行政院國家科學委員會專題研究計畫期中進度報告:豬第二型環狀病毒單獨感染及混合豬生殖與呼吸綜合症病毒感染對豬隻免疫細胞之影響及其可能之作用機制(1/3)
Date Issued
2004
Date
2004
Author(s)
DOI
922313B002141
Abstract
Porcine circovirus 2 (PCV2) is currently
considered the primary causative agent of
postweaning multisystemic wasting syndrome
(PMWS). Pigs affected by PMWS often suffered
from secondary viral, bacterial, and fungal
infection. In addition, dual infection of PCV2
and porcine reproductive and respiratory
syndrome virus (PRRSV) in pigs is common. It
is known that the target cells of both PCV2 and
PRRSV are monocytes/macrophages. Thus,
evaluating the immunological effects and
possible mechanism of action of PCV2 and
PRRSV infection should contribute to the
control and limiting of the disease. The present
study was to compare the effects of the infection
of both viruses, singular or combined, on swine
alveolar macrophages (AMs). Six groups were
designated, including control (G1), PCV2 alone
(G2), PRRSV alone (G3), PRRSV following 18
h of initial PCV2 infection (G4), PCV2
following 18 h of initial PRRSV infection (G5),
and concurrent PCV2/PRRSV infection (G6).
High antigen containing rate without cytocidal
effect in G2 suggested that AMs were an
important reservoir of PCV2. A low but constant
infectious rate about 5-10% was noted in all
PRRSV-infected groups except for G4. In G4,
the PRRSV infectious rate was about 5% and
gradually reduced and dropped to 1-2%. A
transient decrease in phagocytosis but persistent
significant reduction in microbial killing of
Candida albicans in G2 indicated that
PCV2-infected AMs might become dysfunction
in against secondary pulmonary pathogens. In
G3 and G5, there was a marked increase in AM
death and apoptosis, and reduction in its
phagocytic and microbicidal capacities. In
addition, inhibition in the production of oxygen
free radical, O2
- and H2O2, were also observed in
both PCV2 and/or PRRSV infected groups. A
lower PRRSV infectious rate, cell death, and
apoptosis, and higher phagocytic capacity than
G3 and G5 were seen in G4 and G6. The results
suggest that in dual infection the pre-existing or
co-existing PCV2 may reduce not only PRRSV
replication but also PRRSV-related AM
dysfunction. High levels of interferon-α (IFN-α)
and increasing levels of tumor necrosis factor α
(TNF-α) productions were seen in all
PCV2-infected and in all PCV2 and/or
PRRSV-infected groups, respectively. Further
anti-IFN-α antibody blocking assay revealed
that the PCV2-mediated reduction effect on
PRRSV might be a result of PCV2’s strong
potential of IFN-α induction. In other cytokines’
expression, PCV2 and/or PRRSV infection only
caused a temporary increase in IL-1β but a
significant increased in the secretion of IL-8.
Different infection orders of PCV2 and/or
PRRSV in swine AMs leading to different
results may explain, at least partially, the
prominent clinic variations of PMWS-affected
pigs in the filed. The PCV2 and/or
PRRSV-related IFN-α and TNF-α induction
may also play a role in the pathogenesis of
interstitial pneumonia in PMWS-affected pigs.
Subjects
postweaning multisystemic wasting syndrome (PMWS)
porcine circovirus 2 (PCV2)
porcine reproductive and respiratory syndrome
virus (PRRSV)
virus (PRRSV)
swine alveolar macrophages
(AMs)
(AMs)
Publisher
臺北市：國立臺灣大學獸醫學系暨研究所
Type
report
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