scholarly journals NSm and 78-Kilodalton Proteins of Rift Valley Fever Virus Are Nonessential for Viral Replication in Cell Culture

2006 ◽  
Vol 80 (16) ◽  
pp. 8274-8278 ◽  
Author(s):  
Sungyong Won ◽  
Tetsuro Ikegami ◽  
C. J. Peters ◽  
Shinji Makino
Keyword(s):  
Cell Culture ◽  
Protein Expression ◽  
Growth Kinetics ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Parent Virus ◽  
M Gene ◽  
Valley Fever ◽  
Similar Growth

ABSTRACT Rift Valley fever viruses carrying mutations of the M gene preglycoprotein region, one lacking NSm protein expression, one lacking 78-kDa protein expression, and one lacking expression of both proteins, were compared in cell culture. All of the mutants and their parent virus produced plaques with similar sizes and morphologies in Vero E6 cells and had similar growth kinetics in Vero, C6/36, and MRC5 cells, demonstrating that the NSm and 78-kDa proteins were not needed for the virus to replicate efficiently in cell culture. A competition-propagation assay revealed that the parental virus was slightly more fit than the mutant virus lacking expression of both proteins.

scholarly journals Rescue of Infectious Rift Valley Fever Virus Entirely from cDNA, Analysis of Virus Lacking the NSs Gene, and Expression of a Foreign Gene

2006 ◽  
Vol 80 (6) ◽  
pp. 2933-2940 ◽  
Author(s):  
Tetsuro Ikegami ◽  
Sungyong Won ◽  
C. J. Peters ◽  
Shinji Makino
Keyword(s):  
Protein Expression ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Reverse Genetics ◽  
Rift Valley Fever Virus ◽  
Foreign Gene ◽  
Deletion Mutants ◽  
Luciferase Gene ◽  
Valley Fever ◽  
Virus Rescue

ABSTRACT Rift Valley fever virus (RVFV) (genus Phlebovirus, family Bunyaviridae) has a tripartite negative-strand genome, causes a mosquito-borne disease that is endemic in sub-Saharan African countries and that also causes large epidemics among humans and livestock. Furthermore, it is a bioterrorist threat and poses a risk for introduction to other areas. In spite of its danger, neither veterinary nor human vaccines are available. We established a T7 RNA polymerase-driven reverse genetics system to rescue infectious clones of RVFV MP-12 strain entirely from cDNA, the first for any phlebovirus. Expression of viral structural proteins from the protein expression plasmids was not required for virus rescue, whereas NSs protein expression abolished virus rescue. Mutants of MP-12 partially or completely lacking the NSs open reading frame were viable. These NSs deletion mutants replicated efficiently in Vero and 293 cells, but not in MRC-5 cells. In the latter cell line, accumulation of beta interferon mRNA occurred after infection by these NSs deletion mutants, but not after infection by MP-12. The NSs deletion mutants formed larger plaques than MP-12 did in Vero E6 cells and failed to shut off host protein synthesis in Vero cells. An MP-12 mutant carrying a luciferase gene in place of the NSs gene replicated as efficiently as MP-12 did, produced enzymatically active luciferase during replication, and stably retained the luciferase gene after 10 virus passages, representing the first demonstration of foreign gene expression in any bunyavirus. This reverse genetics system can be used to study the molecular virology of RVFV, assess current vaccine candidates, produce new vaccines, and incorporate marker genes into animal vaccines.

scholarly journals Application of a real-time cell analysis system in the process development and quantification of Rift Valley fever virus clone 13

2020 ◽  
Author(s):  
Boitumelo Moetlhoa ◽  
Leeann Naicker ◽  
Rose Hayeshi ◽  
Anne Grobler ◽  
Nobalanda B. Mokoena ◽  
...  
Keyword(s):  
Cell Culture ◽  
Cell Growth ◽  
Vero Cell ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Cell Analysis ◽  
Roller Bottle ◽  
Valley Fever ◽  
Viral Plaque

Conventional cell-culture viral quantification methods, namely viral plaque and 50 % tissue culture infective dose assays, are time-consuming, subjective and are not suitable for routine testing. The viral plaque formation assay is the main method utilized for Rift Valley fever virus (RVFV) clone 13 quantification. The RVFV is a mosquito-borne RNA Phlebovirus belonging to the family Bunyaviridae. The virus comprises a single serotype and causes the zoonotic Rift Valley fever disease. The real-time cell analysis (RTCA) system has been developed for the monitoring of cell growth, cell adhesion, cell viability and mortality using electronic impedance technology. In this study, Vero cell growth kinetics and RVFV clone 13 replication kinetics were investigated in a roller bottle and RTCA systems. In roller bottles, Vero cell growth was measured by cell counts through trypan blue staining, whilst impedance expressed as the cell index (CI) was used for Vero growth measurement in the RTCA system. Similar growth patterns were observed in both roller bottle and RTCA systems. Exponential growth phase was observed between 48 and 100 h, followed by a stationary phase from 100 to 120 h, before cell death was observed. Viral plaque assay quantification of RVFV clone 13 in the roller bottle system and the time required for the CI to decrease 50 % after virus infection (CIT50) in the RTCA system were comparable. The highest RVFV clone 13 titre was obtained at 120 h in both roller bottle and RTCA systems. An increase in time for cytopathic effect (CPE) formation was observed with a decrease in the concentration of the virus used to infect the RTCA plates. A positive correlation was observed between the viral concentration and the time for a CPE and was used to calculate CIT50. A similar correlation was observed between the viral concentration and the time for a CPE in the roller bottle system. This study shows that the RTCA system can be used as an alternative method for conducting cell culture kinetics and viral quantification.

Complement fixation reaction of Rift Valley fever virus

1950 ◽  
Vol 5 (5) ◽  
pp. 243-247
Author(s):  
Minoru MATSUMOTO ◽  
Saburo IWASA ◽  
Motosige ENDO
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Complement Fixation ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Valley Fever ◽  
Fixation Reaction

scholarly journals The Use of Nanotrap Particles in the Enhanced Detection of Rift Valley Fever Virus Nucleoprotein

PLoS ONE ◽  
2015 ◽  
Vol 10 (5) ◽  
pp. e0128215 ◽  
Author(s):  
Nazly Shafagati ◽  
Lindsay Lundberg ◽  
Alan Baer ◽  
Alexis Patanarut ◽  
Katherine Fite ◽  
...  
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Valley Fever

scholarly journals Serological evidence of Rift Valley fever virus infection among domestic ruminant herds in Uganda

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Deo B. Ndumu ◽  
Barnabas Bakamutumaho ◽  
Edward Miller ◽  
Jesca Nakayima ◽  
Robert Downing ◽  
...  
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Northern Region ◽  
Western Region ◽  
Domestic Ruminant ◽  
The South ◽  
Valley Fever ◽  
Sheep And Goats ◽  
The Western Region

Abstract Background Prior to the first recorded outbreak of Rift Valley fever (RVF) in Uganda, in March 2016, earlier studies done until the 1970’s indicated the presence of the RVF virus (RVFV) in the country, without any recorded outbreaks in either man or animals. While severe outbreaks of RVF occurred in the neighboring countries, none were reported in Uganda despite forecasts that placed some parts of Uganda at similar risk. The Ministry of Agriculture, Animal Industry and Fisheries (MAAIF) undertook studies to determine the RVF sero-prevalence in risk prone areas. Three datasets from cattle sheep and goats were obtained; one from retrospective samples collected in 2010–2011 from the northern region; the second from the western region in 2013 while the third was from a cross-sectional survey done in 2016 in the south-western region. Laboratory analysis involved the use of the Enzyme Linked Immunosorbent Assays (ELISA). Data were subjected to descriptive statistical analyses, including non-parametric chi-square tests for comparisons between districts and species in the regions. Results During the Yellow Fever outbreak investigation of 2010–2011 in the northern region, a total sero-prevalence of 6.7% was obtained for anti RVFV reacting antibodies (IgG and IgM) among the domestic ruminant population. The 2013 sero-survey in the western region showed a prevalence of 18.6% in cattle and 2.3% in small ruminants. The 2016 sero-survey in the districts of Kabale, Kanungu, Kasese, Kisoro and Rubirizi, in the south-western region, had the respective district RVF sero-prevalence of 16.0, 2.1, 0.8, 15.1and 2.7% among the domestic ruminants combined for this region; bovines exhibited the highest cumulative sero-prevalence of 15.2%, compared to 5.3 and 4.0% respectively for sheep and goats per species for the region. Conclusions The absence of apparent outbreaks in Uganda, despite neighboring enzootic areas, having minimal restrictions to the exchange of livestock and their products across borders, suggest an unexpected RVF activity in the study areas that needs to be unraveled. Therefore, more in-depth studies are planned to mitigate the risk of an overt RVF outbreak in humans and animals as has occurred in neighboring countries.

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