scholarly journals STUDIES ON PERSISTENT INFECTIONS OF TISSUE CULTURES

1964 ◽  
Vol 119 (6) ◽  
pp. 895-922 ◽  
Author(s):  
José E. Rodriguez ◽  
Werner Henle
Keyword(s):  
Infectious Virus ◽  
Cellular Growth ◽  
Infectious Process ◽  
Virus Particles ◽  
Secondary Spread ◽  
Persistent Infections ◽  
Induce Resistance ◽  
Infected Cells ◽  
Vesicular Stomatitis ◽  
Infectious Cycle

The initial stages of infection of L(MCN) cell populations with standard Newcastle disease virus (NDVST) were analyzed in an effort to elucidate the steps leading to survival of the cultures and to the indefinite persistence of the infectious process at a low level. Cells were exposed in suspension to NDV at varying multiplicities and the monolayer cultures derived from such cells assayed at intervals for cellular growth rates, percentage of infected cells as determined by immunofluorescence, yields of viral progeny and of interferon, and, on occasion, resistance to superinfection with vesicular stomatitis virus. The percentage of cells calculated to be initially infected on the basis of adsorption data was found to match closely the percentage of immunofluorescent cells resulting from the first infectious cycle (up to 24 hours). Cells initially infected with NDVST produced a mixed progeny of infectious virus (from 15 to 40 pfu/cell) and about 10 times as many non-infectious particles in 24 hours [NDVL(MCN)], but little or no interferon. If all cells were infected the cultures ultimately died. At multiplicities of infection (m) of 2 or less the cultures survived with increasing ease as the percentage of infected cells was reduced. The number of pfu per infected cell was of the above order during the first 3 days; it declined thereafter. Limited secondary spread of the infection was noted by 48 hours and no further cycling was noted thereafter. As m decreased from 2.0 to 0.1 there was an increase in the yields of interferon and the time at which peak titers were reached. Addition of anti-NDV serum 2 hours after infection prevented measurable production of interferon. In contrast, following exposure of cells to NDVL(MCN) at multiplicities ranging from 20.0 to 0.2 (based on infectious virus) all cultures survived, no secondary spread was noted, the number of pfu per infected cells was reduced at the higher multiplicities, and the yields of interferon were similar and maximal by 24 hours and not affected by anti-NDV serum added after an adsorption period of 2 hours. It is concluded that the non-infectious virus particles in the progeny released from NDVST-infected cells induce resistance in remaining cells or, if adsorbed simultaneously with infectious virus, abort the intracellular infectious process. In both instances interferon is produced which may then render additional cells resistant. The non-infectious component is considered an incomplete or defective product of viral replication and not merely thermally inactivated virus. NDVST partially or completely inactivated at 37°C induced neither cellular resistance nor synthesis of interferon. The incomplete viral component behaved in all respects like ultraviolet-inactivated NDVST except that it was significantly more efficient in inducing interferon synthesis. On the basis of the presented data a scheme has been devised and discussed which appears to explain satisfactorily the events which take place on initial infection of L(MCN) cells with NDV and which lead to the persistence of the infectious process.

scholarly journals STUDIES ON PERSISTENT INFECTIONS OF TISSUE CULTURES

1958 ◽  
Vol 108 (4) ◽  
pp. 573-589 ◽  
Author(s):  
Friedrich Deinhardt ◽  
Victor V. Bergs ◽  
Gertrude Henle ◽  
Werner Henle
Keyword(s):  
Infectious Virus ◽  
Test Tube ◽  
Persistently Infected ◽  
Virus Particles ◽  
Linear Mode ◽  
Persistent Infections ◽  
Total Cell Population ◽  
Vesicular Stomatitis ◽  
Reported Data ◽  
Virus Interactions

Efforts were made to obtain information on some of the quantitative aspects of host cell-virus interactions in MCN cultures persistently infected with Newcastle disease, mumps, and 6-6 viruses, and to elicit the mechanism which permits simultaneous maintenance of virus and cells for indefinite periods of time. It was shown by 4 different technics that only between 10 and less than 1 per cent of the cells yield infectious virus, depending upon the agent employed and, possibly, variations in the conditions of the cultures. No evidence was found to indicate production of non-infectious virus materials. Only the cells carrying infectious virus are capable upon transfer to uninfected cultures to transmit the infection. Cells from persistently infected cultures, which are free of infectious virus at the time of transfer, failed to liberate virus at a later time during incubation periods of up to 4 weeks. The virus-producing cells contain at any given moment not more than 1 infectious unit of virus, suggesting a linear mode of production; i.e., as soon as a virus particle is completed, it is released. Upon inoculation of MCN test tube cultures with chick embryo-adapted NDV persistent infection and interference with vesicular stomatitis virus (VSV) is established with considerable delay. In contrast, following transfer of MCN-adapted NDV, in form of MCNNDV cells or first allantoic passage seeds derived therefrom, the number of virus-producing cells increases logarithmically, doubling every 6 to 8 hours until a total of about 104 is reached. Thereafter their numbers rise in proportion to the increase in total cell population; i.e., doubling approximately every 48 hours. At the time when 104 virus-producing cells are present in the culture interference with VSV is solidly established. In order to obtain this result about 106 cells must have adsorbed virus particles, or, in other words, at least 106 virus units must have totally been produced instead of the 104 measured by infectivity assay. The implications of these and previously reported data have been discussed in detail and a scheme of the course of events in persistently infected cultures has been presented.

scholarly journals STRUCTURE OF TYPE 5 ADENOVIRUS

1963 ◽  
Vol 118 (2) ◽  
pp. 295-306 ◽  
Author(s):  
Wesley C. Wilcox ◽  
Harold S. Ginsberg
Keyword(s):  
Virus Particle ◽  
Density Gradient ◽  
Infectious Virus ◽  
Relative Proportion ◽  
Specific Antigen ◽  
Equilibrium Density ◽  
Virus Particles ◽  
Infected Cells ◽  
Specific Antigens ◽  
Virus Antigens

Type 5 adenovirus was purified by fluorocarbon (freon 113) treatment followed by banding in a CsCl equilibrium density gradient. This method permitted separation of virus from normal host cell materials and virus-specific soluble antigens. Virus banded in CsCl with a mean bouyant density of 1.3349 gm/cm3. The three virus-specific soluble antigens (group- and type-specific antigens and toxin) banded together with a mean bouyant density of 1.2832 gm/cm3. The group-specific antigen was the predominant antigen of the purified virus particle, whereas the group- and type-specific antigens were present in equal titers in the antigen band. Infectious virus particles were inactivated by prolonged dialysis at pH 10.5. Centrifugation of inactivated virus preparations in a CsCl equilibrium density gradient resulted in separation of virus DNA from specific antigen: the antigens banded with a mean bouyant density of 1.2832 gm/cm3 and the DNA sedimented to the bottom of the tube. The predominant antigen derived from purified virus particles was the group-specific antigen and it was in the same relative proportion to the type-specific antigen as measured in intact particles. The antigens derived from disrupted virus were immunologically identical with the soluble virus antigens present in infected cells.

Infectious Lymphocytes in Mice Persistently Infected with Lymphocytic Choriomeningitis Virus

1977 ◽  
Vol 32 (11-12) ◽  
pp. 1026-1028 ◽  
Author(s):  
Mircea Popescu ◽  
Jürgen Löhler ◽  
Fritz Lehmann-Grube
Keyword(s):  
Persistent Infection ◽  
Viral Antigen ◽  
Infectious Virus ◽  
Lymphocytic Choriomeningitis ◽  
Lymphocytic Choriomeningitis Virus ◽  
Mononuclear Phagocytes ◽  
Infectious Process ◽  
Persistently Infected ◽  
Infected Cells ◽  
Virus Carrier

Abstract During persistent infection of mice with the lymphocytic choriomeningitis (LCM) virus approximately 3% of leukocytes were found to contain viral antigen and to produce infectious virus. Morphologically, infected cells were shown not to be lymphoblasts and their numbers were not reduced by removal of mononuclear phagocytes. We conclude that in LCM virus carrier mice true lymphocytes participate in the infectious process.

scholarly journals HIV-1 Capsid Core: A Bullet to the Heart of the Target Cell

2021 ◽  
Vol 12 ◽  
Author(s):  
Elenia Toccafondi ◽  
Daniela Lener ◽  
Matteo Negroni
Keyword(s):  
Genetic Material ◽  
Host Factors ◽  
Retroviral Infection ◽  
Infectious Process ◽  
Infected Cells ◽  
Material Translocation ◽  
Infectious Cycle ◽  
Hiv 1 ◽  
Genomic Material

The first step of the intracellular phase of retroviral infection is the release of the viral capsid core in the cytoplasm. This structure contains the viral genetic material that will be reverse transcribed and integrated into the genome of infected cells. Up to recent times, the role of the capsid core was considered essentially to protect this genetic material during the earlier phases of this process. However, increasing evidence demonstrates that the permanence inside the cell of the capsid as an intact, or almost intact, structure is longer than thought. This suggests its involvement in more aspects of the infectious cycle than previously foreseen, particularly in the steps of viral genomic material translocation into the nucleus and in the phases preceding integration. During the trip across the infected cell, many host factors are brought to interact with the capsid, some possessing antiviral properties, others, serving as viral cofactors. All these interactions rely on the properties of the unique component of the capsid core, the capsid protein CA. Likely, the drawback of ensuring these multiple functions is the extreme genetic fragility that has been shown to characterize this protein. Here, we recapitulate the busy agenda of an HIV-1 capsid in the infectious process, in particular in the light of the most recent findings.

scholarly journals SYNTHESIS OF VIRUS-SPECIFIC POLYMERS IN ADENOVIRUS-INFECTED CELLS: EFFECT OF 5-FLUORODEOXYURIDINE

1962 ◽  
Vol 116 (2) ◽  
pp. 141-157 ◽  
Author(s):  
John F. Flanagan ◽  
Harold S. Ginsberg
Keyword(s):  
Hela Cells ◽  
Culture Medium ◽  
Deoxyribonucleic Acid ◽  
Infectious Virus ◽  
Potent Inhibitor ◽  
Virus Production ◽  
Inhibitory Effect ◽  
Virus Particles ◽  
Specific Proteins ◽  
Infected Cells

Biochemical synthesis in adenovirus-infected HeLa cells was studied utilizing 5-fluorodeoxyuridine (5-FUDR), a potent inhibitor of deoxyribonucleic acid production. Synthesis of saline-soluble DNA and infectious virus was completely suppressed by addition of the analogue to cells as late as 10 hours after infection. The inhibitory effect of this compound was totally reversed by addition of 10–6 M thymidine to the culture medium. Synthesis of DNA essential for virus production began 10 hours after infection and was completed by 16 hours after infection. These data support the hypothesis that the saline-soluble DNA is a precursor of infectious virus particles. Studies of antigen production indicated that formation of virus-specific proteins was directly dependent upon synthesis of DNA.

scholarly journals Coordination of Zika Virus Infection and Viroplasm Organization by Microtubules and Microtubule-Organizing Centers

Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3335
Author(s):  
Rebecca A. Buchwalter ◽  
Sarah C. Ogden ◽  
Sara B. York ◽  
Li Sun ◽  
Chunfeng Zheng ◽  
...  
Keyword(s):  
Zika Virus ◽  
Infectious Virus ◽  
Virus Production ◽  
Health Concern ◽  
Zikv Infection ◽  
Virus Particles ◽  
Microtubule Organizing Centers ◽  
Infected Cells ◽  
Congenital Microcephaly ◽  
A Site

Zika virus (ZIKV) became a global health concern in 2016 due to its links to congenital microcephaly and other birth defects. Flaviviruses, including ZIKV, reorganize the endoplasmic reticulum (ER) to form a viroplasm, a compartment where virus particles are assembled. Microtubules (MTs) and microtubule-organizing centers (MTOCs) coordinate structural and trafficking functions in the cell, and MTs also support replication of flaviviruses. Here we investigated the roles of MTs and the cell’s MTOCs on ZIKV viroplasm organization and virus production. We show that a toroidal-shaped viroplasm forms upon ZIKV infection, and MTs are organized at the viroplasm core and surrounding the viroplasm. We show that MTs are necessary for viroplasm organization and impact infectious virus production. In addition, the centrosome and the Golgi MTOC are closely associated with the viroplasm, and the centrosome coordinates the organization of the ZIKV viroplasm toroidal structure. Surprisingly, viroplasm formation and virus production are not significantly impaired when infected cells have no centrosomes and impaired Golgi MTOC, and we show that MTs are anchored to the viroplasm surface in these cells. We propose that the viroplasm is a site of MT organization, and the MTs organized at the viroplasm are sufficient for efficient virus production.

scholarly journals Mutant Human Cytomegalovirus Lacking the Immediate-Early TRS1 Coding Region Exhibits a Late Defect

2002 ◽  
Vol 76 (23) ◽  
pp. 12290-12299 ◽  
Author(s):  
Catherine A. Blankenship ◽  
Thomas Shenk
Keyword(s):  
Human Cytomegalovirus ◽  
Infectious Virus ◽  
Human Fibroblasts ◽  
Reporter Genes ◽  
Immediate Early ◽  
Viral Gene ◽  
Wild Type ◽  
Viral Mrnas ◽  
Virus Particles ◽  
Infected Cells

ABSTRACT The human cytomegalovirus IRS1 and TRS1 open reading frames encode immediate-early proteins with identical N-terminal domains and divergent C-terminal regions. Both proteins have been shown previously to activate reporter genes in transfection assays in cooperation with other viral gene products. We have constructed two viruses carrying substitution mutations within either the IRS1 or TRS1 open reading frame. ADsubIRS1 failed to produce the related IRS1 and IRS1263 proteins, but it replicated with normal kinetics to produce a wild-type yield in human fibroblasts. The addition in trans of the IRS1263 protein, which antagonizes the ability of IRS1 and TRS1 proteins to activate reporter genes, did not inhibit the growth of the mutant virus. ADsubTRS1 failed to produce the TRS1 protein, and it generated an ∼200-fold-reduced yield of infectious virus in comparison to its wild-type parent. Viral DNA accumulated normally, as did a set of viral mRNAs that were monitored in ADsubTRS1-infected cells. However, two tegument proteins were partially mislocalized and infectious virus particles did not accumulate to normal levels within ADsubTRS1-infected cells. Further, infectious ADsubTRS1 particles sedimented abnormally in a glycerol-tartrate gradient, indicating that the structure of the mutant particles is aberrant. Our analysis of the ADsubTRS1 phenotype indicates that the TRS1 protein is required, either directly or indirectly, for efficient assembly of virus particles.

scholarly journals INCOMPLETE SIMIAN PAPOVAVIRUS SV40

1964 ◽  
Vol 119 (2) ◽  
pp. 313-326 ◽  
Author(s):  
Joseph L. Melnick ◽  
Sara E. Stinebaugh ◽  
Fred Rapp
Keyword(s):  
Viral Protein ◽  
Infectious Virus ◽  
Fluorescent Antibody ◽  
Virus Antigen ◽  
Fluorescent Antibody Technique ◽  
Antibody Technique ◽  
Antigenic Protein ◽  
Virus Particles ◽  
Large Numbers ◽  
Infected Cells

A study was made of the effects of 5-fluorouracil (FU) and 5-fluorodeoxyuridine (FUDR) on the replication of the simian papovavirus SV40 in cercopithecus monkey kidney cells and on the production of virus antigen by these cells. Both drugs markedly suppressed the production of new infectious virus by SV40-infected cells. Synthesis of viral protein was also markedly suppressed by FUDR, but not by FU. In the presence of FU, infected cells produced large amounts of viral protein which were detected by the fluorescent antibody technique. The antigen was not distributed in a particulate fashion as in untreated cells. Diffuse virus antigen was observed in the nuclei of FU-treated cells, resembling the distribution of antigen near the end of the eclipse period in untreated, infected cultures. This stage of antigen production presumably preceded viral assembly. Virus particles with or without cores were rarely seen with the electron microscope in infected FU-treated cells, although large numbers of SV40 particles were readily visualized in untreated, infected cells. It appears that at least one antigenic protein of this papovavirus is synthesized abundantly in FU-treated cells, but is not assembled into virus shells in the presence of the inhibitor.

Further Observations on the Virus of Epizootic Diarrhea of Infant Mice. An Electron Microscopic Study

1967 ◽  
Vol 25 ◽  
pp. 110-111
Author(s):  
W. G. Banfield ◽  
G. Kasnic ◽  
J. H. Blackwell
Keyword(s):  
Electron Microscope ◽  
Infected Cell ◽  
Microscopic Study ◽  
Intestinal Epithelium ◽  
Ultrastructural Study ◽  
Osmium Tetroxide ◽  
Lead Citrate ◽  
Electron Microscopic ◽  
Virus Particles ◽  
Infected Cells

An ultrastructural study of the intestinal epithelium of mice infected with the agent of epizootic diarrhea of infant mice (EDIM virus) was first performed by Adams and Kraft. We have extended their observations and have found developmental forms of the virus and associated structures not reported by them.Three-day-old NLM strain mice were infected with EDIM virus and killed 48 to 168 hours later. Specimens of bowel were fixed in glutaraldehyde, post fixed in osmium tetroxide and embedded in epon. Sections were stained with uranyl magnesium acetate followed by lead citrate and examined in an updated RCA EMU-3F electron microscope.The cells containing virus particles (infected) are at the tips of the villi and occur throughout the intestine from duodenum through colon. All developmental forms of the virus are present from 48 to 168 hours after infection. Figure 1 is of cells without virus particles and figure 2 is of an infected cell. The nucleus and cytoplasm of the infected cells appear clearer than the cells without virus particles.

Studies of a Defective Measles Virus

1968 ◽  
Vol 26 ◽  
pp. 208-209
Author(s):  
R. M. McCombs ◽  
M. Benyesh-Melnick ◽  
J. P. Brunschwig
Keyword(s):  
Inclusion Bodies ◽  
Measles Virus ◽  
Giant Cells ◽  
Helical Structures ◽  
Thin Sections ◽  
Virus Particles ◽  
Extracellular Virus ◽  
Culture Cells ◽  
Infected Cells ◽  
Eosinophilic Inclusions

Measles virus is an agent that is capable of replicating in a number of different culture cells and generally causes the formation of multinucleated giant cells. As a result of infection, virus is released from the cells into the culture fluids and reinfection can be initiated by this cell-free virus. The extracellular virus has been examined by negative staining with phosphotungstic acid and has been shown to be a rather pleomorphic particle with a diameter of about 140 mμ. However, no such virus particles have been detected in thin sections of the infected cells. Rather, the only virus-induced structures present in the giant cells are eosinophilic inclusions (intracytoplasmic or intranuclear). These inclusion bodies have been shown to contain helical structures, resembling the nucleocapsid observed in negatively stained preparations.

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