Reduction of porcine reproductive and respiratory syndrome virus (PRRSV) infection in swine alveolar macrophages by porcine circovirus 2(PCV2)-induced interferon-alpha
Resource
Veterinary Microbiology (108),167–177
Journal
Veterinary Microbiology
Pages
-
Date Issued
2005
Date
2005
Author(s)
Liu, J.J
Lin, Tsang-Long
Chang, Chih-Cheng
Chia, Mi-Yuan
Tsai, Yi-Chieh
Pang, V.F.
DOI
246246/2006111501232907
Abstract
Two common viral pathogens of swine, namely, porcine circovirus type 2 (PCV2) and porcine reproductive and
respiratory syndrome virus (PRRSV), were investigated in regard to their effects on monolayer cultures of swine alveolar
macrophages (AMs). The purpose was to identify selected cellular changes and responses potentially associated with the
clinical reactions of pigs infected with either or both of these viruses. Measurements included the (1) absolute and relative
numbers of infected, viable, and apoptotic cells; (2) distribution of viral antigens; (3) levels of interferon-alpha (IFN-a) and
tumor necrosis factor-alpha (TNF-a) produced and their association with the extent of virus-induced cytopathology. Four
groups of AMs were studied, including mock-infected, PCV2 alone-infected (PCV2-A), PRRSValone-infected (PRRSV-A),
and PCV2 and PRRSV dually infected (PCV2/PRRSV) groups. The AMs of PCV2-A group had high antigen-containing rate
without cell death. There was a marked increase in cell death and apoptosis in PRRSV-A group. However, a lower PRRSVinduced
infectious rate, cell death, and apoptosis were seen in PCV2/PRRSV group. High levels of IFN-a production were
detected in PCV2-infected groups, but not in mock-infected and PRRSV-A groups. The PRRSV-induced cytopathic effect
(CPE) on MARC-145 cells or swine AMs was markedly reduced by pre-incubation of the cells with UV-treated or non-UVtreated
supernatants of PCV2-infected AMs. In addition, the reduction in CPE was abolished when the supernatants of
PCV2-infected AMs were pre-treated with a mouse anti-recombinant porcine IFN-a antibody. The results suggest that swine
AMs were an important reservoir of PCV2; PCV2 infection reduced PRRSV infection and PRRSV-associated CPE in PCV2/
PRRSVAMs; the reduction of PRRSV infection in AMs was mediated by IFN-a generated by PCV2 infection. The reduced PRRSV-associated CPE in AMs and increased pro-inflammatory cytokine production may lead to a more severe pneumonic
lesion in those dually infected pigs.
Publisher
Taipei:National Taiwan University Dept Elect Engn
Type
journal article
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