scholarly journals Rift Valley fever virus (family Bunyaviridae, genus Phlebovirus). Isolations from Diptera collected during an inter-epizootic period in Kenya

1985 ◽  
Vol 95 (1) ◽  
pp. 197-209 ◽  
Author(s):  
K. J. Linthicum ◽  
F. G. Davies ◽  
A. Kairo ◽  
C. L. Bailey
Keyword(s):  
Adult Male ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Mosquito Species ◽  
Transovarial Transmission ◽  
Immature Stages ◽  
Valley Fever ◽  
Virus Family ◽  
Male And Female

SUMMARYA total of 134876 Diptera collected in Kenya during a 3-year period were tested in 3383 pools for Rift Valley fever (RVF) virus. Nineteen pools of unengorged mosquitoes were found positive for RVF. All isolations were made from specimens collected at or near the naturally or artificially flooded grassland depressions that serve as the developmental sites for the immature stages of many mosquito species. The isolation of virus from adult male and female A. lineatopennis which had been reared from field-collected larvae and pupae suggests that transovarial transmission of the virus occurs in this species.

scholarly journals An Epidemiological Model of Rift Valley Fever with Spatial Dynamics

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Tianchan Niu ◽  
Holly D. Gaff ◽  
Yiannis E. Papelis ◽  
David M. Hartley
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Mosquito Species ◽  
Horizontal Transmission ◽  
Spatial Dynamics ◽  
The United States ◽  
Trade Restrictions ◽  
Valley Fever ◽  
Supply Chain Disruptions

As a category A agent in the Center for Disease Control bioterrorism list, Rift Valley fever (RVF) is considered a major threat to the United States (USA). Should the pathogen be intentionally or unintentionally introduced to the continental USA, there is tremendous potential for economic damages due to loss of livestock, trade restrictions, and subsequent food supply chain disruptions. We have incorporated the effects of space into a mathematical model of RVF in order to study the dynamics of the pathogen spread as affected by the movement of humans, livestock, and mosquitoes. The model accounts for the horizontal transmission of Rift Valley fever virus (RVFV) between two mosquito and one livestock species, and mother-to-offspring transmission of virus in one of the mosquito species. Space effects are introduced by dividing geographic space into smaller patches and considering the patch-to-patch movement of species. For each patch, a system of ordinary differential equations models fractions of populations susceptible to, incubating, infectious with, or immune to RVFV. The main contribution of this work is a methodology for analyzing the likelihood of pathogen establishment should an introduction occur into an area devoid of RVF. Examples are provided for general and specific cases to illustrate the methodology.

scholarly journals Three-Dimensional Organization of Rift Valley Fever Virus Revealed by Cryoelectron Tomography

2008 ◽  
Vol 82 (21) ◽  
pp. 10341-10348 ◽  
Author(s):  
Alexander N. Freiberg ◽  
Michael B. Sherman ◽  
Marc C. Morais ◽  
Michael R. Holbrook ◽  
Stanley J. Watowich
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Three Dimensional ◽  
Average Diameter ◽  
Fever Virus ◽  
Icosahedral Symmetry ◽  
Valley Fever ◽  
Virus Family ◽  
Virus Surface

ABSTRACT Rift Valley fever virus (RVFV) is a member of the Bunyaviridae virus family (genus Phlebovirus) and is considered to be one of the most important pathogens in Africa, causing viral zoonoses in livestock and humans. Here, we report the characterization of the three-dimensional structural organization of RVFV vaccine strain MP-12 by cryoelectron tomography. Vitrified-hydrated virions were found to be spherical, with an average diameter of 100 nm. The virus glycoproteins formed cylindrical hollow spikes that clustered into distinct capsomeres. In contrast to previous assertions that RVFV is pleomorphic, the structure of RVFV MP-12 was found to be highly ordered. The three-dimensional map was resolved to a resolution of 6.1 nm, and capsomeres were observed to be arranged on the virus surface in an icosahedral lattice with clear T=12 quasisymmetry. All icosahedral symmetry axes were visible in self-rotation functions calculated using the Fourier transform of the RVFV MP-12 tomogram. To the best of our knowledge, a triangulation number of 12 had previously been reported only for Uukuniemi virus, a bunyavirus also within the Phlebovirus genus. The results presented in this study demonstrate that RVFV MP-12 possesses T=12 icosahedral symmetry and suggest that other members of the Phlebovirus genus, as well as of the Bunyaviridae family, may adopt icosahedral symmetry. Knowledge of the virus architecture may provide a structural template to develop vaccines and diagnostics, since no effective anti-RVFV treatments are available for human use.

Rift Valley fever virus transmission by different Egyptian mosquito species

1987 ◽  
Vol 81 (4) ◽  
pp. 694-698 ◽  
Author(s):  
Adel M. Gad ◽  
Mosaad M. Hassan ◽  
Sharif El Said ◽  
Mahmoud I. Moussa ◽  
Owen L. Wood
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Mosquito Species ◽  
Virus Transmission ◽  
Fever Virus ◽  
Valley Fever

Vector Potential of Selected North American Mosquito Species for Rift Valley Fever Virus

1988 ◽  
Vol 38 (2) ◽  
pp. 440-446 ◽  
Author(s):  
Thomas P. Gargan ◽  
David J. Dohm ◽  
Michael J. Turell ◽  
Charles L. Bailey ◽  
Gary G. Clark
Keyword(s):  
North American ◽  
Vector Potential ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Mosquito Species ◽  
Fever Virus ◽  
Valley Fever

scholarly journals Detection of Rift Valley Fever Virus RNA in Formalin-Fixed Mosquitoes by In Situ Hybridization (RNAscope®)

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1079
Author(s):  
Sarah Lumley ◽  
Laura Hunter ◽  
Kirsty Emery ◽  
Roger Hewson ◽  
Anthony R. Fooks ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Mosquito Species ◽  
Fever Virus ◽  
Sub Saharan Africa ◽  
Support Vector ◽  
Valley Fever

Rift Valley fever virus (RVFV) causes a zoonotic mosquito-borne haemorrhagic disease that emerges to produce rapid large-scale outbreaks in livestock within sub-Saharan Africa. A range of mosquito species in Africa have been shown to transmit RVFV, and recent studies have assessed whether temperate mosquito species are also capable of transmission. In order to support vector competence studies, the ability to visualize virus localization in mosquito cells and tissue would enhance the understanding of the infection process within the mosquito body. Here, the application of in situ hybridization utilizing RNAscope® to detect RVFV infection within the mosquito species, Culex pipiens, derived from the United Kingdom was demonstrated. Extensive RVFV replication was detected in many tissues of the mosquito with the notable exception of the interior of ovarian follicles.

scholarly journals Wolbachia effects on Rift Valley fever virus infection in Culex tarsalis mosquitoes

2017 ◽  
Author(s):  
Brittany L. Dodson ◽  
Elizabeth S. Andrews ◽  
Michael J. Turell ◽  
Jason L. Rasgon
Keyword(s):  
West Nile Virus ◽  
Virus Infection ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Mosquito Species ◽  
West Nile Virus Infection ◽  
Fever Virus ◽  
Culex Tarsalis ◽  
Valley Fever

AbstractInnovative tools are needed to alleviate the burden of mosquito-borne diseases, and strategies that target the pathogen instead of the mosquito are being considered. A possible tactic is the use of Wolbachia, a maternally inherited, endosymbiotic bacterium that can suppress diverse pathogens when introduced to naive mosquito species. We investigated effects of somatic Wolbachia (strain wAlbB) infection on Rift Valley fever virus (RVFV) in Culex tarsalis mosquitoes. When compared to Wolbachia-uninfected mosquitoes, there was no significant effect of Wolbachia infection on RVFV infection, dissemination, or transmission frequencies, nor on viral body or saliva titers. Within Wolbachia-infected mosquitoes, there was a modest negative correlation between RVFV body titers and Wolbachia density, suggesting that Wolbachia may suppress RVFV in a density-dependent manner in this mosquito species. These results are contrary to previous work in the same mosquito species, showing Wolbachia-induced enhancement of West Nile virus infection rates. Taken together, these results highlight the importance of exploring the breadth of phenotypes induced by Wolbachia.Author SummaryAn integrated vector management program utilizes several practices, including pesticide application and source reduction, to reduce mosquito populations. However, mosquitoes are developing resistance to some of these methods and new control approaches are needed. A novel technique involves the bacterium Wolbachia that lives naturally in many insects. Wolbachia can be transferred to uninfected mosquitoes and can block pathogen transmission to humans. Additionally, Wolbachia is maternally inherited, allowing it to spread quickly through uninfected field populations of mosquitoes. We studied the impacts of Wolbachia on Rift Valley fever virus (RVFV) in the naturally uninfected mosquito, Culex tarsalis. Wolbachia had no effects on the ability of Culex tarsalis to become infected with or transmit RVFV. High densities of Wolbachia were associated with no virus infection or low levels of virus, suggesting that Wolbachia might suppress RVFV at high densities. These results contrast with our previous study that showed Wolbachia enhances West Nile virus infection in Culex tarsalis. Together, these studies highlight the importance of studying Wolbachia effects on a variety of pathogens so that control methods are not impeded.

scholarly journals Reproducing the Rift Valley fever virus mosquito-lamb-mosquito transmission cycle

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paul J. Wichgers Schreur ◽  
Rianka P. M. Vloet ◽  
Jet Kant ◽  
Lucien van Keulen ◽  
Jose L. Gonzales ◽  
...  
Keyword(s):  
Animal Models ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Vector Competence ◽  
Mosquito Species ◽  
Fever Virus ◽  
Valley Fever ◽  
Transmission Cycle ◽  
Membrane Feeding

AbstractRift Valley fever virus (RVFV) is a mosquito-borne bunyavirus that is pathogenic to ruminants and humans. The virus is endemic to Africa and the Arabian Peninsula where outbreaks are characterized by abortion storms and mortality of newborns, particularly in sheep herds. Vector competence experiments in laboratory settings have suggested that over 50 mosquito species are capable of transmitting RVFV. Transmission of mosquito-borne viruses in the field is however influenced by numerous factors, including population densities, blood feeding behavior, extrinsic incubation period, longevity of vectors, and viremia levels in vertebrate hosts. Animal models to study these important aspects of RVFV transmission are currently lacking. In the present work, RVFV was transmitted to European (Texel-swifter cross-breed) lambs by laboratory-reared Aedes aegypti mosquitoes that were infected either by membrane feeding on a virus-spiked blood meal or by feeding on lambs that developed viremia after intravenous inoculation of RVFV. Feeding of mosquitoes on viremic lambs resulted in strikingly higher infection rates as compared to membrane feeding. Subsequent transmission of RVFV from lamb to lamb by infected mosquitoes was highly efficient in both models. The animal models described here can be used to study mosquito-mediated transmission of RVFV among the major natural target species and to evaluate the efficacy of vaccines against mosquito-mediated RVFV infection.

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