Abstract
Defensins and surfactant protein A (SP-A) and SP-D are antimicrobial components of the pulmonary innate immune system. The purpose of this study was to determine the extent to which parainfluenza type 3 virus infection in neonatal lambs alters expression of sheep beta-defensin 1 (SBD-1), SP-A, and SP-D, all of which are constitutively transcribed by respiratory epithelia. Parainfluenza type 3 viral antigen was detected by immunohistochemistry (IHC) in the bronchioles of all infected lambs 3 days postinoculation and at diminished levels 6 days postinoculation, but it was absent 17 days postinoculation. At all times postinoculation, lung homogenates from parainfluenza type 3 virus-inoculated animals had increased SBD-1, SP-A, and SP-D mRNA levels as detected by fluorogenic real-time reverse transcriptase PCR. Protein levels of SP-A in lung homogenates detected by quantitative-competitive enzyme-linked immunosorbent assay and protein antigen of SP-A detected by IHC were not altered. These studies demonstrate that parainfluenza type 3 virus infection results in enhanced expression of constitutively transcribed innate immune factors expressed by respiratory epithelia and that this increased expression occurs concurrently with decreased viral replication.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Animals, Newborn
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Antibodies, Viral / blood
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Antigens, Viral / analysis
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Antigens, Viral / immunology
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Body Temperature
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Enzyme-Linked Immunosorbent Assay
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Epithelial Cells / chemistry
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Epithelial Cells / virology
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Female
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Gene Expression
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Immunohistochemistry
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Lung / chemistry
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Lung / pathology
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Lung / virology
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Macrophages, Alveolar / chemistry
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Macrophages, Alveolar / virology
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Male
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Paramyxoviridae Infections / genetics
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Paramyxoviridae Infections / immunology*
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Paramyxoviridae Infections / veterinary
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Pneumonia / genetics
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Pneumonia / immunology*
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Pneumonia / veterinary
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Pulmonary Surfactant-Associated Protein A / genetics*
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Pulmonary Surfactant-Associated Protein A / metabolism
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Pulmonary Surfactant-Associated Protein D / genetics
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RNA, Messenger / genetics
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RNA, Messenger / metabolism*
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Respirovirus / chemistry
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Respirovirus / growth & development
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Respirovirus / immunology
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Reverse Transcriptase Polymerase Chain Reaction
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Sheep
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Sheep Diseases / genetics
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Sheep Diseases / immunology
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Sheep Diseases / virology
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Virus Replication*
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beta-Defensins / genetics*
Substances
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Antibodies, Viral
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Antigens, Viral
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Pulmonary Surfactant-Associated Protein A
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Pulmonary Surfactant-Associated Protein D
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RNA, Messenger
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beta-Defensins