyelitis	IHC in CNS lesions	Virus particles in the spinal cord by EM	Virus neutralization titre	RT-PCR
									Serum	Cerebrum	Brain-stem	Cerebellum	Spinal cord	Tonsil	Liver	Lung	Small intestine	Large intestine
1	IV	6	+	–	+	+	–	2	+	++	++	++	++	++	++	++	++	++
2		6	–	–	+	+	–	2	+	++	++	++	++	++	++	++	++	++
3		13	+	+	+	+	+	16	++	++	++	++	++	++	++	++	++	++
4		13	–	+	+	+	+	32	++	++	++	++	++	++	++	++	++	++
5		20	+	–	+	+	+	256	–	++	++	++	++	++	++	+	++	++
6		20	+	+	+	+	+	128	+	++	++	++	++	++	++	++	++	++
7	O	6	–	–	+	+	–	4	+	++	++	++	++	++	++	++	++	++
8		6	–	–	+	+	–	2	+	++	++	++	++	++	++	++	++	++
9		13	+	+	+	+	+	32	+	++	++	++	++	++	+	++	++	++
10		13	+	–	+	+	+	128	+	++	++	++	++	++	–	++	++	++
11		20	+, R	+	+	+	+	256	+	++	++	++	++	++	–	++	++	++
12		20	+, R	–	+	+	+	256	–	++	++	++	++	++	–	++	++	++
13		28	+, R	–	+	–	–	1,024	–	+	++	++	++	++	–	+	–	++
14		28	+, R	–	+	–	–	1,024	–	–	–	–	–	–	–	–	–	–
15	IN	6	–	–	+	+	–	2	+	++	++	++	++	++	++	++	++	++
16		6	–	–	+	+	–	2	+	++	++	++	++	++	++	++	++	++
17		13	+	–	+	+	+	128	+	++	++	++	++	++	+	++	++	++
18		13	+	–	+	+	+	64	+	++	++	++	++	++	+	++	++	++
19		20	+, R	+	+	+	+	256	+	++	++	++	++	++	–	++	++	++
20		20	+, R	–	+	+	+	256	+	++	++	++	++	++	–	++	++	++
21		28	+, R	–	+	–	–	1,024	–	–	++	+	++	++	–	++	–	++
22		28	+, R	–	+	–	–	512	–	++	++	++	++	++	–	–	–	+
23	Control	20	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–
24		20	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–	–
25		28	–	–	–	–	ND	–	–	ND	ND	ND	ND	ND	ND	ND	ND	ND
26		28	–	–	–	–	ND	–	–	ND	ND	ND	ND	ND	ND	ND	ND	ND

IV, intravenous; O, oral; IN, intranasal; dpi, days post infection; R, recovery; ND, not done; IHC, immunohistochemistry; CNS, central nervous system; EM, electron microscopy; RT-PCR, reverse-transcriptase polymerase chain reaction; +, present; –, absent.

For RT-PCR data ++, positive for first PCR; +, positive for nested PCR; –, negative.