Virus-cell Relationship Research Articles

Enfermedad de Carrión - Ensayo de etiopatogenia

1. La Bartonella baciliformis es un germen rickettsioide,- endoteliotropo - y muy adaptado al medio endocelular. 2. En la Bartonellosis grave hay una intensa colonización del sistema celular endotelial por el agente causal y paralelamente, como consecuencia, hemodifusión proporcional del torrente circulatorio por el virus.3. La relación causal entre Anemia Infecciosa Grave y Bartonella baciliformis es difícil de explicar si se prescinde de la acción de substancias tóxicas producidas por la destrucción del virus. La reacción de la célula albergante limita progresivamente el número de los parásitos y es durante este trabajo celular que transcurre la fase aguda de la enfermedad, clínicamente caracterizada por un grave estado infeccioso, tóxico; anatomo patológicamente por particulares lesiones degenerativas : hipertrofia, hiperplasia y reacción mieloide en el sector mesenquimal, quiebra numérica total del cuadro hemático y aparición, en la sangre circulante, de elementos inmaduros de todo orden. 4. Muy frecuentemente la enfermedad aguda se ve complicada por una infección concurrente, habitualmente producida por una Salmonella, cuyo significado es muchas veces decisivo para el sujeto, que desfigura el cuadro anatómico, modifica la respuesta orgánica y agrava el síndrome infeccioso. 5. La Bartonellosis Humana es un ejemplo del rol inmediato que el elemento célula juega en la Inmunidad. Anemia de CARHTON, sus equivalentes, erupción verrucosa y latencia no son otra cosa que la expresión de la modalidad actual existente en la relación virus-célula.

Varicella Zoster Virus (VZV)-Human Neuron Interaction

Varicella zoster virus (VZV) is a highly neurotropic, exclusively human herpesvirus. Primary infection causes varicella (chickenpox), wherein VZV replicates in multiple organs, particularly the skin. Widespread infection in vivo is confirmed by the ability of VZV to kill tissue culture cells in vitro derived from any organ. After varicella, VZV becomes latent in ganglionic neurons along the entire neuraxis. During latency, virus DNA replication stops, transcription is restricted, and no progeny virions are produced, indicating a unique virus-cell (neuron) relationship. VZV reactivation produces zoster (shingles), often complicated by serious neurological and ocular disorders. The molecular trigger(s) for reactivation, and thus the identity of a potential target to prevent it, remains unknown due to an incomplete understanding of the VZV-neuron interaction. While no in vitro system has yet recapitulated the findings in latently infected ganglia, recent studies show that VZV infection of human neurons in SCID mice and of human stem cells, including induced human pluripotent stem cells and normal human neural progenitor tissue-like assemblies, can be established in the absence of a cytopathic effect. Usefulness of these systems in discovering the mechanisms underlying reactivation awaits analyses of VZV-infected, highly pure (>90%), terminally differentiated human neurons capable of prolonged survival in vitro.

Molecular pathogenesis of viral hepatitis.

The global burden of chronic liver disease caused by persistent infection with hepatitis B and C viruses has meant the urgent development of therapeutic strategies designed to control active replication and therefore prevent subsequent clinical sequelae. Advances in these therapeutic strategies are now clearly happening, mainly as a consequence of a better understanding of the viral life cycle and the unique pathogenesis of each disease. Further progress should continue as further insights into the virus-cell relationship are derived, which will sharpen attention on specific viral targets as well as shift and enhance host cytokine responses.

Kaposi's sarcoma (KS)-associated herpesvirus-like DNA sequences in peripheral blood mononuclear cells: association with KS and persistence in patients receiving anti-herpesvirus drugs

Herpesvirus-like DNA sequences (KSHV/HHV-8) have recently been described in AIDS-associated Kaposi's sarcoma (KS) lesions. Many questions remain regarding the role of this virus in KS and the therapeutic implications of this finding. In the current study, KSHV/HHV-8 DNA was detected in peripheral blood mononuclear cells (PBMCs) from human immunodeficiency virus (HIV)-infected patients with KS (34/98) more often than in HIV-infected individuals without KS (12/64, P = .03). The detection of KSHV/HHV-8 DNA did not correlate with the CD4 lymphocyte count. Five patients demonstrated KSHV/HHV-8 DNA in their PBMCs during administration of intravenous foscarnet and/or ganciclovir. The continued detection of KSHV/HHV-8 DNA in the PBMCs of patients receiving these anti-herpesvirus drugs has potential implications regarding the virus-cell relationship of KSHV/HHV-8, as well as for the value of these drugs in treating or preventing KS, but additional studies are needed.

Kaposi's sarcoma (KS)-associated herpesvirus-like DNA sequences in peripheral blood mononuclear cells: association with KS and persistence in patients receiving anti-herpesvirus drugs

Herpesvirus-like DNA sequences (KSHV/HHV-8) have recently been described in AIDS-associated Kaposi's sarcoma (KS) lesions. Many questions remain regarding the role of this virus in KS and the therapeutic implications of this finding. In the current study, KSHV/HHV-8 DNA was detected in peripheral blood mononuclear cells (PBMCs) from human immunodeficiency virus (HIV)-infected patients with KS (34/98) more often than in HIV-infected individuals without KS (12/64, P = .03). The detection of KSHV/HHV-8 DNA did not correlate with the CD4 lymphocyte count. Five patients demonstrated KSHV/HHV-8 DNA in their PBMCs during administration of intravenous foscarnet and/or ganciclovir. The continued detection of KSHV/HHV-8 DNA in the PBMCs of patients receiving these anti-herpesvirus drugs has potential implications regarding the virus-cell relationship of KSHV/HHV-8, as well as for the value of these drugs in treating or preventing KS, but additional studies are needed.

Single cell transcript analysis of human immunodeficiency virus gene expression in the transition from latent to productive infection

In the lymph nodes of individuals infected with human immunodeficiency virus (HIV), there is evidence that points to threekinds of virus-cell relationships. Virions may be associated with CD4 + lymphocytes that are actively producing virus or may be bound at the surfaces of follicular dendritic cells like other antigens. HIV is also harbored in CD4 + lymphocytes and monocytes/macrophages in a latent form as transcriptionally silenced provirus. To ultimately investigate in vivo these and other HIV-cell interactions that play such critical roles in the persistence of virus, immune dysregulation, and depletion, we have developed an in situ hybridization method that discriminates multiply spliced from singly or unspliced viral tran scripts. In this report we describe the method and the results obtained with it in an analysis of the switch from latent to productive infection of chronically infected T lymphocytes in culture. We found with this single-cell technique that there are two subpopulations in the culture, a minor one of productively infected cells and a major one of latently infected cells in which only low levels of viral transcripts terminated close to the 5′ end of the viral genome were detected. Shortly after activation of viral gene expression with phorbol ester, transcripts encoding Tat and Rev increase in abundancy in individual latently infected cells and this is followed by increases in and cytoplasmic export of singly or unspliced mRNAs encoding structural proteins. These studies provide insights into the regulation of HIV gene expression from a single-cell perspective and, from that perspective, transcript profiles of productively infected cells as a frame of reference for defining HIV-cell relationships in individual cells in tissue sections.

Analysis of human immunodeficiency virus-infected tissues by amplification and in situ hybridization reveals latent and permissive infections at single-cell resolution.

Latent and productive viral infections are at the extremes of the spectrum of virus-cell interactions that are thought to play a major role in the ability of such important human pathogens as human immunodeficiency virus (HIV) to elude host defenses and cause disease. The recent development of PCR-based methods to amplify target sequences in individual cells in routinely fixed tissues affords opportunities to directly examine the subtle and covert virus-cell relationships at the latent end of the spectrum that are inaccessible to analysis by conventional in situ hybridization techniques. We have now used PCR in situ with in situ hybridization to document latent and permissive HIV infection in routinely fixed and paraffin-embedded tissue. In one of the first specimens we examined, a tumor biopsy from an HIV-infected individual, we found many of the lymphocytes and lymphocytes infiltrating the tumor had HIV DNA that was detectable only by PCR in situ. The fraction of positive cells varied regionally, but there were foci where most of the cells contained HIV DNA. Most of these lymphocytes and macrophages are latently infected, as we could detect HIV RNA in fewer than one in a thousand of these cells. We also detected HIV RNA, surprisingly, in 6% of the tumor cells, where the number of copies of viral RNA per cell was equivalent to productively infected cell lines. The alternative states of HIV-gene expression and high local concentration of latently infected lymphocytes and monocytes revealed by these studies conceptually supports models of lentiviral pathogenesis that attribute persistence to the reservoir of latently infected cells and disease to the consequences of viral-gene expression in this population. The magnitude of infection of lymphocytes documented in this report is also consistent with the emerging view that HIV infection per se could contribute substantially to depletion of immune cells in AIDS.

Mechanisms of HIV-1 latency

This review describes some of the virus-cell relationships that might contribute to the state of latency observed in HIV infection. Viruses use many mechanisms to persist in their host, and the molecular interactions evoked by the virus and the cell on each other can influence the outcome of an infection. The topics of cellular effects on the virus versus viral effects on the cell are discussed in the context of viral life-cycle, activation and defective viruses, as well as latency concepts in relation to in vivo findings and in vitro cell models.

Virological applications of the grid-cell-culture technique.

Whole mounts of intact virus-infected cells have been used for several decades to examine virus-cell relationships and virus structure. The general concept of studying virus structure in association with the host cell has recently been expanded to reveal interactions between viruses and the cytoskeleton. The procedure permits utilization of immuno-gold protocols using both the transmission and scanning electron microscopes. The grid-cell-culture technique is reviewed to explain how it can be exploited to provide valuable information about virus structure and replication in both diagnostic and research laboratories. The use of the technique at the research level is discussed using bluetongue virus as a model. The procedure can provide basic structural information about intact virions and additional data on the intracellular location of viruses and virus-specific structures and about the mode of virus release from infected cells. Application of immunoelectron microscopy reveals information on the protein composition of not only released virus particles but also cell surface and cytoskeletal-associated viruses and virus-specific structures. Collectively, this simple and physically gentle technique has provided information which would otherwise be difficult to obtain.

Effect of virus inactivation on Tipula iridescent virus-cell relationships

Infectious Tipula iridescent virus (TIV) inhibits thymidine incorporation in nuclei of infected cells as determined by light microscope autoradiography. In the electron microscope these nuclei have little condensed chromatin as compared to those of normal cells. Both noninfectious partially filled virions and empty capsids have a similar effect on nuclei as infectious TIV. When TIV is inactivated by uv, nuclei respond as though cells were inoculated with infectious TIV, but nuclei of cells inoculated with virus treated with β-propiolactone (BPL), or uv first, then BPL, incorporated thymidine and contained condensed chromatin clumps as normal cells.

Etude de la relation parasitaire initiale entre un virus du groupe L 1 de Gourlay et une population cellulaire d'Acholeplasma laidlawii

The study of the relationship between MVL 51 virus, of the Gourlay group L 1, and the Mycoplasma cells of A. laidlawii during the first 35 min of infection leads to the conclusion that a "carrier state" has been established, free virus as well as infected and noninfected cells being present at the same time in the cultures. The evidence of a virus growth after 20 min of infection and the high level of remaining viable cells (1.15 x 10(8) CFU) at the end of the experiment also indicate that the carrier state should persist, at least for some time, being probably an important factor of the virus-cell relationship in the viral group L 1.

Latency and the tumour virus problem

Virus-cell relationships in latency and the association between oncogenic viruses and transformed cells have been compared in the light of Theobald Smith's dictum that “a damaging parasite tends to become a symbiont when the relationship between it, and its native host, has existed long”. This may be particularly significant in consideration of the oncogenicity of the herpesviruses.

Neuronal parasitism and cell fusion in mouse cytomegalovirus encephalitis

Intracerebral inoculation of mouse cytomegalovirus (MCMV) into neonatal and young suckling mice induces severe meningoencephalitis in which neuronal involvement and giant cell formation are prominent features. Characteristic markers for cell parasitism are hematoxylinophilic nuclear inclusions with a broad surrounding halo zone and globular phloxinophilic cytoplasmic inclusions. A remarkable feature of the polykaryocytes formed by virus-induced fusion of neurons is the bimodal nuclear population, composed of normal-appearing and inclusion-bearing nuclei. This dual population points to the recruitment of noninfected by infected cells into a syncytium by action of virus upon cell membranes and suggests a ready means of intraparenchymatous spread by a virus which is largely cell associated. Viral neurocytotropism involves postmitotic Purkinje cells as well as differentiated maturing cerebral cortical neurons and undifferentiated intermitotic cerebellar external germinal cells. This virus-cell relationship indicates that cell division is not a prerequisite condition for activation of MCMV.

Persistent infection of cells in culture by respiratory syncytial virus.

The virus-cell relationship of RS virus and the HEp-2 cell line has been examined. The production of cytopathic effect (c.p.e.) on HEp-2 cells has been found to be dependent upon the passage level of the cell line. Cells at lower passage levels exhibit c.p.e. in the form of syncytium formation, while those at higher passage levels no longer exhibit this effect. Cells infected at higher passage levels are covertly infected and continue to produce large amounts of infectious virus which remains cell-associated. On continued passage, these cells remain infected with virus but show no c.p.e. and release little if any infectious virus into the medium. Examination of the RNA species present in infected cells revealed that similar species are present in both the overtly and covertly infected cells.

Histopathologic and ultrastructural study of tumors induced by murine sarcoma virus (msv) (author's transl)

Various growth phases of Moloney murine sarcoma virus (M-MSV) induced tumors in suckling and young adult BALB/c mice have been studied by light and electron microscopy. In the early phase (3-6 days following M-MSV), observations at the injection site of the thigh muscles consisted of endo- and perimysial edema "activated" muscle satellite, cells, endothelial cells and fibroblasts, scattered type C virus particles within the muscle fibers, muscle fibers and endomysial cells undergoing necrosis and macrophage and granulocyte infiltration. During the overt tumor phase (6-12 days following M-MSV), observation of neoplastic tissue disclosed proliferation of several cell type (endothelial, periosteal, fibroblasts, etc.), poorly differentiated myoblasts along with atypical rhabdomyoblast-like cells and sarcolytes, type C virus budding from muscle fiber and myoblast plasma membrane, and intense degenerative and regenerative changes in the muscle fibers together with more profuse granulocyte infiltration. The regressive phase (13-21 days following M-MSV) presented reduced cellularity of the neoplastic tissue, a decrease in blast cells, diminishing granulocyte infiltration with contemporaneous appearance of prominent lymphocyte foci and gradual disappearance of virus particles. Although many cell types of mesenchymal origin proliferate following M-MSV infection, the above morphological findings indicate that striated muscle is a preferential site for virus replication and transformation. Furthermore, the peculiar virus cell relationships leading to cell lysis and continuous recruitment of newly infected cells have been widely documented. In the light of these findings it is suggested that, besides the host immune control of virus spread and tumor cell multiplication, the non clonal growth pattern of M-MSV induced tumors is a crucial factor in determining the spontaneous regression which occurs with high frequency in this experimental system.

Persistence of West Nile virus in L-929 mouse fibroblasts.

SummaryWhen West Nile virus was added to cultures of L-929 mouse fibroblasts, characteristic morphological changes were produced. The infected cultures were not destroyed although infectious virus was consistently demonstrated in the growth medium. Infected cells were readily subcultured and the virus-cell relationship was continued without any alteration in cultural procedures.

Hemadsorption-negative plaque test: new assay for rubella virus revealing a unique interference.

A simple and rapid plaque procedure has been developed for detecting and accurately assaying rubella virus in a noncytopathic virus-cell relationship. Plaque-formation is based on the development, in individual cells infected with rubella virus, of a unique type of intrinsic interference to infection with Newcastle disease virus. Rubella virus-infected cells challenged with Newcastle disease virus and tested for hemadsorption 15 hours later stand out as hemadsorption-negative areas. Individual living cells infected with rubella virus can be resolved under conditions allowing standard cloning procedures. In principle, the hemadsorption-negative plaque test can be used to search for a new class of noncytopathic, non-hemadsorbing viruses-those that induce an intrinsic interference to infection by any hemadsorbing virus.

On the emergence of influenza virus filaments from host cells

Whole mounts of intact virus-infected cells have been used for several decades to examine virus-cell relationships and virus structure. The general concept of studying virus structure in association with the host cell has recently been expanded to reveal interactions between viruses and the cytoskeleton. The procedure permits utilization of immuno-gold protocols using both the transmission and scanning electron microscopes. The grid-cell-culture technique is reviewed to explain how it can be exploited to provide valuable information about virus structure and replication in both diagnostic and research laboratories. The use of the technique at the research level is discussed using bluetongue virus as a model. The procedure can provide basic structural information about intact virions and additional data on the intracellular location of viruses and virus-specific structures and about the mode of virus release from infected cells. Application of immunoelectron microscopy reveals information on the protein composition of not only released virus particles but also cell surface and cytoskeletal-associated viruses and virus-specific structures. Collectively, this simple and physically gentle technique has provided information which would otherwise be difficult to obtain.

Progress in Medical Virology

The high point of this volume is without doubt the analysis of the polyoma virus-cell relationship by A. M. Prince. In a masterfully concise manner he sets out to answer certain basic questions, clearly spelled out in the introduction, regarding the action of tumor viruses in their host cells. This is no mere collection of pertinent data. For every experiment cited, Prince outlines the reason for running it, what the experimenter thought the data showed, and where better design, more controls, or further confirmation are indicated. The review discusses infections which yield virus and those which do not, separately, and each is in turn subdivided into in vivo and in vitro sections. Each of these carry their own summary of conclusions. Practical aspects of tumor pathology appear side by side with more sophisticated views, such as the analogy between tumor induction and lysogenic conversion.It is to be hoped that the editors can now persuade Prince to discuss the Rous sarcoma virus.

The mammalian cell-virus relationship. VI. Sustained infection of HeLa cells by Coxsackie B3 virus and effect on superinfection.

Sustained infection of HeLa cells by Coxsackie B3 virus, dependent on presence of viral inhibitor in culture medium, was achieved. Persistent treatment of carrier cultures with anti-Coxsackie B3 hyperimmune monkey serum eventually eliminated virus from carrier cultures indicating that a lysogenic virus-cell relationship was not operative. Free virus was produced continuously by carrier cultures despite washing and neutralization with antiserum to eliminate free virus temporarily. In carrier cultures, about 1.5 to 1.9 plaque-forming units of virus per cell were cell-associated; approximately 6 per cent of this cell-associated virus was not neutralizable by antiserum. In growth medium containing anti-B3 antibody, cells from carrier cultures formed colonies as efficiently as cells from B3-cured cultures. Assays of carrier cultures for infectious centers indicated that less than 1 per cent of cells produced free infectious virus. The Coxsackie B3 virus-carrier state appeared to represent surface residence of B3 virus on the majority of carrier cells with restriction of productive infection to a small proportion of the population. Coxsackie B3 carrier HeLa cultures, unlike control cultures, were not destroyed by challenge with Coxsackie B1, B3, or B5 viruses. The B3 carrier state did not interfere with superinfection by herpes, vaccinia, and types 1 to 3 polioviruses. In contrast to parental or B3-cured lines, B3-carrier HeLa cultures superinfected with Coxsackie B1 virus produced no significant virus, and cultures superinfected with B5 viruses produced new virus to a limited extent only. Specific interference with Coxsackie virus superinfection by the B3-carrier state of HeLa cells was shown to be attributable to failure of attachment in the instance of Coxsackie B1 virus, and failure of penetration and/or eclipse in the instance of B5 virus. The interfering effect was circumvented successfully by superinfection of carrier cells with ribonucleic acid extracted from Coxsackie B1 and B5 viruses.