Development and characterization of Rift Valley fever virus-like particles

Abstract

ABSTRACT. Rift Valley fever (RVF) is an acute, febrile zoonotic disease that is caused by the RVF virus (RVFV) and spread by arthropod vectors. RVF is currently prevalent in Africa and the Arabian Peninsula, and causes substantial economic losses. Furthermore, this disease poses a serious threat to animal and human health in regions worldwide, making it a serious public health concern. However, RVFV vaccines for human use are still unavailable, and hence there is an urgent need for novel efficient vaccines against RVFV. Vaccine preparation techniques have become a crucial factor in developing new vaccines. In the current study, the N and G protein genes of RVFV were inserted into the pFastBacDual baculovirus expression vector downstream of the pP10 and pPH promoters. The resultant recombinant vector, pFastBacDual-S-M, was transfected into Sf9 insect cells by lipofection. The recombinant baculovirus, named rBac-N-G, was retrieved and infected into Sf9 insect cells to generate RVFV viruslike particles (VLPs). Using polyclonal antibodies against RVFV proteins in immunofluorescence and western blot analyses, we positively identified the presence of the RVFV proteins in VLP preparations. Sucrose density gradient centrifugation and transmission electron microscopy revealed that the morphology of the RVFV VLPs was consistent with previous reports of RVFV virions. This study describes a technique for efficient production of RVFV VLPs, and has laid the foundation for future VLP-based RVFV vaccines.

Exosomes originating from infection with the cytoplasmic single-stranded RNA virus Rift Valley fever virus (RVFV) protect recipient cells by inducing RIG-I mediated IFN-B response that leads to activation of autophagy

“…This is consistent with the fact that CD9 is present on the plasma membrane (from which late endosomal membranes and therefore exosomes derive) whereas it is absent from the golgi [ 47 – 49 ] through which RVFV trafficking and assembly takes place [ 50 , 51 ]. The reported characterization of RVFV VLPs [ 52 ] provides yet further support for our findings that the observed biological effects is caused by the EXi-RVFV and not VLPs/noninfectious virions. On sucrose density gradients, RVFV VLPs migrate to a fraction corresponding to about 50–55% sucrose, which is also fully consistent with the reported density of around 1.21 g/ml for bunyaviruses.…”

Bacterium-Like Particles Displaying the Rift Valley Fever Virus Gn Head Protein Induces Efficacious Immune Responses in Immunized Mice

“…While three veterinary vaccines are commercially available for use in endemic countries ( Barteling and Woortmeyer, 1984 ; Minke et al, 2004 ; Faburay et al, 2013 ; Chamchod et al, 2015 ), there currently remains no licensed human vaccines for preventing RVFV infection ( Kortekaas, 2014 ). However, a number of RVF vaccine platforms are reported in recent years, including a DNA vaccine ( Bhardwaj et al, 2010 ), equine herpesvirus type 1 (EHV-1) vector vaccine ( Said et al, 2017 ), a DNA prime with modified vaccinia virus Ankara (MVA) boost ( Lorenzo et al, 2018 ), Newcastle disease virus (NDV)-based vector vaccine ( Kortekaas et al, 2010 ), Lumpy skin disease virus (LSDV) vector vaccine ( Wallace et al, 2020 ), and virus-like particle (VLP) vaccines ( Mandell et al, 2010 ; Li et al, 2016 ).…”

Immunogenicity Assessment of Rift Valley Fever Virus Virus-Like Particles in BALB/c Mice

“…In this study, a previously constructed recombinant baculovirus (9), rBac-N-G, which contains the RVFV Gn, Gc, and N proteins, was used to infect Sf9 insect cells to express RVFV VLPs. Although the virion cannot replicate, it can be adsorbed to cell receptors, in a manner similar to that of cells infected with RVFV.…”

“…The recombinant baculovirus rBac-N-G, which contains the RVFV Gn, Gc and N proteins, was constructed in a previous study (9). A suspension of Sf9 insect cells (Spodoptera frugiperda Sf9 cells) was preserved by the Laboratory of Animal Virology and Special Animal Lemology at the Military Veterinary Research Institute in China; these cells were cultivated per a previously described method (9).…”

“…In a previous study, our research group successfully developed a method for the preparation of RVFV VLPs based on an insect baculovirus system (9). In this study, large quantities of high quality RVFV VLPs were obtained using large-scale preparation, concentration, and purification methods, and the prepared VLPs were used to perform mouse immunization studies.…”