Experimental Passage of St. Louis Encephalitis Virus In Vivo in Mosquitoes and Chickens Reveals Evolutionarily Significant Virus Characteristics

St. Louis encephalitis virus (SLEV; Flaviviridae, flavivirus) was the major cause of epidemic flaviviral encephalitis in the U.S. prior to the introduction of West Nile virus (WNV) in 1999. However, outbreaks of SLEV have been significantly more limited then WNV in terms of levels of activity and geographic dispersal. One possible explanation for these variable levels of activity is that differences in the potential for each virus to adapt to its host cycle exist. The need for arboviruses to replicate in disparate hosts is thought to result in constraints on both evolution and host-specific adaptation. If cycling is the cause of genetic stability observed in nature and arboviruses lack host specialization, then sequential passage should result in both the accumulation of mutations and specialized viruses better suited for replication in that host. Previous studies suggest that WNV and SLEV differ in capacity for both genetic change and host specialization, and in the costs each accrues from specializing. In an attempt to clarify how selective pressures contribute to epidemiological patterns of WNV and SLEV, we evaluated mutant spectra size, consensus genetic change, and phenotypic changes for SLEV in vivo following 20 sequential passages via inoculation in either Culex pipiens mosquitoes or chickens. Results demonstrate that the capacity for genetic change is large for SLEV and that the size of the mutant spectrum is host-dependent using our passage methodology. Despite this, a general lack of consensus change resulted from passage in either host, a result that contrasts with the idea that constraints on evolution in nature result from host cycling alone. Results also suggest that a high level of adaptation to both hosts already exists, despite host cycling. A strain significantly more infectious in chickens did emerge from one lineage of chicken passage, yet other lineages and all mosquito passage strains did not display measurable host-specific fitness gains. In addition, increased infectivity in chickens did not decrease infectivity in mosquitoes, which further contrasts the concept of fitness trade-offs for arboviruses

Collective voices online. Discursive activism in #MeToo

The chapter investigates how women use the practice of speaking out in their activism to bring issues that are significant to them from the private sphere into the public sphere. Specifically, it focuses on analyzing how this was achieved in the case of the #MeToo movement, taken as the most prominent example of activism against sexual harassment in recent years. Using the conceptual tool of counter public sphere developed by Nancy Fraser, the chapter examines two relevant events from #MeToo: the sexual misconduct allegations against actor Aziz Ansari and the circulation of the so-called “Shitty Media Men” list

Building Engagement in K-12 Online Learning

Engagement refers to a learner\u27s interest in their own learning. Engaged students care about what they are learning and spend the time necessary to learn more. Learner engagement leads to increased achievement in a course and also increased satisfaction with the learning experience. This chapter explores elements of engagement from both a researcher and practitioner perspective. The authors explore the definition of engagement along with an explanation of the most influential theories of engagement. They also explain what classroom practices are most likely to build engagement and suggest future research directions

Proportion of <i>Cx. pipiens</i> mosquitoes infected following inoculation of 10-fold dilutions of SLEV before (P0) or after passage in mosquitoes (MP) or chickens (CP).

<p>1Calculated using Reed-Muench formula.</p