title: Characterization of a high molecular weight tumor necrosis factor-alpha mRNA in influenza A virus-infected macrophages.
abstract: Infection by influenza A virus has previously been shown to prime macrophages for a high TNF-alpha production. Influenza A virus induced a TNF-alpha mRNA accumulation that consisted of two types: a regular 1.7 kb and an additional high m.w. 2.4 kb species in murine macrophages, and a high m.w. 3.6 kb species in human monocytes. In this study, we further characterized this virus-induced, novel high m.w. TNF-alpha mRNA. The additional high m.w. TNF-alpha mRNA represented a true polyadenylated mRNA and its induction required exposure to infectious viruses. The regular and the high m.w. TNF-alpha mRNA were both found in the nuclear fraction and the cytoplasm. We excluded that the novel high m.w. TNF-alpha mRNA was an intron-containing precursor TNF-alpha mRNA that could have persisted in virus-infected macrophages. When TNF-alpha exons 1 to 4 and TNF-alpha exons 2 to 4 were amplified by polymerase chain reaction, only regular and no high m.w. bands were detected. By use of specific TNF-alpha intron I and intron III cDNA we could definitely demonstrate the absence of introns in the high m.w. TNF-alpha mRNA. The high m.w. TNF-alpha mRNA was free of TNF-beta and TNF intergenic region elements but contained the 5' and 3' untranslated region of TNF-alpha. Influenza A virus infection also induced a double band of IL-1 beta and IL-6 mRNA. Whether this novel high m.w. TNF-alpha mRNA represents a virus-induced abnormality or a superinduction of an otherwise normal but minor TNF-alpha transcript, and whether this high m.w. TNF-alpha mRNA species codes for a biologically active product, remains to be examined.
authors.affiliation: Institute of Immunology, Philipps University, Marburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Sprenger
authors.forename: M
authors.initials: M
authors.lastname: Bacher
authors.forename: E
authors.initials: E
authors.lastname: Rischkowsky
authors.forename: A
authors.initials: A
authors.lastname: Bender
authors.forename: M
authors.initials: M
authors.lastname: Nain
authors.forename: D
authors.initials: D
authors.lastname: Gemsa
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D009980:Influenza A virus / Q000502:physiology*; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011061:Poly A / Q000096:biosynthesis; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D011061:Poly A