ABSTRACT
@#Objective To construct recombinant chimeric vesicular stomatitis virus(VSV)expressing G protein of rabies virus(RV)using VSV as vector.MethodsTo rescue the recombinant virus,G gene of VSV antigenome was replaced with G gene of RV vaccine CTN-1 strain,and co-transfected into 293T cells with helper plasmids coding T7 RNA polymerase and proteins N,P and L of VSV. The expression of RV G gene and G protein was detected by RT-PCR,immunofluorescence assay and Western blot. The recombinant virus was subcultured in Vero cells,the virus titer of different generations was detected and the virus growth curve was drawn.ResultsThe recombinant virus VSV-RVG was successfully rescued. RTPCR results demonstrated that the RV G gene was successfully inserted into the genome of the recombinant virus,and the expression of RVG protein was detected by immunofluorescence assay and Western blot. The recombinant virus was continuously passaged for 5 generations,and the virus titer was stable within 7. 5 ～ 8. 5 lgTCID50/mL.ConclusionThe recombinant chimeric VSV expressing RV G protein was successfully constructed with good genetic stability,which lays a foundation of the construction of reverse genetics technology platform based on VSV vector.
ABSTRACT
@#In recent years,more and more coronaviruses(CoV)have crossed the species barriers and spread from animals to human,causing many serious public health events and a blow to the global economy. Vaccination is the most effective measure to prevent coronavirus pandemic. A safe,effective and time-save vaccine platform is a critical requirement of vaccine research and development. With the increasing maturity of reverse genetics technology,it also plays an increasingly important role in the development of CoV vaccines. This paper reviewed several reverse genetics techniques used in CoV research and their possible directions in CoV vaccine development.
ABSTRACT
Objective:To investigate the effects of genomic location of a foreign gene in Shanghai-191 strain measles virus (MV) vector on gene expression and virus replication.Methods:The nucleotide sequence encoding S1 protein of SARS-CoV-2 was inserted at different positions in MV antigenome (the upstream of the N gene, between P and M genes, between H and L genes), and co-transfected into 293T cells with helper plasmids coding T7 RNA polymerase and N, P, and L proteins, respectively. The transfected cells were lysed and the supernatants were used to infected Vero cells to harvest recombinant viruses. S1 proteins expressed by the recombinant viruses were identified by RT-PCR, indirect immunofluorescence assay, Western blot and ELISA. Growth kinetics of the recombinant viruses were analyzed.Results:Recombinant viruses were failed to be rescued when the S1 protein-coding sequence was cloned into the upstream of N gene. Two recombinant viruses, MV-M-S1 and MV-L-S1, were successfully rescued when cloning the S1 protein-coding sequence into the intergenic region between P and M genes, or H and L genes, and could express S1 protein. MV-M-S1 expressed more S1 protein than MV-L-S1, but the titer of MV-M-S1 was lower.Conclusions:Inserting a foreign gene at different positions in the MV genome might have different effects on gene expression and virus replication. This study provided reference for the subsequent construction of MV vector.
ABSTRACT
Plant phenomics is a high-throughput path-breaking area that meets all the requirements for the collection ofaccurate, rapid and multi-faceted phenotypic data. Plant phenomics is an approach to envisage complex traitsthat are appropriate for selection, and provides relevant information as to why particular genotype can stand outin particular environmental conditions. The technique of plant phenotyping can be operated in variousdimensions, from the gene to the whole-plant level under a specific environment, and management practices.Through this review, we discuss the recent advances in plant phenomics, highlighting different field andconfined high-throughput technologies for utilization in forward and reverse genetics. These plant phenomicstechnique are very relevant in stress identification, study physiological processes, rapid and efficient screening,dissection and confirmation for understanding the genetic basis of different traits, genes and aspects. Highthroughput phenomics technologies are essential to avoid human error and to reduce time consumption whilephenotyping large germplasm populations, or for confirmation of gene or trait functional analysis.
ABSTRACT
BACKGROUND Imitation SWItch (ISWI) ATPase is the catalytic subunit in diverse chromatin remodeling complexes. These complexes modify histone-DNA interactions and therefore play a pivotal role in different DNA-dependent processes. In Trypanosoma cruzi, a protozoan that controls gene expression principally post-transcriptionally, the transcriptional regulation mechanisms mediated by chromatin remodeling are poorly understood. OBJECTIVE To characterise the ISWI remodeler in T. cruzi (TcISWI). METHODS A new version of pTcGW vectors was constructed to express green fluorescent protein (GFP)-tagged TcISWI. CRISPR-Cas9 system was used to obtain parasites with inactivated TcISWI gene and we determined TcISWI partners by cryomilling-affinity purification-mass spectrometry (MS) assay as an approximation to start to unravel the function of this protein. FINDINGS Our approach identified known ISWI partners [nucleoplasmin-like protein (NLP), regulator of chromosome condensation 1-like protein (RCCP) and phenylalanine/tyrosine-rich protein (FYRP)], previously characterised in T. brucei, and new components in TcISWI complex [DRBD2, DHH1 and proteins containing a domain characteristic of structural maintenance of chromosomes (SMC) proteins]. Data are available via ProteomeXchange with identifier PXD017869. MAIN CONCLUSIONS In addition to its participation in transcriptional silencing, as it was reported in T. brucei, the data generated here provide a framework that suggests a role for TcISWI chromatin remodeler in different nuclear processes in T. cruzi, including mRNA nuclear export control and chromatin compaction. Further work is necessary to clarify the TcISWI functional diversity that arises from this protein interaction study.
Subject(s)
Animals , Transcription Factors/genetics , Trypanosoma cruzi/genetics , Adenosine Triphosphatases/genetics , Chromatin Assembly and Disassembly/genetics , Gene Expression Regulation , Blotting, Western , Flow CytometryABSTRACT
Objective@#To construct a stable infectious clone of live attenuated dengue virus (DENV) type 4 Ban18HK20 strain for better understanding the virulence determinants of DENV and improving the development of chimeric vaccines.@*Methods@#Specific primers were constructed according to the genome of Ban18HK20 strain and used to subclone six cDNA fragments, which were linked into a high-copy plasmid pSPTM to obtain a stable full-length cDNA clone of DENV. RNA was transcribed from the full-length cDNA in vitro and electrotransfected into Vero cells to recover the virus. Biological characteristics of the recovered virus were identified using plaque assay, indirect immunofluorescence assay, growth kinetics test and pathogenicity study in mouse brain. Genetic stability of the virus passaged 15 generations was studied using RT-PCR amplification.@*Results@#Restriction enzyme digestion and sequencing analysis indicated that the infectious clone was constructed successfully. The recovered virus was consistent with the parental virus in terms of plaque morphology, DENV E protein expression, growth characteristics and pathogenicity in mouse brain. Sequencing analysis showed that the recovered virus had the same genome sequence as the parental virus with good hereditary stability.@*Conclusions@#A stable infection clone of Ban18HK20 was constructed and a reverse genetics technology platform for DENV research was established.
ABSTRACT
Reverse genetics approaches can directly manipulate the genome of virus at the gene level, making it possible to quickly, directly and thoroughly study the mechanisms of virus replication and pathogenesis. At present, many viruses of the family Reoviridae, such as mammalian orthoreovirus ( MRV) and bluetongue virus ( BTV) , have made great progress in basic viral research using the powerful tool of re-verse genetics. However, for members of the genus Rotavirus in the family Reoviridae, progress in the con-struction of reverse genetic systems has been slow. The remarkable reverse genetics system based on helper-viruses was established in 2006, and it was not until 2017 that the entirely plasmid-based reverse genetics system was successfully established. This paper briefly reviewed the development of reverse genetics systems for rotavirus and prospected the direction for future research in order to provide technical support for acceler-ating the basic research on mechanisms of rotavirus infection.
ABSTRACT
Porcine epidemic diarrhea virus (PEDV) is one of the major etiologies responsible for the acute, highly contagious disease in the digestive tract of pigs, especially neonatal piglets. Since PEDV was first identified in Europe in the late 1970s, it has resulted in significant economic losses in many Asian swine-raising countries, including China. Recently, reverse genetics techniques including targeted RNA recombination, bacteria artificial chromosome system and in vitro ligation have been successfully used to manipulate the genome of PEDV, which providing new strategies for the clear delineation of the functions of the viral proteins, the mechanisms behind PEDV pathogenesis and the design of novel vaccines against PEDV. Here, we review the progresses of different reverse genetics platforms developed for PEDV and their applications, covering the roles of trypsin in PEDV propagation, functions of S and ORF3 protein and the development of next generation PED vaccines, and the perspectives of reverse genetics for PEDV.
ABSTRACT
Twelve nucleotides located at the 3′ end of viral genomic RNA (vRNA) are conserved among influenza A viruses (IAV) and have a promoter function. Hoffmann's 8-plasmid reverse genetics vector system introduced mutations at position 4, C nucleotide (C4) to U nucleotide (U4), of the 3′ ends of neuraminidase (NA) and matrix (M) vRNAs of wild-type A/PR/8/34 (PR8). This resulted in a constellation of C4 and U4 vRNAs coding for low (polymerases) and relatively high (all others) copy number proteins, respectively. U4 has been reported to increase promoter activity in comparison to C4, but the constellation effect on the replication efficiency and pathogenicity of reverse genetics PR8 (rgPR8) has not been fully elucidated. In the present study, we generated 3 recombinant viruses with C4 in the NA and/or M vRNAs and rgPR8 by using reverse genetics and compared their pathobiological traits. The mutant viruses showed lower replication efficiency than rgPR8 due to the low transcription levels of NA and/or M genes. Furthermore, C4 in the NA and/or M vRNAs induced lower PR8 virus pathogenicity in BALB/c mice. The results suggest that the constellation of C4 and U4 among vRNAs may be one of the multigenic determinants of IAV pathogenicity.
Subject(s)
Animals , Mice , Clinical Coding , Influenza A virus , Influenza, Human , Neuraminidase , Nucleotides , Orthomyxoviridae , Reverse Genetics , RNA , VirulenceABSTRACT
Recent advances in reverse genetics techniques make it possible to manipulate the genome of RNA viruses such as Newcastle disease virus (NDV). Several NDV vaccine strains have been used as vaccine vectors in poultry, mammals, and humans to express antigens of different pathogens. The safety, immunogenicity, and protective efficacy of these NDV-vectored vaccines have been evaluated in pre-clinical and clinical studies. The vaccines are safe in mammals, humans, and poultry. Bivalent NDV-vectored vaccines against pathogens of economic importance to the poultry industry have been developed. These bivalent vaccines confer solid protective immunity against NDV and other foreign antigens. In most cases, NDV-vectored vaccines induce strong local and systemic immune responses against the target foreign antigen. This review summarizes the development of NDV-vectored vaccines and their potential use as a base for designing other effective vaccines for veterinary and human use.
Subject(s)
Animals , Humans , Genome , Mammals , Newcastle disease virus , Newcastle Disease , Poultry , Reverse Genetics , RNA Viruses , VaccinesABSTRACT
A/Puerto Rico/8/34 (PR8)-derived recombinant viruses have been used for seasonal flu vaccines; however, they are insufficient for vaccines against some human-fatal H5N1 highly pathogenic avian influenza (HPAI) viruses (HPAIV) due to low productivity. Additionally, the polymerase basic 2 (PB2) protein, an important mammalian-pathogenicity determinant, of PR8 possesses several mammalian-pathogenic mutations. We previously reported two avian PB2 genes (01310 and 0028) related to efficient replication in embryonated chicken eggs (ECEs) and nonpathogenicity in BALB/c mice. In this study, we generated PR8-derived H5N1 recombinant viruses harboring hemagglutinin (attenuated) and neuraminidase genes of a clade 2.3.2.1c H5N1 HPAIV (K10-483), as well as the 01310 or 0028 PB2 genes, and investigated their replication and immunogenicity. Compared with a control virus harboring six internal PR8 genes (rK10-483), the recombinant viruses possessing the 01310 and 0028 PB2 genes showed significantly higher replication efficiency in ECEs and higher antibody titers in chickens. In contrast to rK10-483, none of the viruses replicated in BALB/c mice, and all showed low titers in Madin-Darby canine kidney cells. Additionally, the recombinant viruses did not induce a neutralization antibody but elicited decreased protective immune responses against K10-483 in mice. Thus, the highly replicative and mammalian nonpathogenic recombinant H5N1 strains might be promising vaccine candidates against HPAI in poultry.
Subject(s)
Animals , Mice , Chickens , Efficiency , Eggs , Hemagglutinins , Influenza in Birds , Influenza Vaccines , Kidney , Neuraminidase , Ovum , Poultry , Reverse Genetics , Seasons , Vaccines , VirulenceABSTRACT
Abstract The open reading frame of a Brazilian bovine viral diarrhea virus (BVDV) strain, IBSP4ncp, was recombined with the untranslated regions of the reference NADL strain by homologous recombination in Saccharomyces cerevisiae, resulting in chimeric full-length cDNA clones of BVDV (chi-NADL/IBSP4ncp#2 and chi-NADL/IBSP4ncp#3). The recombinant clones were successfully recovered, resulting in viable viruses, having the kinetics of replication, focus size, and morphology similar to those of the parental virus, IBSP4ncp. In addition, the chimeric viruses remained stable for at least 10 passages in cell culture, maintaining their replication efficiency unaltered. Nucleotide sequencing revealed a few point mutations; nevertheless, the phenotype of the rescued viruses was nearly identical to that of the parental virus in all experiments. Thus, genetic stability of the chimeric clones and their phenotypic similarity to the parental virus confirm the ability of the yeast-based homologous recombination to maintain characteristics of the parental virus from which the recombinant viruses were derived. The data also support possible use of the yeast system for the manipulation of the BVDV genome.
Subject(s)
Animals , Cattle , Yeasts/genetics , Genome, Viral , DNA, Complementary , Diarrhea Viruses, Bovine Viral/genetics , Homologous Recombination , Virus Replication , Yeasts/metabolism , Cell Line , Open Reading Frames , Sequence Analysis, DNA , Diarrhea Viruses, Bovine Viral/physiology , Diarrhea Viruses, Bovine Viral/ultrastructureABSTRACT
Objective To construct a reverse genetic platform for influenza B virus and to rescue influenza B virus.Methods Eight plasmids carrying the gene segments of B/Florida/4/2006 virus were constructed by using the bidirectional promoter vector pHW2000.293T cells were co-cultured with MadinDarby canine kidney (MDCK) cells and then transfected with the eight plasmids.The supernatants of cell culture and cell debris were collected after transfection and then injected into embryonated chicken eggs and MDCK cells for rescuing the influenza B virus strains.Results This reverse genetic system could be used for the preparation of reassortant influenza B virus strains.The titers of hemagglutination units of the rescued virus achieved 128-256/50μl.Most of the reassortant virus particles were spherical under electron microscope.Conclusion The pHW2000 reverse genetic system could be used for the rescue of influenza B virus.Moreover,it could also be used for the construction of influenza B virus with specific mutations for further in vestigation on the characteristics of influenza B virus and the construction of vaccine strain.
ABSTRACT
The functional characterisation of thousands of
Subject(s)
Genetic Vectors/genetics , Trypanosoma cruzi/genetics , Chromatography, Affinity , Cloning, Molecular , Expressed Sequence Tags/metabolism , Gene Expression/genetics , PlasmidsABSTRACT
Objective Vaccination is a most effective method for the prevention of severe diseases caused by pandemic influenza and microRNA ( miRNA) mediated gene silencing has offered a novel approach to the construction of new vaccines.Our study aimed to construct a recombinant influenza A ( H1 N1 ) virus with the PB1 gene that carries the target fragment of miRNA Let-7b. Methods After comparing the sequence of the A/Nanjing/108/2009 H1N1 viral fragments with that of Let-7b, we selected PB1 as the optimal gene sequence, inserted the Let-7b binding target gene into PB1, ligated the modified fragments with pDP 2000, and named the recombinant plasmids pDP-mu-PB1 and pDP-sclb-PB1, respectively.We co-transfected the MDCK and 293T cells with the recombinant and other seven plasmids and injected the supernatant into the allantoic cavity of the chickenembryo for virus propagation, followed by detection of the virus by hemagglutination ( HA) assay and measurement of the viral titer by TCID50 .We amplified the viral cRNA by RT-PCR and identified the viruses by agarose gel electrophoresis and nucleotide sequence analysis. Results PB1 was the optimal sequence ( 83 bp -107bp) for the attenuation of viruses.The HA-titers of miRT-H1N1 and scbl-H1N1 were 1∶32 and 1∶64, and their viral loads were 4.68 ×105 and 7.94 ×104 TCID50/mL, respectively.Nucleotide sequence analysis showed the expected fragment in the rescued virus. Conclusion A recombinant strain vaccine was successfully constructed, which has laid the foundation for fur-ther assessment of virulence.
ABSTRACT
PURPOSE: New rabies vaccine bait for both pets and raccoon dogs residing in Korea is needed to eradicate rabies infection among animals. In this study, we constructed a recombinant rabies virus (RABV), the ERAG3G strain, using a reverse genetics system. Then we investigated the efficacy of this strain in mice after oral administration and the safety of this strain in cats after intramuscular administration. MATERIALS AND METHODS: The ERAG3G strain was rescued in BHK/T7-9 cells using the full-length genome mutated at the amino acid position 333 of the glycoprotein gene of RABV and helper plasmids. Four-week-old mice underwent one or two oral administrations of the ERAG3G strain and were challenged with the highly virulent RABV strain CVSN2c 14 days after the second administration. Clinical symptoms were observed and body weights were measured every day after the challenge. RESULTS: All mice showed complete protection against virulent RABV. In addition, cats intramuscularly inoculated with the ERAG3G strain showed high antibody titers ranging from 2.62 to 23.9 IU/mL at 28-day postinoculation. CONCLUSION: The oral immunization of the ERAG3G strain plays an important role in conferring complete protection in mice, and intramuscular inoculation of the ERAG3G strain induces the formation of anti-rabies neutralizing antibody in cats.
Subject(s)
Animals , Cats , Mice , Administration, Oral , Antibodies, Neutralizing , Body Weight , Genome , Glycoproteins , Immunization , Korea , Plasmids , Rabies , Rabies Vaccines , Rabies virus , Raccoon Dogs , Reverse GeneticsABSTRACT
The Infectious Bursal Disease Virus (IBDV) causes immunosuppression in young chickens. Advances in molecular virology and vaccines for IBDV have been achieved by viral reverse genetics (VRG). VRG for IBDV has undergone changes over time, however all strategies used to generate particles of IBDV involves multiple rounds of amplification and need of in vitro ligation and restriction sites. The aim of this research was to build the world's first VRG for IBDV by yeast-based homologous recombination; a more efficient, robust and simple process than cloning by in vitro ligation. The wild type IBDV (Wt-IBDV-Br) was isolated in Brazil and had its genome cloned in pJG-CMV-HDR vector by yeast-based homologous recombination. The clones were transfected into chicken embryo fibroblasts and the recovered virus (IC-IBDV-Br) showed genetic stability and similar phenotype to Wt-IBDV-Br, which were observed by nucleotide sequence, focus size/morphology and replication kinetics, respectively. Thus, IBDV reverse genetics by yeast-based homologous recombination provides tools to IBDV understanding and vaccines/viral vectors development.
Subject(s)
Animals , Chick Embryo , Homologous Recombination , Infectious bursal disease virus/genetics , Reverse Genetics/methods , Brazil , Cells, Cultured , Fibroblasts/virology , Genetic Vectors , Genomic Instability , Infectious bursal disease virus/isolation & purification , Infectious bursal disease virus/physiology , Saccharomyces cerevisiae/genetics , Transfection , Virus Cultivation , Virus ReplicationABSTRACT
Objective To construct a stable infectious clone of S191 virus strain used for the pro-duction of live attenuated measles vaccine. Methods Full length cDNA of S191 strain and gene fragments encoding nucleocapsid(N),phosphoprotein(P)and RNA polymerase(L)were synthesis and respectively cloned into the vector pVAX1. The 293T cells were respectively transfected with the recombinant expression plasmids and co-cultured with Vero cells. The supernatants of cell culture were collected for identifying res-cued viruses. The indirect immunofluorescence assay was performed for virus identification. The rescued viruses at different passages in Vero cells and the sequences of the rescued viruses were analyzed. Results Restriction enzyme digestion and sequence analysis showed that the recombinant expression plasmids contai-ning the full length cDNA with an artificially engineered mutation at nucleotide 2101(C-A)and gene frag-ments encoding N,P and L proteins of S191 strain were constructed successfully. The N and P proteins were detected in Vero cells with immunofluorescence assay. A cytopathogenic effect on Vero cells was induced by rescued viruses. Conclusion The stable infectious clones of S191 virus used for the production of live at-tenuated measles vaccine were rescued successfully. An approach by using reverse genetics technique for S191 strain study was established which could be used for the development of new chimeric vaccines against measles virus.
ABSTRACT
Novel reassortant H3N2 swine influenza viruses (SwIV) with the matrix gene from the 2009 H1N1 pandemic virus have been isolated in many countries as well as during outbreaks in multiple states in the United States, indicating that H3N2 SwIV might be a potential threat to public health. Since southern China is the world's largest producer of pigs, efficient vaccines should be developed to prevent pigs from acquiring H3N2 subtype SwIV infections, and thus limit the possibility of SwIV infection at agricultural fairs. In this study, a high-growth reassortant virus (GD/PR8) was generated by plasmid-based reverse genetics and tested as a candidate inactivated vaccine. The protective efficacy of this vaccine was evaluated in mice by challenging them with another H3N2 SwIV isolate [A/Swine/Heilongjiang/1/05 (H3N2) (HLJ/05)]. Prime and booster inoculation with GD/PR8 vaccine yielded high-titer serum hemagglutination inhibiting antibodies and IgG antibodies. Complete protection of mice against H3N2 SwIV was observed, with significantly reduced lung lesion and viral loads in vaccine-inoculated mice relative to mock-vaccinated controls. These results suggest that the GD/PR8 vaccine may serve as a promising candidate for rapid intervention of H3N2 SwIV outbreaks in China.
Subject(s)
Animals , Female , Mice , Influenza A Virus, H3N2 Subtype/genetics , Influenza Vaccines/genetics , Mice, Inbred BALB C , Orthomyxoviridae Infections/immunology , Reassortant Viruses/genetics , Reverse Genetics/methods , Swine , Swine Diseases/immunology , Vaccines, Inactivated , Virus ReplicationABSTRACT
Dengue virulence and fitness are important factors that determine disease outcome. However, dengue virus (DENV) molecular biology and pathogenesis are not completely elucidated. New insights on those mechanisms have been facilitated by the development of reverse genetic systems in the past decades. Unfortunately, instability of flavivirus genomes cloned in Escherichia coli has been a major problem in these systems. Here, we describe the development of a complete reverse genetics system, based on the construction of an infectious clone and replicon for a low passage DENV-3 genotype III of a clinical isolate. Both constructs were assembled into a newly designed yeast- E. coli shuttle vector by homologous recombination technique and propagated in yeast to prevent any possible genome instability in E. coli . RNA transcripts derived from the infectious clone are infectious upon transfection into BHK-21 cells even after repeated passages of the plasmid in yeast. Transcript-derived DENV-3 exhibited growth kinetics, focus formation size comparable to original DENV-3 in mosquito C6/36 cell culture. In vitro characterisation of DENV-3 replicon confirmed its identity and ability to replicate transiently in BHK-21 cells. The reverse genetics system reported here is a valuable tool that will facilitate further molecular studies in DENV replication, virus attenuation and pathogenesis.