MVA-based H5N1 vaccine affords cross-clade protection in mice against influenza A/H5N1 viruses at low doses and after single immunization.

Human infections with highly pathogenic avian influenza viruses of the H5N1 subtype, frequently reported since 2003, result in high morbidity and mortality. It is feared that these viruses become pandemic, therefore the development of safe and effective vaccines is desirable. MVA-based H5N1 vaccines already proved to be effective when two immunizations with high doses were used. Dose-sparing strategies would increase the number of people that can be vaccinated when the amount of vaccine preparations that can be produced is limited. Furthermore, protective immunity is induced ideally after a single immunization. Therefore the minimal requirements for induction of protective immunity with a MVA-based H5N1 vaccine were assessed in mice. To this end, mice were vaccinated once or twice with descending doses of a recombinant MVA expressing the HA gene of influenza virus A/Vietnam/1194/04. The protective efficacy was determined after challenge infection with the homologous clade 1 virus and a heterologous virus derived from clade 2.1, A/Indonesia/5/05 by assessing weight loss, virus replication and histopathological changes. It was concluded that MVA-based vaccines allowed significant dose-sparing and afford cross-clade protection, also after a single immunization, which are favorable properties for an H5N1 vaccine candidate

Nitrate radicals and biogenic volatile organic compounds: oxidation, mechanisms, and organic aerosol

Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO_3) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO_3-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol. Despite its long history of research and the significance of this topic in atmospheric chemistry, a number of important uncertainties remain. These include an incomplete understanding of the rates, mechanisms, and organic aerosol yields for NO_3-BVOC reactions, lack of constraints on the role of heterogeneous oxidative processes associated with the NO_3 radical, the difficulty of characterizing the spatial distributions of BVOC and NO_3 within the poorly mixed nocturnal atmosphere, and the challenge of constructing appropriate boundary layer schemes and non-photochemical mechanisms for use in state-of-the-art chemical transport and chemistry–climate models. This review is the result of a workshop of the same title held at the Georgia Institute of Technology in June 2015. The first half of the review summarizes the current literature on NO_3-BVOC chemistry, with a particular focus on recent advances in instrumentation and models, and in organic nitrate and secondary organic aerosol (SOA) formation chemistry. Building on this current understanding, the second half of the review outlines impacts of NO_3-BVOC chemistry on air quality and climate, and suggests critical research needs to better constrain this interaction to improve the predictive capabilities of atmospheric models

Interleukin-1 beta receptor expressed by modified vaccinia virus Ankara interferes with interleukin-1 beta activity produced in various virus-infected antigen-presenting cells

Background: Modified vaccinia virus Ankara (MVA) is a highly attenuated virus and a promising vaccine vector with potent immune stimulating properties. Deletion of the gene encoding the viral interleukin-1beta receptor (vIL-1 beta R) in MVA (MVA Delta IL-1 beta R) was previously shown to enhance memory T cell function. Here, we investigated the influence of vIL-1 beta R on blocking interleukin-1beta (IL-1 beta) upon MVA infection in various antigen presenting cells of murine and human origin, and analyzed whether inflammasome function contributes to IL-1 beta production in different cell types. Findings: Extending previous studies, immunizing mice with low doses of MVA Delta IL-1 beta R still showed enhanced memory CD8(+) T cell activation compared to MVA wild-type (MVAwt) immunization. In vitro, murine myeloid dendritic cells, and activated, but not naive primary macrophages were identified as potent producers of IL-1 beta upon infection with MVA. Importantly, free IL-1 beta was only detected in the absence of vIL-1 beta R. Moreover, MVA Delta IL-1 beta R increased amounts of bioactive IL-1 beta compared to MVAwt after infection of human THP-1 cells, as detected using a reporter system that only responds to active and free IL-1 beta. The MVA-mediated induction of IL-1 beta was confirmed to depend on inflammasome function in human and murine cells, however in murine cells this apparently involves caspase-1-independent pathways. Conclusions: MVA lacking IL-1 beta blocking activity leads to increased concentrations of free IL-1 beta upon infection of murine and human antigen presenting cells; this is likely responsible for enhanced memory T cell activation upon MVA Delta IL-1 beta R immunization of mice. Moreover, our results suggest that MVA-mediated IL-1 beta induction is a multifactorial process

Functional F11L and K1L genes in modified vaccinia virus Ankara restore virus-induced cell motility but not growth in human and murine cells

AbstractModified vaccinia virus Ankara (MVA) was generated by serial passaging in chicken embryo fibroblasts. During this attenuation, MVA lost the capacity to productively grow in human and most other mammalian cell lines, as well as acquiring a multitude of deletions and mutations in the MVA genome. This means that the precise molecular basis for the MVA host-range restriction is still unknown. The vaccinia virus (VACV) genes F11L and K1L are mutated or truncated in MVA. F11L was previously implicated in VACV-induced cell motility and virion maturation. Here, we demonstrate that the restoration of F11L gene expression in MVA rescued virus-induced cell motility, but had no impact on MVA virion maturation and host-range restriction. Additional insertion of the K1L gene, which restores MVA replication in RK-13 cells, was not sufficient to extend MVA growth capacity to other mammalian cells

The bet Gene of Feline Foamy Virus Is Required for Virus Replication

AbstractFoamy viruses (FV) are complex retroviruses with additional bel genes located between env and the 3′ long-terminal repeat. The functions of the bel 2 and bet genes are unknown and both are dispensable for replication of the prototypic human foamy virus in cell cultures. We examined the function(s) of bel 2 and bet of the distantly related feline foamy virus (FFV) in the proviral context. Mutagenesis was used to alter the Bel 2 and Bet or to abrogate their expression. The Bel 2/Bet mutants showed a 1000-fold reduced viral titer in feline kidney cells; in human 293T cells, viral titer was only about 10-fold reduced compared to wild-type FFV. In both cell types, the Bel 2/Bet mutations resulted in a reduced release of FFV particles. The results indicate that FFV Bet is required for efficient virus replication. The functions of the Bel 2 and Bet proteins are discussed

The Orthopoxvirus 68-Kilodalton Ankyrin-Like Protein Is Essential for DNA Replication and Complete Gene Expression of Modified Vaccinia Virus Ankara in Nonpermissive Human and Murine Cells▿

Modified vaccinia virus Ankara (MVA) is a highly attenuated and replication-deficient vaccinia virus (VACV) that is being evaluated as replacement smallpox vaccine and candidate viral vector. MVA lacks many genes associated with virulence and/or regulation of virus tropism. The 68-kDa ankyrin-like protein (68k-ank) is the only ankyrin repeat-containing protein that is encoded by the MVA genome and is highly conserved throughout the Orthopoxvirus genus. We showed previously that 68k-ank is composed of ankyrin repeats and an F-box-like domain and forms an SCF ubiquitin ligase complex together with the cellular proteins Skp1a and Cullin-1. We now report that 68k-ank (MVA open reading frame 186R) is an essential factor for completion of the MVA intracellular life cycle in nonpermissive human and murine cells. Infection of mouse NIH 3T3 and human HaCaT cells with MVA with a deletion of the 68k-ank gene (MVA-Δ68k-ank) was characterized by an extensive reduction of viral intermediate RNA and protein, as well as late transcripts and drastically impaired late protein synthesis. Furthermore, infections with MVA-Δ68k-ank failed to induce the host protein shutoff that is characteristic of VACV infections. Although we demonstrated that proteasome function in general is essential for the completion of the MVA molecular life cycle, we found that a mutant 68k-ank protein with a deletion of the F-box-like domain was able to fully complement the deficiency of MVA-Δ68k-ank to express all classes of viral genes. Thus, our data demonstrate that the 68k-ank protein contains another critical domain that may function independently of SCF ubiquitin ligase complex formation, suggesting multiple activities of this interesting regulatory protein