scholarly journals Host serine proteases TMPRSS2 and TMPRSS11D mediate proteolytic activation and trypsin-independent infection in group A rotaviruses

2021 ◽  
Author(s):  
Michihito Sasaki ◽  
Yukari Itakura ◽  
Mai Kishimoto ◽  
Koshiro Tabata ◽  
Kentaro Uemura ◽  
...  
Keyword(s):  
Research And Development ◽  
Serine Proteases ◽  
Late Phase ◽  
Influenza Viruses ◽  
Activation Process ◽  
Virus Species ◽  
Proteolytic Activation ◽  
Group A Rotaviruses ◽  
Group A

Group A rotaviruses (RVAs) are representative enteric virus species and major causes of diarrhea in humans and animals. The RVA virion is a triple-layered particle, and the outermost layer consists of the glycoprotein VP7 and spike protein VP4. To increase the infectivity of RVA, VP4 is proteolytically cleaved into VP5* and VP8* subunits by trypsin; and these subunits form a rigid spike structure on the virion surface. In this study, we investigated the growth of RVAs in cells transduced with type II transmembrane serine proteases (TTSPs), which cleave fusion proteins and promote infection by respiratory viruses, such as influenza viruses, paramyxoviruses, and coronaviruses. We identified TMPRSS2 and TMPRSS11D as host TTSPs that mediate trypsin-independent and multi-cycle infection by human and animal RVA strains. In vitro cleavage assays revealed that recombinant TMPRSS11D cleaved RVA VP4. We also found that TMPRSS2 and TMPRSS11D promote the infectious entry of immature RVA virions, but they could not activate nascent progeny virions in the late phase of infection. This observation differed from the TTSP-mediated activation process of paramyxoviruses, revealing the existence of virus species-specific activation processes in TTSPs. Our study provides new insights into the interaction between RVAs and host factors, and TTSP-transduced cells offer potential advantages for RVA research and development. Importance Proteolytic cleavage of the viral VP4 protein is essential for virion maturation and infectivity in group A rotaviruses (RVAs). In cell culture, RVAs are propagated in culture medium supplemented with the exogenous protease trypsin, which cleaves VP4 and induces the maturation of progeny RVA virions. In this study, we demonstrated that the host proteases TMPRSS2 and TMPRSS11D mediate the trypsin-independent infection and growth of RVA. Our data revealed that the proteolytic activation of RVAs by TMPRSS2 and TMPRSS11D occurs at the viral entry step. Because TMPRSS2 and TMPRSS11D gene expression induced similar or higher levels of RVA growth as trypsin-supplemented culture, this approach offers potential advantages for RVA research and development.

scholarly journals Proteolytic Activation of Influenza Viruses by Serine Proteases TMPRSS2 and HAT from Human Airway Epithelium

2006 ◽  
Vol 80 (19) ◽  
pp. 9896-9898 ◽  
Author(s):  
Eva Böttcher ◽  
Tatyana Matrosovich ◽  
Michaela Beyerle ◽  
Hans-Dieter Klenk ◽  
Wolfgang Garten ◽  
...  
Keyword(s):  
Serine Proteases ◽  
Mammalian Cells ◽  
Mdck Cells ◽  
Influenza Viruses ◽  
Human Respiratory Tract ◽  
Proteolytic Activation ◽  
Mammalian Expression ◽  
Human Airway Epithelium

ABSTRACT Host cell proteases that cleave the hemagglutinin (HA) of influenza viruses in the human respiratory tract are still not identified. Here we cloned two human type II transmembrane serine proteases with known airway localization, TMPRSS2 and HAT, into mammalian expression vector. Cotransfection of mammalian cells with plasmids encoding HA and either protease resulted in HA cleavage in situ. Transient expression of either protease in MDCK cells enabled multicycle replication of influenza viruses in these cells in the absence of exogenous trypsin. These data suggest that TMPRSS2 and HAT are candidates for proteolytic activation of influenza viruses in vivo.

scholarly journals TMPRSS2 and TMPRSS4 Facilitate Trypsin-Independent Spread of Influenza Virus in Caco-2 Cells

2010 ◽  
Vol 84 (19) ◽  
pp. 10016-10025 ◽  
Author(s):  
Stephanie Bertram ◽  
Ilona Glowacka ◽  
Paulina Blazejewska ◽  
Elizabeth Soilleux ◽  
Paul Allen ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Serine Proteases ◽  
Alveolar Epithelium ◽  
Influenza Viruses ◽  
Target Cells ◽  
Human Respiratory Tract ◽  
Proteolytic Activation ◽  
Viral Spread ◽  
Endogenous Expression ◽  
Influenza Virus Hemagglutinin

ABSTRACT Proteolysis of influenza virus hemagglutinin by host cell proteases is essential for viral infectivity, but the proteases responsible are not well defined. Recently, we showed that engineered expression of the type II transmembrane serine proteases (TTSPs) TMPRSS2 and TMPRSS4 allows hemagglutinin (HA) cleavage. Here we analyzed whether TMPRSS2 and TMPRSS4 are expressed in influenza virus target cells and support viral spread in the absence of exogenously added protease (trypsin). We found that transient expression of TMPRSS2 and TMPRSS4 resulted in HA cleavage and trypsin-independent viral spread. Endogenous expression of TMPRSS2 and TMPRSS4 in cell lines correlated with the ability to support the spread of influenza virus in the absence of trypsin, indicating that these proteases might activate influenza virus in naturally permissive cells. Indeed, RNA interference (RNAi)-mediated knockdown of both TMPRSS2 and TMPRSS4 in Caco-2 cells, which released fully infectious virus without trypsin treatment, markedly reduced the spread of influenza virus, demonstrating that these proteases were responsible for efficient proteolytic activation of HA in this cell line. Finally, TMPRSS2 was found to be coexpressed with the major receptor determinant of human influenza viruses, 2,6-linked sialic acids, in human alveolar epithelium, indicating that viral target cells in the human respiratory tract express TMPRSS2. Collectively, our results point toward an important role for TMPRSS2 and possibly TMPRSS4 in influenza virus replication and highlight the former protease as a potential therapeutic target.

scholarly journals The process for the activation of frog epidermis pro-tyrosinase

1982 ◽  
Vol 205 (2) ◽  
pp. 397-404 ◽  
Author(s):  
R Peñafiel ◽  
J D Galindo ◽  
E Pedreño ◽  
J A Lozano
Keyword(s):  
Quaternary Structure ◽  
Polypeptide Chain ◽  
Rana Esculenta ◽  
Single Type ◽  
Low Molecular Weight ◽  
Activation Process ◽  
Proteolytic Activation ◽  
Molecular Weights ◽  
Quaternary Structures

1. Purified pro-tyrosinase from epidermis of the frog Rana esculenta ridibunda can be activated in vitro by several proteinases (trypsin, alpha-chymotrypsin, Pronase) and by light. 2. Both pro-tyrosinase and tyrosinase are composed of a single type of subunit having pI 7.2 and approximate molecular weights 68000 and 62000 respectively. A peptide of low molecular weight is released as a consequence of the proteolytic activation. Pro-tyrosinase and tyrosinase have different quaternary structures, the proenzyme being a dimer of Mr approx. 115000 and the enzyme a tetramer of Mr approx. 210 000. 3. The activation process was affected by several agents (L-3,4-dihydroxyphenylalanine, urea, formamide) that prevented, partially or totally, the activation of pro-tyrosinase. 4. The activation of pro-tyrosinase seems to be the result of a cleavage of the polypeptide chain that determines changes in tertiary or quaternary structure.

scholarly journals Integration of Deep Multi-Omics Profiling Veals New Insights into the Biology of Poor-Risk Acute Myeloid Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 39-40
Author(s):  
Ana Rio-Machin ◽  
Pedro Casado-Izquierdo ◽  
Juho Miettinen ◽  
Findlay Bewicke-Copley ◽  
Naeem Khan ◽  
...  
Keyword(s):  
Research Funding ◽  
Drug Sensitivity ◽  
Germ Line ◽  
Late Phase ◽  
Rna Seq ◽  
Poor Risk ◽  
Group A ◽  
Group B ◽  
Acute Myeloid

Background: The poor-risk cytogenetic subgroup of acute myeloid leukaemia (AML) includes various chromosomal aberrations and represents a heterogeneous population of patients with a dismal 10-year overall survival. While the success of genetic landscaping studies is encouraging, it is debatable whether genomics, or indeed any single-omics platform alone, is sufficient to capture the biology of a disease that continues to evade our existing treatments so effectively. Instead, we need to develop a much better understanding of the complexity of this subgroup of AMLs: the relationship and interdependencies across biochemical pathways, how these may differ between patients and their impact on the leukemia and normal stem cell compartments. To launch this process, we have completed a multi-omics profiling programme to shed new light on the genetic and biochemical features of poor-risk AML (https://poor-risk-aml.bham.ac.uk/). Aims: Application of multi-omics and integrative approaches to decipher the complexities of cytogenetically poor-risk AML Methods: Sample inclusion criteria were based on cytogenetics and availability of sufficient diagnostic bone marrow or peripheral blood material for analysis. The 50 primary AMLs included 17 cases with complex karyotype, 13 -7/del(7), 11 KMT2A rearrangements (with the exception of t(9;11)), 4 t(6;9), 3 -5/de(5), 1 del(17) and 1 inv(3). Profiles consisted of a combination of genomics (whole genome sequencing (WGS, 60X for tumour and 30X for germ-line controls), targeted sequencing of 54 myeloid loci, and total RNA-seq (100 million reads per bulk sample), mass spectrometry proteomics and phosphoproteomics (with >6,000 proteins and > 25,000 phosphorylation sites detected and quantified), mass cytometry (CyTOF, 39 markers), drug screening (ranging from 200-500 approved or investigational compounds) and the selective generation of patient-derived xenograft (PDX) models. Results: Near complete datasets have been compiled on all 50 primary AMLs, with the exception of WGS analysis where profiling was restricted to cases where corresponding germline DNA was available. Integration of WGS and RNA-seq data identified 122 genes having notable allele-specific expression (ASE) in ≥ 5 samples supported by ≥ 3 SNPs and these included the transcription factor GATA2 and the DNA topoisomerase TOP1MT. Use of RNA fusion capture tools resolved novel inter- and intra- chromosomal gene rearrangements that were confirmed by WGS. The four t(6;9)(p23;q34)/DEK-NUP214 cases, with a mean age of diagnosis of 43.5 years and all harboring FLT3-ITD mutations, arose from the most immature hematopoietic compartment (CD34+CD117+ enrichment) and demonstrated a unique transcriptomic signature, which included upregulation of FOXO3 and GRP56. Collectively, t(6;9) primary samples also showed a selective drug sensitivity to XPO1 (selinexor and eltanexor) and JAK inhibitors (ruxolitinib, tofacitinib and momelotinib) compared to other cytogenetic risk groups. On the other hand, a comparison of in vitro drug sensitivity data with genomic data of our entire cohort of patients demonstrated that TP53 wt AMLs (n=37) were more sensitive to all four MDM2 inhibitors (AMG-232, idasanutlin, SAR405838 and NVP-CGM097) compared to TP53 mutated cases (n=13). Comparisons of transcriptomics with the in vitro sensitivity to drugs included in early/late phase AML clinical trials, identified signatures of response associated with MDM2 and Aurora B kinase (AZD1152-HQPA) inhibitors. Phosphoproteomics analysis and machine learning modeling separated KMT2A rearranged leukemias into 2 discrete groups (group A: MLLT4, MLLT10 and TET1; group B with MLLT6, ELL and SEP9 fusion partners). Functionally, group A presented with elevated HOXA10 protein expression and enhanced in vitro response to genotoxic drugs and cell cycle inhibitors when compared to group B leukemia. Conclusions: Our study demonstrates the feasibility of simultaneously generating omics data from several different platforms and highlights that a combination of genetic and proteomic profiles may help to inform the choice of therapies based on the underlying biology of a patient's AML. Disclosures Wennerberg: Novartis: Research Funding; Pfizer: Honoraria. Heckman:Celgene: Research Funding; Novartis: Research Funding; Oncopeptides: Research Funding; Orion Pharma: Research Funding; Innovative Mediicines Initiative project Harmony: Research Funding.

In vivo contribution of serine proteases to the proteolytic activation of γENaC in aldosterone-infused rats

2012 ◽  
Vol 303 (7) ◽  
pp. F939-F943 ◽  
Author(s):  
Kohei Uchimura ◽  
Yutaka Kakizoe ◽  
Tomoaki Onoue ◽  
Manabu Hayata ◽  
Jun Morinaga ◽  
...  
Keyword(s):  
Protease Inhibitor ◽  
Serine Protease ◽  
Serine Proteases ◽  
Serine Protease Inhibitor ◽  
Proteolytic Activation ◽  
New Strategy ◽  
Salt Sensitive Hypertension ◽  
Primary Cleavage

Aldosterone plays an important role in the regulation of blood pressure by modulating the activity of the epithelial sodium channel (ENaC) that consists of α-, β-, and γ-subunits. Aldosterone induces a molecular weight shift of γENaC from 85 to 70 kDa that is necessary for the channel activation. In vitro experiments demonstrated that a dual cleavage mechanism is responsible for this shift. It has been postulated that furin executes the primary cleavage in the Golgi and that the second cleavage is provided by other serine proteases such as prostasin or plasmin at the plasma membrane. However, the in vivo contribution of serine proteases to this cleavage remains unclear. To address this issue, we administered the synthetic serine protease inhibitor camostat mesilate (CM) to aldosterone-infused rats. CM decreased the abundance of the 70-kDa form of ENaC and led to a new 75-kDa form with a concomitant increase in the urinary Na-to-K ratio. Because CM inhibits the protease activity of serine proteases such as prostasin and plasmin, but not furin, our findings strongly indicate that CM inhibited the second cleavage of γENaC and subsequently suppressed ENaC activity. The results of our current studies also suggest the possibility that the synthetic serine protease inhibitor CM might represent a new strategy for the treatment of salt-sensitive hypertension in humans.

scholarly journals Kallikrein-Related Peptidase 5 Contributes to H3N2 Influenza Virus Infection in Human Lungs

2017 ◽  
Vol 91 (16) ◽  
Author(s):  
Mélia Magnen ◽  
Fabien Gueugnon ◽  
Antoine Guillon ◽  
Thomas Baranek ◽  
Virginie C. Thibault ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Respiratory Tract ◽  
Serine Proteases ◽  
Lower Respiratory Tract ◽  
Influenza A ◽  
Seasonal Influenza ◽  
Influenza Viruses ◽  
H3n2 Virus ◽  
Influenza A Viruses

ABSTRACT Hemagglutinin (HA) of influenza virus must be activated by proteolysis before the virus can become infectious. Previous studies indicated that HA cleavage is driven by membrane-bound or extracellular serine proteases in the respiratory tract. However, there is still uncertainty as to which proteases are critical for activating HAs of seasonal influenza A viruses (IAVs) in humans. This study focuses on human KLK1 and KLK5, 2 of the 15 serine proteases known as the kallikrein-related peptidases (KLKs). We find that their mRNA expression in primary human bronchial cells is stimulated by IAV infection. Both enzymes cleaved recombinant HA from several strains of the H1 and/or H3 virus subtype in vitro, but only KLK5 promoted the infectivity of A/Puerto Rico/8/34 (H1N1) and A/Scotland/20/74 (H3N2) virions in MDCK cells. We assessed the ability of treated viruses to initiate influenza in mice. The nasal instillation of only the KLK5-treated virus resulted in weight loss and lethal outcomes. The secretion of this protease in the human lower respiratory tract is enhanced during influenza. Moreover, we show that pretreatment of airway secretions with a KLK5-selective inhibitor significantly reduced the activation of influenza A/Scotland/20/74 virions, providing further evidence of its importance. Differently, increased KLK1 secretion appeared to be associated with the recruitment of inflammatory cells in human airways regardless of the origin of inflammation. Thus, our findings point to the involvement of KLK5 in the proteolytic activation and spread of seasonal influenza viruses in humans. IMPORTANCE Influenza A viruses (IAVs) cause acute infection of the respiratory tract that affects millions of people during seasonal outbreaks every year. Cleavage of the hemagglutinin precursor by host proteases is a critical step in the life cycle of these viruses. Consequently, host proteases that activate HA can be considered promising targets for the development of new antivirals. However, the specific proteases that activate seasonal influenza viruses, especially H3N2 viruses, in the human respiratory tract have remain undefined despite many years of work. Here we demonstrate that the secreted, extracellular protease KLK5 (kallikrein-related peptidase 5) is efficient in promoting the infectivity of H3N2 IAV in vitro and in vivo. Furthermore, we found that its secretion was selectively enhanced in the human lower respiratory tract during a seasonal outbreak dominated by an H3N2 virus. Collectively, our data support the clinical relevance of this protease in human influenza pathogenesis.

Kallikrein-related peptidase 5 and seasonal influenza viruses, limitations of the experimental models for activating proteases

2018 ◽  
Vol 399 (9) ◽  
pp. 1053-1064 ◽  
Author(s):  
Mélia Magnen ◽  
Brigitta Margit Elsässer ◽  
Olga Zbodakova ◽  
Petr Kasparek ◽  
Fabien Gueugnon ◽  
...  
Keyword(s):  
Serine Proteases ◽  
Influenza A ◽  
Mdck Cells ◽  
Experimental Models ◽  
Influenza Viruses ◽  
Virus Infectivity ◽  
Peptide Substrates ◽  
Viral Hemagglutinin

Abstract Every year, influenza A virus (IAV) affects and kills many people worldwide. The viral hemagglutinin (HA) is a critical actor in influenza virus infectivity which needs to be cleaved by host serine proteases to exert its activity. KLK5 has been identified as an activating protease in humans with a preference for the H3N2 IAV subtype. We investigated the origin of this preference using influenza A/Puerto Rico/8/34 (PR8, H1N1) and A/Scotland/20/74 (Scotland, H3N2) viruses. Pretreatment of noninfectious virions with human KLK5 increased infectivity of Scotland IAV in MDCK cells and triggered influenza pneumonia in mice. These effects were not observed with the PR8 IAV. Molecular modeling and in vitro enzymatic studies of peptide substrates and recombinant HAs revealed that the sequences around the cleavage site do not represent the sole determinant of the KLK5 preference for the H3N2 subtype. Using mouse Klk5 and Klk5-deficient mice, we demonstrated in vitro and in vivo that the mouse ortholog protease is not an IAV activating enzyme. This may be explained by unfavorable interactions between H3 HA and mKlk5. Our data highlight the limitations of some approaches used to identify IAV-activating proteases.

scholarly journals Group A Rotavirus VP1 Polymerase and VP2 Core Shell Proteins: Intergenotypic Sequence Variation andIn VitroFunctional Compatibility

2018 ◽  
Vol 93 (2) ◽  
Author(s):  
Courtney L. Steger ◽  
Crystal E. Boudreaux ◽  
Leslie E. LaConte ◽  
James B. Pease ◽  
Sarah M. McDonald
Keyword(s):  
Nucleotide Sequence ◽  
Protein Level ◽  
Core Shell ◽  
Gene Encoding ◽  
Cutoff Value ◽  
Shell Protein ◽  
Shell Proteins ◽  
Group A Rotaviruses ◽  
Group A

ABSTRACTGroup A rotaviruses (RVAs) are classified according to a nucleotide sequence-based system that assigns a genotype to each of the 11 double-stranded RNA (dsRNA) genome segments. For the segment encoding the VP1 polymerase, 22 genotypes (R1 to R22) are defined with an 83% nucleotide identity cutoff value. For the segment encoding the VP2 core shell protein, which is a functional VP1-binding partner, 20 genotypes (C1 to C20) are defined with an 84% nucleotide identity cutoff value. However, the extent to which the VP1 and VP2 proteins encoded by these genotypes differ in their sequences or interactions has not been described. Here, we sought to (i) delineate the relationships and sites of variation for VP1 and VP2 proteins belonging to the known RVA genotypes and (ii) correlate intergenotypic sequence diversity with functional VP1-VP2 interaction(s) during dsRNA synthesis. Using bioinformatic approaches, we revealed which VP1 and VP2 genotypes encode divergent proteins and identified the positional locations of amino acid changes in the context of known structural domains/subdomains. We then employed anin vitrodsRNA synthesis assay to test whether genotype R1, R2, R4, and R7 VP1 polymerases could be enzymatically activated by genotype C1, C2, C4, C5, and C7 VP2 core shell proteins. Genotype combinations that were incompatible informed the rational design andin vitrotesting of chimeric mutant VP1 and VP2 proteins. The results of this study connect VP1 and VP2 nucleotide-level diversity to protein-level diversity for the first time, and they provide new insights into regions/residues critical for VP1-VP2 interaction(s) during viral genome replication.IMPORTANCEGroup A rotaviruses (RVAs) are widespread in nature, infecting numerous mammalian and avian hosts and causing severe gastroenteritis in human children. RVAs are classified using a system that assigns a genotype to each viral gene according to its nucleotide sequence. To date, 22 genotypes have been described for the gene encoding the viral polymerase (VP1), and 20 genotypes have been described for the gene encoding the core shell protein (VP2). Here, we analyzed if/how the VP1 and VP2 proteins encoded by the known RVA genotypes differ from each other in their sequences. We also used a biochemical approach to test whether the intergenotypic sequence differences influenced how VP1 and VP2 functionally engage each other to mediate RNA synthesis in a test tube. This work is important because it increases our understanding of RVA protein-level diversity and raises new ideas about the VP1-VP2 binding interface(s) that is important for viral replication.

scholarly journals Co-Infection by Waterborne Enteric Viruses in Children with Gastroenteritis in Nepal

Healthcare ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 9 ◽  
Author(s):  
Sarmila Tandukar ◽  
Jeevan Sherchand ◽  
Surendra Karki ◽  
Bikash Malla ◽  
Rajani Ghaju Shrestha ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Acute Gastroenteritis ◽  
Enteric Viruses ◽  
Enteric Virus ◽  
Viral Agent ◽  
Virus Species ◽  
Group A Rotaviruses ◽  
Group A ◽  
Stool Samples

Enteric viruses are highly contagious and a major cause of waterborne gastroenteritis in children younger than five years of age in developing world. This study examined the prevalence of enteric virus infection in children with gastroenteritis to identify risk factors for co-infections. In total, 107 stool samples were collected from patients with acute gastroenteritis along with samples of their household drinking water and other possible contamination sources, such as food and hand. The presence of major gastroenteritis-causing enteric virus species (group A rotaviruses, enteroviruses, adenoviruses, and noroviruses of genogroup I) in stool and water samples was examined using quantitative polymerase chain reaction. Among the 107 stool samples tested, 103 (96%) samples contained at least one of the four tested enteric viruses, and the combination of group A rotaviruses and enteroviruses was the most common co-infection (52%, n = 54/103). At least one viral agent was detected in 16 (16%) of 103 drinking water samples. Identical enteric viruses were detected in both the stool and water samples taken from the same patients in 13% of cases (n = 13/103). Group A rotaviruses were most frequently found in children suffering from acute diarrhea. No socio-demographic and clinical factors were associated with the risk of co-infection compared with mono-infection. These less commonly diagnosed viral etiological agents in hospitals are highly prevalent in patients with acute gastroenteritis.

scholarly journals Rearranged Genomic RNA Segments Offer a New Approach to the Reverse Genetics of Rotaviruses

2010 ◽  
Vol 84 (13) ◽  
pp. 6711-6719 ◽  
Author(s):  
Cécile Troupin ◽  
Axelle Dehée ◽  
Aurélie Schnuriger ◽  
Patrice Vende ◽  
Didier Poncet ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Reverse Genetics ◽  
Nonstructural Protein ◽  
Helper Virus ◽  
Wild Type ◽  
Human Rotavirus ◽  
Protein Functions ◽  
Group A Rotaviruses ◽  
Group A

ABSTRACT Group A rotaviruses (RV), members of the Reoviridae family, are a major cause of infantile acute gastroenteritis. The RV genome consists of 11 double-stranded RNA segments. In some cases, an RNA segment is replaced by a rearranged RNA segment, which is derived from its standard counterpart by partial sequence duplication. We report here a reverse genetics system for RV based on the preferential packaging of rearranged RNA segments. Using this system, wild-type or in vitro-engineered forms of rearranged segment 7 from a human rotavirus (encoding the NSP3 protein), derived from cloned cDNAs and transcribed in the cytoplasm of COS-7 cells with the help of T7 RNA polymerase, replaced the wild-type segment 7 of a bovine helper virus (strain RF). Recombinant RF viruses (i.e., engineered monoreassortant RF viruses) containing an exogenous rearranged RNA were recovered by propagating the viral progeny in MA-104 cells, with no need for additional selective pressure. Our findings offer the possibility to extend RV reverse genetics to segments encoding nonstructural or structural proteins for which no potent selective tools, such as neutralizing antibodies, are available. In addition, the system described here is the first to enable the introduction of a mutated gene expressing a modified nonstructural protein into an infectious RV. This reverse genetics system offers new perspectives for investigating RV protein functions and developing recombinant live RV vaccines containing specific changes targeted for attenuation.

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