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Seroprevalence of Rift Valley fever virus in livestock during inter-epidemic period in Egypt, 2014/15.

BACKGROUND: Rift Valley fever virus (RVFV) caused several outbreaks throughout the African continent and the Arabian Peninsula posing significant threat to human and animal health. In Egypt the first and most important Rift Valley fever epidemic occurred during 1977/78 with a multitude of infected humans and huge economic losses in livestock. After this major outbreak, RVF epidemics re-occurred in irregular intervals between 1993 and 2003. Seroprevalence of anti-RVFV antibodies in livestock during inter-epidemic periods can be used for supporting the evaluation of the present risk exposure for…

Интерэпидемический вирус лихорадки Рифт-Вэлли сероконверсии в рамках ирригационных систем в Буре, юго-восточная Кения.

Жар в долине Рифт (RVF) — острый вирусный зооноз, переходящий через комары, вспышки которого часто ассоциируются с длительными дождями и наводнениями, в ходе которых возникает большое число переносчиков. Недавние исследования по межэпидемическому поддержанию вируса RVF (RVFV) показывают, что как вертикальная передача в векторах, так и прямая передача между приемными устройствами действуют в сочетании с предрасполагающими факторами стойкости вируса. С сентября 2014 года по июнь 2015 года в графстве Тана, Кения, было проведено сравнительное продольное обследование орошаемых, речных и пастбищных

Совпадение в аннотации оригинала
Rift Valley fever (RVF) is an acute mosquito-borne viral zoonosis whose outbreaks are often associated with prolonged rainfall and flooding, during which large numbers of vectors emerge. Recent studies into the inter-epidemic maintenance of RVF virus (RVFV) suggest that both vertical transmission in vectors and direct transmission between hosts act in combin…

Elevated antibodies against Rift Valley fever virus among humans with exposure to ruminants in Saudi Arabia.

In 2000, an outbreak of Rift Valley fever virus (RVFV) occurred in the Kingdom of Saudi Arabia (KSA). Since then there have been sparse efforts to monitor for RVFV reemergence. During 2012, we enrolled 300 individuals with ruminant exposure and 50 age-group matched non-exposed controls in southwestern KSA, in a cross-sectional epidemiological study of RVFV. Sera from the participants were screened with an enzyme-linked immunosorbent assay (ELISA) for anti-RVFV IgG antibodies of which 39 (11.1%) were positive. Sixteen (41.0%) of those 39 were also positive by a plaque reduction neutralization a…

Computational prediction and biochemical characterization of novel RNA aptamers to Rift Valley fever virus nucleocapsid protein.

Rift Valley fever virus (RVFV) is a potent human and livestock pathogen endemic to sub-Saharan Africa and the Arabian Peninsula that has potential to spread to other parts of the world. Although there is no proven effective and safe treatment for RVFV infections, a potential therapeutic target is the virally encoded nucleocapsid protein (N). During the course of infection, N binds to viral RNA, and perturbation of this interaction can inhibit viral replication. To gain insight into how N recognizes viral RNA specifically, we designed an algorithm that uses a distance matrix and multidimensiona…

Broad spectrum antiviral activity of favipiravir (T-705): protection from highly lethal inhalational Rift Valley Fever.

BACKGROUND: Development of antiviral drugs that have broad-spectrum activity against a number of viral infections would be of significant benefit. Due to the evolution of resistance to currently licensed antiviral drugs, development of novel anti-influenza drugs is in progress, including Favipiravir (T-705), which is currently in human clinical trials. T-705 displays broad-spectrum in vitro activity against a number of viruses, including Rift Valley Fever virus (RVFV). RVF is an important neglected tropical disease that causes human, agricultural, and economic losses in endemic regions. RVF ha…

Creation of Rift Valley fever viruses with four-segmented genomes reveals flexibility in bunyavirus genome packaging.

UNLABELLED: Bunyavirus genomes comprise a small (S), a medium (M), and a large (L) RNA segment of negative polarity. Although the untranslated regions have been shown to comprise signals required for transcription, replication, and encapsidation, the mechanisms that drive the packaging of at least one S, M, and L segment into a single virion to generate infectious virus are largely unknown. One of the most important members of the Bunyaviridae family that causes devastating disease in ruminants and occasionally humans is the Rift Valley fever virus (RVFV). We studied the flexibility of RVFV ge…

Anti-nucleocapsid protein immune responses counteract pathogenic effects of Rift Valley fever virus infection in mice.

The known virulence factor of Rift Valley fever virus (RVFV), the NSs protein, counteracts the antiviral effects of the type I interferon response. In this study we evaluated the expression of several genes in the liver and spleen involved in innate and adaptive immunity of mice immunized with a RVFV recombinant nucleocapsid protein (recNP) combined with Alhydrogel adjuvant and control animals after challenge with wild type RVFV. Mice immunized with recNP elicited an earlier IFNβ response after challenge compared to non-immunized controls. In the acute phase of liver infection in non-immunized…

Tissue tropism and target cells of NSs-deleted rift valley fever virus in live immunodeficient mice.

BACKGROUND: Rift Valley fever virus (RVFV) causes disease in livestock and humans. It can be transmitted by mosquitoes, inhalation or physical contact with the body fluids of infected animals. Severe clinical cases are characterized by acute hepatitis with hemorrhage, meningoencephalitis and/or retinitis. The dynamics of RVFV infection and the cell types infected in vivo are poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: RVFV strains expressing humanized Renilla luciferase (hRLuc) or green fluorescent protein (GFP) were generated and inoculated to susceptible Ifnar1-deficient mice. We inv…

Kinetics of Rift Valley Fever Virus in experimentally infected mice using quantitative real-time RT-PCR.

Rift Valley Fever (RVF) is an important viral zoonosis in Africa affecting animals and humans. Since no protective vaccines or effective treatments are available for human use, accurate and reliable diagnostic methods are essential for surveillance of the disease in order to implement adequate public health actions. To study the kinetics of the RVF Virus (RVFV) infection, a SYBR Green-based quantitative real-time RT-PCR assay was developed. By using primers targeting the S-segment of RVFV, the detection limit of this assay was estimated to 30 RNA templates. Blood and organs of experimentally i…

T7 RNA polymerase-dependent and -independent systems for cDNA-based rescue of Rift Valley fever virus.

Rift Valley fever virus (RVFV) is responsible for large and recurrent outbreaks of acute febrile illness among humans and domesticated animals in Africa. It belongs to the family Bunyaviridae, genus Phlebovirus, and its negative-stranded RNA genome consists of three segments. Here, we report the establishment and characterization of two different systems to rescue the RVFV wild-type strain ZH548. The first system is based on the BHK-21 cell clone BSR-T7/5, which stably expresses T7 RNA polymerase (T7 pol). Rescue of wild-type RVFV was achieved with three T7 pol-driven cDNA plasmids representin…

Rift Valley fever epizootic in small ruminants in southern Mauritania (October 1993): risk of extensive outbreaks.

Following the 1987 Rift Valley fever (RVF) epizootic/epidemic in southern Mauritania, RVF antibody prevalence in small ruminants decreased significantly from 1988 to 1992. In October 1993, at the end of the rainy season, an active RVF virus transmission was detected in several locations of southern Mauritania in small ruminants, in association with an increase of abortions. RVF IgM and IgG antibodies were recorded respectively in 65/390 (16.67%) and 73/390 (18.72%) animals. RVF IgM antibody prevalence was significantly higher in the > or = 2 years old group (26.02%) than in the 0.5- < 2 year o…

Topological mapping of antigenic sites on the Rift Valley fever virus envelope glycoproteins using monoclonal antibodies.

A panel of 17 monoclonal antibodies (MAbs) to the G1 and G2 envelope glycoproteins of Rift Valley fever (RVF) virus were used to analyze the topography and functional properties of the viral antigenic sites. Four heterogeneous antigenic regions which may be interlinked were identified on the G1 protein and four distinct domains on the G2 protein by competitive binding assays. Comparison of the biological activities and epitope specificities of the MAbs against G1 showed that the antigenic domains I, II, and IV were involved in virus neutralization and haemagglutination at different potencies. …

Prevalence and associated factors of human haemorrhagic fevers in Senegal: a comprehensive analysis of Hantaan, Crimean-Congo haemorrhagic fever and Rift Valley fever.

INTRODUCTION: Viral haemorrhagic fevers such as Rift Valley fever, Crimean-Congo haemorrhagic fever, and hantavirus disease continue to threaten public health in Africa. This study assessed the seroprevalence and associated factors of these infections in Senegal. METHODS: A cross-sectional survey was conducted from September 2022 to June 2024 among asymptomatic individuals living in close contact with livestock in two regions: Matam, a transboundary area; and Thiès, a non-transboundary area with high livestock density. Participants completed standardized questionnaires, and serum samples were…

Development and validation of serological assays for viral hemorrhagic fevers and determination of the prevalence of Rift Valley fever in Borno State, Nigeria.

BACKGROUND: Rift Valley fever (RVF) is endemic to the tropical regions of eastern and southern Africa. The seroprevalence of RVF was investigated among the human population in Borno State, Nigeria to determine the occurrence of the disease in the study area in comparison with that of Lassa fever and Crimean-Congo Hemorrhagic fever. METHODS: Recombinant nucleoprotein (rNP)-based IgG-ELISAs for the detection of serum antibodies against RVF virus (RVFV), Lassa fever virus (LASV), and Crimean-Congo hemorrhagic fever virus (CCHFV) were used to test human sera in Borno State, Nigeria. The presence …

A Newly Established ELISA for the Surveillance of Rift Valley Fever in Dromedary Camels and Their Owners, Kenya 2018.

In 2024 Kenya had a population of 4.78 million camels that contributed to the livelihoods of pastoralist communities in northern Kenya. Previous studies in Kenya, Saudi Arabia and eastern Africa demonstrated high seroprevalence of Middle East respiratory syndrome coronavirus (MERS-CoV)-specific antibodies in dromedary camels, as well as sporadic transmission of MERS-CoV from camels to humans. Based on the MERS-CoV data and the very close contact between owners and their camels in northern Kenya, we speculated that camels may also transmit other zoonotic viruses, such as Rift Valley fever virus…

Maternal vaccination protects dams and prevents in utero transmission of Rift Valley fever virus in rats.

UNLABELLED: In utero transmission and spontaneous fetal death are hallmarks of Rift Valley fever virus (RVFV) infection in pregnant animals. Compounding evidence indicates pregnant individuals are particularly vulnerable to RVFV, as in utero transmission and increased rates of miscarriage have been reported in people infected during pregnancy. Further, human placenta explants are permissive to RVFV infection. Viable vaccine candidates intended for veterinary or human use must protect vulnerable populations, including pregnant individuals and fetuses. Using a pregnant rat model, we show that ma…

Increasing evolution, prevalence, and outbreaks for rift valley fever virus in the process of breaking geographical barriers.

BACKGROUND: Rift valley fever (RVF) is listed as one of prioritized diseases by WHO. This study aims to describe RVF virus' landscape distribution globally, and to insight dynamics change of its evolution, prevalence, and outbreaks in the process of breaking geographical barriers. METHODS: A systematic literature review and meta-analyses was conducted to estimate RVF prevalence by hosts using a random-effect model. Molecular clock-based phylogenetic analyses were performed to estimate RVF virus nucleotide substitution rates using nucleotide sequences in NCBI database. RVF virus prevalence, nu…

Immune correlates of protection of the four-segmented Rift Valley fever virus candidate vaccine in mice.

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease caused by RVF virus (RVFV). RVFV infections in humans are usually asymptomatic or associated with mild febrile illness, although more severe cases of haemorrhagic disease and encephalitis with high mortality also occur. Currently, there are no licensed human vaccines available. The safety and efficacy of a genetically engineered four-segmented RVFV variant (hRVFV-4s) as a potential live-attenuated human vaccine has been tested successfully in mice, ruminants, and marmosets though the correlates of protection of this vaccine are still…

Rift Valley fever virus coordinates the assembly of a programmable E3 ligase to promote viral replication.

Viruses encode strategies to degrade cellular proteins to promote infection and pathogenesis. Here, we revealed that the non-structural protein NSs of Rift Valley fever virus forms a filamentous E3 ligase to trigger efficient degradation of targeted proteins. Reconstitution in vitro and cryoelectron microscopy analysis with the 2.9-Å resolution revealed that NSs forms right-handed helical fibrils. The NSs filamentous oligomers associate with the cellular FBXO3 to form a remodeled E3 ligase. The NSs-FBXO3 E3 ligase targets the cellular TFIIH complex through the NSs-P62 interaction, leading to u…