title: Inhibition of NF-kappaB activation in vivo impairs establishment of gammaherpesvirus latency.
abstract: A critical determinant in chronic gammaherpesvirus infections is the ability of these viruses to establish latency in a lymphocyte reservoir. The nuclear factor (NF)-kappaB family of transcription factors represent key players in B-cell biology and are targeted by gammaherpesviruses to promote host cell survival, proliferation, and transformation. However, the role of NF-kappaB signaling in the establishment of latency in vivo has not been addressed. Here we report the generation and in vivo characterization of a recombinant murine gammaherpesvirus 68 (gammaHV68) that expresses a constitutively active form of the NF-kappaB inhibitor, IkappaBalphaM. Inhibition of NF-kappaB signaling upon infection with gammaHV68-IkappaBalphaM did not affect lytic replication in cell culture or in the lung following intranasal inoculation. However, there was a substantial decrease in the frequency of latently infected lymphocytes in the lung (90% reduction) and spleens (97% reduction) 16 d post intranasal inoculation. Importantly, the defect in establishment of latency in lung B cells could not be overcome by increasing the dose of virus 100-fold. The observed decrease in establishment of viral latency correlated with a loss of activated, CD69(hi) B cells in both the lungs and spleen at day 16 postinfection, which was not apparent by 6 wk postinfection. Constitutive expression of Bcl-2 in B cells did not rescue the defect in the establishment of latency observed with gammaHV68-IkappaBalphaM, indicating that NF-kappaB-mediated functions apart from Bcl-2-mediated B-cell survival are critical for the efficient establishment of gammaherpesvirus latency in vivo. In contrast to the results obtained following intranasal inoculation, infection of mice with gammaHV68-IkappaBalphaM by the intraperitoneal route had only a modest impact on splenic latency, suggesting that route of inoculation may alter requirements for establishment of virus latency in B cells. Finally, analyses of the pathogenesis of gammaHV68-IkappaBalphaM provides evidence that NF-kappaB signaling plays an important role during multiple stages of gammaHV68 infection in vivo and, as such, represents a key host regulatory pathway that is likely manipulated by the virus to establish latency in B cells.
authors.affiliation: Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, United States of America.
authors.forename: Laurie T
authors.initials: LT
authors.lastname: Krug
authors.forename: Janice M
authors.initials: JM
authors.lastname: Moser
authors.forename: Shelley M
authors.initials: SM
authors.lastname: Dickerson
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Speck
mesh_terms: D000818:Animals; D018941:Antigens, CD19 / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology / Q000821:virology; D001483:Base Sequence; D005260:Female; D020672:I-kappa B Proteins / Q000502:physiology; D008168:Lung / Q000821:virology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000502:physiology; D041681:NIH 3T3 Cells; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D018144:Rhadinovirus / Q000502:physiology*; D015398:Signal Transduction; D013154:Spleen / Q000821:virology; D019562:Viral Load; D017735:Virus Latency; D014779:Virus Replication
chemical_list: D018941:Antigens, CD19; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D000072000:NF-KappaB Inhibitor alpha