Abstract
Housing of pigs in barren, stimulus-poor housing conditions may influence their immune status, including antibody responses to (auto-)antigens, and thus affect immune protection, which will influence the onset and outcome of infection. In the present study, we investigated the effects of environmental enrichment versus barren housing on the level of natural (auto-)antibodies (NA(A)b) and their isotypes (IgM and IgG) binding keyhole limpet hemocyanin (KLH), myelin basic protein (MBP), and phosphorycholine conjugated to bovine serum albumin (PC-BSA) in pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae). Pigs (n = 56) were housed in either barren or enriched pens from birth to 54 days of age. They were infected with PRRSV on 44 days of age, and with A. pleuropneumoniae 8 days later. Blood samples were taken on 7 different sampling days. Housing significantly affected the overall serum levels of NA(A)b binding KLH, MBP and PC-BSA, and before infection barren housed pigs had significantly higher levels of NA(A)b than enriched housed pigs, except for KLH-IgM and PC-BSA-IgG. Infection only affected the IgM, but not the IgG isotype. Moreover, changes in MBP-IgM and PC-BSA-IgM following infection were different for enriched and barren housed pigs. These results suggest that the effect of infection on NA(A)b is influenced by housing conditions and that NA(A)b, especially IgM may be affected by infection.
Highlights
Commercial pigs usually live in barren, stimulus-poor housing conditions
myelin basic protein (MBP) is an important protein in the nervous system, and levels of antibodies binding MBP were affected by mental stress [15]
In this study, we investigated the effect of environmental enrichment versus barren housing on the level of NA(A) b binding keyhole limpet hemocyanin (KLH), MBP, and phosphorycholine conjugated to bovine serum albumin (PC-BSA) prior to transport and relocation, after transport and after infection with porcine reproductive and respiratory syndrome virus (PRRSV) and A. pleuropneumoniae
Summary
Commercial pigs usually live in barren, stimulus-poor housing conditions. The limited possibilities to express important behaviours under such conditions may lead to signs of chronic stress [1–3], and the development of damaging behaviours directed at group members, such as tail or ear biting [4–6]. Reimert et al [16] reported that enriched housed pigs had higher levels of natural antibodies (NAb) binding keyhole limpet hemocyanin (KLH) than barren housed pigs. IgG can recognize a range of Gram-negative and Gram-positive bacteria with the aid of serum lectin pattern recognition receptors (PRRs) which are known to bind to sugar residues on the bacteria. In this way, IgG can collaborate with lectin, swiftly and effectively kill invading pathogens [24]. It has been proposed that natural IgM-producing B cells do not undergo affinity maturation or activation, and subsequently shift to IgG, but in contrast to antigen-specific immunoglobulin producing B2 cells, provide a readily available poly-specific source of defence, in response to activation of innate receptors, like TLRs [19]
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