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The Rift Valley fever epizootic in Egypt 1977-78. 1. Description of the epizzotic and virological studies.

From October to December 1977, an extensive epizootic occurred in Egypt resulting in abortions and increased mortality in domestic animals, and severe clinical disease with fatalities in man. Rift Valley Fever (RVF) virus was isolated and identified as the causative agent. In humans, acute febrile, encephalitic, ocular and fatal haemorrhagic diseases were documented as resulting from RVF virus infection. A retrospective serological survey indicated RVF was recently introduced into the area. The 1977 epizootic extensively involved five Governorates. In the summer and autumn of 1978, epizootic R…

The pathology of Rift Valley fever. I. Lesions occurring in natural cases in new-born lambs.

A widespread epizootic of Rift Valley fever occurred in the Republic of South Africa and South West Africa during 1974--75. This is a report on the gross pathology of 34 new-born lambs and the histopathology of 93 new-born lambs that died during this outbreak. The liver was affected in every case and showed the most pronounced lesions. The organ was grossly enlarged in most cases, with scattered greyish-white necrotic foci 1--2 mm in diameter and haemorrhages of varying size throughout. Haemorrhages were also frequently seen in the mucosa of the abomasum. The massive diffuse necrosis of hepato…

Large-Scale Serological Survey of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in Small Ruminants in Senegal.

Crimean-Congo hemorrhagic fever (CCHF) and Rift Valley fever (RVF) are among the list of emerging zoonotic diseases that require special attention and priority. RVF is one of the six priority diseases selected by the Senegalese government. Repeated epidemic episodes and sporadic cases of CCHF and RVF in Senegal motivated this study, involving a national cross-sectional serological survey to assess the distribution of the two diseases in this country throughout the small ruminant population. A total of 2127 sera from small ruminants (goat and sheep) were collected in all regions of Senegal. The…

NSs protein of severe fever with thrombocytopenia syndrome virus suppresses interferon production through different mechanism than Rift Valley fever virus.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly identified Phlebovirus that causes severe fever with thrombocytopenia s … -inhibiting activity after deleting the 25 amino acids in N-terminal. Furthermore, the mechanism of Rift Valley fever virus (RVFV) NSs blocking IFN-β response were also investigated. Preliminary results showed that RVFV NSs proteins could neither interact nor co-localize with TBK1 in cytoplasm, but suppressed its expression levels, phosphorylation and dimerization …

Characterization of Rift Valley fever virus MP-12 strain encoding NSs of Punta Toro virus or sandfly fever Sicilian virus.

Rift Valley fever virus (RVFV; genus Phlebovirus, family Bunyaviridae) is a mosquito-borne zoonotic pathogen which can cause hemorrhagic fever, neurological disorders or blindness in humans, and a high rate of abortion in ruminants. MP-12 strain, a live-attenuated candidate vaccine, is attenuated in the M- and L-segments, but the S-segment retains the virulent phenotype. MP-12 was manufactured as an Investigational New Drug vaccine by using MRC-5 cells and encodes a functional NSs gene, the major virulence factor of RVFV which 1) induces a shutoff of the host transcription, 2) inhibits interfe…

Recoverability of Rift Valley fever and sandfly fever Sicilian viruses from infected Phlebotomus papatasi (Diptera: Psychodidae) trapped in various oils.

We studied the effects of various oils used to trap sand flies on the recovery of virus from infected adult Phlebotomus papatasi. Both Rift Valley fever and sandfly fever Sicilian viruses were readily recovered from virus-inoculated specimens held at 26 degrees C on mineral, olive or castor oil-soaked sheets for up to 12 h. However, after 50 h on oil-soaked paper, significantly greater titers were recovered from sand flies trapped with mineral oil than from sand flies trapped with either of the other oils. This indicates that sand flies trapped on oil-soaked paper would be suitable for virus i…

Live-cell 3D-SIM of Rift Valley fever virus NSs filaments reveals a polygon web architecture.

A defining feature of Rift Valley fever virus (RVFV) is the incorporation of the NSs protein into large filamentous assemblies inside infected nuclei [R. Swanepoel, N. K. Blackburn, J. Gen. Virol. 34, 557-561 (1977).], as judged from fixed specimens. To gain insight into the 3D structure of NSs filaments within live-cell nuclei, we used genetic-code expansion (GCE) to incorporate trans-cyclooct-2-en-L-lysine into the protein. This enabled site-specific fluorescent labeling with tetrazine dyes for live-cell structured illumination microscopy (SIM). Our superresolved images revealed the complete…

NanoLuc-based microneutralization assay for high-throughput detection of neutralizing antibodies against rift valley fever virus.

Plaque reduction neutralization tests (PRNTs) are the gold standard for measuring neutralizing antibodies but are labor-intensive, low-throughput, and subject to variability from manual plaque counting. We developed a NanoLuc-based microneutralization (mNT) assay using rMP12-NanoLuc that quantifies luminescence in culture supernatants as a surrogate for infection. The assay runs in 96-well plates without overlay, fixation, or staining, using 35 focus-forming unit (FFU) per well and a 40 hour readout with back-titration to ensure accuracy. mNT titers from vaccinated animal sera showed strong co

Simulating the Transmission of Rift Valley Fever Virus via Raw Milk Consumption in Inter-Epidemic Periods.

Rift Valley fever virus (RVFV) is a zoonotic, vector-borne disease affecting livestock and humans. The consumption of raw unpasteurized milk has been epidemiologically linked to RVFV exposure in humans and recognized as a potentially important non-vector route for RVFV transmission. This study aims to investigate the potential of RVFV transmission to humans through the consumption of infected raw milk. For this purpose, we conducted agent-based stochastic simulations to assess the potential for RVFV transmission through ingestion of contaminated raw milk. We created synthetic populations of co…

Spatial heterogeneity of Rift Valley fever burden in Kenya: a 10-year One Health zDALY evaluation.

BACKGROUND: Rift Valley fever (RVF) is an endemic zoonotic disease in Kenya, with recurring outbreaks that affect both humans and livestock. Despite its impact, the full burden of RVF remains poorly quantified. This study presents the first integrated and spatially disaggregated estimates of RVF burden in Kenya using a One Health approach. METHODS: We quantified the national and subnational burden of RVF in Kenya from 2014 to 2024 using the zoonotic disability-adjusted life years (zDALYs) framework, which combines human health loss (disability-adjusted life years [DALYs]) and livestock-relate…

Widening geographic range of Rift Valley fever disease clusters associated with climate change in East Africa.

BACKGROUND: Recent epidemiology of Rift Valley fever (RVF) disease in Africa suggests growing frequency and expanding geographic range of small disease clusters in regions that previously had not reported the disease. We investigated factors associated with the phenomenon by characterising recent RVF disease events in East Africa. METHODS: Data on 100 disease events (2008-2022) from Kenya, Uganda and Tanzania were obtained from public databases and institutions, and modelled against possible geoecological risk factors of occurrence including altitude, soil type, rainfall/precipitation, temper…

Analysis of Negative-Strand RNA Viruses by RT-qPCR: Rift Valley Fever Virus and Toscana Virus.

RT-qPCR allows the detection of viruses and the monitoring of viral replication. This technique was extensively employed during the SARS-CoV-2 pandemic, where it demonstrated its efficiency and robustness. Here we describe the analysis of Rift Valley fever and Toscana virus infections over time, achieved through the RT-qPCR quantification of the viral genome. We further elaborate on the method to discriminate between genomic and antigenomic viral RNAs by using primers specific for each strand during the reverse transcription step.

Structural Modifications and Biological Evaluations of Rift Valley Fever Virus Inhibitors Identified from Chemical Library Screening.

The Rift Valley fever virus (RVFV) is an emerging high-priority pathogen endemic in Africa with pandemic potential. There is no specific treatment or approved antiviral drugs for the RVFV. We previously developed a cell-based high-throughput assay to screen small molecules targeting the RVFV and identified a potential effective antiviral compound (1-N-(2-(biphenyl-4-yloxy)ethyl)propane-1,3-diamine) as a lead compound. Here, we investigated how structural modifications of the lead compound affected the biological properties and the antiviral effect against the RVFV. We found that the length of …

Structural Elucidation of Rift Valley Fever Virus L Protein towards the Discovery of Its Potential Inhibitors.

Rift valley fever virus (RVFV) is the causative agent of a viral zoonosis that causes a significant clinical burden in domestic and wild ruminants. Major outbreaks of the virus occur in livestock, and contaminated animal products or arthropod vectors can transmit the virus to humans. The viral RNA-dependent RNA polymerase (RdRp; L protein) of the RVFV is responsible for viral replication and is thus an appealing drug target because no effective and specific vaccine against this virus is available. The current study reported the structural elucidation of the RVFV-L protein by in-depth homology …

Evaluations of rationally designed rift valley fever vaccine candidate RVax-1 in mosquito and rodent models.

Rift Valley fever (RVF) is a mosquito-borne zoonosis endemic to Africa and the Arabian Peninsula, which causes large outbreaks among humans and ruminants. Single dose vaccinations using live-attenuated RVF virus (RVFV) support effective prevention of viral spread in endemic countries. Due to the segmented nature of RVFV genomic RNA, segments of vaccine strain-derived genomic RNA could be incorporated into wild-type RVFV within co-infected mosquitoes or animals. Rationally designed vaccine candidate RVax-1 displays protective epitopes fully identical to the previously characterized MP-12 vaccin…

Inter-epidemic Rift Valley fever virus infection incidence and risks for zoonotic spillover in northern Tanzania.

Rift Valley fever virus (RVFV) is a mosquito-borne pathogen that has caused epidemics involving people and animals across Africa and the Arabian Peninsula. A number of studies have found evidence for the circulation of RVFV among livestock between these epidemics but the population-level incidence of infection during this inter-epidemic period (IEP) is rarely reported. General force of infection (FOI) models were applied to age-adjusted cross-sectional serological data to reconstruct the annual FOI and population-level incidence of RVFV infection among cattle, goats, and sheep in northern Tanz…

Reconstructing Mayotte 2018-19 Rift Valley Fever outbreak in humans by combining serological and surveillance data.

BACKGROUND: Rift Valley Fever (RVF) is a zoonosis that affects large parts of Africa and the Arabian Peninsula. RVF virus (RVFV) is transmitted to humans through contacts with infected animals, animal products, mosquito bites or aerosols. Its pathogenesis in humans ranges from asymptomatic forms to potentially deadly haemorrhagic fevers, and the true burden of human infections during outbreaks is generally unknown. METHODS: We build a model fitted to both passive surveillance data and serological data collected throughout a RVF epidemic that occurred in Mayotte Island in 2018-2019. RESULTS: …

Платформа для доставки вакцин ДНК, основанная на Эластине-Лике Рекомбинамер Наносистем для Вируса Рифт-Вэлли.

В ходе этой работы анализируется иммуногенность шести генетически модифицированных конструкций, основанных на эластинах, похожих на рекомбинамеры (ЭЛР), сплавившихся в Gn glycoprotein из вируса лихорадки Рифт-Вэлли (RVFV). При трансфекции все конструкции не оказывали никакого влияния на жизнеспособность клеток. В то время как составы синтеза, включая блоки ELR, содержащие гидрофобные аминокислоты (аланин или изолюцин), не увеличили экспрессию вирусных Gn в эукариотических клетках, белки, содержащие глютамиковую кислоту или валин, продемонстрировали повышенный уровень экспрессии по сравнению со

Совпадение в аннотации оригинала
This work analyzes the immunogenicity of six genetically engineered constructs based on elastin-like recombinamers (ELRs) fused to the Gn glycoprotein from Rift Valley fever virus (RVFV). Upon transfection, all constructs showed no effect on cell viability. While fusion constructs including ELR blocks containing hydrophobic amino acids (alanine or isoleucine…

Rift Valley Fever Virus Exposure amongst Farmers, Farm Workers, and Veterinary Professionals in Central South Africa.

Rift Valley fever (RVF) is a re-emerging arboviral disease of public health and veterinary importance in Africa and the Arabian Peninsula. Major RVF epidemics were documented in South Africa in 1950⁻1951, 1974⁻1975, and 2010⁻2011. The number of individuals infected during these outbreaks has, however, not been accurately estimated. A total of 823 people in close occupational contact with livestock were interviewed and sampled over a six-month period in 2015⁻2016 within a 40,000 km² study area encompassing parts of the Free State and Northern Cape provinces that were affected during the 2010⁻20…