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F Lehmann-Grube

Publications and source records attributed to F Lehmann-Grube.

At least 55 records · Page 3Linked to original sources
PubMed1986

Lymphocytic choriomeningitis virus. IX. Properties of the nucleocapsid.

Nucleocapsids (NC) of lymphocytic choriomeningitis (LCM) virus were obtained by treatment of purified infectious virus with detergent and salt at high concentrations, followed by gradient centrifugation. NC thus prepared contained 31 S RNA, 23 S RNA, and a protein with an apparent mol wt 63,000 and an isoelectric point pH 5.7 (p63), assumed to be the nucleoprotein. We had previously observed that the intact LCM virus contained two kinds of protein with mol wt 63,000 separable by their isoelectric points which were pH 5.7 and 7.7, respectively. We now found that the latter component was removed from the NC together with the glycoproteins, and labeling studies revealed that it was closely associated with the viral envelope. We have named the protein with a mol wt of 63,000 and an isoelectric point pH 7.7 p63E (E for envelope). By limited proteolysis both viral components of mol wt 63,000 could not be distinguished, indicating that they are basically identical. It appears that p63E is the phosphorylated form of p63.

Capsid↗
PubMed1985

Mechanism of recovery from acute virus infection. II. Effect of treatment of mice with cyclosporin A on their ability to eliminate the lymphocytic choriomeningitis virus.

Illness and death of mice infected by intracerebral inoculation with lymphocytic choriomeningitis virus are pathologic immune phenomena, and mice thus infected were protected when immunosuppressed with cyclosporin A (CSA), although the virus multiplied extensively in all major organs. Concentrations remained high as long as the drug was administered but declined when the treatment was discontinued; also, cytotoxic T lymphocytes appeared. Virus elimination was slower and cytotoxic T cell activity lower than in mice not previously treated with CSA.

Animals↗
PubMed1985

Mechanism of recovery from acute virus infection. III. Subclass of T lymphocytes mediating clearance of lymphocytic choriomeningitis virus from the spleens of mice.

Spleen T lymphocytes from mice undergoing acute infection with lymphocytic choriomeningitis virus (LCM virus) were negatively selected by treatment with anti-Lyt or anti-L3T4 antibodies and complement. The subsets thus obtained were tested for their potential to lyse LCM virus-infected target cells in vitro and to confer on infected syngeneic recipients the ability to eliminate virus rapidly from their spleens. Both capacities were found to be associated with Lyt-1-2+, L3T4- cells. Previous studies had shown that LCM virus-specific cytotoxicity in vitro as well as reduction of replication of LCM virus in the adoptively immunized mouse requires compatibility at K and/or D of the major histocompatibility complex, and we conclude that clearance of LCM virus from the mouse's spleen is mediated by the subset of T lymphocytes that is functionally characterized as cytotoxic/suppressive.

Animals↗
PubMed1985

Mechanism of recovery from acute virus infection. I. Role of T lymphocytes in the clearance of lymphocytic choriomeningitis virus from spleens of mice.

Adult mice were infected by i.v. inoculation with 10(3) mouse infectious doses of lymphocytic choriomeningitis virus (LCM virus). Despite widespread replication of the agent, overt illness did not develop; histopathologic alterations were moderate. High virus concentrations were attained in the spleen, which was chosen for further study. Cytotoxic spleen T cell responses were found to vary among inbred mouse strains, and as a rule, these were correlated with other virus-specific cell-mediated immune phenomena. However, high- and low-responder mice eliminated the virus equally fast and already at times when spleen cytotoxic T lymphocytes were just beginning to appear (and before delayed-type hypersensitivity could be demonstrated). Adoptive transfer experiments showed that very few immune T lymphocytes were capable of reducing virus replication in the recipients' spleens and, furthermore, that protection was rapidly induced; when low numbers of cells were transferred, the effect was apparent 8 hr later, and with higher numbers diminished virus replication was evident after an interval as short as 6 hr. In fact, the data suggest that virus was actually inactivated. In spite of this marked efficiency, morphologic alterations in spleens of adoptively immunized mice were absent. Attempts to reveal expansion of immune cells in the recipients have failed, and the observation that adoptive transfer was as efficient in nude mice as in their furred counterparts makes it unlikely that the recipients' T lymphocytes participated to any extent. The low number of T lymphocytes causing reduction of virus, the short interval after which the effect became measurable, and the lack of histopathologic alterations has led to a working hypothesis in which it is assumed that immunologically activated T lymphocytes secrete lymphokines that directly interfere with virus replication in neighboring cells.

Animals↗
PubMed1984

Lymphocytic choriomeningitis virus. VIII. Reciprocal formation of pseudotypes with vesicular stomatitis virus.

Large numbers of VSV (LCMV) pseudotypes with the genomes of vesicular stomatitis virus (VSV) and the coat proteins of lymphocytic choriomeningitis virus (LCMV) were produced by infecting L cells first with LCMV and subsequently with VSV, the latter in the presence of tunicamycin. Separation by gradient centrifugation from the concomitantly produced LCMV genotypes, followed by polyacrylamide gel electrophoresis (PAGE), failed to reveal measurable quantities of the one glycoprotein ("G") of VSV. By serologic analysis it could be shown that anti-VSV antibody still attached, although with low efficiency. VSV (LCMV) retained its infectivity during purification. Reversal of the sequence of infection under otherwise identical conditions led to the formation of LCMV (VSV) pseudotypes. When separated from VSV genotypes, PAGE did not disclose glycoproteins of LCMV, and serologic analysis failed to detect attachment of anti-LCM virus antibody. LCMV (VSV) lost its infectivity during purification.

Animals↗
PubMed1984

Lymphocytic choriomeningitis virus. VII. Structural alterations of the virion by treatment with proteolytic enzymes without loss of infectivity.

Treatment of lymphocytic choriomeningitis virus with proteolytic enzymes, hyaluronidase, and phospholipase C increased infectious titres. Biochemical analysis of bromelain- and trypsin-treated virus revealed that infectivity was high in spite of the decrease to low or undetectable levels of all viral glycoproteins as well as partial degradation of the nucleoprotein.

Antigens, Viral↗
PubMed1984

The immune response of the mouse to lymphocytic choriomeningitis virus. IV. Enumeration of antibody-producing cells in spleens during acute and persistent infection.

The solid-phase immunoenzymatic technique for the enumeration of single rat cells producing antibodies against ovalbumin has been adapted to mouse cells producing antibodies against lymphocytic choriomeningitis (LCM) virus. After intravenous (i.v.) infection with 10(3) infectious units, IgM- and IgG-producing cells appeared on days 4 and 5, respectively. They rose to high numbers on days 7, 8, and 9 and were still detectable on day 38. After a second i.v. inoculation of 10(7) infectious units, antibody-producing cells (APC), most of which made IgG, appeared faster and reached much higher numbers. Mutatis mutandis, very similar results were obtained with mice inoculated with vesicular stomatitis virus. Antibodies were specific as to virus, but probably corresponded to more than one viral antigen. Relatively low numbers of APC were also detected in the spleens of NMRI strain carrier mice, which develop severe immune complex disease in later life, but not in spleens of persistently infected young mice of strains that remain free of late immune complex disease, namely CBA/J, C3H/HeJ, and gray house mice; APC were detected in spleens of aging CBA/J but not gray house mice.

Acute Disease↗
PubMed1983

Lymphocytic choriomeningitis virus. VI. Isolation of a glycoprotein mediating neutralization.

A structural glycoprotein of lymphocytic choriomeningitis virus was obtained in pure form by immunoaffinity chromatography using a monoclonal antibody with high neutralizing activity. It blocked neutralization of viral infectivity by antibody and in polyacrylamide gel electrophoresis it migrated with an apparent molecular weight of 44 X 10(3). We conclude that the isolated material is identical with the previously described gp44 (GP-1).

Animals↗
PubMed1983

The immune response of the mouse to lymphocytic choriomeningitis virus. III. Differences of numbers of cytotoxic T lymphocytes in spleens of mice of different strains.

By use of an accurate procedure for the measurement of relative numbers of murine cytotoxic T lymphocytes (CTL) marked differences of lymphocytic choriomeningitis virus-specific CTL in spleens were found among mouse strains that ranged from low over intermediate and high to very high, suggesting a gradient of responses rather than distinct classes. Differences were also found between mice sharing the major histocompatibility complex.

Animals↗
PubMed1983

Evidence for cytotoxic T-lymphocyte-target cell interaction in brains of mice infected intracerebrally with lymphocytic choriomeningitis virus.

Murine lymphocytic choriomeningitis is a T-cell-mediated pathologic immune phenomenon. The name of this experimental illness was derived from the principal histopathologic alterations of the central nervous system (CNS) of adult mice infected intracerebrally with lymphocytic choriomeningitis virus, i.e., lymphocytic infiltrations of plexus choroidei and meninges. The general assumption that the main event in the pathogenesis is damage to virus-infected target cells by cytotoxic T-lymphocytes is plausible but direct evidence is scarce. We have studied the ultrastructural alterations of both types of cells that are thought to participate in this immunopathologic interaction. Lymphocytes with signs of T-cell transformation were first evident on day 4 after infection. One day later, lymphoblasts, often extending uropods and containing cytoplasmic dense and compound multivesicular bodies, predominated. They were sometimes seen in intimate contact with connective tissue cells of the leptomeninx and epithelial cells of the choroid plexuses which were shown to be infected by immunofluorescence procedure. Lymphoblasts occasionally invaginated the cytoplasm of the putative target cells with cytoplasmic processes, and were even found inside the latter, exhibiting the phenomenon of emperipolesis. Lymphocytic transformation was at its maximum 6 days after infection. At this time, individual leptomeningeal cells and groups of plexus epithelial cells showed signs of cytolysis, and in a few instances these damaged cells were in close spatial association with lymphoblasts. Similar observations have been reported by others who studied the interaction between cytotoxic T-lymphocytes and their appropriate targeted cells in vitro. We interpret our findings as providing direct evidence for the assumption that one link in the chain of events leading to the cerebral form of lymphocytic choriomeningitis of the mouse is damage to virus-infected leptomeningeal and plexus cells by cytotoxic T-lymphocytes.

Animals↗
PubMed1983

Persistent infection of cultivated cells with lymphocytic choriomeningitis virus: regulation of virus replication. Brief report.

L cells were infected with lymphocytic choriomeningitis virus (LCM virus). They were subcultivated and infectious virus and interfering virus were quantified at intervals. Both entities fluctuated in perfect parallelism. Superinfection with LCM virus revealed a pattern of interference that bore no simple relationship with the quantity of interfering virus present. We explain the oscillating pattern of virus replication, which characterizes this type of LCM virus carrier cultures, as being due to spontaneous shutdown of virus synthesis in conjunction with the action of a resistance factor produced by cells coinfected with infectious virus and interfering virus.

Animals↗
PubMed1983

Properties of lymphocytic choriomeningitis virus interfering particles.

Lymphocytic choriomeningitis virus (LCM virus) interfering particles (IP) were generated in cultivated cells and their properties determined. Unlike true defective interfering (DI) particles, LCM virus IP did not show the phenomenon of enrichment and, consequently, passaging the virus undiluted did not result in their accumulation; in fact, more IP were produced during dilute passages. Furthermore, the progeny of each of 20 plaques contained high numbers of IP. On the basis of these and previous observations, we consider LCM virus IP not deletion mutants but by-products of virus synthesis.

Animals↗
PubMed1983

Lymphocytic choriomeningitis virus. IV. Electron microscopic investigation of the virion.

The structure of lymphocytic choriomeningitis virus (LCM virus) was investigated by a variety of conventional as well as novel electron microscopic procedures. Thin sections of infected cells revealed the characteristic arenavirus entities whose interiors contain ribosome-like granules but look otherwise empty. In contrast, most thin-sectioned virus particles from infectious cell culture fluid, both untreated and highly purified with little loss of initial infectivity, appeared to be filled with rather homogeneous cores. Cores rather than granules were also found in positively contrasted whole and thin-sectioned virus particles. We favor the explanation that the sandy grains, which have given this group of viruses its name, are altered cores that happen to look like ribosomes. However, the alternative cannot yet be excluded, namely, that LCM virus-infected cells produce two types of particles, of which only the core-containing ones represent virions.

Lymphocytic choriomeningitis virus↗
PubMed1983

Lymphocytic choriomeningitis virus. V. Proposed structural arrangement of proteins in the virion.

Previous work by M.J. Buchmeier and his colleagues and by our group has led to the conclusion that the lymphocytic choriomeningitis (LCM) virus contains seven distinct structural proteins, which we have named p200, gp85, p77, p63, gp60, gp44, and gp35. Their arrangement in the virion has now been analysed by establishing nearest-neighbour relationships with a homobifunctional crosslinker, by performing polyacrylamide gel electrophoresis in parallel under reducing and non-reducing conditions, and by determining the proteins that are covalently bound to viral lipids. A hypothetical model of the virion of LCM virus is proposed. Its envelope is assumed to consist of a membranous layer composed of gp60 and lipids and two types of spikes with either gp85 or gp44 as tips and gp35 as bases. The last-mentioned glycoprotein also appears to be complexed with p63, the main protein component of the nucleocapsid, and this in turn was found to be spatially associated with p200. Probably p77 is also an internal component, but a more exact position cannot yet be assigned to this protein.

Cross-Linking Reagents↗
PubMed1983

Lymphocytic choriomeningitis virus. III. Structural proteins of the virion.

Analysis of radioactively labelled and highly purified infectious lymphocytic choriomeningitis (LCM) virus by polyacrylamide gel electrophoresis (PAGE) revealed 12 components which, according to their apparent molecular weight and glycosylation status, were designated as p19, p25, p26, gp35, p38, gp44, gp60, p63, p77, gp85, gp130, and p200. As shown by immunoprecipitation, they all bound to rabbit anti-LCM virus antibodies. Three proteins, namely gp35 (= 'GP-2'), gp44 (= 'GP-1') and p63 (= 'NP'), had previously been described by others as major constituents of the virion. Our results confirm this and suggest that gp60, p77, gp85, and p200 are further distinct structural proteins. In contrast, p25 and p38 appear to be cleavage or degradation products of p63; p19 and p26 seem to belong to gp60, which could be the monomeric form of a dimer, gp130. Peptide mapping by limited proteolysis revealed considerable overlapping of amino acid sequences among the major glycoproteins with one peptide being common to all. From the results of PAGE performed after external labelling of intact virions, we conclude that gp44, gp60, and gp85 (but not gp35) form the surface of the virus envelope. Analytical isoelectric focusing under non-reducing conditions has shown that the major glycoproteins appeared to consist of several components with different isoelectric points.

Electrophoresis, Polyacrylamide Gel↗
PubMed1983

Age-dependent susceptibility of murine T lymphocytes to lymphocytic choriomeningitis virus.

In neonatal or congenital lymphocytic choriomeningitis (LCM) virus carrier mice, low numbers of T lymphocytes were always infected, but attempts to infect resting or stimulated T lymphocytes in previously uninfected adult mice have consistently failed. Only T cells in newborn mice were susceptible to LCM virus and their infection persisted when the animals grew older. Infectibility declined with increasing age of the mice. Initially, the majority was demonstrated among thymocytes, but later more splenic cells were infected. In contrast to neonatal carrier mice, in drug-induced carriers (in which persistent infection had been established later in life by immuno-suppression after infection) spleens and thymi contained initially no or a few infectious T lymphocytes; their numbers increased with the age of the mice but remained relatively low and erratic. We follow the hypothesis that LCM virus-specific immunological tolerance of carrier mice is due to age-dependent virus susceptibility of T lymphocytes and propose that murine T lymphocytes in general lack viral receptors for LCM virus, but that the few that carry LCM virus-specific immunological receptors bind the virus. If this occurs during an early stage of cellular development, infection results and functional inactivation is the consequence.

Age Factors↗
PubMed1982

The immune response of the mouse to lymphocytic choriomeningitis virus. II. Active suppression of cell-mediated immunity by infection with high virus doses.

Infection of CBA/J mice with low doses of strain WE lymphocytic choriomeningitis (LCM) virus resulted in high cell-mediated and relatively low humoral virus-specific immune phenomena; anamnestic responses were marked. In contrast, infection with high doses of this virus induced no or low degrees of cell-mediated immune phenomena but higher antibody concentrations. Subsequent challenge of these mice did not reveal cell-mediated immunity. However, transfer of spleen cells from mice suppressed as to cell-mediated immunity together with virus into X-irradiated recipients led to marked anamnestic responses. Furthermore, when spleen cells from mice previously infected with low virus doses were injected into mice previously infected with high virus doses, cell-mediated immune phenomena could not be induced by concomitantly inoculated virus, although in controls anamnestic responses were readily evoked. Thus, infection with high doses of LCM virus actively suppressed LCM virus-specific cell-mediated immune responses but led to increased production of antibodies. suppressor cells could not be demonstrated.

Animals↗