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Heterogeneity of Rift Valley fever virus transmission potential across livestock hosts, quantified through a model-based analysis of host viral load and vector infection.

Quantifying the variation of pathogens' life history traits in multiple host systems is crucial to understand their transmission dynamics. It is particularly important for arthropod-borne viruses (arboviruses), which are prone to infecting several species of vertebrate hosts. Here, we focus on how host-pathogen interactions determine the ability of host species to transmit a virus to susceptible vectors upon a potentially infectious contact. Rift Valley fever (RVF) is a viral, vector-borne, zoonotic disease, chosen as a case study. The relative contributions of livestock species to RVFV transm…

Intact Type I Interferon Receptor Signaling Prevents Hepatocellular Necrosis but Not Encephalitis in a Dose-Dependent Manner in Rift Valley Fever Virus Infected Mice.

Rift Valley fever (RVF) is a zoonotic and emerging disease, caused by the RVF virus (RVFV). In ruminants, it leads to "abortion storms" and enhanced mortality rates in young animals, whereas in humans it can cause symptoms like severe hemorrhagic fever or encephalitis. The role of the innate and adaptive immune response in disease initiation and progression is still poorly defined. The present study used the attenuated RVFV strain clone 13 to investigate viral spread, tissue tropism, and histopathological lesions after intranasal infection in C57BL/6 wild type (WT) and type I interferon (IFN-I…

Black rats (Rattus rattus) as potential reservoir hosts for Rift Valley fever phlebovirus: Experimental infection results in viral replication and shedding without clinical manifestation.

Rift Valley fever phlebovirus (RVFV) is an arthropod-borne virus that can cause severe disease in ruminants and humans. Epidemics occur mainly after heavy rainfall, which leads to a significant increase in the occurrence of RVFV-transmitting mosquitoes. During inter-epidemic periods, the virus is assumed to be maintained between mosquitoes, susceptible livestock and yet unknown wildlife. The widespread rodent Rattus rattus (black rat) has been suspected to be involved in RVFV maintenance. In order to elucidate its susceptibility and thus its possible role in the transmission cycle of the virus…

Sero-prevalence of West Nile virus and Rift Valley fever virus infections among cattle under extensive production system in South Omo area, southern Ethiopia.

West Nile fever (WNF) and Rift Valley fever (RVF) are emerging and re-emerging zoonotic diseases of veterinary and public health importance in Africa. Despite the existence of potential vectors and a wide range of hosts, the transmission of these diseases in domestic animals has not been well documented in the South Omo area of Ethiopia. This study aimed to estimate the sero-prevalence of IgG antibodies produced against West Nile virus (WNV) and Rift Valley fever virus (RVFV) infections among cattle in the South Omo area. Between May and June 2019, blood samples were collected from 397 cattle …

Retrospective phylogenetic analyses of formalin-fixed paraffin-embedded samples from the 2011 Rift Valley fever outbreak in South Africa, through sequencing of targeted regions.

The last major Rift Valley fever outbreak in South Africa was between 2008 and 2011. Viruses isolated between 2008 and 2010 were phylogenetically assigned to Lineage C, Lineage K and the novel lineage H. The 2011 outbreaks occurred primarily in the Eastern, Western and Northern Cape provinces, with no sequence data or phylogenetic relationship published. Samples from these outbreaks were submitted to the Faculty of Veterinary Sciences, University of Pretoria, for immunohistochemical confirmation of Rift Valley fever phlebovirus presence. These samples were formalin-fixed and paraffin-embedded …

Efficacy of different DNA and MVA prime-boost vaccination regimens against a Rift Valley fever virus (RVFV) challenge in sheep 12 weeks following vaccination.

The aim of this work was to evaluate the immunogenicity and efficacy of DNA and MVA vaccines encoding the RVFV glycoproteins Gn and Gc in an ovine model of RVFV infection. Adult sheep of both sexes were challenged 12 weeks after the last immunization and clinical, virological, biochemical and immunological consequences, were analyzed. Strategies based on immunization with homologous DNA or heterologous DNA/MVA prime-boost were able to induce a rapid in vitro neutralizing antibody response as well as IFNγ production after in vitro virus specific re-stimulation. In these animals we observed redu

Arabidopsis thaliana plants expressing Rift Valley fever virus antigens: Mice exhibit systemic immune responses as the result of oral administration of the transgenic plants.

The zoonotic Rift Valley fever virus affects livestock and humans in Africa and on the Arabian Peninsula. The economic impact of this pathogen due to livestock losses, as well as its relevance to public health, underscores the importance of developing effective and easily distributed vaccines. Vaccines that can be delivered orally are of particular interest. Here, we report the expression in transformed plants (Arabidopsis thaliana) of Rift Valley fever virus antigens. The antigens used in this study were the N protein and a deletion mutant of the Gn glycoprotein. Transformed lines were analys…

Re-Emergence of Rift Valley Fever Virus Lineage H in Senegal in 2022: In Vitro Characterization and Impact on Its Global Emergence in West Africa.

Rift Valley fever (RVF) is a re-emerging vector-borne zoonosis with a high public health and veterinary impact. In West Africa, many lineages were previously detected, but since 2020, lineage H from South Africa has been the main cause of the outbreaks. In this study, clinical samples collected through national surveillance were screened for RVF virus (RVFV) acute infection by RT-PCR and IgM ELISA tests. Sequencing, genome mapping and in vitro phenotypic characterization in mammal cells were performed on RT-PCR positive samples in comparison with other epidemic lineages (G and C). Four RVFV hu…

Effects of Irrigation and Rainfall on the Population Dynamics of Rift Valley Fever and Other Arbovirus Mosquito Vectors in the Epidemic-Prone Tana River County, Kenya.

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that is found in most regions of sub-Saharan Africa, and it affects humans, livestock, and some wild ungulates. Outbreaks are precipitated by an abundance of mosquito vectors associated with heavy persistent rainfall with flooding. We determined the impact of flood-irrigation farming and the effect of environmental parameters on the ecology and densities of primary and secondary vectors of the RVF virus (RVFV) in an RVF-epidemic hotspot in the Tana River Basin, Kenya. Mosquito sampling was conducted in farms and villages (settlements) …

A Stochastic Model to Study Rift Valley Fever Persistence with Different Seasonal Patterns of Vector Abundance: New Insights on the Endemicity in the Tropical Island of Mayotte.

Rift Valley fever (RVF) is a zoonotic vector-borne disease causing abortion storms in cattle and human epidemics in Africa. Our aim was to evaluate RVF persistence in a seasonal and isolated population and to apply it to Mayotte Island (Indian Ocean), where the virus was still silently circulating four years after its last known introduction in 2007. We proposed a stochastic model to estimate RVF persistence over several years and under four seasonal patterns of vector abundance. Firstly, the model predicted a wide range of virus spread patterns, from obligate persistence in a constant or trop…

Моделирование распределения вектора < < Пипиены > > западного Нила и Рифт-Вэлли в засушливых и полузасушливых районах Ближнего Востока и Северной Африки.

РЕГИОНА Ближнего Востока Северной Африки (МЕНА) находится под постоянной угрозой повторного появления вируса Западного Нила (ВНН) и вируса лихорадки Рифт-Вэлли (РВФ), двух патогенов, передаваемых переносчиком Culex pipiens. Для прогнозирования районов, подверженных высокому риску передачи болезней, требуется точная модель распределения векторов, однако большинство моделей распределения Cx. pipiens были ограничены умеренными, лесистыми местообитаниями. Для моделирования распределения видов по разнородной ландшафтной структуре требуется гибкий метод моделирования, позволяющий зафиксировать вариа

Совпадение в аннотации оригинала
BACKGROUND: The Middle East North Africa (MENA) region is under continuous threat of the re-emergence of West Nile virus (WNV) and Rift Valley Fever virus (RVF), two pathogens transmitted by the vector species Culex pipiens. Predicting areas at high risk for disease transmission requires an accurate model of vector distribution, however, most Cx. pipiens dis…

Development and evaluation of one-step rRT-PCR and immunohistochemical methods for detection of Rift Valley fever virus in biosafety level 2 diagnostic laboratories.

Rift Valley fever virus (RVFV) is a zoonotic insect transmitted virus endemic to Africa and the Arabian Peninsula. Infection causes abortions and high mortality in newborn ruminants. The overall human infection rate is <1%; however, fatality rates in those with severe clinical disease have been reported as high as 29%. The potential of RVFV as a bioterrorism agent and/or being accidentally introduced into North America is widely recognized. Currently, regional veterinary biosafety level 2 (BSL-2) diagnostic laboratories lack safe, modern, validated diagnostic tests to detect RVFV. An existing …

Rapid detection and quantification of RNA of Ebola and Marburg viruses, Lassa virus, Crimean-Congo hemorrhagic fever virus, Rift Valley fever virus, dengue virus, and yellow fever virus by real-time reverse transcription-PCR.

Viral hemorrhagic fevers (VHFs) are acute infections with high case fatality rates. Important VHF agents are Ebola and Marburg viruses (MBGV/EBOV), Lassa virus (LASV), Crimean-Congo hemorrhagic fever virus (CCHFV), Rift Valley fever virus (RVFV), dengue virus (DENV), and yellow fever virus (YFV). VHFs are clinically difficult to diagnose and to distinguish; a rapid and reliable laboratory diagnosis is required in suspected cases. We have established six one-step, real-time reverse transcription-PCR assays for these pathogens based on the Superscript reverse transcriptase-Platinum Taq polymeras…

Complete coding sequence of Rift Valley fever virus identified by metagenomic sequencing in patient with undifferentiated febrile illness at Marigat sub-district hospital, Kenya.

We report on the complete coding sequence of Rift Valley Fever Virus inadvertently identified through metagenomics in a child with undifferentiated fever at Marigat sub-county hospital, Kenya. On phylogeny, the genome clustered with sequences obtained during the 2017 human outbreak in Uganda and the 2021 cattle outbreak in Kiambu, Kenya.

A Novel Quadruple Gene-Deleted BoHV-1-Vectored RVFV Subunit Vaccine Induces Humoral and Cell-Mediated Immune Response against Rift Valley Fever in Calves.

Rift Valley fever virus (RVFV) is considered to be a high biodefense priority based on its threat to livestock and its ability to cause human hemorrhagic fever. RVFV-infected livestock are also a significant risk factor for human infection by direct contact with contaminated blood, tissues, and aborted fetal materials. Therefore, livestock vaccination in the affected regions has the direct dual benefit and one-health approach of protecting the lives of millions of animals and eliminating the risk of severe and sometimes lethal human Rift Valley fever (RVF) disease. Recently, we have developed …

Tra2beta-Dependent Regulation of RIO Kinase 3 Splicing During Rift Valley Fever Virus Infection Underscores the Links Between Alternative Splicing and Innate Antiviral Immunity.

Rift Valley fever virus (RVFV) is an emerging pathogen that has potential to cause severe disease in humans and domestic livestock. Propagation of RVFV strain MP-12 is negatively impacted by the actions of RIOK3, a protein involved in the cellular immune response to viral infection. During RVFV infection, RIOK3 mRNA is alternatively spliced to produce an isoform that correlates with the inhibition of interferon β signaling. Here, we identify splicing factor TRA2-β (also known as TRA2beta and hTRA2-β) as a key regulator governing the relative abundance of RIOK3 splicing isoforms. Using RT-PCR a…

A quantitative exploration of nomadic pastoralists' knowledge and practices towards Rift Valley fever in Niger State, North-central Nigeria: The associated socio-cultural drivers.

Rift Valley fever (RVF) is a vector-borne re-emerging viral zoonosis that mainly affects poor and marginalized populations in Africa and the Middle East. The study assessed pastoralists' knowledge/awareness and preventive measures towards RVF in Fulani nomadic pastoral communities of Niger State, North-central Nigeria. An interview questionnaire-based cross-sectional survey was conducted in randomly selected 403 Fulani nomadic pastoral households. Descriptive and analytical statistical analyses were performed. About 97% (389/403) of the pastoralists responded. Majority (74.0%) of them was male…

NSs Virulence Factor of Rift Valley Fever Virus Engages the F-Box Proteins FBXW11 and β-TRCP1 To Degrade the Antiviral Protein Kinase PKR.

UNLABELLED: Rift Valley fever virus (RVFV, family Bunyaviridae, genus Phlebovirus) is a relevant pathogen of both humans and livestock in Africa. The nonstructural protein NSs is a major virulence factor known to suppress the type I interferon (IFN) response by inhibiting host cell transcription and by proteasomal degradation of a major antiviral IFN effector, the translation-inhibiting protein kinase PKR. Here, we identified components of the modular SCF (Skp1, Cul1, F-box protein)-type E3 ubiquitin ligases as mediators of PKR destruction by NSs. Small interfering RNAs (siRNAs) against the co…

Aerosol exposure to Rift Valley fever virus causes earlier and more severe neuropathology in the murine model, which has important implications for therapeutic development.

Rift Valley fever virus (RVFV) is an important mosquito-borne veterinary and human pathogen that can cause severe disease including acute-onset hepatitis, delayed-onset encephalitis, retinitis and blindness, or a hemorrhagic syndrome. Currently, no licensed vaccine or therapeutics exist to treat this potentially deadly disease. Detailed studies describing the pathogenesis of RVFV following aerosol exposure have not been completed and candidate therapeutics have not been evaluated following an aerosol exposure. These studies are important because while mosquito transmission is the primary means…

Rainfall patterns and population dynamics of Aedes (Aedimorphus) vexans arabiensis, Patton 1905 (Diptera: Culicidae), a potential vector of Rift Valley Fever virus in Senegal.

The importance of rainfall for the development of Aedes vexans arabiensis populations, one of the potential vectors of Rift Valley Fever in West Africa, was demonstrated in a two-year follow-up study conducted in the Ferlo region of Senegal. In 2003, the rainy season began with heavy rains and, as a result, temporary ponds, the breeding places for mosquitoes, were flooded at their maximum level immediately. In such conditions, Aedes vexans arabiensis populations are abundant at the very beginning of the season, when the majority of eggs in quiescence are flooded. Females, hatching from eggs la…