Animal Industry Report

Extension Number

ASL R2925



Summary and Implications

This study examined serum porcine reproductive and respiratory syndrome virus (PRRSV) N protein-specific IgG levels from sera collected from 464 Large White-Landrace commercial crossbred piglets from three separate experimental infection trials with PRRSV isolate NVSL-97- 7895. IgG levels at 42 days post infection (dpi) were measured by fluorescent microsphere immunoassay, herein referred to as total antibody (tAb) response. tAb levels were assessed for an association with different disease-related traits, the presence of a heritable genetic component, and for genomic regions associated with tAb response. tAb response was negatively associated with viral load (VL) and weight gain from 28-42 dpi (WG) and positively associated with virus rebound (REB) and neutralizing antibody (nAb) levels. Furthermore, tAb response had a heritable genetic component, with a major QTL located on chromosome 7 in the major histocompatibility complex (MHC), whereby heterozygous individuals had a lower tAb response and increased weight gain from 28-42 dpi. These results suggest that genetic selection for tAb response may be useful for selecting for pigs that have increased resistance or reduced susceptibility to PRRSV.