Evolution of the immunocyte subpopulation in each experimentally infected group. (A) The relative proportions of CD3+CD4+CD8– cells to CD3+ cells increased continuously, with the lowest percentage in the HP-PRRSV/PCV2 group. (B) The proportions of CD3+CD4--CD8+ cells increased from 7 dpi, except in the PCV2 group, which showed a decline. (C) NK cells decreased in all groups over time. (D) The number of monocytes was greater in the HP-PRRSV/PCV2 group than in the other groups, and started to increase on day 7. Error bars show the standard deviations.* indicates significantly higher or lower values. * p < 0.05, ** p < 0.01; and n.s., not significant.