397,738 research outputs found
Moduli of Galois p-covers in mixed characteristics
We define a proper moduli stack for degree covers f:Y \to \cX where
\cX is a twisted stable curve in the sense of [5] and [4], and is a
stable curve which via is a torsor over \cX under a finite flat group
scheme \cG \to \cX.Comment: 22 page
Continuity of the radius of convergence of p-adic differential equations on Berkovich analytic spaces
We consider a vector bundle with integrable connection (\cE,\na) on an
analytic domain U in the generic fiber \cX_{\eta} of a smooth formal p-adic
scheme \cX, in the sense of Berkovich. We define the \emph{diameter}
\delta_{\cX}(\xi,U) of U at \xi\in U, the \emph{radius} \rho_{\cX}(\xi) of the
point \xi\in\cX_{\eta}, the \emph{radius of convergence} of solutions of
(\cE,\na) at \xi, R(\xi) = R_{\cX}(\xi, U,(\cE, \na)). We discuss (semi-)
continuity of these functions with respect to the Berkovich topology. In
particular, under we prove under certain assumptions that \delta_{\cX}(\xi,U),
\rho_{\cX}(\xi) and R_{\xi}(U,\cE,\na) are upper semicontinuous functions of
\xi; for Laurent domains in the affine space, \delta_{\cX}(-,U) is continuous.
In the classical case of an affinoid domain U of the analytic affine line, R is
a continuous function.Comment: 19 pages. We have simplified and improved the expositio
Culex tarsalis is a competent vector species for Cache Valley virus
Background: Cache Valley virus (CVV) is a mosquito-borne orthobunyavirus endemic in North America. The virus is
an important agricultural pathogen leading to abortion and embryonic lethality in ruminant species, especially
sheep. The importance of CVV in human public health has recently increased because of the report of severe
neurotropic diseases. However, mosquito species responsible for transmission of the virus to humans remain to be
determined. In this study, vector competence of three Culex species mosquitoes of public health importance, Culex
pipiens, Cx. tarsalis and Cx. quinquefasciatus, was determined in order to identify potential bridge vector species
responsible for the transmission of CVV from viremic vertebrate hosts to humans.
Results: Variation of susceptibility to CVV was observed among selected Culex species mosquitoes tested in this
study. Per os infection resulted in the establishment of infection and dissemination in Culex tarsalis, whereas Cx.
pipiens and Cx. quinquefasciatus were highly refractory to CVV. Detection of viral RNA in saliva collected from
infected Cx. tarsalis provided evidence supporting its role as a competent vector.
Conclusions: Our study provided further understanding of the transmission cycles of CVV and identifies Cx. tarsalis
as a competent vector
Vector competence of Aedes vexans (Meigen), Culex poicilipes (Theobald) and Cx. quinquefasciatus Say from Senegal for West and East African lineages of Rift Valley fever virus
Background
Rift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is a mosquito–borne, zoonotic pathogen. In Senegal, RVFV was first isolated in 1974 from Aedes dalzieli (Theobald) and thereafter from Ae. fowleri (de Charmoy), Ae. ochraceus Theobald, Ae. vexans (Meigen), Culex poicilipes (Theobald), Mansonia africana (Theobald) and Ma. uniformis (Theobald). However, the vector competence of these local species has never been demonstrated making hypothetical the transmission cycle proposed for West Africa based on serological data and mosquito isolates.
Methods
Aedes vexans and Cx. poicilipes, two common mosquito species most frequently associated with RVFV in Senegal, and Cx. quinquefasciatus, the most common domestic species, were assessed after oral feeding with three RVFV strains of the West and East/central African lineages. Fully engorged mosquitoes (420 Ae. vexans, 563 Cx. quinquefasciatus and 380 Cx. poicilipes) were maintained at 27 ± 1 °C and 70–80 % relative humidity. The saliva, legs/wings and bodies were tested individually for the RVFV genome using real-time RT-PCR at 5, 10, 15 and 20 days post exposure (dpe) to estimate the infection, dissemination, and transmission rates. Genotypic characterisation of the 3 strains used were performed to identify factors underlying the different patterns of transmission.
Results
The infection rates varied between 30.0–85.0 % for Ae. vexans, 3.3–27 % for Cx. quinquefasciatus and 8.3–46.7 % for Cx. poicilipes, and the dissemination rates varied between 10.5–37 % for Ae. vexans, 9.5–28.6 % for Cx. quinquefasciatus and 3.0–40.9 % for Cx. poicilipes. However only the East African lineage was transmitted, with transmission rates varying between 13.3–33.3 % in Ae. vexans, 50 % in Cx. quinquefasciatus and 11.1 % in Cx. poicilipes. Culex mosquitoes were less susceptible to infection than Ae. vexans. Compared to other strains, amino acid variation in the NSs M segment proteins of the East African RVFV lineage human-derived strain SH172805, might explain the differences in transmission potential.
Conclusion
Our findings revealed that all the species tested were competent for RVFV with a significant more important role of Ae. vexans compared to Culex species and a highest potential of the East African lineage to be transmitted
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