Fritz Lehmann-Grube

Lymphocytic Choriomeningitis Virus

Lymphocytic choriomeningitis (LCM) virus-specific complement-fixing (CF) antigen (ECFA) has been solubilized, concentrated, and partially purified. When inoculated together with Freunds adjuvant, ECFA induced CF antibody but not neutralizing antibody or protective immunity. By itself it boosted pre-existing CF antibody but not neutralizing antibody. In double diffusion tests one line developed between ECFA and its antiserum, and a corresponding line became visible when ECFA interacted with an antiserum directed against all LCM virus-specific antigens. Absorption of either serum with ECFA abolished all ECFA-precipitating qualities. Ouchterlony tests also revealed that ECFA prepared from cells and tissues of various species is immunologically identical. By a variety of procedures ECFA was not found to be represented on the surface of either the virion or the infected cell. When purified infectious LCM virus was disrupted, a CF antigen corresponding immunologically to ECFA was set free. In double diffusion tests this antigen gave a line of identity with ECFA. Thus, ECFA appears to be an internal component of the infectious LCM virus.

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 choriomentingitis 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 mouses spleen is mediated by the subset of T lymphocytes that is functionally characterized as cytotoxic/suppressive.

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).

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.

Defective interfering particles in mice infected with lymphocytic choriomengingitis virus

Abstract Tissues of mice infected with lymphocytic choriomeningitis (LCM) virus contain defective interfering (DI) particles. These were detected and quantitatively measured on the basis of their ability to protect circumscribed areas (foci) of L-cell monolayer cultures against cytolysis by concomitantly added LCM challenge virus. In mice infected as adults, the highest concentrations of both infectious virus (PFU) and interference focus-forming units (IFU) were attained in the spleen. In newborn mice, both PFU and IFU multiplied rapidly to maximum titers of 5.7 × 10 8 and 8.0 × 10 6 units/g of tissue, respectively. Later, the concentrations declined, reaching a constant level when the animals were 1 to 2 months old. Quantities of both entities as well as their ratios varied among organs and also changed with time.

Lymphocytic choriomeningitis virus. II. Characterization of extractable complement-fixing activity.

Lymphocytic choriomeningitis (LCM) virus-specific complement-fixing (CF) antigen (ECFA) has been solubilized, concentrated, and partially purified. When inoculated together with Freunds adjuvant, ECFA induced CF antibody but not neutralizing antibody or protective immunity. By itself it boosted pre-existing CF antibody but not neutralizing antibody. In double diffusion tests one line developed between ECFA and its antiserum, and a corresponding line became visible when ECFA interacted with an antiserum directed against all LCM virus-specific antigens. Absorption of either serum with ECFA abolished all ECFA-precipitating qualities. Ouchterlony tests also revealed that ECFA prepared from cells and tissues of various species is immunologically identical. By a variety of procedures ECFA was not found to be represented on the surface of either the virion or the infected cell. When purified infectious LCM virus was disrupted, a CF antigen corresponding immunologically to ECFA was set free. In double diffusion tests this antigen gave a line of identity with ECFA. Thus, ECFA appears to be an internal component of the infectious LCM virus.

Infectious lymphocytes in lymphocytic choriomeningitis virus carrier mice.

The infectivity of blood and lymphoid organs of mice persistently infected with lymphocytic choriomeningitis virus was found to be predominantly associated with lymphocytes and both T and B cells were infectious. A hypothesis is presented in which it is assumed that lymphocytes in carrier mice are infected via their LCM virus-specific antigen receptors, thereby leading to their antigen-triggered clonal expansion followed by infection and functional inactivation.

Lymphocytic choriomeningitis of the mouse. IV. Depression of the allograft reaction.

SummaryMice infected with the virus of lymphocytic choriomeningitis have impaired ability to reject allografts across strong histocompatibility differences. This deficiency of cellular immunologic responsiveness is transient and independent of apparent pathological alterations in lymphoid tissues.

Host cell-dependent homologous interference in lymphocytic choriomeningitis virus infection

The generation of virus progeny as well as transcription, translation, and replication of the viral small RNA (S-RNA), which codes for the nucleoprotein (NP) and the glycoprotein precursor (GPC), was followed in L and MDCK cells after infection with multiplicities (m.o.i.) ranging from 0.01 to 100. In L cells, the yields of both plaque-forming units and interfering particles varied inversely with the m.o.i. Northern blot analysis revealed that early after infection with high multiplicity NP-mRNA was present, but later few or no signals of any specificity were registered. After low m.o.i. the results were negative at 8 hr, but large quantities of mRNAs for NP and GPC as well as viral genomic S-RNA and genomic-sized complementary S-RNA had been synthesized at 48 hr. In MDCK cells, throughout the range of m.o.i. both entities attained lower levels and most were generated at m.o.i. one. The degree of hybridization correlated roughly with the quantity of infectious virus to which the cells had been exposed. In the cells of both lines the NP-mRNA corresponded to the synthesis of its translation product, but once produced, most of it appeared to be retained in the phosphorylated form. We assume that the homologous interference seen in L cells after infection with high m.o.i. results from a host-dependent inhibition of viral transcription and replication mediated by NP.

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.