Susceptibility of immunodeficient mice to aerosol and systemic infection with virulent strains of Francisella tularensis

2004 ◽  
Vol 36 (6) ◽  
pp. 311-318 ◽  
Author(s):  
Wangxue Chen ◽  
Rhonda KuoLee ◽  
Hua Shen ◽  
J Wayne Conlan
Keyword(s):  
Francisella Tularensis ◽  
Systemic Infection ◽  
Immunodeficient Mice ◽  
Virulent Strains

scholarly journals Establishment of a Novel Humanized Mouse Model To Investigate In Vivo Activation and Depletion of Patient-Derived HIV Latent Reservoirs

2019 ◽  
Vol 93 (6) ◽  
Author(s):  
Nina C. Flerin ◽  
Ariola Bardhi ◽  
Jian Hua Zheng ◽  
Maria Korom ◽  
Joy Folkvord ◽  
...  
Keyword(s):  
Mouse Model ◽  
Hiv Infection ◽  
Mononuclear Cells ◽  
Systemic Infection ◽  
Humanized Mouse Model ◽  
Peripheral Blood Mononuclear ◽  
Immunodeficient Mice ◽  
Latently Infected ◽  
Infected Cells

ABSTRACT Curing HIV infection has been thwarted by the persistent reservoir of latently infected CD4+ T cells, which reinitiate systemic infection after antiretroviral therapy (ART) interruption. To evaluate reservoir depletion strategies, we developed a novel preclinical in vivo model consisting of immunodeficient mice intrasplenically injected with peripheral blood mononuclear cells (PBMC) from long-term ART-suppressed HIV-infected donors. In the absence of ART, these mice developed rebound viremia which, 2 weeks after PBMC injection, was 1,000-fold higher (mean = 9,229,281 HIV copies/ml) in mice injected intrasplenically than in mice injected intraperitoneally (mean = 6,838 HIV copies/ml) or intravenously (mean = 591 HIV copies/ml). One week after intrasplenic PBMC injection, in situ hybridization of the spleen demonstrated extensive disseminated HIV infection, likely initiated from in vivo-reactivated primary latently infected cells. The time to viremia was delayed significantly by treatment with a broadly neutralizing antibody, 10-1074, compared to treatment with 10-1074-FcRnull, suggesting that 10-1074 mobilized Fc-mediated effector mechanisms to deplete the replication-competent reservoir. This was supported by phylogenetic analysis of Env sequences from viral-outgrowth cultures and untreated, 10-1074-treated, or 10-1074-FcRnull-treated mice. The predominant sequence cluster detected in viral-outgrowth cultures and untreated mouse plasma was significantly reduced in the plasma of 10-1074-treated mice, whereas two new clusters emerged that were not detected in viral-outgrowth cultures or plasma from untreated mice. These new clusters lacked mutations associated with 10-1074 resistance. Taken together, these data indicated that 10-1074 treatment depletes the reservoir of latently infected cells harboring replication competent HIV. Furthermore, this mouse model represents a new in vivo approach for the preclinical evaluation of new HIV cure strategies. IMPORTANCE Sustained remission of HIV infection is prevented by a persistent reservoir of latently infected cells capable of reinitiating systemic infection and viremia. To evaluate strategies to reactivate and deplete this reservoir, we developed and characterized a new humanized mouse model consisting of highly immunodeficient mice intrasplenically injected with peripheral blood mononuclear cells from long-term ART-suppressed HIV-infected donors. Reactivation and dissemination of HIV infection was visualized in the mouse spleens in parallel with the onset of viremia. The applicability of this model for evaluating reservoir depletion treatments was demonstrated by establishing, through delayed time to viremia and phylogenetic analysis of plasma virus, that treatment of these humanized mice with a broadly neutralizing antibody, 10-1074, depleted the patient-derived population of latently infected cells. This mouse model represents a new in vivo approach for the preclinical evaluation of new HIV cure strategies.

scholarly journals Inhibitors of Ribosome Rescue Arrest Growth of Francisella tularensis at All Stages of Intracellular Replication

2016 ◽  
Vol 60 (6) ◽  
pp. 3276-3282 ◽  
Author(s):  
Tyler D. P. Goralski ◽  
Kalyan K. Dewan ◽  
John N. Alumasa ◽  
Victoria Avanzato ◽  
David E. Place ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Francisella Tularensis ◽  
Ex Vivo ◽  
Eukaryotic Cells ◽  
Content Type ◽  
Antibiotic Development ◽  
Bacterial Proliferation ◽  
Virulent Strains ◽  
Arrest Growth

Bacteria require at least one pathway to rescue ribosomes stalled at the ends of mRNAs. The primary pathway for ribosome rescue istrans-translation, which is conserved in >99% of sequenced bacterial genomes. Some species also have backup systems, such as ArfA or ArfB, which can rescue ribosomes in the absence of sufficienttrans-translation activity. Small-molecule inhibitors of ribosome rescue have broad-spectrum antimicrobial activity against bacteria grown in liquid culture. These compounds were tested against the tier 1 select agentFrancisella tularensisto determine if they can limit bacterial proliferation during infection of eukaryotic cells. The inhibitors KKL-10 and KKL-40 exhibited exceptional antimicrobial activity against both attenuated and fully virulent strains ofF. tularensisin vitroand duringex vivoinfection. Addition of KKL-10 or KKL-40 to macrophages or liver cells at any time after infection byF. tularensisprevented further bacterial proliferation. When macrophages were stimulated with the proinflammatory cytokine gamma interferon before being infected byF. tularensis, addition of KKL-10 or KKL-40 reduced intracellular bacteria by >99%, indicating that the combination of cytokine-induced stress and a nonfunctional ribosome rescue pathway is fatal toF. tularensis. Neither KKL-10 nor KKL-40 was cytotoxic to eukaryotic cells in culture. These results demonstrate that ribosome rescue is required forF. tularensisgrowth at all stages of its infection cycle and suggest that KKL-10 and KKL-40 are good lead compounds for antibiotic development.

scholarly journals Francisella tularensis Type A Strains Cause the Rapid Encystment of Acanthamoeba castellanii and Survive in Amoebal Cysts for Three Weeks Postinfection

2009 ◽  
Vol 75 (23) ◽  
pp. 7488-7500 ◽  
Author(s):  
Sahar H. El-Etr ◽  
Jeffrey J. Margolis ◽  
Denise Monack ◽  
Richard A. Robison ◽  
Marissa Cohen ◽  
...  
Keyword(s):  
Host Range ◽  
Francisella Tularensis ◽  
Vaccine Strain ◽  
Causative Agent ◽  
Acanthamoeba Castellanii ◽  
Broad Host Range ◽  
Live Vaccine Strain ◽  
Environmental Persistence ◽  
Virulent Strains ◽  
Bioterrorism Agent

ABSTRACT Francisella tularensis, the causative agent of the zoonotic disease tularemia, has recently gained increased attention due to the emergence of tularemia in geographical areas where the disease has been previously unknown and to the organism's potential as a bioterrorism agent. Although F. tularensis has an extremely broad host range, the bacterial reservoir in nature has not been conclusively identified. In this study, the ability of virulent F. tularensis strains to survive and replicate in the amoeba Acanthamoeba castellanii was explored. We observe that A. castellanii trophozoites rapidly encyst in response to F. tularensis infection and that this rapid encystment phenotype is caused by factor(s) secreted by amoebae and/or F. tularensis into the coculture medium. Further, our results indicate that in contrast to the live vaccine strain LVS, virulent strains of F. tularensis can survive in A. castellanii cysts for at least 3 weeks postinfection and that the induction of rapid amoeba encystment is essential for survival. In addition, our data indicate that pathogenic F. tularensis strains block lysosomal fusion in A. castellanii. Taken together, these data suggest that interactions between F. tularensis strains and amoebae may play a role in the environmental persistence of F. tularensis.

Peripheral human γδ T cells control growth of both avirulent and highly virulent strains of Francisella tularensis in vitro

2012 ◽  
Vol 14 (7-8) ◽  
pp. 584-589 ◽  
Author(s):  
Caroline A. Rowland ◽  
M. Gill Hartley ◽  
Helen Flick-Smith ◽  
Thomas R. Laws ◽  
Jim E. Eyles ◽  
...  
Keyword(s):  
T Cells ◽  
Francisella Tularensis ◽  
Γδ T Cells ◽  
Virulent Strains ◽  
Control Growth ◽  
Highly Virulent

scholarly journals High and novel genetic diversity of Francisella tularensis in Germany and indication of environmental persistence

2016 ◽  
Vol 144 (14) ◽  
pp. 3025-3036 ◽  
Author(s):  
C. SCHULZE ◽  
K. HEUNER ◽  
K. MYRTENNÄS ◽  
E. KARLSSON ◽  
D. JACOB ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Phylogenetic Diversity ◽  
Systemic Infection ◽  
Environmental Water ◽  
Phylogenomic Analysis ◽  
Nyctereutes Procyonoides ◽  
Wild Animals ◽  
Eurasian Beaver ◽  
Natural Hosts ◽  
Serological Studies

SUMMARYIn Germany tularemia is a re-emerging zoonotic disease. Therefore, we investigated wild animals and environmental water samples for the presence and phylogenetic diversity of Francisella tularensis in the poorly studied Berlin/Brandenburg region. The phylogenomic analysis of three isolates from wild animals revealed three new subclades within the phylogenetic tree of F. tularensis [B.71 from a raccoon dog (Nyctereutes procyonoides); B.74 from a red fox (Vulpes vulpes), and B.75 from a Eurasian beaver (Castor fiber albicus)]. The results from histological, PCR, and genomic investigations on the dead beaver showed that the animal suffered from a systemic infection. Indications were found that the bacteria were released from the beaver carcass into the surrounding environment. We demonstrated unexpectedly high and novel phylogenetic diversity of F. tularensis in Germany and the fact that the bacteria persist in the environment for at least one climatic season. These findings support a broader host species diversity than previously known regarding Germany. Our data further support the assumption derived from previous serological studies of an underestimated frequency of occurrence of the pathogen in the environment and in wild animals. F. tularensis was isolated from animal species not previously reported as natural hosts in Germany.

scholarly journals Identification of Differentially Regulated Francisella tularensis Genes by Use of a Newly Developed Tn5-Based Transposon Delivery System

2008 ◽  
Vol 74 (9) ◽  
pp. 2637-2645 ◽  
Author(s):  
Blake W. Buchan ◽  
Molly K. McLendon ◽  
Bradley D. Jones
Keyword(s):  
Francisella Tularensis ◽  
Delivery System ◽  
Iron Acquisition ◽  
Antibiotic Resistance Gene ◽  
Systemic Infection ◽  
Defined Medium ◽  
Etiologic Agent ◽  
Nucleotide Sequence Analysis ◽  
Temperature Sensitive ◽  
Dependent Manner

ABSTRACT Francisella tularensis is the etiologic agent of an intracellular systemic infection of the lymphatic system in humans called tularemia. The organism has become the subject of considerable research interest due to its classification as a category A select agent by the CDC. To aid genetic analysis of this pathogen, we have constructed a temperature-sensitive Tn5-based transposon delivery system that is capable of generating chromosomal reporter fusions with lacZ or luxCDABE, enabling us to monitor gene expression. Transposition is catalyzed by the hyperactive Tn5 transposase, whose expression is driven by the Francisella groES promoter. When high-temperature selection (42°C) is applied to a bacterial culture carrying the transposon delivery plasmid, ∼0.1% of the population is recovered with Tn5 insertions in the chromosome. Nucleotide sequence analysis of a sample of mutants revealed that the insertions occur randomly throughout the chromosome. The kanamycin-selectable marker of the transposon is also flanked by FLP recombination target sequences that allow deletion of the antibiotic resistance gene when desired. This system has been used to generate transposon mutant libraries for the F. tularensis live vaccine strain as well as two different virulent F. tularensis strains. Chromosomal reporters delivered with the transposon were used to identify genes upregulated by growth in Chamberlain's defined medium. Genes in the fsl operon, reported to be involved in iron acquisition, as well as genes in the igl gene cluster were among those identified by the screen. Further experiments implicate the ferric uptake regulator (Fur) protein in the negative regulation of fsl but not igl reporters, which occurs in an iron-dependent manner. Our results indicate that we have created a valuable new transposon that can be used to identify and characterize virulence genes in F. tularensis strains.

scholarly journals Transformation of nonencapsulated Streptococcus pneumoniae during systemic infection

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jessica L. Bradshaw ◽  
Iftekhar M. Rafiqullah ◽  
D. Ashley Robinson ◽  
Larry S. McDaniel
Keyword(s):  
Streptococcus Pneumoniae ◽  
Systemic Infection ◽  
Dna Uptake ◽  
Pathogenic Potential ◽  
Bacterial Surface ◽  
Capsule Production ◽  
Virulent Strains ◽  
Capsule Locus ◽  
Ear Infections ◽  
Complement Deposition

Abstract Streptococcus pneumoniae (pneumococcus) is a principal cause of bacterial middle ear infections, pneumonia, and meningitis. Capsule-targeted pneumococcal vaccines have likely contributed to increased carriage of nonencapsulated S. pneumoniae (NESp). Some NESp lineages are associated with highly efficient DNA uptake and transformation frequencies. However, NESp strains lack capsule that may increase disease severity. We tested the hypothesis that NESp could acquire capsule during systemic infection and transform into more virulent pneumococci. We reveal that NESp strains MNZ67 and MNZ41 are highly transformable and resistant to multiple antibiotics. Natural transformation of NESp when co-administered with heat-killed encapsulated strain WU2 in a murine model of systemic infection resulted in encapsulation of NESp and increased virulence during bacteremia. Functional capsule production increased the pathogenic potential of MNZ67 by significantly decreasing complement deposition on the bacterial surface. However, capsule acquisition did not further decrease complement deposition on the relatively highly pathogenic strain MNZ41. Whole genome sequencing of select transformants demonstrated that recombination of up to 56.7 kbp length occurred at the capsule locus, along with additional recombination occurring at distal sites harboring virulence-associated genes. These findings indicate NESp can compensate for lack of capsule production and rapidly evolve into more virulent strains.

scholarly journals Feline Lectin Activity Is Critical for the Cellular Entry of Feline Infectious Peritonitis Virus

2010 ◽  
Vol 84 (15) ◽  
pp. 7917-7921 ◽  
Author(s):  
Andrew D. Regan ◽  
David G. Ousterout ◽  
Gary R. Whittaker
Keyword(s):  
Systemic Infection ◽  
Lectin Activity ◽  
Feline Infectious Peritonitis Virus ◽  
Feline Infectious Peritonitis ◽  
Virulent Strains ◽  
Serotype 1 ◽  
Cellular Entry ◽  
Feline Coronavirus

ABSTRACT Feline infectious peritonitis is a lethal disease of felids caused by systemic infection with a feline coronavirus. Here, we report identification and analysis of the feline homologue to the human lectin DC-SIGN and show that it is a coreceptor for virulent strains of serotype 1 and serotype 2 feline coronaviruses.

Sign in / Sign up

Export Citation Format

Share Document