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A new mouse model reveals a critical role for host innate immunity in resistance to Rift Valley fever.

Rift Valley fever (RVF) is an arthropod-borne viral disease repeatedly reported in many African countries and, more recently, in Saudi Arabia and Yemen. RVF virus (RVFV) primarily infects domesticated ruminants, resulting in miscarriage in pregnant females and death for newborns and young animals. It also has the ability to infect humans, causing a feverish syndrome, meningoencephalitis, or hemorrhagic fever. The various outcomes of RVFV infection in animals and humans argue for the existence of host genetic determinants controlling the disease. We investigated the susceptibility of inbred mou…

Pathogenesis of Rift Valley fever virus in mosquitoes--tracheal conduits & the basal lamina as an extra-cellular barrier.

Knowledge of the fate of an arbovirus in a mosquito is fundamental to understanding the mosquito's competence to transmit the virus. When a competent mosquito ingests viremic vertebrate blood, virus infects midgut epithelial cells and replicates, then disseminates to other tissues, including salivary glands and/or ovaries. The virus is then transmitted to the next vertebrate host horizontally via bite and/or vertically to the mosquito's offspring. Not all mosquitoes that ingest virus become infected or, if infected, transmit virus. Several "barriers" to arbovirus passage, and ultimately transm

A study of the effect of chemical inactivants on the epitopes of Rift Valley fever virus glycoproteins using monoclonal antibodies.

A panel of 23 monoclonal antibodies (mAbs) was used to study the effect of formalin, beta propriolactone (BPL) and binary ethylenimine (BEI) on the epitopes of the Rift Valley fever virus glycoproteins. After the initial inactivation period BEI had very little adverse affect on the epitopes whereas BPL significantly altered seven and formalin partially changed the conformation or accessibility of most of the epitopes. The epitopes of all of the inactivated antigens showed a reduced activity against the specific mAbs over a six month storage period.

Rapid diagnosis of Rift Valley fever: a comparison of methods for the direct detection of viral antigen in human sera.

Human sera collected during the 1987 Rift Valley fever (RVF) epidemic in the Senegal River basin were analysed using three enzyme immunoassays to establish the best method for rapid diagnosis of RVF. A biotin-avidin-enhanced antigen detection method utilizing monoclonal antibodies proved most sensitive. Eighty-two viremic human sera were tested, and this assay detected antigen in 29.3% of the samples.

The use of veterinary vaccines for prevention and control of Rift Valley fever: memorandum from a WHO/FAO meeting.

This Memorandum considers the use of veterinary vaccines for the prevention of Rift Valley fever (RVF) and for its control during outbreaks. Veterinary vaccines are the first line of defence against RVF. Existing live and inactivated vaccines have been used extensively in Africa but further development of both is warranted. The live virus vaccine may cause abortion and its potential for reversion to virulence has not been adequately investigated. It should be used only in enzootic and epizootic areas. The inactivated vaccines are effective and safe, but they are more expensive and at least 2 d…

Воздействие лабораторной колонизации на векторно-патогенное взаимодействие египетских пипиенов и вируса лихорадки Рифт-Вэлли.

Полевые и лабораторные исследования показали, что в период эпизоотики/эпидемии в Египте в 1977-1978 годах в качестве вектора лихорадки Рифт-Вэлли (RVF) использовался Кьюлекс Пипиенс. В ходе этого исследования была проведена оценка изменений в показателях инфицирования и передачи вируса, а также вирусных титеров в организме F1-F16 поколения Cx. pipiens комаров, перорально инфицированных вирусом RVF. В ходе процесса колонизации существенно изменились темпы заражения и передачи вируса RVF этим видом. Однако процесс колонизации не отразился на высших вирусных титерах либо передающих, либо инфициро

Совпадение в аннотации оригинала
Field and laboratory findings implicated Culex pipiens as a vector of Rift Valley fever (RVF) virus during the 1977-1978 epizootics/epidemics in Egypt. This study evaluated changes in infection and transmission rates, and viral titers in F1 through F16 generation Cx. pipiens mosquitoes orally infected with RVF virus. Infection and transmission rates of RVF v…

Reduced pathogenicity associated with a small plaque variant of the Egyptian strain of Rift Valley fever virus (ZH501).

Variants of Rift Valley fever virus producing plaques in CER cells of four different sizes are described. A plaque-forming unit (PFU) variant forming minute plaques was isolated and purified. Virus derived from this variant was not pathogenic to adult Swiss albino mice by the intraperitoneal (i.p.) route and was less pathogenic than the parent strain (ZH501) to adult Sprague Dawley rats by i.p. route, but produced typical severe liver necrosis in adult Syrian hamsters with intranuclear and intracytoplasmic eosinophilic inclusions. Antigen and antiserum to the minute variant prepared in mice re…

Epidemiologic and Genomic Characterization of an Outbreak of Rift Valley Fever Among Humans and Dairy Cattle in Northern Tanzania.

BACKGROUND: A periurban outbreak of Rift Valley fever virus (RVFV) among dairy cattle from May through August 2018 in northern Tanzania was detected through testing samples from prospective livestock abortion surveillance. We sought to identify concurrent human infections, their phylogeny, and epidemiologic characteristics in a cohort of febrile patients enrolled from 2016 to 2019 at hospitals serving the epizootic area. METHODS: From September 2016 through May 2019, we conducted a prospective cohort study that enrolled febrile patients hospitalized at 2 hospitals in Moshi, Tanzania. Archived…

Cryo-EM structure of the Rift Valley fever virus envelope protein in complex with a potent neutralization antibody.

Entry of Rift Valley fever virus (RVFV) into host cells is mediated by the viral glycoproteins Gn and Gc. Structural details and assembly mechanism of Gn and Gc on the surface of RVFV remain unclear. Here, we stabilized the GnGc with the neutralizing monoclonal antibody RVFV-140 and determined a near-atomic resolution structure of the GnGc hexamer in complex with the fragment antigen binding (Fab) domain of RVFV-140 (Fab140). Our structure showed that RVFV-140 recognizes a ternary epitope and crosslinks two adjacent Gn heads within the hexamer, thus preventing the prefusion to postfusion trans…

Evidence of Eretmapodites subsimplicipes and Aedes albopictus as competent vectors for Rift Valley fever virus transmission in Mayotte.

Rift Valley fever (RVF) recently re-emerged in Mayotte. We described, for the first time, that the mosquito species Eretmapodites subsimplicipes, a highly abundant species in Mayotte, is a competent vector for the transmission of RVF virus using three distinct populations native to Mayotte. We also showed that Aedes albopictus specimens are able to transmit RVF virus (RVFV) as previously observed in mosquito populations of other countries emphasizing the need of the increase vigilance for this highly invasive species of global distribution. Altogether, these results underline the epidemiologic…

Mosquito survey in Mauritania: Detection of Rift Valley fever virus and dengue virus and the determination of feeding patterns.

In Mauritania, several mosquito-borne viruses have been reported that can cause devastating diseases in animals and humans. However, monitoring data on their occurrence and local distribution are limited. Rift Valley fever virus (RVFV) is an arthropod-borne virus that causes major outbreaks throughout the African continent and the Arabian Peninsula. The first Rift Valley fever (RVF) epidemic in Mauritania occurred in 1987 and since then the country has been affected by recurrent outbreaks of the disease. To gain information on the occurrence of RVFV as well as other mosquito-borne viruses and …

На двух рынках Яунде, Камерун, распространенность вируса лихорадки Рифт-Вэлли у местных червей различного происхождения.

Жар в долине Рифт (RVF) является эндемическим зоонозом, передаваемым через комары в Африке. В связи с тем, что о бремени или эпидемиологии вируса RVF (RVFV) в Камеруне известно мало, цель этого исследования заключалась в определении степени распространенности вируса RVFV у домашних червей различного происхождения на двух рынках Яунде, Камерун. МЕТОДОЛОГИЯ/ПРИНСИПАЛ ФИНИНИНГЫ: Было зарегистрировано происхождение животных, произвольно отобранных на двух рынках скота в Яунде, и были собраны пробы плазмы для конкурентоспособного и улавливаемого иммуносорбента (ЭЛИСА) для определения распространенн

Совпадение в аннотации оригинала
BACKGROUND: Rift Valley fever (RVF) is a mosquito-borne zoonosis endemic in Africa. With little known of the burden or epidemiology of RVF virus (RVFV) in Cameroon, this study aimed to determine the seroprevalence of RVFV in domestic ruminants of various origins in two markets of Yaoundé, Cameroon. METHODOLOGY/PRINCIPAL FINDINGS: The origin of animals rando…

The role of livestock movements in the spread of Rift Valley fever virus in animals and humans in Mayotte, 2018-19.

Rift Valley fever (RVF) is a vector-borne viral disease of major animal and public health importance. In 2018-19, it caused an epidemic in both livestock and human populations of the island of Mayotte. Using Bayesian modelling approaches, we assessed the spatio-temporal pattern of RVF virus (RVFV) infection in livestock and human populations across the island, and factors shaping it. First, we assessed if (i) livestock movements, (ii) spatial proximity from communes with infected animals, and (iii) livestock density were associated with the temporal sequence of RVFV introduction into Mayotte c…

A multiplex fluorescence microsphere immunoassay for increased understanding of Rift Valley fever immune responses in ruminants in Kenya.

Rift Valley fever virus (RVFV) is an important mosquito-borne pathogen with devastating impacts on agriculture and public health. With outbreaks being reported beyond the continent of Africa to the Middle East, there is great concern that RVFV will continue to spread to non-endemic areas such as the Americas and Europe. There is a need for safe and high throughput serological assays for rapid detection of RVFV during outbreaks and for surveillance. We evaluated a multiplexing fluorescence microsphere immunoassay (FMIA) for the detection of IgG and IgM antibodies in ruminant sera against the RV…

Seroprevalence and Associated Risk Factors of Rift Valley Fever in Domestic Small Ruminants in the North Region of Cameroon.

Rift Valley fever (RVF) is a zoonotic vector borne infectious disease of major medical and veterinary importance particularly in sub-Saharan Africa. However, there is dearth of epidemiological knowledge of the disease in Cameroon. We conducted a cross-sectional study (January 2016-January 2017) to investigate the seroprevalence and potential risk factors of Rift Valley fever virus (RVFV) in sheep and goats in the North region of Cameroon. Stratified sampling approach was used to select herds where sera were collected from 680 randomly selected small ruminants (355 goats and 325 sheep) in eight…

Rift Valley fever vaccines: an overview of the safety and efficacy of the live-attenuated MP-12 vaccine candidate.

Rift Valley fever (RVF) is a mosquito-borne zoonotic viral disease endemic to Africa and the Arabian Peninsula. High rates of abortion among infected ruminants and hemorrhagic fever in infected humans are major public health concerns. Commercially available veterinary RVF vaccines are important for preventing the spread of the Rift Valley fever virus (RVFV) in endemic countries; however, RVFV outbreaks continue to occur frequently in endemic countries in the 21st century. In the U.S., the live-attenuated MP-12 vaccine has been developed for both animal and human vaccination. This vaccine strai…

First External Quality Assessment of Molecular and Serological Detection of Rift Valley Fever in the Western Mediterranean Region.

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis which affects humans and a wide range of domestic and wild ruminants. The large spread of RVF in Africa and its potential to emerge beyond its geographic range requires the development of surveillance strategies to promptly detect the disease outbreaks in order to implement efficient control measures, which could prevent the widespread of the virus to humans. The Animal Health Mediterranean Network (REMESA) linking some Northern African countries as Algeria, Egypt, Libya, Mauritania, Morocco, Tunisia with Southern European ones as Fran…

Biology of mosquitoes that are potential vectors of Rift Valley Fever virus in different biotopes of the central highlands of Madagascar.

There were epidemic-epizootics of Rift Valley Fever (RVF) affecting humans and cattle in Madagascar in the district of Anjozorobe in 2008. Little is known about the role of Malagasy mosquitoes in the circulation of RVF virus. Therefore, we investigated the species diversity, dynamics and biology of potential RVF virus vectors in the rainforest, rainforest edge (village of Anorana), and savanna biotope (village of Antanifotsy) of this district between November 2008 and July 2010. We captured 56,605 adults of 35 different species. Anopheles squamosus (Theobald), Anopheles coustani (Laveran), Cul…