Skip to main content
PMC home page
Journal of Virology logoLink to Journal of Virology
. 1996 Dec;70(12):8527–8533. doi: 10.1128/jvi.70.12.8527-8533.1996

An IkappaB homolog encoded by African swine fever virus provides a novel mechanism for downregulation of proinflammatory cytokine responses in host macrophages.

P P Powell 1, L K Dixon 1, R M Parkhouse 1
PMCID: PMC190944  PMID: 8970976

Abstract

Cytokines stimulate inflammatory defenses against viral infections. In order to evade host defenses, viruses have developed strategies to counteract antiviral cytokines. African swine fever virus (ASFV) is a large, double-stranded DNA virus that infects macrophages. This study demonstrates that ASFV effectively inhibited phorbol myristic acid-induced synthesis of antiviral, proinflammatory cytokines alpha interferon, tumor necrosis factor alpha, and interleukin-8 in infected macrophages as assessed by enzyme-linked immunosorbent assay and reverse transcriptase PCR. In contrast, levels of mRNA and protein for transforming growth factor beta, an anti-inflammatory cytokine, were increased by ASFV infection, suggesting that ASFV-induced inhibition of cytokine synthesis may be limited to cytokines activated by NFkappaB. An interleukin-8 promoter, containing an NFkappaB enhancer site, driving expression of a luciferase reporter gene was used to show that NFkappaB-dependent transcription was inhibited by the virus and by a cloned ASFV gene, A238L. This gene encodes a protein with homology to IkappaB, the inhibitor of NFkappaB. Electrophoretic mobility shift assay showed that cells expressing the A238L gene inhibited NFkappaB binding to DNA. These results suggest that the A238L gene product interacts with NFkappaB to prevent transcription and downregulate proinflammatory cytokine production. This novel viral evasion strategy encoded in a single IkappaB-like protein may be capable of inhibiting most macrophage NFkappaB-dependent antiviral mechanisms and may provide insights into how ASFV causes a fatal hemorrhagic disease of domestic pigs and a persistent infection in the African warthog, which is its natural permissive host.

Full Text

The Full Text of this article is available as a PDF (303.8 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ahuja S. K., Gao J. L., Murphy P. M. Chemokine receptors and molecular mimicry. Immunol Today. 1994 Jun;15(6):281–287. doi: 10.1016/0167-5699(94)90008-6. [DOI] [PubMed] [Google Scholar]
  2. Alcamí A., Smith G. L. Cytokine receptors encoded by poxviruses: a lesson in cytokine biology. Immunol Today. 1995 Oct;16(10):474–478. doi: 10.1016/0167-5699(95)80030-1. [DOI] [PubMed] [Google Scholar]
  3. Baeuerle P. A., Henkel T. Function and activation of NF-kappa B in the immune system. Annu Rev Immunol. 1994;12:141–179. doi: 10.1146/annurev.iy.12.040194.001041. [DOI] [PubMed] [Google Scholar]
  4. Bertoni G., Kuhnert P., Peterhans E., Pauli U. Improved bioassay for the detection of porcine tumor necrosis factor using a homologous cell line: PK(15). J Immunol Methods. 1993 Apr 2;160(2):267–271. doi: 10.1016/0022-1759(93)90187-c. [DOI] [PubMed] [Google Scholar]
  5. Cao J. X., Gershon P. D., Black D. N. Sequence analysis of HindIII Q2 fragment of capripoxvirus reveals a putative gene encoding a G-protein-coupled chemokine receptor homologue. Virology. 1995 May 10;209(1):207–212. doi: 10.1006/viro.1995.1244. [DOI] [PubMed] [Google Scholar]
  6. Chomczynski P., Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem. 1987 Apr;162(1):156–159. doi: 10.1006/abio.1987.9999. [DOI] [PubMed] [Google Scholar]
  7. Dixon L. K., Wilkinson P. J. Genetic diversity of African swine fever virus isolates from soft ticks (Ornithodoros moubata) inhabiting warthog burrows in Zambia. J Gen Virol. 1988 Dec;69(Pt 12):2981–2993. doi: 10.1099/0022-1317-69-12-2981. [DOI] [PubMed] [Google Scholar]
  8. Esparza I., González J. C., Viñuela E. Effect of interferon-alpha, interferon-gamma and tumour necrosis factor on African swine fever virus replication in porcine monocytes and macrophages. J Gen Virol. 1988 Dec;69(Pt 12):2973–2980. doi: 10.1099/0022-1317-69-12-2973. [DOI] [PubMed] [Google Scholar]
  9. HESS W. R., COX B. F., HEUSCHELE W. P., STONE S. S. PROPAGATION AND MODIFICATION OF AFRICAN SWINE FEVER VIRUS IN CELL CULTURES. Am J Vet Res. 1965 Jan;26:141–146. [PubMed] [Google Scholar]
  10. Haresnape J. M., Wilkinson P. J., Mellor P. S. Isolation of African swine fever virus from ticks of the Ornithodoros moubata complex (Ixodoidea: Argasidae) collected within the African swine fever enzootic area of Malawi. Epidemiol Infect. 1988 Aug;101(1):173–185. doi: 10.1017/s0950268800029332. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Hingamp P. M., Arnold J. E., Mayer R. J., Dixon L. K. A ubiquitin conjugating enzyme encoded by African swine fever virus. EMBO J. 1992 Jan;11(1):361–366. doi: 10.1002/j.1460-2075.1992.tb05058.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hu F. Q., Smith C. A., Pickup D. J. Cowpox virus contains two copies of an early gene encoding a soluble secreted form of the type II TNF receptor. Virology. 1994 Oct;204(1):343–356. doi: 10.1006/viro.1994.1539. [DOI] [PubMed] [Google Scholar]
  13. Lefèvre F., L'Haridon R., Borras-Cuesta F., La Bonnardière C. Production, purification and biological properties of an Escherichia coli-derived recombinant porcine alpha interferon. J Gen Virol. 1990 May;71(Pt 5):1057–1063. doi: 10.1099/0022-1317-71-5-1057. [DOI] [PubMed] [Google Scholar]
  14. Liou H. C., Baltimore D. Regulation of the NF-kappa B/rel transcription factor and I kappa B inhibitor system. Curr Opin Cell Biol. 1993 Jun;5(3):477–487. doi: 10.1016/0955-0674(93)90014-h. [DOI] [PubMed] [Google Scholar]
  15. Maeda H., Kuwahara H., Ichimura Y., Ohtsuki M., Kurakata S., Shiraishi A. TGF-beta enhances macrophage ability to produce IL-10 in normal and tumor-bearing mice. J Immunol. 1995 Nov 15;155(10):4926–4932. [PubMed] [Google Scholar]
  16. Michaely P., Bennett V. The ANK repeat: a ubiquitous motif involved in macromolecular recognition. Trends Cell Biol. 1992 May;2(5):127–129. doi: 10.1016/0962-8924(92)90084-z. [DOI] [PubMed] [Google Scholar]
  17. Mukaida N., Shiroo M., Matsushima K. Genomic structure of the human monocyte-derived neutrophil chemotactic factor IL-8. J Immunol. 1989 Aug 15;143(4):1366–1371. [PubMed] [Google Scholar]
  18. Neote K., DiGregorio D., Mak J. Y., Horuk R., Schall T. J. Molecular cloning, functional expression, and signaling characteristics of a C-C chemokine receptor. Cell. 1993 Feb 12;72(3):415–425. doi: 10.1016/0092-8674(93)90118-a. [DOI] [PubMed] [Google Scholar]
  19. Nowacki W., Charley B. Enrichment of coronavirus-induced interferon-producing blood leukocytes increases the interferon yield per cell: a study with pig leukocytes. Res Immunol. 1993 Feb;144(2):111–120. doi: 10.1016/0923-2494(93)80066-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Pahl H. L., Baeuerle P. A. Expression of influenza virus hemagglutinin activates transcription factor NF-kappa B. J Virol. 1995 Mar;69(3):1480–1484. doi: 10.1128/jvi.69.3.1480-1484.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Rodríguez J. M., Yáez R. J., Rodríguez J. F., Viñuela E., Salas M. L. The DNA polymerase-encoding gene of African swine fever virus: sequence and transcriptional analysis. Gene. 1993 Dec 22;136(1-2):103–110. doi: 10.1016/0378-1119(93)90453-a. [DOI] [PubMed] [Google Scholar]
  22. Salas M. L., Kuznar J., Viñuela E. Effect of rifamycin derivatives and coumermycin A1 on in vitro RNA synthesis by African swine fever virus. Brief report. Arch Virol. 1983;77(1):77–80. doi: 10.1007/BF01314866. [DOI] [PubMed] [Google Scholar]
  23. Sha W. C., Liou H. C., Tuomanen E. I., Baltimore D. Targeted disruption of the p50 subunit of NF-kappa B leads to multifocal defects in immune responses. Cell. 1995 Jan 27;80(2):321–330. doi: 10.1016/0092-8674(95)90415-8. [DOI] [PubMed] [Google Scholar]
  24. Spriggs M. K. Cytokine and cytokine receptor genes 'captured' by viruses. Curr Opin Immunol. 1994 Aug;6(4):526–529. doi: 10.1016/0952-7915(94)90136-8. [DOI] [PubMed] [Google Scholar]
  25. Spriggs M. K., Hruby D. E., Maliszewski C. R., Pickup D. J., Sims J. E., Buller R. M., VanSlyke J. Vaccinia and cowpox viruses encode a novel secreted interleukin-1-binding protein. Cell. 1992 Oct 2;71(1):145–152. doi: 10.1016/0092-8674(92)90273-f. [DOI] [PubMed] [Google Scholar]
  26. Symons J. A., Alcamí A., Smith G. L. Vaccinia virus encodes a soluble type I interferon receptor of novel structure and broad species specificity. Cell. 1995 May 19;81(4):551–560. doi: 10.1016/0092-8674(95)90076-4. [DOI] [PubMed] [Google Scholar]
  27. Wang P., Wu P., Siegel M. I., Egan R. W., Billah M. M. Interleukin (IL)-10 inhibits nuclear factor kappa B (NF kappa B) activation in human monocytes. IL-10 and IL-4 suppress cytokine synthesis by different mechanisms. J Biol Chem. 1995 Apr 21;270(16):9558–9563. doi: 10.1074/jbc.270.16.9558. [DOI] [PubMed] [Google Scholar]
  28. Wechsler A. S., Gordon M. C., Dendorfer U., LeClair K. P. Induction of IL-8 expression in T cells uses the CD28 costimulatory pathway. J Immunol. 1994 Sep 15;153(6):2515–2523. [PubMed] [Google Scholar]
  29. Weih F., Carrasco D., Durham S. K., Barton D. S., Rizzo C. A., Ryseck R. P., Lira S. A., Bravo R. Multiorgan inflammation and hematopoietic abnormalities in mice with a targeted disruption of RelB, a member of the NF-kappa B/Rel family. Cell. 1995 Jan 27;80(2):331–340. doi: 10.1016/0092-8674(95)90416-6. [DOI] [PubMed] [Google Scholar]
  30. Wold W. S., Hermiston T. W., Tollefson A. E. Adenovirus proteins that subvert host defenses. Trends Microbiol. 1994 Nov;2(11):437–443. doi: 10.1016/0966-842x(94)90801-x. [DOI] [PubMed] [Google Scholar]
  31. Yáez R. J., Rodríguez J. M., Nogal M. L., Yuste L., Enríquez C., Rodriguez J. F., Viñuela E. Analysis of the complete nucleotide sequence of African swine fever virus. Virology. 1995 Apr 1;208(1):249–278. doi: 10.1006/viro.1995.1149. [DOI] [PubMed] [Google Scholar]
  32. Zabel U., Henkel T., Silva M. S., Baeuerle P. A. Nuclear uptake control of NF-kappa B by MAD-3, an I kappa B protein present in the nucleus. EMBO J. 1993 Jan;12(1):201–211. doi: 10.1002/j.1460-2075.1993.tb05646.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. de Martin R., Vanhove B., Cheng Q., Hofer E., Csizmadia V., Winkler H., Bach F. H. Cytokine-inducible expression in endothelial cells of an I kappa B alpha-like gene is regulated by NF kappa B. EMBO J. 1993 Jul;12(7):2773–2779. doi: 10.1002/j.1460-2075.1993.tb05938.x. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Journal of Virology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES