Critical Role of Alpha-Toxin and Protective Effects of Its Neutralization by a Human Antibody in Acute Bacterial Skin and Skin Structure Infections

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) causes large-scale epidemics of acute bacterial skin and skin structure infections (ABSSSI) within communities across the United States. Animal models that reproduce ABSSSI as they occur in humans are urgently needed to test new therapeutic strategies. Alpha-toxin plays a critical role in a variety of staphylococcal infection models in mice, but its role in the pathogenesis of ABSSSI remains to be elucidated in rabbits, which are similar to humans in their susceptibility toS. aureussuperantigens and certain bicomponent pore-forming leukocidins. We report here a new rabbit model of ABSSSI and show that those infected with a mutant deficient in expression of alpha-toxin (Δhla) developed a small dermonecrotic lesion, whereas those infected with isogenic USA300 MRSA wild-type or complemented Δhlastrains developed ABSSSI that mimic the severe infections that occur in humans, including the large central dermonecrotic core surrounded by erythema, induration, and marked subcutaneous hemorrhage. More importantly, immunoprophylaxis with MEDI4893*, an anti-alpha-toxin human monoclonal antibody, significantly reduced the severity of disease caused by a USA300 wild-type strain to that caused by the Δhlamutant, indicating that this toxin could be completely neutralized during infection. Thus, this study illustrates a potential high standard for the development of new immunotherapeutic agents in which a toxin-neutralizing antibody provides protection to the same degree achieved with a toxin gene knockout. When MEDI4893* was administered as adjunctive therapy with a subtherapeutic dose of linezolid, the combination was significantly more efficacious than either agent alone in reducing the severity of ABSSSI.

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Chromosomal Insertions in the Lactobacillus caseiuppGene That Are Useful for Vaccine Expression

Applied and Environmental Microbiology ◽

10.1128/aem.00175-14 ◽

2014 ◽

Vol 80 (11) ◽

pp. 3321-3326 ◽

Cited By ~ 25

Author(s):

Bai-fen Song ◽

Long-zhu Ju ◽

Yi-jing Li ◽

Li-jie Tang

Keyword(s):

Pcr Amplification ◽

Effective Vaccine ◽

Enzyme Linked Immunosorbent Assay ◽

Toxin Gene ◽

Temperature Sensitive ◽

Alpha Toxin ◽

Wild Type ◽

Recombinant Bacteria ◽

Content Type ◽

Marker Free

ABSTRACTTo develop a stable and marker-freeLactobacillusstrain useful for the expression of vaccines, we developed a temperature-sensitive suicide plasmid with expression cassettes containing an HCE promoter, a PgsA anchor, the alpha-toxin gene, and anrrnBT1T2 terminator (PPαT) that uses a 5-fluorouracil (5-FU) counterselectable marker forLactobacillus casei. Three strains containing the correct PPαT expression cassettes were produced via the selective pressure of 5-FU screening. We confirmed that theuppgene was deleted and that the PPαT expression cassettes were inserted into theuppsite ofL. caseiATCC 393 by genomic PCR amplification and sequencing. 5-FU resistance in recombinant bacteria could be stably inherited for as long as 40 generations following insertion. However, bacteria containing the integrated DNA grew more slowly than wild-typeL. casei. An indirect enzyme-linked immunosorbent assay (ELISA) analysis demonstrated that the alpha-toxin gene was expressed. Also, we visualized expression of the protein on the surface ofL. caseicells using laser confocal microscopy. These results taken together demonstrate that these recombinant bacteria should provide a safe tool for effective vaccine production.

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Phagocytes from Mice Lacking the Sts Phosphatases Have an Enhanced Antifungal Response to Candida albicans

mBio ◽

10.1128/mbio.00782-18 ◽

2018 ◽

Vol 9 (4) ◽

Cited By ~ 8

Author(s):

David Frank ◽

Shamoon Naseem ◽

Gian Luigi Russo ◽

Cindy Li ◽

Kaustubh Parashar ◽

...

Keyword(s):

Bone Marrow ◽

Immune Response ◽

Candida Albicans ◽

Tyrosine Kinase ◽

Critical Role ◽

Inflammasome Activation ◽

Wild Type ◽

Content Type ◽

Enhanced Production ◽

Immunological Mechanisms

ABSTRACT Mice lacking expression of the homologous phosphatases Sts-1 and Sts-2 (Sts−/− mice) are resistant to disseminated candidiasis caused by the fungal pathogen Candida albicans. To better understand the immunological mechanisms underlying the enhanced resistance of Sts−/− mice, we examined the kinetics of fungal clearance at early time points. In contrast to the rapid C. albicans growth seen in normal kidneys during the first 24 h postinfection, we observed a reduction in kidney fungal CFU within Sts−/− mice beginning at 12 to 18 h postinfection. This corresponds to the time period when large numbers of innate leukocytes enter the renal environment to counter the infection. Because phagocytes of the innate immune system are important for host protection against pathogenic fungi, we evaluated responses of bone marrow leukocytes. Relative to wild-type cells, Sts−/− marrow monocytes and bone marrow-derived dendritic cells (BMDCs) displayed a heightened ability to inhibit C. albicans growth ex vivo. This correlated with significantly enhanced production of reactive oxygen species (ROS) by Sts−/− BMDCs downstream of Dectin-1, a C-type lectin receptor that plays a critical role in stimulating host responses to fungi. We observed no visible differences in the responses of other antifungal effector pathways, including cytokine production and inflammasome activation, despite enhanced activation of the Syk tyrosine kinase downstream of Dectin-1 in Sts−/− cells. Our results highlight a novel mechanism regulating the immune response to fungal infections. Further understanding of this regulatory pathway could aid the development of therapeutic approaches to enhance protection against invasive candidiasis. IMPORTANCE Systemic candidiasis caused by fungal Candida species is becoming an increasingly serious medical problem for which current treatment is inadequate. Recently, the Sts phosphatases were established as key regulators of the host antifungal immune response. In particular, genetic inactivation of Sts significantly enhanced survival of mice infected intravenously with Candida albicans. The Sts−/− in vivo resistance phenotype is associated with reduced fungal burden and an absence of inflammatory lesions. To understand the underlying mechanisms, we studied phagocyte responses. Here, we demonstrate that Sts−/− phagocytes have heightened responsiveness to C. albicans challenge relative to wild-type cells. Our data indicate the Sts proteins negatively regulate phagocyte activation via regulating selective elements of the Dectin-1–Syk tyrosine kinase signaling axis. These results suggest that phagocytes lacking Sts respond to fungal challenge more effectively and that this enhanced responsiveness partially underlies the profound resistance of Sts−/− mice to systemic fungal challenge.

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Linezolid Attenuates Lethal Lung Damage during Postinfluenza Methicillin-Resistant Staphylococcus aureus Pneumonia

Infection and Immunity ◽

10.1128/iai.00538-19 ◽

2019 ◽

Vol 87 (10) ◽

Cited By ~ 2

Author(s):

Atul K. Verma ◽

Christopher Bauer ◽

Vijaya Kumar Yajjala ◽

Shruti Bansal ◽

Keer Sun

Keyword(s):

Staphylococcus Aureus ◽

Therapeutic Effect ◽

Critical Role ◽

Lung Damage ◽

Alpha Toxin ◽

Methicillin Resistant ◽

Content Type ◽

Linezolid Therapy ◽

Staphylococcus Aureus Pneumonia ◽

The Impact

ABSTRACT Postinfluenza methicillin-resistant Staphylococcus aureus (MRSA) infection can quickly develop into severe, necrotizing pneumonia, causing over 50% mortality despite antibiotic treatments. In this study, we investigated the efficacy of antibiotic therapies and the impact of S. aureus alpha-toxin in a model of lethal influenza virus and MRSA coinfection. We demonstrate that antibiotics primarily attenuate alpha-toxin-induced acute lethality, even though both alpha-toxin-dependent and -independent mechanisms significantly contribute to animal mortality after coinfection. Furthermore, we found that the protein synthesis-suppressing antibiotic linezolid has an advantageous therapeutic effect on alpha-toxin-induced lung damage, as measured by protein leak and lactate dehydrogenase (LDH) activity. Importantly, using a Panton-Valentine leucocidin (PVL)-negative MRSA isolate from patient sputum, we show that linezolid therapy significantly improves animal survival from postinfluenza MRSA pneumonia compared with vancomycin treatment. Rather than improved viral or bacterial control, this advantageous therapeutic effect is associated with a significantly attenuated proinflammatory cytokine response and acute lung damage in linezolid-treated mice. Together, our findings not only establish a critical role of alpha-toxin in the extreme mortality of secondary MRSA pneumonia after influenza but also provide support for the possibility that linezolid could be a more effective treatment than vancomycin to improve disease outcomes.

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VibA, a Homologue of a Transcription Factor for Fungal Heterokaryon Incompatibility, Is Involved in Antifungal Compound Production in the Plant-Symbiotic Fungus Epichloë festucae

Eukaryotic Cell ◽

10.1128/ec.00034-14 ◽

2014 ◽

Vol 14 (1) ◽

pp. 13-24 ◽

Cited By ~ 14

Author(s):

Jennifer T. Niones ◽

Daigo Takemoto

Keyword(s):

Transcription Factor ◽

Antifungal Activity ◽

Critical Role ◽

Antifungal Compound ◽

Symbiotic Association ◽

Wild Type ◽

Exogenous Dna ◽

Content Type ◽

Type Isolate ◽

Epichloë Festucae

ABSTRACT Symbiotic association of epichloae endophytes ( Epichloë/Neotyphodium species) with cool-season grasses of the subfamily Pooideae confers bioprotective benefits to the host plants against abiotic and biotic stresses. While the production of fungal bioprotective metabolites is a well-studied mechanism of host protection from insect herbivory, little is known about the antibiosis mechanism against grass pathogens by the mutualistic endophyte. In this study, an Epichloë festucae mutant defective in antimicrobial substance production was isolated by a mutagenesis approach. In an isolated mutant that had lost antifungal activity, the exogenous DNA fragment was integrated into the promoter region of the vibA gene, encoding a homologue of the transcription factor VIB-1. VIB-1 in Neurospora crassa is a regulator of genes essential in vegetative incompatibility and promotion of cell death. Here we show that deletion of the vibA gene severely affected the antifungal activity of the mutant against the test pathogen Drechslera erythrospila . Further analyses showed that overexpressing vibA enhanced the antifungal activity of the wild-type isolate against test pathogens. Transformants overexpressing vibA showed an inhibitory activity on test pathogens that the wild-type isolate could not. Moreover, overexpressing vibA in a nonantifungal E. festucae wild-type Fl1 isolate enabled the transformant to inhibit the mycelial and spore germination of D. erythrospila . These results demonstrate that enhanced expression of vibA is sufficient for a nonantifungal isolate to obtain antifungal activity, implicating the critical role of VibA in antifungal compound production by epichloae endophytes.

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Construction of an Alpha Toxin Gene Knockout Mutant of Clostridium perfringens Type A by Use of a Mobile Group II Intron

Applied and Environmental Microbiology ◽

10.1128/aem.71.11.7542-7547.2005 ◽

2005 ◽

Vol 71 (11) ◽

pp. 7542-7547 ◽

Cited By ~ 96

Author(s):

Yue Chen ◽

Bruce A. McClane ◽

Derek J. Fisher ◽

Julian I. Rood ◽

Phalguni Gupta

Keyword(s):

Clostridium Perfringens ◽

Gene Knockout ◽

Antibiotic Resistance Genes ◽

Group Ii Intron ◽

Toxin Gene ◽

No Production ◽

Alpha Toxin ◽

Knockout Mutant ◽

New Strategy ◽

Group Ii

ABSTRACT In developing Clostridium perfringens as a safe vaccine vector, the alpha toxin gene (plc) in the bacterial chromosome must be permanently inactivated. Disrupting genes in C. perfringens by traditional mutagenesis methods is very difficult. Therefore, we developed a new strategy using group II intron-based Target-Tron technology to inactivate the plc gene in C. perfringens ATCC 3624. Western blot analysis showed no production of alpha toxin protein in the culture supernatant of the plc mutant. Advantages of this technology, such as site specificity, relatively high frequency of insertion, and introduction of no antibiotic resistance genes into the chromosome, could facilitate construction of other C. perfringens mutants.

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Ceftobiprole Activity against Bacteria from Skin and Skin Structure Infections in the United States from 2016 through 2018

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02566-19 ◽

2020 ◽

Vol 64 (6) ◽

Author(s):

Robert K. Flamm ◽

Leonard R. Duncan ◽

Kamal A. Hamed ◽

Jennifer I. Smart ◽

Rodrigo E. Mendes ◽

...

Keyword(s):

United States ◽

The United States ◽

Generation Cephalosporin ◽

Clinical Isolates ◽

Surveillance Program ◽

Coagulase Negative Staphylococci ◽

Gram Positive ◽

Content Type ◽

Skin Structure ◽

Highly Active

ABSTRACT Ceftobiprole medocaril is an advanced-generation cephalosporin prodrug that has qualified infectious disease product status granted by the US FDA and is currently being evaluated in phase 3 clinical trials in patients with acute bacterial skin and skin structure infections (ABSSSIs) and in patients with Staphylococcus aureus bacteremia. In this study, the activity of ceftobiprole and comparators was evaluated against more than 7,300 clinical isolates collected in the United States from 2016 through 2018 from patients with skin and skin structure infections. The major species/pathogen groups were S. aureus (53%), Enterobacterales (23%), Pseudomonas aeruginosa (7%), beta-hemolytic streptococci (6%), Enterococcus spp. (4%), and coagulase-negative staphylococci (2%). Ceftobiprole was highly active against S. aureus (MIC50/90, 0.5/1 mg/liter; 99.7% susceptible by EUCAST criteria; 42% methicillin-resistant S. aureus [MRSA]). Ceftobiprole also exhibited potent activity against other Gram-positive cocci. The overall susceptibility of Enterobacterales to ceftobiprole was 84.8% (>99.0% susceptible for isolate subsets that exhibited a non-extended-spectrum β-lactamase [ESBL] phenotype). A total of 74.4% of P. aeruginosa, 100% of beta-hemolytic streptococci and coagulase-negative staphylococci, and 99.6% of Enterococcus faecalis isolates were inhibited by ceftobiprole at ≤4 mg/liter. As expected, ceftobiprole was largely inactive against Enterobacterales that contained ESBL genes and Enterococcus faecium. Overall, ceftobiprole was highly active against most clinical isolates from the major Gram-positive and Gram-negative skin and skin structure pathogen groups collected at U.S. medical centers participating in the SENTRY Antimicrobial Surveillance Program during 2016 to 2018. The broad-spectrum activity of ceftobiprole, including potent activity against MRSA, supports its further evaluation for a potential ABSSSI indication.

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An Attenuated Salmonella enterica Serovar Typhimurium Strain and Galacto-Oligosaccharides Accelerate Clearance of Salmonella Infections in Poultry through Modifications to the Gut Microbiome

Applied and Environmental Microbiology ◽

10.1128/aem.02526-17 ◽

2017 ◽

Vol 84 (5) ◽

Cited By ~ 17

Author(s):

M. Andrea Azcarate-Peril ◽

Natasha Butz ◽

Maria Belen Cadenas ◽

Matthew Koci ◽

Anne Ballou ◽

...

Keyword(s):

United States ◽

Gut Microbiota ◽

Gut Microbiome ◽

Salmonella Enterica ◽

The United States ◽

Wild Type ◽

Content Type ◽

Salmonella Infections ◽

Serovar Typhimurium ◽

The Impact

ABSTRACT Salmonella is estimated to cause one million foodborne illnesses in the United States every year. Salmonella -contaminated poultry products are one of the major sources of salmonellosis. Given the critical role of the gut microbiota in Salmonella transmission, a manipulation of the chicken intestinal microenvironment could prevent animal colonization by the pathogen. In Salmonella , the global regulator gene fnr ( f umarate n itrate r eduction) regulates anaerobic metabolism and is essential for adapting to the gut environment. This study tested the hypothesis that an attenuated Fnr mutant of Salmonella enterica serovar Typhimurium (attST) or prebiotic galacto-oligosaccharides (GOS) could improve resistance to wild-type Salmonella via modifications to the structure of the chicken gut microbiome. Intestinal samples from a total of 273 animals were collected weekly for 9 weeks to evaluate the impact of attST or prebiotic supplementation on microbial species of the cecum, duodenum, jejunum, and ileum. We next analyzed changes to the gut microbiome induced by challenging the animals with a wild-type Salmonella serovar 4,[5],12:r:− (Nal r ) strain and determined the clearance rate of the virulent strain in the treated and control groups. Both GOS and the attenuated Salmonella strain modified the gut microbiome but elicited alterations of different taxonomic groups. The attST produced significant increases of Alistipes and undefined Lactobacillus , while GOS increased Christensenellaceae and Lactobacillus reuteri . The microbiome structural changes induced by both treatments resulted in a faster clearance after a Salmonella challenge. IMPORTANCE With an average annual incidence of 13.1 cases/100,000 individuals, salmonellosis has been deemed a nationally notifiable condition in the United States by the Centers for Disease Control and Prevention (CDC). Earlier studies demonstrated that Salmonella is transmitted by a subset of animals (supershedders). The supershedder phenotype can be induced by antibiotics, ascertaining an essential role for the gut microbiota in Salmonella transmission. Consequently, modulation of the gut microbiota and modification of the intestinal microenvironment could assist in preventing animal colonization by the pathogen. Our study demonstrated that a manipulation of the chicken gut microbiota by the administration of an attenuated Salmonella strain or prebiotic galacto-oligosaccharides (GOS) can promote resistance to Salmonella colonization via increases of beneficial microorganisms that translate into a less hospitable gut microenvironment.

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Multicenter Study of Method-Dependent Epidemiological Cutoff Values for Detection of Resistance in Candida spp. and Aspergillus spp. to Amphotericin B and Echinocandins for the Etest Agar Diffusion Method

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01792-16 ◽

2016 ◽

Vol 61 (1) ◽

Cited By ~ 21

Author(s):

A. Espinel-Ingroff ◽

M. Arendrup ◽

E. Cantón ◽

S. Cordoba ◽

E. Dannaoui ◽

...

Keyword(s):

Amphotericin B ◽

Susceptibility Testing ◽

The United States ◽

Fungal Isolate ◽

Diffusion Method ◽

Wild Type ◽

Candida Spp ◽

Content Type ◽

Phenotypic Resistance ◽

Cutoff Values

ABSTRACTMethod-dependent Etest epidemiological cutoff values (ECVs) are not available for susceptibility testing of eitherCandidaorAspergillusspecies with amphotericin B or echinocandins. In addition, reference caspofungin MICs forCandidaspp. are unreliable.CandidaandAspergillusspecies wild-type (WT) Etest MIC distributions (microorganisms in a species-drug combination with no detectable phenotypic resistance) were established for 4,341Candida albicans, 113C. dubliniensis, 1,683C. glabrataspecies complex (SC), 709C. krusei, 767C. parapsilosisSC, 796C. tropicalis, 1,637Aspergillus fumigatusSC, 238A. flavusSC, 321A. nigerSC, and 247A. terreusSC isolates. Etest MICs from 15 laboratories (in Argentina, Europe, Mexico, South Africa, and the United States) were pooled to establish Etest ECVs. Anidulafungin, caspofungin, micafungin, and amphotericin B ECVs (in micrograms per milliliter) encompassing ≥97.5% of the statistically modeled population were 0.016, 0.5, 0.03, and 1 forC. albicans; 0.03, 1, 0.03, and 2 forC. glabrataSC; 0.06, 1, 0.25, and 4 forC. krusei; 8, 4, 2, and 2 forC. parapsilosisSC; and 0.03, 1, 0.12, and 2 forC. tropicalis. The amphotericin B ECV was 0.25 μg/ml forC. dubliniensisand 2, 8, 2, and 16 μg/ml for the complexes ofA. fumigatus,A. flavus,A. niger, andA. terreus, respectively. While anidulafungin Etest ECVs classified 92% of theCandida fksmutants evaluated as non-WT, the performance was lower for caspofungin (75%) and micafungin (84%) cutoffs. Finally, although anidulafungin (as an echinocandin surrogate susceptibility marker) and amphotericin B ECVs should identifyCandidaandAspergillusisolates with reduced susceptibility to these agents using the Etest, these ECVs will not categorize a fungal isolate as susceptible or resistant, as breakpoints do.

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SREBP-Dependent Triazole Susceptibility in Aspergillus fumigatus Is Mediated through Direct Transcriptional Regulation oferg11A(cyp51A)

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05027-11 ◽

2011 ◽

Vol 56 (1) ◽

pp. 248-257 ◽

Cited By ~ 41

Author(s):

Sara J. Blosser ◽

Robert A. Cramer

Keyword(s):

Aspergillus Fumigatus ◽

Regulatory Element ◽

Critical Role ◽

Clinical Importance ◽

Growth Defect ◽

Ergosterol Biosynthesis ◽

Wild Type ◽

Transcript Levels ◽

Content Type ◽

Conditional Expression

ABSTRACTAs triazole antifungal drug resistance during invasiveAspergillus fumigatusinfection has become more prevalent, the need to understand mechanisms of resistance inA. fumigatushas increased. The presence of twoerg11(cyp51) genes inAspergillusspp. is hypothesized to account for the inherent resistance of this mold to the triazole fluconazole (FLC). Recently, anA. fumigatusnull mutant of a transcriptional regulator in the sterol regulatory element binding protein (SREBP) family, the ΔsrbAstrain, was found to have increased susceptibility to FLC and voriconazole (VCZ). In this study, we examined the mechanism engendering the observed increase inA. fumigatustriazole susceptibility in the absence of SrbA. We observed a significant reduction in theerg11Atranscript in the ΔsrbAstrain in response to FLC and VCZ. Transcript levels oferg11Bwere also reduced but not to the extent oferg11A. Interestingly,erg11Atranscript levels increased upon extended VCZ, but not FLC, exposure. Construction of anerg11Aconditional expression strain in the ΔsrbAstrain was able to restoreerg11Atranscript levels and, consequently, wild-type MICs to the triazole FLC. The VCZ MIC was also partially restored upon increasederg11Atranscript levels; however, total ergosterol levels remained significantly reduced compared to those of the wild type. Induction of theerg11Aconditional strain did not restore the hypoxia growth defect of the ΔsrbAstrain. Taken together, our results demonstrate a critical role for SrbA-mediated regulation of ergosterol biosynthesis and triazole drug interactions inA. fumigatusthat may have clinical importance.

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Reverse Genetics System for Severe Fever with Thrombocytopenia Syndrome Virus

Journal of Virology ◽

10.1128/jvi.03432-14 ◽

2014 ◽

Vol 89 (6) ◽

pp. 3026-3037 ◽

Cited By ~ 37

Author(s):

Benjamin Brennan ◽

Ping Li ◽

Shuo Zhang ◽

Aqian Li ◽

Mifang Liang ◽

...

Keyword(s):

Reverse Genetics ◽

Far East ◽

Gastrointestinal Symptoms ◽

Case Fatality ◽

The United States ◽

Cdna Clones ◽

Wild Type ◽

Content Type ◽

Recombinant Viruses ◽

Severe Fever

ABSTRACTSevere fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne pathogen that was first reported in China in 2009. Phylogenetic analysis of the viral genome showed thatSFTS virusrepresents a new lineage within thePhlebovirusgenus, distinct from the existing sandfly fever and Uukuniemi virus groups, in the familyBunyaviridae. SFTS disease is characterized by gastrointestinal symptoms, chills, joint pain, myalgia, thrombocytopenia, leukocytopenia, and some hemorrhagic manifestations with a case fatality rate of about 2 to 15%. Here we report the development of reverse genetics systems to study STFSV replication and pathogenesis. We developed and optimized functional T7 polymerase-based M- and S-segment minigenome assays, which revealed errors in the published terminal sequences of the S segment of the Hubei 29 strain of SFTSV. We then generated recombinant viruses from cloned cDNAs prepared to the antigenomic RNAs both of the minimally passaged virus (HB29) and of a cell culture-adapted strain designated HB29pp. The growth properties, pattern of viral protein synthesis, and subcellular localization of viral N and NSs proteins of wild-type HB29pp (wtHB29pp) and recombinant HB29pp viruses were indistinguishable. We also show that the viruses fail to shut off host cell polypeptide production. The robust reverse genetics system described will be a valuable tool for the design of therapeutics and the development of killed and attenuated vaccines against this important emerging pathogen.IMPORTANCESFTSV and related tick-borne phleboviruses such as Heartland virus are emerging viruses shown to cause severe disease in humans in the Far East and the United States, respectively. Study of these novel pathogens would be facilitated by technology to manipulate these viruses in a laboratory setting using reverse genetics. Here, we report the generation of infectious SFTSV from cDNA clones and demonstrate that the behavior of recombinant viruses is similar to that of the wild type. This advance will allow for further dissection of the roles of each of the viral proteins in the context of virus infection, as well as help in the development of antiviral drugs and protective vaccines.

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