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Temperature-sensitive mutations for live-attenuated Rift Valley fever vaccines: implications from other RNA viruses.

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease endemic to the African continent. RVF is characterized by high rate of abortions in ruminants and hemorrhagic fever, encephalitis, or blindness in humans. RVF is caused by the Rift Valley fever virus (RVFV: genus Phlebovirus, family Bunyaviridae). Vaccination is the only known effective strategy to prevent the disease, but there are no licensed RVF vaccines available for humans. A live-attenuated vaccine candidate derived from the wild-type pathogenic Egyptian ZH548 strain, MP-12, has been conditionally licensed for veterinary use in…

Molecular detection of Rift Valley fever virus in serum samples from selected areas of Tanzania.

Rift Valley fever (RVF) is an acute mosquito-borne viral zoonotic disease affecting domestic animals and humans caused by the Rift Valley fever virus (RVFV). The virus belongs to the genus Phlebovirus of the family Bunyaviridae. The main aim of this study was to detect the presence of antibodies to RVFV as well as the virus in the serum samples that were collected from livestock during the 2006/2007 RVF outbreaks in different locations in Tanzania. Analysis of selected samples was done using a RVF-specific inhibition enzyme-linked immunosorbent assay (I-ELISA) and reverse transcription polymer…

Evidence of Rift Valley fever seroprevalence in the Sahrawi semi-nomadic pastoralist system, Western Sahara.

BACKGROUND: The increasing global importance of Rift Valley fever (RVF) is clearly demonstrated by its geographical expansion. The presence of a wide range of host and vector species, and the epidemiological characteristics of RVF, have led to concerns that epidemics will continue to occur in previously unaffected regions of Africa. The proximity of the Sahrawi territories of Western Sahara to endemic countries, such as Mauritania, Senegal, and Mali with periodic isolation of virus and serological evidence of RVF, and the intensive livestock trade in the region results in a serious risk of RVF…

Rift Valley fever virus MP-12 vaccine encoding Toscana virus NSs retains neuroinvasiveness in mice.

Rift Valley fever is a mosquito-borne zoonotic disease endemic to sub-Saharan Africa. Rift Valley fever virus (RVFV; genus Phlebovirus, family Bunyaviridae) causes high rates of abortion and fetal malformation in pregnant ruminants, and haemorrhagic fever, neurological disorders or blindness in humans. The MP-12 strain is a highly efficacious and safe live-attenuated vaccine candidate for both humans and ruminants. However, MP-12 lacks a marker to differentiate infected from vaccinated animals. In this study, we originally aimed to characterize the efficacy of a recombinant RVFV MP-12 strain e…

Rift Valley fever virus strain MP-12 enters mammalian host cells via caveola-mediated endocytosis.

Rift Valley fever virus (RVFV) is a zoonotic pathogen capable of causing serious morbidity and mortality in both humans and livestock. The lack of efficient countermeasure strategies, the potential for dispersion into new regions, and the pathogenesis in humans and livestock make RVFV a serious public health concern. The receptors, cellular factors, and entry pathways used by RVFV and other members of the family Bunyaviridae remain largely uncharacterized. Here we provide evidence that RVFV strain MP-12 uses dynamin-dependent caveola-mediated endocytosis for cell entry. Caveolae are lipid raft…

Structure of the Rift Valley fever virus nucleocapsid protein reveals another architecture for RNA encapsidation.

Rift Valley fever virus (RVFV) is a negative-sense RNA virus (genus Phlebovirus, family Bunyaviridae) that infects livestock and humans and is endemic to sub-Saharan Africa. Like all negative-sense viruses, the segmented RNA genome of RVFV is encapsidated by a nucleocapsid protein (N). The 1.93-A crystal structure of RVFV N and electron micrographs of ribonucleoprotein (RNP) reveal an encapsidated genome of substantially different organization than in other negative-sense RNA virus families. The RNP polymer, viewed in electron micrographs of both virus RNP and RNP reconstituted from purified N…

Experimental infection of young adult European breed sheep with Rift Valley fever virus field isolates.

The increasing interest in Rift Valley fever virus (RVFV) and its potential impact on naive animal populations deserve revisiting experimental reproduction of RVFV infection, particularly in those animal breeds for which no data about their susceptibility to RVFV infection have ever been recorded. In this study we show the susceptibility of 9-10 weeks old European sheep (Ripollesa breed) to RVFV infection, showing a mild, subacute form of disease. Four different viral isolates efficiently replicated in vivo after subcutaneous experimental inoculation, and consistent viral loads in blood and vi…

Potential for stable flies and house flies (Diptera: Muscidae) to transmit Rift Valley fever virus.

Rift Valley fever (RVF), a disease of ruminants and humans, has been responsible for large outbreaks in Africa that have resulted in hundreds of thousands of human infections and major economic disruption due to loss of livestock and to trade restrictions. As indicated by the rapid spread of West Nile viral activity across North America since its discovery in 1999 and the rapid and widespread movement of chikungunya virus from Africa throughout the Indian Ocean Islands to Asia and Europe, an introduced exotic arbovirus can be rapidly and widely established across wide geographical regions. Alt…

Vector competence of Kenyan Culex zombaensis and Culex quinquefasciatus mosquitoes for Rift Valley fever virus.

Rift Valley fever (RVF) continues to be a significant problem in Kenya as well as in Egypt, Yemen, and Saudi Arabia. In order to determine the ability of Kenyan mosquitoes to transmit RVF virus (RVFV), we collected mosquitoes in the Lake Naivasha region of Kenya and evaluated them for their potential to transmit RVFV under laboratory conditions. After feeding on a hamster (Mesocricetus auratus) with a viremia of 10(9.7) plaque-forming units of virus/ml of blood, Culex zombaensis were highly susceptible to infection with RVFV, with 89% becoming infected. In contrast, Cx. quinquefasciatus that w…

Rift Valley fever virus noncoding regions of L, M and S segments regulate RNA synthesis.

Rift Valley fever virus (RVFV) (Phlebovirus, Bunyaviridae) possesses a genome composed of three negative-stranded RNA molecules. Each segment contains 3' and 5' noncoding regions with terminal complementary sequences forming a panhandle structure. We showed that transcription-replication of the L, M and S segments is regulated, and we established a minigenome rescue system expressing a CAT reporter to investigate the role of the noncoding regions in this process. The L, M and S segment-based minigenomes were shown to drive bona fide transcription and replication and to express variable levels …

Стойкость к вирусу лихорадки Рифт-Вэлли в Рэттусе Норвегикусе: генетическая изменчивость в определенных "внутренних" штаммах.

Вирус лихорадки Рифт-Вэлли (RVFV) является причиной лихорадки Рифт-Вэлли, широко распространенной болезнью домашних животных и людей в странах Африки к югу от Сахары. Лабораторные крысы часто используются в качестве животной модели для изучения патогенеза лихорадки Рифт-Вэлли. Здесь показано, что крысы Льюиса (LEW/моль) подвержены инфекции RVFV, в то время как крысы Вистар-Фурт (WF/моль) устойчивы к инфекции RVFV. У крыс LEW/моль возник острый гепатит и они умерли после инфекции с штаммом RVFV ZH 548, в то время как WF/моль крысы пережили инфекцию. Переплетение резистентных крыс WF/моль с восп

Совпадение в аннотации оригинала
Rift Valley fever virus (RVFV) is the causative agent of Rift Valley fever, a widespread disease of domestic animals and humans in sub-Saharan Africa. Laboratory rats have frequently been used as an animal model for studying the pathogenesis of Rift Valley fever. It is shown here that Lewis rats (LEW/mol) are susceptible to infection with RVFV, whereas Wista…

First isolation of the Rift Valley fever virus from Culex poicilipes (Diptera: Culicidae) in nature.

Following the reemergence of Rift Valley fever (RVF) virus in southeastern Mauritania in 1998, an entomological survey was undertaken in the boundary area in Senegal to assess the extent of the virus circulation. During this study, RVF virus (36 strains) was isolated for the first time from Culex poicilipes in nature. The possible role of Cx. poicilipes as an RVF vector is discussed regarding its biology and ecology.

Облегчение передачи вируса лихорадки Рифт-Вэлли Plasmodium bergei sporozoites в Anopheles stephensi комаров.

Некоторые виды комаров подвержены вирусной инфекции, но не могут передать вирус из-за слюнной железы. Мы предположили, что такие виды могут передавать вирус, если комар заразится как вирусом, так и паразитами малярии. Малярийные сорозоиты нарушают целостность слюнных желез комаров и тем самым могут уничтожать слюнные железные барьеры для вирусной передачи. Для изучения этого постулата использовались модельная система вируса лихорадки Рифт-Вэлли (RVF) и грызунового паразита Plasmodium bergei в анофелях stephensi комаров. Были сопоставлены коэффициенты передачи вирусных вирусных анофолинов, кото

Совпадение в аннотации оригинала
Certain mosquito species are susceptible to viral infection but cannot transmit the virus due to a salivary gland barrier. We hypothesized t … stroy salivary gland barriers to viral transmission. To examine this postulate, the model system of Rift Valley fever (RVF) virus and a rodent parasite, Plasmodium berghei, in Anopheles stephensi mosquitoes was used. Viral transmission rates for RVF virus-inoculated anophelines that were previously fed either gametocytemic blood (malaria-infected) or normal blood ( …

Rift Valley fever virus M segment: cell-free transcription and translation of virus-complementary RNA.

A cell-free system has been used to study gene expression of the M segment RNA of the Phlebovirus Rift Valley fever virus (RVFV). RVFV sequence-containing plasmids were used to synthesize M segment mRNA-like transcripts. These transcripts were then translated in vitro in the absence or presence of microsomal membranes. Cell-free translation of a transcript which closely resembled authentic M segment mRNA (RNA-7) yielded a primary translation product of 133 kilodaltons (kDa), the size expected of a polypeptide encompassing the entire open reading frame (ORF) of the M segment. When translations …

Entomological survey of the potential vectors of Rift Valley fever virus and absence of detection of the virus genome from the vectors in various niches in the southern half of the Great Rift Valley of Ethiopia.

BACKGROUND: Rift Valley fever virus (RVFV) is the cause of one of the most important mosquito-borne emerging diseases negatively affecting the health of humans and animals, particularly in Africa. In Ethiopia, the status of RVFV and the existence of potential vectors are unknown. OBJECTIVES: This study aimed to survey the mosquito vectors of RVFV and the detection of the virus in selected sites (Batu, Hawassa, Arba Minch and Borana) in Ethiopia. METHODS: CDC light traps baited with the sugar-yeast solution were set up at various locations for a total of 29 trap nights. Mosquitoes identificat…

Seroprevalence of Crimean-Congo Hemorrhagic Fever and Rift Valley Fever Viruses Among Ruminants in Nigeria: A Descriptive Epizootiological Analysis.

Crimean-Congo hemorrhagic fever (CCHF) and Rift Valley fever (RVF) are major zoonotic diseases, spread by arthropods, with livestock serving as amplifying hosts. Despite Nigeria's large ruminant population and robust cross-border animal trade, data on the seroprevalence of the viral agents causing these diseases remain limited. A longitudinal serological survey was conducted in five major livestock markets across Nigeria. A total of 3450 animals (cattle, sheep, and goats) were tested for Crimean-Congo hemorrhagic fever virus (CCHFV) and Rift Valley fever virus (RVFV) antibodies using ELISA. Da…

Isolation of west nile and sindbis viruses from mosquitoes collected in the Nile Valley of Egypt during an outbreak of Rift Valley fever.

As part of an evaluation of potential vectors of arboviruses during a Rift Valley fever (RVF) outbreak in the Nile Valley of Egypt in August 1993, we collected mosquitoes in villages with known RVF viral activity. Mosquitoes were sorted to species, pooled, and processed for virus isolation both by intracerebral inoculation into suckling mice and by inoculation into cell culture. A total of 33 virus isolates was made from 36,024 mosquitoes. Viruses were initially identified by indirect fluorescent antibody testing and consisted of 30 flaviviruses (all members of the Japanese encephalitis comple…