Comparison of host genetic factors influencing pig response to infection with two North American isolates of porcine reproductive and respiratory syndrome virus

Table 3 Least square means, heritabilities, litter effects, and phenotypic standard deviations (SD) of responses to infection with the NVSL and KS06 isolates

Trait	LS means^a,b		P value^c	Heritability^b,d		Litter^b,d		Phenotypic sd^b,d
Trait	NVSL (se)	KS06 (se)	P value^c	NVSL (se)	KS06 (se)	NVSL (se)	KS06 (se)	NVSL	KS06
WG	15.8 (1.1)	19.5 (1.4)	0.076	0.33 (0.06)	0.31 (0.09)	0.07 (0.03)	0.03 (0.04)	3.90	3.91
VL	110.5 (1.4)	95.0 (1.6)	<0.001	0.31 (0.06)	0.51 (0.09)	0.24 (0.03)	0.01 (0.04)	7.90	7.46
TP	7.0 (0.4)	9.5 (0.4)	0.004	0.22 (0.05)	0.20 (0.09)	0.16 (0.03)	0.10 (0.05)	1.36	1.54
PV	6.6 (0.1)	5.8 (0.1)	<0.001	0.17 (0.05)	0.45 (0.08)	0.27 (0.04)	0.00 (0.00)	0.40	0.41
Tmax	15.4 (0.5)	19.3 (0.6)	0.002	0.21 (0.05)	0.16 (0.09)	0.15 (0.03)	0.14 (0.05)	2.38	2.73
Vmax	0.30 (0.02)	0.22 (0.02)	0.033	0.09 (0.05)	0.26 (0.09)	0.08 (0.03)	0.01 (0.04)	0.08	0.05

WG weight gain (kg), VL viral load (area under the Wood’s curve of log₁₀ serum viremia from 0 to 21 days post-infection; viremia * days), TP time to peak viremia (days), PV peak viremia (log₁₀ serum viremia), Tmax time to maximal rate of viremia decay (days), Vmax maximal rate of viremia decay (log₁₀ serum viremia/day), se standard error
^aFull G-matrix used
^bEstimates were obtained by fitting isolate in the model and only included trials in which pigs from the same genetic background were infected with both NVSL and KS06
^cP value for the difference in the estimated least square (LS) means between NVSL and KS06
^dEstimates were obtained by using the full G-matrix; NVSL and KS06 estimates were estimated separately, and included all animals infected with that isolate, except trial 13

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