scholarly journals Laboratory demonstration of the vertical transmission of Rift Valley fever virus by Culex tarsalis mosquitoes

2021 ◽  
Vol 15 (3) ◽  
pp. e0009273
Author(s):  
Nicholas A. Bergren ◽  
Erin M. Borland ◽  
Daniel A. Hartman ◽  
Rebekah C. Kading
Keyword(s):  
Vertical Transmission ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Preliminary Evidence ◽  
Fever Virus ◽  
Oral Exposure ◽  
Culex Tarsalis ◽  
Valley Fever ◽  
Field Evidence

Rift Valley fever virus (RVFV) is a mosquito-transmitted virus with proven ability to emerge into naïve geographic areas. Limited field evidence suggests that RVFV is transmitted vertically from parent mosquito to offspring, but until now this mechanism has not been confirmed in the laboratory. Furthermore, this transmission mechanism has allowed for the prediction of RVFV epizootics based on rainfall patterns collected from satellite information. However, in spite of the relevance to the initiation of epizootic events, laboratory confirmation of vertical transmission has remained an elusive research aim for thirty-five years. Herein we present preliminary evidence of the vertical transmission of RVFV by Culex tarsalis mosquitoes after oral exposure to RVFV. Progeny from three successive gonotrophic cycles were reared to adults, with infectious RVFV confirmed in each developmental stage. Virus was detected in ovarian tissues of parental mosquitoes 7 days after imbibing an infectious bloodmeal. Infection was confirmed in progeny as early as the first gonotrophic cycle, with infection rates ranging from 2.0–10.0%. Virus titers among progeny were low, which may indicate a host mechanism suppressing replication.

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

2017 ◽  
Vol 11 (10) ◽  
pp. e0006050 ◽  
Author(s):  
Brittany L. Dodson ◽  
Elizabeth S. Andrews ◽  
Michael J. Turell ◽  
Jason L. Rasgon
Keyword(s):  
Virus Infection ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Culex Tarsalis ◽  
Valley Fever

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 Rift Valley fever virus induces fetal demise in Sprague-Dawley rats through direct placental infection

2018 ◽  
Vol 4 (12) ◽  
pp. eaau9812 ◽  
Author(s):  
Cynthia M. McMillen ◽  
Nitin Arora ◽  
Devin A. Boyles ◽  
Joseph R. Albe ◽  
Michael R. Kujawa ◽  
...  
Keyword(s):  
Vertical Transmission ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Intrauterine Fetal Death ◽  
Pregnant Rats ◽  
Fetal Demise ◽  
Valley Fever ◽  
Placental Infection

Rift Valley fever virus (RVFV) infections in pregnant livestock cause high rates of fetal demise; miscarriage in pregnant women has also been associated with RVFV infection. To address how RVFV infection during pregnancy causes detrimental effects on the fetus, we developed a pregnant rodent model of RVFV infection. We found that pregnant rats were more susceptible to RVFV-induced death than their nonpregnant counterparts and that RVFV infection resulted in intrauterine fetal death and severe congenital abnormalities, even in pups from infected asymptomatic pregnant rats. Virus distribution in infected dams was widespread, with a previously unrecognized preference for infection, replication, and tissue damage in the placenta. In human mid-gestation placental tissue, RVFV directly infected placental chorionic villi, with replication detected in the outermost syncytial layer. Our work identifies direct placental infection by RVFV as a mechanism for vertical transmission. This is the first study to show vertical transmission of RVFV with a lethal outcome in a species other than livestock. This study highlights the potential impact of a future epidemic of this emerging mosquito-borne virus.

Vertical Transmission of Rift Valley Fever Virus Without Detectable Maternal Viremia

2013 ◽  
Vol 13 (8) ◽  
pp. 601-606 ◽  
Author(s):  
A.F.G. Antonis ◽  
J. Kortekaas ◽  
J. Kant ◽  
R. P. M. Vloet ◽  
A. Vogel-Brink ◽  
...  
Keyword(s):  
Vertical Transmission ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Valley Fever

scholarly journals Rift Valley fever virus: strategies for maintenance, survival and vertical transmission in mosquitoes

2017 ◽  
Vol 98 (5) ◽  
pp. 875-887 ◽  
Author(s):  
Sarah Lumley ◽  
Daniel L Horton ◽  
Luis L. M Hernandez-Triana ◽  
Nicholas Johnson ◽  
Anthony R Fooks ◽  
...  
Keyword(s):  
Vertical Transmission ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Valley Fever

scholarly journals Rift Valley fever virus induces fetal demise through direct placental infection

2018 ◽  
Author(s):  
Cynthia M. McMillen ◽  
Nitin Arora ◽  
Devin A. Boyles ◽  
Joseph R. Albe ◽  
Michael R. Kujawa ◽  
...  
Keyword(s):  
Vertical Transmission ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Intrauterine Fetal Death ◽  
Pregnant Rats ◽  
Fetal Demise ◽  
Valley Fever ◽  
Placental Infection

AbstractRift Valley fever virus (RVFV) infections in pregnant livestock are associated with high rates of fetal demise and have been linked to miscarriage in pregnant women. To address how acute RVFV infection during pregnancy causes detrimental effects on the fetus, we developed an immunocompetent pregnant rodent model of RVFV infection. We found that pregnant rats were more susceptible to RVFV-induced death than their non-pregnant counterparts and that RVFV infection resulted in intrauterine fetal death and severe congenital abnormalities, even in pups from infected asymptomatic pregnant rats. Virus distribution in infected dams was widespread, with a previously unrecognized preference for infection, replication, and tissue damage in the placenta. In human mid-gestation placental tissue, RVFV directly infected placental chorionic villi, with replication detected in the outermost syncytial layer. Our work identifies direct placental infection by RVFV as a mechanism for vertical transmission and points to the teratogenic potential of this virus in humans. This is the first time vertical transmission of RVFV has been shown in species other than livestock. This study highlights the potential impact of a future epidemic of this emerging mosquito-borne virus.

scholarly journals Susceptibility and barriers to infection of Colorado mosquitoes with Rift Valley fever virus

2021 ◽  
Vol 15 (10) ◽  
pp. e0009837
Author(s):  
Daniel A. Hartman ◽  
Nicholas A. Bergren ◽  
Therese Kondash ◽  
William Schlatmann ◽  
Colleen T. Webb ◽  
...  
Keyword(s):  
United States ◽  
Vertical Transmission ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Plaque Assay ◽  
The United States ◽  
Fever Virus ◽  
Sub Saharan Africa ◽  
Valley Fever

Rift Valley fever virus (RVFV) causes morbidity and mortality in humans and domestic ungulates in sub-Saharan Africa, Egypt, and the Arabian Peninsula. Mosquito vectors transmit RVFV between vertebrates by bite, and also vertically to produce infectious progeny. Arrival of RVFV into the United States by infected mosquitoes or humans could result in significant impacts on food security, human health, and wildlife health. Elucidation of the vectors involved in the post-introduction RVFV ecology is paramount to rapid implementation of vector control. We performed vector competence experiments in which field-collected mosquitoes were orally exposed to an epidemic strain of RVFV via infectious blood meals. We targeted floodwater Aedes species known to feed on cattle, and/or deer species (Aedes melanimon Dyar, Aedes increpitus Dyar, Aedes vexans Meigen). Two permanent-water-breeding species were targeted as well: Culiseta inornata Williston of unknown competence considering United States populations, and Culex tarsalis Coquillett as a control species for which transmission efficiency is known. We tested the potential for midgut infection, midgut escape (dissemination), ovarian infection (vertical transmission), and transmission by bite (infectious saliva). Tissues were assayed by plaque assay and RT-qPCR, to quantify infectious virus and confirm virus identity. Tissue infection data were analyzed using a within-host model under a Bayesian framework to determine the probabilities of infection ‘outcomes’ (midgut-limited infection, disseminated infection, etc.) while estimating barriers to infection between tissues. Permanent-water-breeding mosquitoes (Cx. tarsalis and Cs. inornata) exhibited more efficient horizontal transmission, as well as potential for vertical transmission, which is contrary to the current assumptions of RVFV ecology. Barrier estimates trended higher for Aedes spp., suggesting systemic factors in the differences between these species and Cx. tarsalis and Cs. inornata. These data indicate higher potential for vertical transmission than previously appreciated, and support the consensus of RVFV transmission including a broad range of potential vectors.

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