scholarly journals Comparative Pathogenesis of Different Phylogroup I Bat Lyssaviruses in a Standardized Mouse Model

2021 ◽  
Author(s):  
Antonia Klein ◽  
Elisa Eggerbauer ◽  
Madlin Potratz ◽  
Luca M. Zaeck ◽  
Sten Calvelage ◽  
...  
Keyword(s):  
Clinical Signs ◽  
Infection Model ◽  
Virus Species ◽  
Species Barrier ◽  
Pathogenic Potential ◽  
Virus Shedding ◽  
Mouse Infection Model ◽  
Infected Cells ◽  
Resolution Imaging ◽  
Two Parameters

A plethora of bat-associated lyssaviruses potentially capable of causing the fatal disease rabies are known today. Transmitted via infectious saliva, occasionally-reported spillover infections from bats to other mammals demonstrate the permeability of the species-barrier and highlight the zoonotic potential of bat-related lyssaviruses. However, it is still unknown whether and, if so, to what extent, viruses from different lyssavirus species vary in their pathogenic potential. In order to characterize and systematically compare a broader group of lyssavirus isolates for their viral replication kinetics, pathogenicity, and virus release through saliva-associated virus shedding, we used a mouse infection model comprising a low (102 TCID50) and a high (10 5 TCID50) inoculation dose as well as three different inoculation routes (intramuscular, intranasal, intracranial). Clinical sings, incubation periods, and survival were investigated. Based on the latter two parameters, a novel pathogenicity matrix was introduced to classify lyssavirus isolates. Using a total of 13 isolates from ten different virus species, this pathogenicity index varied within and between virus species. Interestingly, Irkut virus (IRKV) and Bokeloh bat lyssavirus (BBLV) obtained higher pathogenicity scores (1.14 for IRKV and 1.06 for BBLV) compared to RABV isolates ranging between 0.19 and 0.85. Also, clinical signs differed significantly between RABV and other bat lyssaviruses. Altogether, our findings suggest a high diversity among lyssavirus isolates concerning survival, incubation period, and clinical signs. Virus shedding significantly differed between RABVs and other lyssaviruses. Our results demonstrated that active shedding of infectious virus was exclusively associated with two RABV isolates only (92% for RABV-DogA and 67% for RABV-Insectbat), thus providing a potential explanation as to why sustained spillovers are solely attributed to RABVs. Interestingly, high-resolution imaging of a selected panel of brain samples from bat-associated lyssaviruses demonstrated a significantly increased percentage of infected astrocytes in mice infected with IRKV (10.03%; SD±7.39) compared to RABV-Vampbat (2.23%; SD±2.4), and BBLV (0.78%; SD±1.51), while only individual infected cells were identified in the DUVV-infected mice. These results corroborate previous studies on RABV that suggest a role of astrocyte infection in the pathogenicity of lyssaviruses.

scholarly journals Effect of Macrolide and Rifampin Resistance on Fitness of Rhodococcus equi during Intramacrophage Replication and In Vivo

2019 ◽  
Vol 87 (10) ◽  
Author(s):  
Jennifer M. Willingham-Lane ◽  
Londa J. Berghaus ◽  
Roy D. Berghaus ◽  
Kelsey A. Hart ◽  
Steeve Giguère
Keyword(s):  
Resistant Strain ◽  
Clinical Signs ◽  
Rhodococcus Equi ◽  
Infection Model ◽  
Content Type ◽  
Mouse Infection Model ◽  
Pulmonary Macrophages ◽  
Rifampin Resistance

ABSTRACT The soil-dwelling, saprophytic actinomycete Rhodococcus equi is a facultative intracellular pathogen of macrophages and causes severe bronchopneumonia when inhaled by susceptible foals. Standard treatment for R. equi disease is dual-antimicrobial therapy with a macrolide and rifampin. Thoracic ultrasonography and early treatment with antimicrobials prior to the development of clinical signs are used as means of controlling endemic R. equi infection on many farms. Concurrently with the increased use of macrolides and rifampin for chemoprophylaxis and the treatment of subclinically affected foals, a significant increase in the incidence of macrolide- and rifampin-resistant R. equi isolates has been documented. Previously, our laboratory demonstrated decreased fitness of R. equi strains that were resistant to macrolides, rifampin, or both, resulting in impaired in vitro growth in iron-restricted media and in soil. The objective of this study was to examine the effect of macrolide and/or rifampin resistance on intracellular replication of R. equi in equine pulmonary macrophages and in an in vivo mouse infection model in the presence and absence of antibiotics. In equine macrophages, the macrolide-resistant strain did not increase in bacterial numbers over time and the dual macrolide- and rifampin-resistant strain exhibited decreased proliferation compared to the susceptible isolate. In the mouse model, in the absence of antibiotics, the susceptible R. equi isolate outcompeted the macrolide- or rifampin-resistant strains.

scholarly journals Identification of Helicobacter pylori Genes That Contribute to Stomach Colonization

2006 ◽  
Vol 75 (2) ◽  
pp. 1005-1016 ◽  
Author(s):  
David N. Baldwin ◽  
Benjamin Shepherd ◽  
Petra Kraemer ◽  
Michael K. Hall ◽  
Laura K. Sycuro ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Pathogenic Bacteria ◽  
Null Alleles ◽  
Infection Model ◽  
Genetic Loci ◽  
Pathogenic Potential ◽  
Mouse Infection Model ◽  
Urease Enzyme ◽  
Transposon Mutants ◽  
H Pylori

ABSTRACT Chronic infection of the human stomach by Helicobacter pylori leads to a variety of pathological sequelae, including peptic ulcer and gastric cancer, resulting in significant human morbidity and mortality. Several genes have been implicated in disease related to H. pylori infection, including the vacuolating cytotoxin and the cag pathogenicity island. Other factors important for the establishment and maintenance of infection include urease enzyme production, motility, iron uptake, and stress response. We utilized a C57BL/6 mouse infection model to query a collection of 2,400 transposon mutants in two different bacterial strain backgrounds for H. pylori genetic loci contributing to colonization of the stomach. Microarray-based tracking of transposon mutants allowed us to monitor the behavior of transposon insertions in 758 different gene loci. Of the loci measured, 223 (29%) had a predicted colonization defect. These included previously described H. pylori virulence genes, genes implicated in virulence in other pathogenic bacteria, and 81 hypothetical proteins. We have retested 10 previously uncharacterized candidate colonization gene loci by making independent null alleles and have confirmed their colonization phenotypes by using competition experiments and by determining the dose required for 50% infection. Of the genetic loci retested, 60% have strain-specific colonization defects, while 40% have phenotypes in both strain backgrounds for infection, highlighting the profound effect of H. pylori strain variation on the pathogenic potential of this organism.

scholarly journals Protection against the New Equine Influenza Virus Florida Clade I Outbreak Strain Provided by a Whole Inactivated Virus Vaccine

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 784
Author(s):  
Sylvia Reemers ◽  
Sander van Bommel ◽  
Qi Cao ◽  
David Sutton ◽  
Saskia van de Zande
Keyword(s):  
Influenza Virus ◽  
Virus Vaccine ◽  
Clinical Signs ◽  
Field Strain ◽  
Equine Influenza Virus ◽  
Outbreak Strain ◽  
Virus Shedding ◽  
Equine Influenza ◽  
Vaccine Type ◽  
High Level

Equine influenza virus (EIV) is a major cause of respiratory disease in horses. Vaccination is an effective tool for infection control. Although various EIV vaccines are widely available, major outbreaks occurred in Europe in 2018 involving a new EIV H3N8 FC1 strain. In France, it was reported that both unvaccinated and vaccinated horses were affected despite >80% vaccination coverage and most horses being vaccinated with a vaccine expressing FC1 antigen. This study assessed whether vaccine type, next to antigenic difference between vaccine and field strain, plays a role. Horses were vaccinated with an ISCOMatrix-adjuvanted, whole inactivated virus vaccine (Equilis Prequenza) and experimentally infected with the new FC1 outbreak strain. Serology (HI), clinical signs, and virus shedding were evaluated in vaccinated compared to unvaccinated horses. Results showed a significant reduction in clinical signs and a lack of virus shedding in vaccinated horses compared to unvaccinated controls. From these results, it can be concluded that Equilis Prequenza provides a high level of protection to challenge with the new FC1 outbreak strain. This suggests that, apart from antigenic differences between vaccine and field strain, other aspects of the vaccine may also play an important role in determining field efficacy.

scholarly journals An epitope-based malaria vaccine targeting the junctional region of circumsporozoite protein

npj Vaccines ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Lucie Jelínková ◽  
Hugo Jhun ◽  
Allison Eaton ◽  
Nikolai Petrovsky ◽  
Fidel Zavala ◽  
...  
Keyword(s):  
Mouse Model ◽  
Malaria Vaccine ◽  
High Titer ◽  
Circumsporozoite Protein ◽  
Infection Model ◽  
Vaccine Platform ◽  
Junctional Region ◽  
Mouse Infection Model ◽  
Virus Like Particle ◽  
Major Surface

AbstractA malaria vaccine that elicits long-lasting protection and is suitable for use in endemic areas remains urgently needed. Here, we assessed the immunogenicity and prophylactic efficacy of a vaccine targeting a recently described epitope on the major surface antigen on Plasmodium falciparum sporozoites, circumsporozoite protein (CSP). Using a virus-like particle (VLP)-based vaccine platform technology, we developed a vaccine that targets the junctional region between the N-terminal and central repeat regions of CSP. This region is recognized by monoclonal antibodies, including mAb CIS43, that have been shown to potently prevent liver invasion in animal models. We show that CIS43 VLPs elicit high-titer and long-lived anti-CSP antibody responses in mice and is immunogenic in non-human primates. In mice, vaccine immunogenicity was enhanced by using mixed adjuvant formulations. Immunization with CIS43 VLPs conferred partial protection from malaria infection in a mouse model, and passive transfer of serum from immunized macaques also inhibited parasite liver invasion in the mouse infection model. Our findings demonstrate that a Qβ VLP-based vaccine targeting the CIS43 epitope combined with various adjuvants is highly immunogenic in mice and macaques, elicits long-lasting anti-CSP antibodies, and inhibits parasite infection in a mouse model. Thus, the CIS43 VLP vaccine is a promising pre-erythrocytic malaria vaccine candidate.

scholarly journals Genome-Wide Mutagenesis of Dengue Virus Reveals Plasticity of the NS1 Protein and Enables Generation of Infectious Tagged Reporter Viruses

2017 ◽  
Vol 91 (23) ◽  
Author(s):  
Nicholas S. Eyre ◽  
Stephen M. Johnson ◽  
Auda A. Eltahla ◽  
Maria Aloi ◽  
Amanda L. Aloia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Insertional Mutagenesis ◽  
High Resolution Imaging ◽  
Ns1 Protein ◽  
Reporter Virus ◽  
Genome Wide ◽  
Infected Cells ◽  
Resolution Imaging ◽  
Virus Replication Cycle

ABSTRACT Dengue virus (DENV) is a major global pathogen that causes significant morbidity and mortality in tropical and subtropical areas worldwide. An improved understanding of the regions within the DENV genome and its encoded proteins that are required for the virus replication cycle will expedite the development of urgently required therapeutics and vaccines. We subjected an infectious DENV genome to unbiased insertional mutagenesis and used next-generation sequencing to identify sites that tolerate 15-nucleotide insertions during the virus replication cycle in hepatic cell culture. This revealed that the regions within capsid, NS1, and the 3′ untranslated region were the most tolerant of insertions. In contrast, prM- and NS2A-encoding regions were largely intolerant of insertions. Notably, the multifunctional NS1 protein readily tolerated insertions in regions within the Wing, connector, and β-ladder domains with minimal effects on viral RNA replication and infectious virus production. Using this information, we generated infectious reporter viruses, including a variant encoding the APEX2 electron microscopy tag in NS1 that uniquely enabled high-resolution imaging of its localization to the surface and interior of viral replication vesicles. In addition, we generated a tagged virus bearing an mScarlet fluorescent protein insertion in NS1 that, despite an impact on fitness, enabled live cell imaging of NS1 localization and traffic in infected cells. Overall, this genome-wide profile of DENV genome flexibility may be further dissected and exploited in reporter virus generation and antiviral strategies. IMPORTANCE Regions of genetic flexibility in viral genomes can be exploited in the generation of reporter virus tools and should arguably be avoided in antiviral drug and vaccine design. Here, we subjected the DENV genome to high-throughput insertional mutagenesis to identify regions of genetic flexibility and enable tagged reporter virus generation. In particular, the viral NS1 protein displayed remarkable tolerance of small insertions. This genetic flexibility enabled generation of several novel NS1-tagged reporter viruses, including an APEX2-tagged virus that we used in high-resolution imaging of NS1 localization in infected cells by electron microscopy. For the first time, this analysis revealed the localization of NS1 within viral replication factories known as “vesicle packets” (VPs), in addition to its acknowledged localization to the luminal surface of these VPs. Together, this genetic profile of DENV may be further refined and exploited in the identification of antiviral targets and the generation of reporter virus tools.

scholarly journals Safety and immunogenicity of a glycoprotein E gene-deleted bovine herpesvirus 1 strain as a candidate vaccine strain

2016 ◽  
Vol 36 (11) ◽  
pp. 1067-1074
Author(s):  
Marcelo Weiss ◽  
◽  
Deniz Anziliero ◽  
Mathias Martins ◽  
Rudi Weiblen ◽  
...  
Keyword(s):  
Acute Infection ◽  
Clinical Signs ◽  
Bovine Herpesvirus ◽  
Elisa Test ◽  
Bovine Herpesvirus 1 ◽  
Glycoprotein E ◽  
Virus Shedding ◽  
Group I ◽  
Virus Dose ◽  
Herpesvirus 1

ABSTRACT: A glycoprotein E-deleted Brazilian bovine herpesvirus 1 (BoHV-1gEΔ) was tested regarding to safety and immunogenicity. Intramuscular inoculation of young calves with a high virus dose did not result in clinical signs or virus shedding during acute infection or after dexamethasone administration. Calves vaccinated once IM (group I) or subcutaneously (group II) with live BoHV-1gEΔ or twice with inactivated virus plus aluminum hydroxide (group IV) or Montanide™ (group V) developed VN titers of 2 to 8 (GMT:2); 2 to 4 (GMT:1.65); 2 to 16 (GMT:2.45) and 2 to 128 (GMT:3.9), respectively. All BoHV-1gEΔ vaccinated calves remained negative in an anti-gE ELISA. Lastly, six young calves vaccinated with live BoHV-1gEΔ and subsequently challenged with a virulent BoHV-1 strain shed less virus and developed only mild and transient nasal signs comparing to unvaccinated calves. Thus, the recombinant BoHV-1gEΔ is safe and immunogenic for calves and allows for serological differentiation by a gE-ELISA test.

scholarly journals The zinc transporter ZnuABC is critical for the virulence of Chromobacterium violaceum and contributes to diverse zinc-dependent physiological processes

2021 ◽  
Author(s):  
Renato E. R. S. Santos ◽  
Waldir P. da Silva Júnior ◽  
Simone A. Harrison ◽  
Eric P Skaar ◽  
Walter J. Chazin ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Zinc Uptake ◽  
Chromobacterium Violaceum ◽  
Host Protein ◽  
Infection Model ◽  
Uptake System ◽  
Environmental Bacterium ◽  
Mouse Infection Model ◽  
Synthetic Metal

Chromobacterium violaceum is a ubiquitous environmental bacterium that causes sporadic life-threatening infections in humans. How C. violaceum acquires zinc to colonize environmental and host niches is unknown. In this work, we demonstrated that C. violaceum employs the zinc uptake system ZnuABC to overcome zinc limitation in the host, ensuring the zinc supply for several physiological demands. Our data indicated that the C. violaceum ZnuABC transporter is encoded in a zur-CV_RS15045-CV_RS15040-znuCBA operon. This operon was repressed by the zinc uptake regulator Zur and derepressed in the presence of the host protein calprotectin (CP) and the synthetic metal chelator EDTA. A ΔznuCBA mutant strain showed impaired growth under these zinc-chelated conditions. Moreover, the deletion of znuCBA provoked a reduction in violacein production, swimming motility, biofilm formation, and bacterial competition. Remarkably, the ΔznuCBA mutant strain was highly attenuated for virulence in an in vivo mouse infection model and showed a low capacity to colonize the liver, grow in the presence of CP, and resist neutrophil killing. Overall, our findings demonstrate that ZnuABC is essential for C. violaceum virulence, contributing to subvert the zinc-based host nutritional immunity.

scholarly journals A Brazilian glycoprotein E-negative bovine herpesvirus type 1.2a (BHV-1.2a) mutant is attenuated for cattle and induces protection against wild-type virus challenge

2002 ◽  
Vol 22 (4) ◽  
pp. 135-140 ◽  
Author(s):  
Ana Cláudia Franco ◽  
Fernando Rosado Spilki ◽  
Paulo Augusto Esteves ◽  
Marcelo de Lima ◽  
Rudi Weiblen ◽  
...  
Keyword(s):  
Clinical Signs ◽  
Bovine Herpesvirus ◽  
Vaccine Virus ◽  
Parental Virus ◽  
Wild Type Virus ◽  
Wild Type ◽  
Glycoprotein E ◽  
Virus Shedding ◽  
Virus Challenge ◽  
Herpesvirus Type

The authors previously reported the construction of a glycoprotein E-deleted (gE-) mutant of bovine herpesvirus type 1.2a (BHV-1.2a). This mutant, 265gE-, was designed as a vaccinal strain for differential vaccines, allowing the distinction between vaccinated and naturally infected cattle. In order to determine the safety and efficacy of this candidate vaccine virus, a group of calves was inoculated with 265gE-. The virus was detected in secretions of inoculated calves to lower titres and for a shorter period than the parental virus inoculated in control calves. Twenty one days after inoculation, the calves were challenged with the wild type parental virus. Only mild signs of infection were detected on vaccinated calves, whereas non-vaccinated controls displayed intense rhinotracheitis and shed virus for longer and to higher titres than vaccinated calves. Six months after vaccination, both vaccinated and control groups were subjected to reactivation of potentially latent virus. The mutant 265gE- could not be reactivated from vaccinated calves. The clinical signs observed, following the reactivation of the parental virus, were again much milder on vaccinated than on non-vaccinated calves. Moreover, parental virus shedding was considerably reduced on vaccinated calves at reactivation. In view of its attenuation, immunogenicity and protective effect upon challenge and reactivation with a virulent BHV-1, the mutant 265gE- was shown to be suitable for use as a BHV-1 differential vaccine virus.

scholarly journals Analysis of an HTLV/HIV dual infection model with diffusion

2021 ◽  
Vol 18 (6) ◽  
pp. 9430-9473
Author(s):  
A. M. Elaiw ◽  
◽  
N. H. AlShamrani ◽  
◽  
Keyword(s):  
Lyapunov Functions ◽  
Global Solutions ◽  
Dual Infection ◽  
Steady States ◽  
Infection Model ◽  
Well Posedness ◽  
Pde Model ◽  
Existence And Stability ◽  
Infected Cells ◽  
Theoretical Results

<abstract><p>In the literature, several HTLV-I and HIV single infections models with spatial dependence have been developed and analyzed. However, modeling HTLV/HIV dual infection with diffusion has not been studied. In this work we derive and investigate a PDE model that describes the dynamics of HTLV/HIV dual infection taking into account the mobility of viruses and cells. The model includes the effect of Cytotoxic T lymphocytes (CTLs) immunity. Although HTLV-I and HIV primarily target the same host, CD$ 4^{+} $T cells, via infected-to-cell (ITC) contact, however the HIV can also be transmitted through free-to-cell (FTC) contact. Moreover, HTLV-I has a vertical transmission through mitosis of active HTLV-infected cells. The well-posedness of solutions, including the existence of global solutions and the boundedness, is justified. We derive eight threshold parameters which govern the existence and stability of the eight steady states of the model. We study the global stability of all steady states based on the construction of suitable Lyapunov functions and usage of Lyapunov-LaSalle asymptotic stability theorem. Lastly, numerical simulations are carried out in order to verify the validity of our theoretical results.</p></abstract>

scholarly journals Identification and Characterization of Di- and Tripeptide Transporter DtpT of Listeria monocytogenes EGD-e

2005 ◽  
Vol 71 (10) ◽  
pp. 5771-5778 ◽  
Author(s):  
Jeroen A. Wouters ◽  
Torsten Hain ◽  
Ajub Darji ◽  
Eric Hüfner ◽  
Henrike Wemekamp-Kamphuis ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Opportunistic Infections ◽  
Essential Amino Acids ◽  
Defined Medium ◽  
Infection Model ◽  
Intracellular Pathogen ◽  
Mouse Infection Model ◽  
Stress Protection ◽  
Identification And Characterization

ABSTRACT Listeria monocytogenes is a gram-positive intracellular pathogen responsible for opportunistic infections in humans and animals. Here we identified and characterized the dtpT gene (lmo0555) of L. monocytogenes EGD-e, encoding the di- and tripeptide transporter, and assessed its role in growth under various environmental conditions as well as in the virulence of L. monocytogenes. Uptake of the dipeptide Pro-[14C]Ala was mediated by the DtpT transporter and was abrogated in a ΔdtpT isogenic deletion mutant. The DtpT transporter was shown to be required for growth when the essential amino acids leucine and valine were supplied as peptides. The protective effect of glycine- and proline-containing peptides during growth in defined medium containing 3% NaCl was noted only in L. monocytogenes EGD-e, not in the ΔdtpT mutant strain, indicating that the DtpT transporter is involved in salt stress protection. Infection studies showed that DtpT contributes to pathogenesis in a mouse infection model but has no role in bacterial growth following infection of J774 macrophages. These studies reveal that DptT may contribute to the virulence of L. monocytogenes.

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