GAPDH and infection: 18S rRNA was the highest abundannce reference gene and exhibited the highest expression levels with Cq range between 10.48 and 12.75 throughout the different times of vaccination and infection of the rSip and PBS groups, followed by EF1A (17.86 to 21.36), GAPDH (18.48 to 22.75), ACTB (23.46 to 27.41), TUBA (28.12 to 33.92), UBCE (29.53 to 32.40).