Bioluminescence imaging of vaccinia virus: Effects of interferon on viral replication and spread

Abstract

Whole animal imaging allows viral replication and localization to be monitored in intact animals, which provides significant advantages for determining viral and host factors that determine pathogenesis. To investigate effects of interferons on spatial and temporal progression of vaccinia infection, we generated recombinant viruses that express firefly luciferase or a monomeric orange fluorescent protein. These viruses allow vaccinia infection to be monitored with bioluminescence or fluorescence imaging, respectively. The recombinant viruses were not attenuated in vitro or in vivo relative to a control WR virus. In cell culture, reporters could be detected readily by 4 h post-infection, showing that these viruses can be used as early markers of infection. The magnitude of firefly luciferase activity measured with bioluminescence imaging in vitro and in vivo correlated directly with increasing titers of vaccinia virus, validating imaging data as a marker of viral infection. Replication of vaccinia was significantly greater in mice lacking receptors for type I interferons (IFN I R-/-) compared with wild-type mice, although both genotypes of mice developed focal infections in lungs and brain after intranasal inoculation. IFN I R-/- mice had greater dissemination of virus to liver and spleen than wild-type animals even when mortality occurred at the same time point after infection. Protective effects of type I interferons were mediated primarily through parenchymal cells rather than hematopoietic cells as analyzed by bone marrow transplant experiments. Collectively, our data define a new function for type I interferon signaling in systemic dissemination of vaccinia and validate these reporter viruses for studies of pathogenesis.

Adjuvant-enhanced antibody responses to recombinant proteins correlates with protection of mice and monkeys to orthopoxvirus challenges

“…Weight loss, which occurs during the first week following challenge, is directly correlated with virus replication in the lung and provides an objective, non-invasive way of following disease [7,47]. According to our animal protocol, mice were terminated if they lost greater than 30% of their initial weight.…”

Vaccinia virus infection induces dendritic cell maturation but inhibits antigen presentation by MHC class II

“…The recombinant mKO mutant VV expressing orange fluorescent protein (OFP) has been previously described [32].…”

“…Therefore, we investigated whether IFNAR −/− DC can control VV infection. To do this, we utilized a recombinant VV strain (mKO) that expresses OFP under the p7.5 early/late promoter of VV [32]. Infection with the mKO VV is comparable to that of wild type VV [32].…”

“…To do this, we utilized a recombinant VV strain (mKO) that expresses OFP under the p7.5 early/late promoter of VV [32]. Infection with the mKO VV is comparable to that of wild type VV [32]. BMDC from WT and IFNAR −/− mice were infected with mKO and then cultured with or without IFN-β.…”

Interferon and Apoptosis in Systemic Lupus Erythematosus

“…If one cell can undergo apoptosis before a virus can replicate and infect other cells, the infection is halted (Luker, et al, 2005). Fig.…”