1The amount of IgG each piglet received was 100 μg/kg of body weight and PBS was 2 mls via intramuscularly (i.m.) injection.
2The numbers were the days post injection (DPI). 42 DPI was also the 0 days post challenge (DPC).
3On 14 DPI, the piglets received CH-1R, the attenuated PRRSV vaccine and generated from CH-1a, a North American type strain isolated from China (GenBank no. EU807840)  i.m. on the left side of the neck at 2 doses/piglet diluted in 2 ml of PBS.
4On 42 DPI, the piglets were challenged with HP-PRRSV HuN4 strain at 3 × 105 TCID50/piglet and also considered as 0 days post challenge (DPC).