Experimental infection of a US spike-insertion deletion porcine epidemic diarrhea virus in conventional nursing piglets and cross-protection to the original US PEDV infection

Table 3 Clinical signs of pigs after challenge with the original US PEDV strain PC21A

Litter no.	Inoculation piglets at 3–4-days of age	Challenge strain (passage)^C; dose (log₁₀ GE/pig)	Age (day) at challenge (dpi)	Piglet condition								Sow condition
				Morbidity (%)	Mortality (%)	Highest fecal PEDV RNA shedding titer (log₁₀ GE/pig)	Onset of diarrhea (DPC)	Duration of diarrhea (day)			Body weight gain during 0–7 DPC (kg)	Anorexia	Diarrhea (RS ≧ 2)^B	Highest fecal PEDV RNA shedding titer (log₁₀ GE/pig)
				Morbidity (%)	Mortality (%)	Highest fecal PEDV RNA shedding titer (log₁₀ GE/pig)	Onset of diarrhea (DPC)	RS = 3^B	RS ≧ 2^B	RS ≧ 1^B	Body weight gain during 0–7 DPC (kg)	Anorexia	Diarrhea (RS ≧ 2)^B	Highest fecal PEDV RNA shedding titer (log₁₀ GE/pig)
A	Iowa106	PC21A (P2); 10	24 (21)	0 (0/4)	0 (0/4)	6.21 ± 0.99	–	0.00 ± 0.00	0.00 ± 0.00	0.00 ± 0.00	NA	0	0	5.44
B	Iowa106	PC21A (P2, P4); 10^A, 12	29, 32 (25, 29)	0 (0/2)^A	0 (0/2)^A	7.44 ± 0.10^A	–	0.00 ± 0.00^A	0.00 ± 0.00^A	0.00 ± 0.00^A	0.85 ± 0.35^A	0^A	0^A	7.65
C	Iowa106	PC21A (P4); 12	27 (23)	86 (6/7)	0 (0/7)	10.8 ± 0.76^a	1–2	1.00 ± 1.15^a	2.29 ± 1.60	4.00 ± 1.29	0.93 ± 0.36^c	0	0	8.00
D	Iowa106	PC21A (P4); 12	27 (23)	100 (7/7)	0 (0/7)	9.61 ± 1.64^a	1–2	0.29 ± 0.49^b	2.71 ± 1.11	4.00 ± 0.81	1.53 ± 0.24^b	0	0	7.50
E	PC21A	PC21A (P4); 12	26 (20)	0 (0/4)	0 (0/4)	7.24 ± 0.79^b	–	0.00 ± 0.00	0.00 ± 0.00	0.00 ± 0.00	2.47 ± 0.47^a	0	0	6.61
F^A	Mock	PC21A (P2, P4); 10^A, 12	29, 32 (25, 29)	100 (5/5)^A	0 (0/5)^A	10.57 ± 0.81^A	1–2^A	2.00 ± 0.71^a,A	3.80 ± 0.84^A	5.40 ± 0.55^A	2.56 ± 1.51^A	1–2^A	4^A	10.44

dpi, days post-inoculation; dpc, days post-challenge; RS, rectal swab score; NA, not available; GE, genomic equivalents.
^AThe first challenge on 29-day-old piglets did not induce clinical signs and viral shedding in naïve control pigs (litter F), so a higher dose was used. Evaluation of clinical signs of litters B and F was based on the second challenge at 32-days of age.
^BRS score: 0, 1, 2, and 3 corresponded to normal, pasty, semi-liquid and liquid feces, respectively.
^C Virus passaged in gnotobiotic piglets (PC21A), frozen and thaw once, no filtration.
^{a, b, c, d}Different letters in each column mean different levels among litters (P < 0.05). Pigs challenged with lower dose of the original PEDV (litter A) or at older ages (litter B and F) were excluded from statistical analysis.

ISSN: 1297-9716