How Flaviviruses Activate and Suppress the Interferon Response

The flavivirus genus includes viruses with a remarkable ability to produce disease on a large scale. The expansion and increased endemicity of dengue and West Nile viruses in the Americas exemplifies their medical and epidemiological importance. The rapid detection of viral infection and induction of the innate antiviral response are crucial to determining the outcome of infection. The intracellular pathogen receptors RIG-I and MDA5 play a central role in detecting flavivirus infections and initiating a robust antiviral response. Yet, these viruses are still capable of producing acute illness in humans. It is now clear that flaviviruses utilize a variety of mechanisms to modulate the interferon response. The non-structural proteins of the various flaviviruses reduce expression of interferon dependent genes by blocking phosphorylation, enhancing degradation or down-regulating expression of major components of the JAK/STAT pathway. Recent studies indicate that interferon modulation is an important factor in the development of severe flaviviral illness. This suggests that an increased understanding of viral-host interactions will facilitate the development of novel therapeutics to treat these viral infections and improved biological models to study flavivirus pathogenesis

Pine Pitch Canker and Insects: Relationships and Implications for Disease Spread in Europe

Producción CientíficaThe fungal pathogen Fusarium circinatum (Nirenberg and O’ Donnell) is the causal agent of pine pitch canker (PPC) disease, which seriously affects conifer species in forests and nurseries worldwide. In Europe, PPC is only established in the Iberian Peninsula; however, it is presumed that its range could expand through the continent in the near future. Infection caused by this fungus requires open wounds on the tree, including physical damage caused by insects. Therefore, a relationship probably occurs between PPC and a wide variety of insects. The aim of this review is to outline the taxonomic and ecological diversity of insect species with high potential association with F. circinatum in Europe and elsewhere. The insects were classified as vectors, carriers and wounding agents according to the association level with the PPC disease. In addition, we discuss the insect-mediated spreading of PPC disease in relation to the different phases of forest stand development, from seeds and seedlings in nurseries to mature stands. Lastly, to improve our predictive capacities and to design appropriate intervention measures and strategies for controlling disease dissemination by insects, variables such as geographic location, time of the year and host species should be considered,European Cooperation in Science and Technology (COST Action FP1406 PINESTRENGTH)Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-69370-R)Centro de Estudios do Ambiente e do Mar (CESAM) (project UID/AMB/50017/2019)Portuguese Foundation for Science and Technology (projects PTDC/AGR-FOR/2768/2014 , POCI-01-0145-FEDER-016785 , SFRH/BPD/122928/2016)Russian Foundation for Basic Research (grant 17-04-01486)Saint Petersburg State Polytechnical University (project 2019-0420

West Nile Virus from Blood Donors, Vertebrates, and Mosquitoes, Puerto Rico, 2007

West Nile virus (WNV) was isolated from a human blood donor, a dead falcon, and mosquitoes in Puerto Rico in 2007. Phylogenetic analysis of the 4 isolates suggests a recent introduction of lineage I WNV that is closely related to WNV currently circulating in North America

Endurance, Refuge, and Reemergence of Dengue Virus Type 2, Puerto Rico, 1986–2007

To study the evolution of dengue virus (DENV) serotype 2 in Puerto Rico, we examined the genetic composition and diversity of 160 DENV-2 genomes obtained through 22 consecutive years of sampling. A clade replacement took place in 1994–1997 during a period of high incidence of autochthonous DENV-2 and frequent, short-lived reintroductions of foreign DENV-2. This unique clade replacement was complete just before DENV-3 emerged. By temporally and geographically defining DENV-2 lineages, we describe a refuge of this virus through 4 years of low genome diversity. Our analyses may explain the long-term endurance of DENV-2 despite great epidemiologic changes in disease incidence and serotype distribution

An Outbreak of Dengue Fever in St. Croix (US Virgin Islands), 2005

BACKGROUND: Periodic outbreaks of dengue fever occur in the United States Virgin Islands. In June 2005, an outbreak of dengue virus (DENV) serotype-2 with cases of dengue hemorrhagic fever (DHF) was detected in St. Croix, US Virgin Islands. The objective of this report is to describe this outbreak of DENV-2 and the findings of a case-control study examining risk factors for DHF. METHODOLOGY/PRINCIPAL FINDINGS: This is the largest dengue outbreak ever recorded in St. Croix, with 331 suspected dengue cases reported island-wide during 2005 (62.2 cases/10,000 population); 54% were hospitalized, 21% had at least one hemorrhagic manifestation, 28% had thrombocytopenia, 5% had DHF and 1 patient died. Eighty-nine laboratory-positive hospitalized patients were identified. Of these, there were 15 (17%) who met the WHO criteria for DHF (cases) and 74 (83%) who did not (controls). The only variable significantly associated with DHF on bivariate or multivariable analysis was age, with an adjusted odds ratio (95% confidence interval) of 1.033 (1.003,1.064). CONCLUSIONS/SIGNIFICANCE: During this outbreak of DENV-2, a high proportion of cases developed DHF and increasing age was significantly associated with DHF

Dengue Deaths in Puerto Rico: Lessons Learned from the 2007 Epidemic

Dengue is a major public health problem in the tropics and subtropics; an estimated 50 million cases occur annually and 40 percent of the world's population lives in areas with dengue virus (DENV) transmission. Dengue has a wide range of clinical presentations from an undifferentiated acute febrile illness, classic dengue fever, to severe dengue (i.e., dengue hemorrhagic fever or dengue shock syndrome). About 5% of patients develop severe dengue, which is more common with second or subsequent infections. No vaccines are available to prevent dengue, and there are no specific antiviral treatments for patients with dengue. However, early recognition of shock and intensive supportive therapy can reduce risk of death from ∼10% to less than 1% among severe dengue cases. Reviewing dengue deaths is one means to identify issues in clinical management. These findings can be used to develop healthcare provider education to minimize dengue morbidity and mortality

Short-term effects of experimental fire for a soil under eucalyptus forest (SE Australia)

The effects of different fire intensities on physiochemical soil properties have been studied in this research. The experiment was conducted in a eucalyptus forested area near the Namadgi National Park (ACT, Australia), and four fire intensities were achieved by adding different amounts of fuel load: 0kgm-2 (control), 2kgm-2 (low fire intensity), 4kgm-2 (moderate fire intensity) and 8kgm-2 (high fire intensity). Soil surface peak temperatures reached at each plot were 14, 142, 317 and 525°C, respectively. Immediate changes in soil properties under different fuel loads were studied and monitored monthly during a 7-month period.Average pH increased significantly with fuel load immediately after fire and decreased progressively to initial values. Changes in soil pH from burnt plots seem to be caused mainly by an ephemeral ash layer, and the recovery time has been relatively short. The complete oxidation of soil organic matter and the release of substantial amounts of cations after high fire intensity also contributed to increased pH. Only small variations in soil texture have been observed in this study even after high intensity fire, although the clay content decreased slightly during the experiment. This can be due to relatively low pre-burn clay content, but also to spatial variability of texture. In this case, post-fire erosion processes might have contributed to decreased clay content and are probably more important than other processes associated to temperature. Aggregate stability indices showed good correlation coefficients with the organic matter content. The role of organic matter as cementing agent of soil aggregates is extremely important after fire, since aggregate stability indices showed good correlation coefficients with the organic matter content. Low intensity fire enhanced soil water repellency. In this case, fire-enhanced soil water repellency persisted or increased progressively, but decreased below initial levels at the end of the experiment, but soil water repellency was completely destroyed after moderate or high fuel load treatments. The persistence of wettable conditions after destruction of soil water repellency can be considered as an index of fire severity, since it is a direct consequence of strong reduction of organic matter content.Peer Reviewe

t-loops at trypanosome telomeres

Mammalian telomeres form large duplex loops (t-loops) that may sequester chromosome ends by invasion of the 3′ TTAGGG overhang into the duplex TTAGGG repeat array. Here we document t-loops in Trypanosoma brucei, a kinetoplastid protozoan with abundant telomeres due to the presence of many minichromosomes. These telomeres contained 10–20 kb duplex TTAGGG repeats and a 3′ TTAGGG overhang. Electron microscopy of psoralen/UV cross-linked DNA revealed t-loops in enriched telomeric restriction fragments and at the ends of isolated minichromosomes. In mammals, t-loops are large (up to 25 kb), often comprising most of the telomere. Despite similar telomere lengths, trypanosome t-loops were much smaller (∼1 kb), indicating that t-loop sizes are regulated. Coating of non-cross-linked minichromosomes with Escherichia coli single-strand binding protein (SSB) often revealed 3′ overhangs at both telomeres and several cross-linked minichromosomes had t-loops at both ends. These results suggest that t-loops and their prerequisite 3′ tails can be formed on the products of both leading and lagging strand synthesis. We conclude that t-loops are a conserved feature of eukaryotic telomeres