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Comparison of enzyme-linked immunosorbent assay systems using rift valley fever virus nucleocapsid protein and inactivated virus as antigens.

BACKGROUND: Rift Valley Fever (RVF) is a mosquito-borne viral zoonosis. To detect RVF virus (RVFV) infection, indirect immunoglobulin G (IgG) and immunoglobulin M (IgM) enzyme linked immunosorbent assays (ELISAs) which utilize recombinant RVFV nucleocapsid (RVFV-N) protein as assay antigen, have reportedly been used, however, there is still a need to develop more sensitive and specific methods of detection. METHODS: RVFV-N protein was expressed in Escherichia coli (E. coli) and purified by histidine-tag based affinity chromatography. This recombinant RVFV-N (rRVFV-N) protein was then used as …

Anomalous High Rainfall and Soil Saturation as Combined Risk Indicator of Rift Valley Fever Outbreaks, South Africa, 2008-2011.

Rift Valley fever (RVF), a zoonotic vectorborne viral disease, causes loss of life among humans and livestock and an adverse effect on the economy of affected countries. Vaccination is the most effective way to protect livestock; however, during protracted interepidemic periods, farmers discontinue vaccination, which leads to loss of herd immunity and heavy losses of livestock when subsequent outbreaks occur. Retrospective analysis of the 2008-2011 RVF epidemics in South Africa revealed a pattern of continuous and widespread seasonal rainfall causing substantial soil saturation followed by exp…

Seroepidemiological Study of Interepidemic Rift Valley Fever Virus Infection Among Persons with Intense Ruminant Exposure in Madagascar and Kenya.

In this cross-sectional seroepidemiological study we sought to examine the evidence for circulation of Rift Valley fever virus (RVFV) among herders in Madagascar and Kenya. From July 2010 to June 2012, we enrolled 459 herders and 98 controls (without ruminant exposures) and studied their sera (immunoglobulin G [IgG] and IgM through enzyme-linked immunosorbent assay [ELISA] and plaque reduction neutralization test [PRNT] assays) for evidence of previous RVFV infection. Overall, 59 (12.9%) of 459 herders and 7 (7.1%) of the 98 controls were positive by the IgG ELISA assay. Of the 59 ELISA-positi…

Serological Evidence of Rift Valley Fever Virus Circulation in Domestic Cattle and African Buffalo in Northern Botswana (2010-2011).

Rift Valley fever (RVF) is endemic in many countries in Sub-Saharan Africa and is responsible for severe outbreaks in livestock characterized by a sudden onset of abortions and high neonatal mortality. During the last decade, several outbreaks have occurred in Southern Africa, with a very limited number of cases reported in Botswana. To date, published information on the occurrence of RVF in wild and domestic animals from Botswana is very scarce and outdated, despite being critical to national and regional disease control. To address this gap, 863 cattle and 150 buffalo sampled at the interfac…

Generation and application of monoclonal antibodies against Rift Valley fever virus nucleocapsid protein NP and glycoproteins Gn and Gc.

Rift Valley fever virus (RVFV) is a vector-borne virus that causes high neonatal mortality in livestock and deadly haemorrhagic fever in humans. In this paper, we describe the generation of monoclonal antibodies (mabs) against all three structural proteins of RVFV (glycoproteins Gn and Gc and nucleocapsid protein NP). After immunization of BALB/c mice with individual recombinant proteins, a total of 45 clones secreting ELISA-reactive monoclonal antibodies against NP, Gn and Gc epitopes were obtained. Twelve clones were directed to NP, 28 to Gn, and 5 to Gc. Western blot analysis revealed that …

< < Жемчужина долины Рифт > > в Юго-Западной Саудовской Аравии: сероэпидемиологическое исследование, проведенное через семь лет после вспышки 2000 - 2001 годов.

Цель настоящего исследования состояла в том, чтобы измерить сероэпидемиологию вируса лихорадки Рифт-Вэлли в юго-западных районах Саудовской Аравии и определить потенциальные факторы риска, ведущие к вирусу лихорадки Рифт-Вэлли. В ходе серии поездок в учебный район (Джизан, Асир и Аль-Кунфуда) была включена случайная выборка населения (больных и их родственников), посещающего амбулаторные клиники по каким-либо причинам. В ходе опросов на вопроснике были собраны данные об их социально-демографическом состоянии, жилищных условиях, контактах с животными и другой соответствующей информации. Пробы к

Совпадение в аннотации оригинала
The objective of the present study was to measure seroepidemiology of Rift Valley Fever virus infection in the Southwestern regions of Saudi Arabia and to determine the potential risk factors leading to Rift Valley Fever virus infection. Through a series of field trips to the study area (Jizan, Aseer and Al-Qunfuda), a random sample of the general population…

Generation and characterization of a recombinant Rift Valley fever virus expressing a V5 epitope-tagged RNA-dependent RNA polymerase.

The viral RNA-dependent RNA polymerase (RdRp; L protein) of Rift Valley fever virus (RVFV; family Bunyaviridae) is a 238 kDa protein that is crucial for the life cycle of the virus, as it catalyses both transcription of viral mRNAs and replication of the tripartite genome. Despite its importance, little is known about the intracellular distribution of the polymerase or its other roles during infection, primarily because of lack of specific antibodies that recognize L protein. To begin to address these questions we investigated whether the RVFV (MP12 strain) polymerase could tolerate insertion …

Protection against lethal Rift Valley fever virus (RVFV) infection in transgenic IFNAR(-/-) mice induced by different DNA vaccination regimens.

In this work, plasmid constructs encoding two different M segment ORFs, as well as the nucleoprotein N, have been used in different vaccination regimes to test protection against a RVFV-MP12 virus challenge in a transgenic mouse model with impaired interferon type I response (IFNAR(-/-)). We obtained dose dependent protection in animals immunized with a construct encoding both mature glycoproteins (pCMV-M4), whereas only partial protection in animals vaccinated with either N construct (pCMV-N) or a combination of both plasmids (pCMV-M4+pCMV-N). The protection elicited by the expression of the

NSs protein of rift valley fever virus induces the specific degradation of the double-stranded RNA-dependent protein kinase.

Rift Valley fever virus (RVFV) continues to cause large outbreaks of acute febrile and often fatal illness among humans and domesticated animals in Africa, Saudi Arabia, and Yemen. The high pathogenicity of this bunyavirus is mainly due to the viral protein NSs, which was shown to prevent transcriptional induction of the antivirally active type I interferons (alpha/beta interferon [IFN-alpha/beta]). Viruses lacking the NSs gene induce synthesis of IFNs and are therefore attenuated, whereas the noninducing wild-type RVFV strains can only be inhibited by pretreatment with IFN. We demonstrate her…

Synthesis, proteolytic processing and complex formation of N-terminally nested precursor proteins of the Rift Valley fever virus glycoproteins.

The genomic M RNA segment of Rift Valley fever virus is transcribed to produce a single mRNA with multiple translation initiation sites. The products of translation are an N-terminal nested series of polyproteins. These polyproteins enter the secretory system of the host cell and are proteolytically processed to yield the mature virion glycoproteins, Gn and Gc, and two non-structural glycoproteins. By means of pulse-chase immune precipitation experiments we identify the Gn and Gc precursor molecules and also show that signal peptidase cleavage is required for mature Gn and Gc production. We al…

Experimental detection of Rift Valley fever virus by reverse transcription-polymerase chain reaction assay in large samples of mosquitoes.

A reverse transcription-polymerase chain reaction (RT-PCR) was assessed in laboratory tests to detect the presence of single Aedes aegypti (L.) or Eretmapodites quinquevittatus Theobald mosquitoes infected with Rift Valley fever virus in pools of mosquitoes, 50-600 in size, from laboratory colonies or mixed field collections. The viral RNA was detected in all pools containing infected mosquitoes and was shown to be as sensitive as infant mice but more sensitive than Vero cell cultures for virus detection. Pools diluted down to the equivalent of 1:16 000 mosquitoes were also positive by RT-PCR.…

Efficacy of Coxiella burnetii and its chloroform-methanol residue (CMR) fraction against Rift Valley fever virus infection in mice.

Strains of Coxiella burnetii phase I and II whole cells (WC-I and WC-II) or whole cell fractions were assessed for their potential to induce long-lasting protection in endotoxin-non-responder C3H/HeJ or CD-1 mice against Rift Valley fever (RVF) virus challenge. Among the whole cell fractions, only the chloroform-methanol residue (CMR), administered as a single dose (100 micrograms per mouse) 24 h before viral challenge, effectively protected 100% of the mice from RVF virus; the CMR of the Ohio strain of C. burnetii was not protective. Most of the RVF virus-infected mice treated with other C. b…

Isolation of Rift Valley fever virus from mosquitoes (Diptera: Culicidae) collected during an outbreak in domestic animals in Kenya.

During an outbreak of Rift Valley fever (RVF) in livestock near Lake Naivasha, Rift Valley Province, Kenya, 61,347 mosquitoes (1,287 pools) collected in CO2-baited light traps yielded seven viral isolates. Five isolates of RVF virus were recovered from 18,831 Culex zombaensis Theobald and one from 14,439 Mansonia africana (Theobald). One isolate of a Bunyamwera group virus was recovered from 1,175 Aedes quasiunivittatus (Theobald).

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

A total of 134 876 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 th…

Live-attenuated Rift Valley fever virus vaccination leads to durable, protective immunity independent of sex in C57BL/6 mice.

BACKGROUND: Rift Valley fever virus (RVFV) is a zoonotic arbovirus endemic to Africa and the Arabian Peninsula that can cause disease in humans and livestock. There are currently no licensed vaccines for human use, but several candidates are at the clinical trial stage including DDVaxTM, a preparation of live-attenuated RVFV lacking the nonstructural proteins NSs and NSm (ΔNSsΔNSm). Multiple pre-clinical studies have shown that ΔNSsΔNSm is safe and immunogenic. METHODS: The longitudinal study described in this manuscript examined the additional features of duration, sex and dose in immunogeni…

Immunopharmacologsical and structural insights into Rift Valley fever virus envelope glycoproteins: an immunoinformatics approach to multi-epitope vaccine design.

Rift Valley fever (RVF) is a clinically zoonotic pathogen associated with severe systemic and neurological complications, for which no approved vaccine is currently available. This study aimed to design a novel chimeric multi-epitope vaccine candidate targeting the RVFV Envelope polyprotein (Gn and Gc) via an integrative immunoinformatic and structural modeling approach, targeting viral envelope glycoproteins which play a crucial role in host cell entry and immune recognition. The epitopes used in the vaccine assembly were selected on the basis of antigenicity, allergenicity, and toxicity, the…

Achievement of one health multi-sectoral collaboration in containment of Rift Valley Fever outbreak, Sudan, Red Sea State 2019.

Rift Valley Fever is endemic in Sudan, with a notable outbreak declared in 2019, affecting multiple states. In this study, we examine the Red Sea State, Sudan's experience in applying the One Health approach, to contain Red-Sea RVF outbreak. A retrospective analysis of national and sub-national data and a review of literature were conducted to assess the application of One Health response and to derive lessons learned. The analysis revealed a total of 576 human cases and two deaths, with a case fatality rate of 0.35%, from 25 September 2019 to 25 January 2020. Most cases (99%) were from the Re…

Acute Rift Valley fever virus infection induces inflammatory cytokines and cell death in ex vivo rat brain slice culture.

Rift Valley fever virus (RVFV) is an emerging arboviral disease with pandemic potential. While infection is often self-limiting, a subset of individuals may develop late-onset encephalitis, accounting for up to 20 % of severe cases. Importantly, individuals displaying neurologic disease have up to a 53 % case fatality rate, yet the neuropathogenesis of RVFV infection remains understudied. In this study, we evaluated whether ex vivo postnatal rat brain slice cultures (BSCs) could be used to evaluate RVFV infection in the central nervous system. BSCs mounted an inflammatory response after slicin…

Adaptation to a Multiplex Bead Assay and Seroprevalence to Rift Valley Fever N Protein: Nampula Province, Mozambique, 2013-2014.

Rift Valley fever virus (RVFV) is endemic in sub-Saharan Africa (SSA), with outbreaks reported in the Arabian Peninsula and throughout SSA. The natural reservoir for RVFV are ruminants, with livestock populations exceeding 50% exposure rates in some areas of SSA. Transmission to humans can occur through exposure to infected livestock products or multiple species of mosquito vectors. In 2013 and 2014, cross-sectional surveys occurred in two districts of Nacala-a-Velha and Mecubúri in northern Mozambique, and participants provided blood samples for later serological assays. IgG against the N pro…