scholarly journals Persistently Infected Horses Are Reservoirs for Intrastadial Tick-Borne Transmission of the Apicomplexan Parasite Babesia equi

2008 ◽  
Vol 76 (8) ◽  
pp. 3525-3529 ◽  
Author(s):  
Massaro W. Ueti ◽  
Guy H. Palmer ◽  
Glen A. Scoles ◽  
Lowell S. Kappmeyer ◽  
Donald P. Knowles
Keyword(s):  
Surface Proteins ◽  
Mammalian Host ◽  
Infectious Dose ◽  
Persistently Infected ◽  
Babesia Equi ◽  
Persistent Infections ◽  
Tick Infection ◽  
Vector Generation ◽  
Low Efficiency ◽  
High Parasitemia

ABSTRACT Tick-borne pathogens may be transmitted intrastadially and transstadially within a single vector generation as well as vertically between generations. Understanding the mode and relative efficiency of this transmission is required for infection control. In this study, we established that adult male Rhipicephalus microplus ticks efficiently acquire the protozoal pathogen Babesia equi during acute and persistent infections and transmit it intrastadially to naïve horses. Although the level of parasitemia during acquisition feeding affected the efficiency of the initial tick infection, infected ticks developed levels of ≥104 organisms/pair of salivary glands independent of the level of parasitemia during acquisition feeding and successfully transmitted them, indicating that replication within the tick compensated for any initial differences in infectious dose and exceeded the threshold for transmission. During the development of B. equi parasites in the salivary gland granular acini, the parasites expressed levels of paralogous surface proteins significantly different from those expressed by intraerythrocytic parasites from the mammalian host. In contrast to the successful intrastadial transmission, adult female R. microplus ticks that fed on horses with high parasitemia passed the parasite vertically into the eggs with low efficiency, and the subsequent generation (larvae, nymphs, and adults) failed to transmit B. equi parasites to naïve horses. The data demonstrated that intrastadial but not transovarial transmission is an efficient mode for B. equi transmission and that persistently infected horses are an important reservoir for transmission. Consequently, R. microplus male ticks and persistently infected horses should be targeted for disease control.

scholarly journals Borrelia burgdorferi OspC Protein Required Exclusively in a Crucial Early Stage of Mammalian Infection

2006 ◽  
Vol 74 (6) ◽  
pp. 3554-3564 ◽  
Author(s):  
Kit Tilly ◽  
Jonathan G. Krum ◽  
Aaron Bestor ◽  
Mollie W. Jewett ◽  
Dorothee Grimm ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Salivary Glands ◽  
Early Stage ◽  
Natural Infection ◽  
Surface Protein ◽  
Mammalian Host ◽  
Infection Cycle ◽  
Persistently Infected ◽  
Tick Infection ◽  
Mammalian Infection

ABSTRACT This study demonstrates a strict temporal requirement for a virulence determinant of the Lyme disease spirochete Borrelia burgdorferi during a unique point in its natural infection cycle, which alternates between ticks and small mammals. OspC is a major surface protein produced by B. burgdorferi when infected ticks feed but whose synthesis decreases after transmission to a mammalian host. We have previously shown that spirochetes lacking OspC are competent to replicate in and migrate to the salivary glands of the tick vector but do not infect mice. Here we assessed the timing of the requirement for OspC by using an ospC mutant complemented with an unstable copy of the ospC gene and show that B. burgdorferi's requirement for OspC is specific to the mammal and limited to a critical early stage of mammalian infection. By using this unique system, we found that most bacterial reisolates from mice persistently infected with the initially complemented ospC mutant strain no longer carried the wild-type copy of ospC. Such spirochetes were acquired by feeding ticks and migrated to the tick salivary glands during subsequent feeding. Despite normal behavior in ticks, these ospC mutant spirochetes did not infect naive mice. ospC mutant spirochetes from persistently infected mice also failed to infect naive mice by tissue transplantation. We conclude that OspC is indispensable for establishing infection by B. burgdorferi in mammals but is not required at any other point of the mouse-tick infection cycle.

scholarly journals Type I Interferon acts as a major barrier to the establishment of infectious bursal disease virus (IBDV) persistent infections

2020 ◽  
pp. JVI.02017-20
Author(s):  
Laura Broto ◽  
Nicolás Romero ◽  
Fernando Méndez ◽  
Elisabet Diaz-Beneitez ◽  
Oscar Candelas-Rivera ◽  
...  
Keyword(s):  
Disease Virus ◽  
Cell Lines ◽  
Infectious Bursal Disease Virus ◽  
Infectious Bursal Disease ◽  
Type I ◽  
Persistently Infected ◽  
Persistent Infections ◽  
Avian Pathogen ◽  
Bursal Disease ◽  
Infected Cells

Infectious bursal disease virus (IBDV), the best characterized member of the Birnaviridae family, is a highly relevant avian pathogen causing both acute and persistent infections in different avian hosts. Here, we describe the establishment of clonal, long-term, productive persistent IBDV infections in DF-1 chicken embryonic fibroblasts. Although virus yields in persistently-infected cells are exceedingly lower than those detected in acutely infected cells, the replication fitness of viruses isolated from persistently-infected cells is higher than that of the parental virus. Persistently-infected DF-1 and IBDV-cured cell lines derived from them do not respond to type I interferon (IFN). High-throughput genome sequencing revealed that this defect is due to mutations affecting the IFNα/β receptor subunit 2 (IFNAR2) gene resulting in the expression of IFNAR2 polypeptides harbouring large C-terminal deletions that abolish the signalling capacity of IFNα/β receptor complex. Ectopic expression of a recombinant chicken IFNAR2 gene efficiently rescues IFNα responsiveness. IBDV-cured cell lines derived from persistently infected cells exhibit a drastically enhanced susceptibility to establishing new persistent IBDV infections. Additionally, experiments carried out with human HeLa cells lacking the IFNAR2 gene fully recapitulate results obtained with DF-1 cells, exhibiting a highly enhanced capacity to both survive the acute IBDV infection phase and to support the establishment of persistent IBDV infections. Results presented here show that the inactivation of the JAK-STAT signalling pathway significantly reduces the apoptotic response induced by the infection, hence facilitating the establishment and maintenance of IBDV persistent infections.IMPORTANCE Members of the Birnaviridae family, including infectious bursal disease virus (IBDV), exhibit a dual behaviour, causing acute infections that are often followed by the establishment of life-long persistent asymptomatic infections. Indeed, persistently infected specimens might act as efficient virus reservoirs, hence potentially contributing to virus dissemination. Despite the key importance of this biological trait, information about mechanisms triggering IBDV persistency is negligible. Our report evidences the capacity of IBDV, a highly relevant avian pathogen, to establishing long-term, productive, persistent infections in both avian and human cell lines. Data presented here provide novel and direct evidence about the crucial role of type I IFNs on the fate of IBDV-infected cells and their contribution to controlling the establishment of IBDV persistent infections. The use of cell lines unable to respond to type I IFNs opens a promising venue to unveiling additional factors contributing to IBDV persistency.

scholarly journals Type I Interferon acts as a major barrier to the establishment of infectious bursal disease virus (IBDV) persistent infections

2020 ◽  
Author(s):  
Laura Broto ◽  
Nicolás Romero ◽  
Fernando Méndez ◽  
Elisabet Diaz-Beneitez ◽  
Oscar Candelas-Rivera ◽  
...  
Keyword(s):  
Disease Virus ◽  
Cell Lines ◽  
Infectious Bursal Disease Virus ◽  
Infectious Bursal Disease ◽  
Type I ◽  
Persistently Infected ◽  
Persistent Infections ◽  
Avian Pathogen ◽  
Bursal Disease ◽  
Infected Cells

ABSTRACTInfectious bursal disease virus (IBDV), the best characterized member of the Birnaviridae family, is a highly relevant avian pathogen causing both acute and persistent infections in different avian hosts. Here, we describe the establishment of clonal, long-term, productive persistent IBDV infections in DF-1 chicken embryonic fibroblasts. Although virus yields in persistently-infected cells are exceedingly lower than those detected in acutely infected cells, the replication fitness of viruses isolated from persistently-infected cells is higher than that of the parental virus. Persistently-infected DF-1 and IBDV-cured cell lines derived from them do not respond to type I interferon (IFN). High-throughput genome sequencing revealed that this defect is due to mutations affecting the IFNα/β receptor subunit 2 (IFNAR2) gene resulting in the expression of IFNAR2 polypeptides harbouring large C-terminal deletions that abolish the signalling capacity of IFNα/β receptor complex. Ectopic expression of a recombinant chicken IFNAR2 gene efficiently rescues IFNα responsiveness. IBDV-cured cell lines derived from persistently infected cells exhibit a drastically enhanced proneness to establishing new persistent IBDV infections. Additionally, experiments carried out with human HeLa cells lacking the IFNAR2 gene fully recapitulate results obtained with DF-1 cells, exhibiting a highly enhanced capacity to both survive the acute IBDV infection phase and to support the establishment of persistent IBDV infections. Results presented here show that the inactivation of the JAK-STAT signalling pathway significantly reduces the apoptotic response induced by the infection, hence facilitating the establishment and maintenance of IBDV persistent infections.IMPORTANCEMembers of the Birnaviridae family, including infectious bursal disease virus (IBDV), exhibit a dual behaviour, causing acute infections that are often followed by the establishment of life-long persistent asymptomatic infections. Indeed, persistently infected specimens might act as efficient virus reservoirs, hence potentially contributing to virus dissemination. Despite the key importance of this biological trait, information about mechanisms triggering IBDV persistency is negligible. Our report evidences the capacity of IBDV, a highly relevant avian pathogen, to establishing long-term, productive, persistent infections in both avian and human cell lines. Data presented here provide novel and direct evidence about the crucial role of type I IFNs on the fate of IBDV-infected cells and their contribution to controlling the establishment of IBDV persistent infections. The use of cell lines unable to respond to type I IFNs opens a promising venue to unveiling additional factors contributing to IBDV persistency.

scholarly journals Leishmania mexicana Mutants Lacking Glycosylphosphatidylinositol (GPI):Protein Transamidase Provide Insights into the Biosynthesis and Functions of GPI-anchored Proteins

2000 ◽  
Vol 11 (4) ◽  
pp. 1183-1195 ◽  
Author(s):  
James D. Hilley ◽  
Jody L. Zawadzki ◽  
Malcolm J. McConville ◽  
Graham H. Coombs ◽  
Jeremy C. Mottram
Keyword(s):  
Normal Growth ◽  
Surface Proteins ◽  
Host Cells ◽  
Mammalian Host ◽  
Putative Protein ◽  
Major Class ◽  
Major Surface Proteins ◽  
Major Surface

The major surface proteins of the parasitic protozoonLeishmania mexicana are anchored to the plasma membrane by glycosylphosphatidylinositol (GPI) anchors. We have cloned the L. mexicana GPI8 gene that encodes the catalytic component of the GPI:protein transamidase complex that adds GPI anchors to nascent cell surface proteins in the endoplasmic reticulum. Mutants lacking GPI8 (ΔGPI8) do not express detectable levels of GPI-anchored proteins and accumulate two putative protein–anchor precursors. However, the synthesis and cellular levels of other non–protein-linked GPIs, including lipophosphoglycan and a major class of free GPIs, are not affected in the ΔGPI8 mutant. Significantly, the ΔGPI8 mutant displays normal growth in liquid culture, is capable of differentiating into replicating amastigotes within macrophages in vitro, and is infective to mice. These data suggest that GPI-anchored surface proteins are not essential to L. mexicana for its entry into and survival within mammalian host cells in vitro or in vivo and provide further support for the notion that free GPIs are essential for parasite growth.

Persistent Infection of Mouse Fibroblasts (L Cells) with Chlamydia psittaci : Evidence for a Cryptic Chlamydial Form

1980 ◽  
Vol 30 (3) ◽  
pp. 874-883
Author(s):  
James W. Moulder ◽  
Nancy J. Levy ◽  
Laura P. Schulman
Keyword(s):  
Host Cell ◽  
Chlamydia Psittaci ◽  
Host Cells ◽  
Developmental Cycle ◽  
Persistently Infected ◽  
Mouse Fibroblasts ◽  
Persistent Infections ◽  
L Cells ◽  
Infected Cells ◽  
Parasite Multiplication

When monolayers of mouse fibroblasts (L cells) were infected with enough Chlamydia psittaci (strain 6BC) to destroy most of the host cells, 1 in every 10 5 to 10 6 originally infected cells gave rise to a colony of L cells persistently infected with strain 6BC. In these populations, the density of L cells and 6BC fluctuated periodically and reciprocally as periods of host cell increase were followed by periods of parasite multiplication. Successive cycles of L-cell and 6BC reproduction were sustained indefinitely by periodic transfer to fresh medium. Isolation of L cells and 6BC from persistent infections provided no evidence that there had been any selection of variants better suited for coexistence. Persistently infected populations consisting mainly of inclusion-free L cells yielded only persistently infected clones, grew more slowly, and cloned less efficiently. They were also almost completely resistant to superinfection with high multiplicities of either 6BC or the lymphogranuloma venereum strain 440L of Chlamydia trachomatis . These properties of persistently infected L cells may be accounted for by assuming that all of the individuals in these populations are cryptically infected with 6BC and that cryptic infection slows the growth of the host cell and makes it immune to infection with exogenous chlamydiae. According to this hypothesis, the fluctuations in host and parasite density occur because some factor periodically sets off the conversion of cryptic chlamydial forms into reticulate bodies that multiply and differentiate into infectious elementary bodies in a conventional chlamydial developmental cycle.

scholarly journals STUDIES ON PERSISTENT INFECTIONS OF TISSUE CULTURES

1958 ◽  
Vol 108 (4) ◽  
pp. 537-560 ◽  
Author(s):  
Gertrude Henle ◽  
Friedrich Deinhardt ◽  
Victor V. Bergs ◽  
Werner Henle
Keyword(s):  
Chick Embryo ◽  
Influenza A ◽  
Aerobic Glycolysis ◽  
Horse Serum ◽  
Cellular Growth ◽  
Prolonged Treatment ◽  
Plaque Morphology ◽  
Persistently Infected ◽  
Persistent Infections ◽  
The Media

Inoculation of the MCN and Lung-To lines of human cells in continuous culture with Newcastle disease (NDV), mumps, or 6-6 viruses led to slight cytopathic effects (CPE) if the multiplicity of infection exceeded one. On second passage or with smaller initial inocula no CPE became apparent. The viruses multiplied, however, as determined by titrations in HeLa cultures or chick embryos. Indeed, persistently infected sublines of MCN and Lung-To were readily established without resort to special manipulations and some of these have been carried now for over 18 months on the same media and schedules as the uninfected parent strains. The viruses were found to be associated mainly with the cells and only 1, or at most 10 per cent of it was detectable in the media. The titers obtained were always low in relation to the available cell population. Reduction or even omission of the horse serum component in the media or ultraviolet irradiation of the cultures did not increase the yield of virus, and CPE became apparent only when similarly treated, uninfected cultures were, likewise, affected by the manipulations. The persistently infected cultures differed from their uninfected counterparts in that they exhibited (a) decreased cellular growth rates and ultimate yields; (b) increased aerobic glycolysis; and (c) a high degree of resistance to cytopathogenic viruses, influenza A (PR8), herpes simplex and, especially vesicular stomatitis (VSV) viruses. Prolonged treatment of persistently infected cultures by addition of specific antiviral immune sera to the media reduced significantly the amount of virus present and the degree of resistance to VSV. However, upon removal of the sera after as many as 187 days of treatment the viruses reappeared in all but one instance. The cured culture, on reinfection, became again persistently infected. No evidence was obtained to indicate genetic inhomogeneity of the cell populations. Of 50 cloned MCN lines none was destroyed by NDV and all became persistently infected. None were initially resistant to VSV but all after establishment of persistent NBV infection. All 39 cloned lines derived from MCNNDV cultures in the presence of anti-NDV serum, were free of virus and susceptible to VSV, and all acquired persistent infections and with it resistance to VSV following inoculation of NDV. NDV maintained in MCN cultures differed from the parent, chick embryo-adapted strain with respect to its plaque morphology. Whereas the former yielded only plaques on monolayers of chick embryo fibroblasts which were of pin-point size and hazy, those obtained with the latter were rarely of this type and mostly large and clear. This apparent selection of virus particles did not alter significantly their behavior with respect to cytopathogenicity for uninfected MCN cultures.

Anaplasma marginale(Rickettsiales: Anaplasmataceae): recent advances in defining host–pathogen adaptations of a tick-borne rickettsia

Parasitology ◽  
2004 ◽  
Vol 129 (S1) ◽  
pp. S285-S300 ◽  
Author(s):  
K. M. KOCAN ◽  
J. DE LA FUENTE ◽  
E. F. BLOUIN ◽  
J. C. GARCIA-GARCIA
Keyword(s):  
Antigenic Variation ◽  
Control Strategies ◽  
Anaplasma Marginale ◽  
Surface Proteins ◽  
Host Cells ◽  
Developmental Cycle ◽  
Persistent Infections ◽  
Phylogenetic Studies ◽  
Major Surface Proteins ◽  
Major Surface

The tick-borne intracellular pathogenAnaplasma marginale(Rickettsiales: Anaplasmataceae) develops persistent infections in cattle and tick hosts. While erythrocytes appear to be the only site of infection in cattle,A. marginaleundergoes a complex developmental cycle in ticks and transmission occurs via salivary glands during feeding. Many geographic isolates occur that vary in genotype, antigenic composition, morphology and infectivity for ticks. In this chapter we review recent research on the host–vector–pathogen interactions ofA. marginale. Major surface proteins (MSPs) play a crucial role in the interaction ofA. marginalewith host cells. The MSP1a protein, which is an adhesin for bovine erythrocytes and tick cells, is differentially regulated and affects infection and transmission ofA. marginalebyDermacentorspp. ticks. MSP2 undergoes antigenic variation and selection in cattle and ticks, and contributes to the maintenance of persistent infections. Phylogenetic studies ofA. marginalegeographic isolates usingmsp4andmsp1α provide information about the biogeography and evolution ofA. marginale:msp1α genotypes evolve under positive selection pressure. Isolates ofA. marginaleare maintained by independent transmission events and a mechanism of infection exclusion in cattle and ticks allows for only the infection of one isolate per animal. Prospects for development of control strategies by use of pathogen and tick-derived antigens are discussed. TheA. marginale/vector/host studies described herein could serve as a model for research on other tick-borne rickettsiae.

scholarly journals Differential Expression and Sequence Conservation of the Anaplasma marginale msp2 Gene Superfamily Outer Membrane Proteins

2006 ◽  
Vol 74 (6) ◽  
pp. 3471-3479 ◽  
Author(s):  
Susan M. Noh ◽  
Kelly A. Brayton ◽  
Donald P. Knowles ◽  
Joseph T. Agnes ◽  
Michael J. Dark ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Differential Expression ◽  
Outer Membrane Proteins ◽  
Anaplasma Marginale ◽  
Surface Proteins ◽  
Transcriptional Analysis ◽  
Mammalian Host ◽  
Anaplasma Ovis ◽  
Sequence Comparisons

ABSTRACT Bacterial pathogens in the genera Anaplasma and Ehrlichia encode a protein superfamily, pfam01617, which includes the predominant outer membrane proteins (OMPs) of each species, major surface protein 2 (MSP2) and MSP3 of Anaplasma marginale and Anaplasma ovis, Anaplasma phagocytophilum MSP2 (p44), Ehrlichia chaffeensis p28-OMP, Ehrlichia canis p30, and Ehrlichia ruminantium MAP1, and has been shown to be involved in both antigenic variation within the mammalian host and differential expression between the mammalian and arthropod hosts. Recently, complete sequencing of the A. marginale genome has identified an expanded set of genes, designated omp1-14, encoding new members of this superfamily. Transcriptional analysis indicated that, with the exception of the three smallest open reading frames, omp2, omp3, and omp6, these superfamily genes are transcribed in A. marginale-infected erythrocytes, tick midgut and salivary glands, and the IDE8 tick cell line. OMPs 1, 4, 7 to 9, and 11 were confirmed to be expressed as proteins by A. marginale within infected erythrocytes, with expression being either markedly lower (OMPs 1, 4, and 7 to 9) or absent (OMP11) in infected tick cells, which reflected regulation at the transcript level. Although the pfam01617 superfamily includes the antigenically variable MSP2 and MSP3 surface proteins, analysis of the omp1-14 sequences throughout a cycle of acute and persistent infection in the mammalian host and tick transmission reveals a high degree of conservation, an observation supported by sequence comparisons between the St. Maries strain and Florida strain genomes.

scholarly journals Isolation of a heterogeneous population of temperature-sensitive mutants of measles virus from persistently infected human lymphoblastoid cell lines.

1978 ◽  
Vol 147 (6) ◽  
pp. 1637-1652 ◽  
Author(s):  
G Ju ◽  
S Udem ◽  
B Rager-Zisman ◽  
B R Bloom
Keyword(s):  
Cell Lines ◽  
Measles Virus ◽  
Heterogeneous Population ◽  
Lymphoid Cells ◽  
Temperature Sensitive ◽  
Defective Interfering Particles ◽  
Persistently Infected ◽  
Persistent Infections ◽  
Extracellular Virus ◽  
Temperature Sensitive Mutants

Two human lymphoblastoid B-cell lines, WI-L2 and 8866, were infected with the Edmonston strain of measles virus at a multiplicity of infection of 10(-6), and stable persistent infections were established. By immunofluorescence and electron microscopy, the vast majority of cells from both cell lines were expressing viral antigens and releasing virion-like particles. However, very little infectious virus could be detected at 37 degrees C, either by an infectious centers assay or by titration of supernates from persistently infected cultures. When cultures were shifted to 31 degrees C, the cells released a population of virus that was temperature-sensitive. Clonal analysis of supernatant virus at 31 degrees C revealed a highly heterogeneous population of temperature-sensitive mutants, differing in plating efficiency ratios, thermolability, and antigen production at the nonpermissive temperature. Factors such as interferon, defective interfering particles, and extracellular virus do not appear to be important in maintaining the persistent carrier state. These studies have important implications for persistent infections of lymphoid cells in vivo, and the slow neurological diseases associated with measles, subacute sclerosing panencephalitis, and multiple sclerosis.

scholarly journals Composition of the Surface Proteome of Anaplasma marginale and Its Role in Protective Immunity Induced by Outer Membrane Immunization

2008 ◽  
Vol 76 (5) ◽  
pp. 2219-2226 ◽  
Author(s):  
Susan M. Noh ◽  
Kelly A. Brayton ◽  
Wendy C. Brown ◽  
Junzo Norimine ◽  
Gerhard R. Munske ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Protective Immunity ◽  
Vaccine Development ◽  
Bacterial Pathogen ◽  
Protein Composition ◽  
Anaplasma Marginale ◽  
Surface Proteins ◽  
Mammalian Host ◽  
Surface Complexes ◽  
Surface Proteome

ABSTRACT Surface proteins of tick-borne, intracellular bacterial pathogens mediate functions essential for invasion and colonization. Consequently, the surface proteome of these organisms is specifically relevant from two biological perspectives, induction of protective immunity in the mammalian host and understanding the transition from the mammalian host to the tick vector. In this study, the surface proteome of Anaplasma marginale, a tick-transmitted bacterial pathogen, was targeted by using surface-specific cross-linking to form intermolecular bonds between adjacent proteins. Liquid chromatography and tandem mass spectroscopy were then employed to characterize the specific protein composition of the resulting complexes. The surface complexes of A. marginale isolated from erythrocytes of the mammalian host were composed of multiple membrane proteins, most of which belong to a protein family, pfam01617, which is conserved among bacteria in the genus Anaplasma and the closely related genus Ehrlichia. In contrast, the surface proteome of A. marginale isolated from tick cells was much less complex and contained a novel protein, AM778, not identified within the surface proteome of organisms from the mammalian host. Immunization using the cross-linked surface complex induced protection against high-level bacteremia and anemia upon A. marginale challenge of cattle and effectively recapitulated the protection induced by immunization with whole outer membranes. These results indicate that a surface protein subset of the outer membrane is capable of inducing protective immunity and serves to direct vaccine development. Furthermore, the data support that remodeling of the surface proteome accompanies the transition between mammalian and arthropod hosts and identify novel targets for blocking transmission.

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