Virus-lymphocyte interactions. II. Expression of viral sequences during the course of persistent lymphocytic choriomeningitis virus infection and their localization to the L3T4 lymphocyte subset

Viruses that cause in vivo persistent infections need to selectively compromise the host's immunologic surveillance machinery in order to survive. To understand the molecular basis of how this is accomplished we have analyzed persistent virus infection by lymphocytic choriomeningitis in its normal host, the mouse. Earlier we noted by infectious center analysis that five in 10(4) lymphocytes carried by persistently infected mice contained infectious materials throughout the course of infection. A previous publication extended these results, in BALB mice by showing that the L3T4+ lymphocyte subset in lymph nodes and spleens was predominantly involved. Using cDNA labeled probes to the viral genome and in situ hybridization we report that 1 to 2% of circulating lymphocytes from several mouse strains contain viral RNA sequences for the three viral structural genes. By FACS analysis, the Thy-1.2+, L3T4+ subset primarily harbors virus while viral sequences are usually not detected in the Lyt-2+ subset as early as 6 days after initiating infection in newborns and throughout the course of the persistence. These findings suggest that incomplete, presumably defective, virus is generated in a subset of Th lymphocytes during persistent infection and that during this time infection of cytotoxic T cell subsets is minimal.     

Use of lambda gt11 and monoclonal antibodies to map the genes for the six major glycoproteins of equine herpesvirus 1.

To localize the genes for the major glycoproteins of equine herpesvirus 1 (EHV-1), a library of the EHV-1 genome was constructed in the lambda gt11 expression vector. Recombinant bacteriophage expressing EHV-1 glycoprotein epitopes as fusion products with beta-galactosidase were detected by immunoscreening with monoclonal antibodies specific for each of six EHV-1 glycoproteins. Seventy-four recombinant lambda gt11 clones reactive with EHV-1 monoclonal antibodies were detected among 4 X 10(5) phage screened. Phage expressing determinants on each of the six EHV-1 glycoproteins were represented in the library. Herpesviral DNA sequences contained in lambda gt11 recombinants expressing epitopes of EHV-1 glycoproteins were used as hybridization probes for mapping insert sequences on the viral genome. Genes for five EHV-1 glycoproteins (gp2, gp10, gp13, gp14, and gp21/22a) mapped to the genome L component; only one EHV-1 glycoprotein (gp17/18) was expressed from the unique S region of the genome where genes of several major glycoproteins of other herpesviruses have been located. Two glycoproteins of EHV-1, gp13 and gp14, mapped to positions colinear with genes of major glycoproteins identified in several other alphaherpesviruses (gC- and gB-like glycoproteins, respectively). The genomic locations of other EHV-1 glycoproteins indicated the existence of major glycoproteins of EHV-1 (gp2, gp10, and gp21/22a) for which no genetic homologs have yet been detected in other herpesviruses. The results confirm the general utility of the lambda gt11 expression system for localizing herpesvirus genes and suggest that the genomic positioning of several high-abundance glycoproteins of EHV-1 may be different from that of the prototype alphaherpesvirus, herpes simplex virus.     

Determination of thermostable and thermolabile enterotoxins in Escherichia coli strains by genetic, biological, and immunoserological methods]

The Escherichia coli strains (75) isolated from patients suffering from diarrhea were screened for ability to produce the temperature-labile or stable toxins (ST or LT) by the different techniques (the hybridization with DNA probes, biological, enzyme immunoassay). The majority of tested strains was shown to harbor the tox-genes controlling the synthesis of ST, LT or both enterotoxins. However, the phenotypic expression of the genes was registered in only some of the strains. The hybridization with the DNA probes is noted to be most perspective in the mass screening of toxigenic strains. The DNA probe used contained the fused estA-eltB genes that makes one able to detect the genes for both enterotoxins.     

Differences in the localization of Alu-repeats in various chromosomes of peripheral blood cells from normal donors and bone marrow cells from patients with acute leukemia

The dispersion of the Alu-family DNA repeats in phytohemagglutinin-stimulated lymphocytes from peripheral blood of normal donors as well as in nonstimulated bone marrow cells of four patients suffering from acute leukemia was studied by hybridization on metaphase chromosomes in situ. DNA of bacteriophage lambda CAR42 clone containing the insertion of at least 8 copies of Alu-family DNA-repeats and labelled with tritium was used as a probe in hybridization. All patients with acute leukemia had the same pattern of changes in hybridization of the bone marrow cells. It consists of silver grains clustering over 3q26, 8p12, 14q24. The pattern may reflect amplification transposition of Alu-family DNA repeats in the human genome connected with cellular differentiation or malignant transformation of blood cells.     

Electron microscopic study of measles virus infection: unusual antibody-triggered redistribution of antigens on giant cells.

Vero cells infected with measles virus fuse to form multinucleated cells which incorporated virus-specific antigens in their membrane. The distribution of these antigens was analyzed after a brief treatment with human anti-measles immunoglobulin G, using autoradiography and immunoperoxidase labeling combined with transmission and scanning electron microscopy. Virs-specific antigens were distributed over the entire surface of giant cells treated at 4 degrees C with human anti-measles immunoglobulin G and labeled Protein A. When cells were shifted to 37 degrees C, labeled antigen-antibody complexes were redistributed in two stages. Patch formation occurred in 5 to 15 min. Later, antigen-antibody complexes became concentrated in a paracentral "ring" rather than typical caps. Patch formation occurred in the presence of metabolic inhibitors, whereas ring formation was inhibited by metabolic inhibitors. These rings contained membrane folds, villi, and viral buds, whereas the rest of the membrane was smooth. In addition, shedding, endocytosis of antigen-antibody complexes, and reexpression of antigens were observed. Antibodies to nonviral membrane antigens induced the same pattern of redistribution. Infected cells treated with anti-measles Fab' fragments maintained a homogenous distribution of label throughout the experiments. In conclusion, intact immunoglobulins, but not Fab' fragments, were able to induce a dramatic redistribution of viral antigen on the membrane of giant cells infected with measles virus.     

The Clinical Spectrum of Renal Insufficiency During Acute Glomerulonephritis in the Adult

Twenty-seven adults with acute poststreptococcal glomerulonephritis were divided into two groups according to the severity of reduction in renal function: (1) 14 patients with mild depression of renal function, and (2) 13 patients with more severe renal insufficiency. In the first group the outcome was favourable, with complete clinical recovery in 11 patients. Only two patients in the second group have recovered. Five have died of renal failure and in six the chronic stage has developed. The most notable histopathological lesion observed in this group of patients was severe proliferative glomerulonephritis with a large number of epithelial crescents. According to the mode of development and time of onset of renal failure, these 13 patients could be divided into three sub-groups: (1) early renal failure without oliguria (three patients), (2) early renal failure with severe oliguria or anuria (three patients) and (3) delayed renal failure (seven patients).Although there are exceptions, the development of renal insufficiency in an adult patient suffering from acute glomerulonephritis is usually associated with a guarded prognosis.     

Reliability of the RNA-DNA Filter Hybridization for the Detection of Oncornavirus-Specific DNA Sequences

Denatured DNA from leukemic myeloblasts or uninfected chicken embryos, immobilized on nitrocellulose filters, was hybridized to a vast excess of [(3)H]70S RNA from purified avian myeloblastosis virus. The viral RNA was eluted from the RNA-DNA hybrids, purified, and then rehybridized in solution to an excess of either leukemic or normal chicken embryonic DNA. This study revealed that all the slow and the fast hybridizing viral RNA sequences detectable by liquid hybridization in DNA excess had hybridized to the filter bound DNA. Both techniques also gave similar values for the number of 28S ribosomal RNA genes contained in a chicken cell genome: 210 by the liquid hybridization procedure and 218 by the filter hybridization technique. Therefore, filter hybridization can accurately detect DNA sequences present in relatively few numbers in the genome of higher organisms.     

Non-specific polyclonal antibody response induced by Mycoplasma pneumoniae

The ability of heat-killed Mycoplasma pneumoniae (MP) organisms to induce polyclonal antibody production in cultures of blood lymphocytes of healthy subjects was studied. MP induced both IgM and IgG production, with a predominance of IgM. Supernatants of MP-stimulated lymphocyte cultures were tested by an enzyme-linked immunosorbent assay for antibodies to measles, rubella, and herpes simplex virus. MP as well as pokeweed mitogen induced production of viral antibodies of IgG class in lymphocytes of donors who had serum antibodies to the corresponding viral antigens. The MP-induced non-specific antibody response was T-cell-dependent. Lymphocytes from four patients with MP pneumonia, collected nine to 13 days after onset of illness, were tested for in vitro Ig production in the absence of MP. These lymphocytes spontaneously produced increased amounts of IgM and/or IgG. Lymphocytes from three of these four patients spontaneously produced viral IgG antibodies to measles and/or varicella antigens, indicating that MP had induced non-specific activation of memory B cells in vivo. Spontaneous viral antibody production was not found in lymphocyte cultures of healthy donors. The non-specific activation of blood B cells in vitro is probably induced by non-specific helper factors from MP-activated T cells. It is possible that in vivo MP also may have a direct activating effect on B cells.     

Titration of integrated simian virus 40 DNA sequences, using highly radioactive, single-stranded DNA probes.

Nick-translated simian virus 40 (SV40) [32P]DNA fragments (greater than 2 X 10(8) cpm/micrograms) were resolved into early- and late-strand nucleic acid sequences by hybridization with asymmetric SV40 complementary RNA. Both single-stranded DNA fractions contained less than 0.5% self-complementary sequences; both included [32P]-DNA sequences that derived from all regions of the SV40 genome. In contrast to asymmetric SV40 complementary RNA, both single-stranded [32P]DNAs annealed to viral [3H]DNA at a rate characteristic of SV40 DNA reassociation. Kinetics of reassociation between the single-stranded [32P]DNAs indicated that the two fractions contain greater than 90% of the total nucleotide sequences comprising the SV40 genome. These preparations were used as hybridization probes to detect small amounts of viral DNA integrated into the chromosomes of Chinese hamster cells transformed by SV40. Under the conditions used for hybridization titrations in solution (i.e., 10- to 50-fold excess of radioactive probe), as little as 1 pg of integrated SV40 DNA sequence was assayed quantitatively. Among the transformed cells analyzed, three clones contained approximately one viral genome equivalent of SV40 DNA per diploid cell DNA complement; three other clones contained between 1.2 and 1.6 viral genome equivalents of SV40 DNA; and one clone contained somewhat more than two viral genome equivalents of SV40 DNA. Preliminary restriction endonuclease maps of the integrated SV40 DNAs indicated that four clones contained viral DNA sequences located at a single, clone-specific chromosomal site. In three clones, the SV40 DNA sequences were located at two distinct chromosomal sites.     

Complement-dependent cytotoxicity of sera obtained from subacute sclerosing panencephalitis patients

Human lymphoid cells (NC-37) persistently infected with either measles virus (Schwarz and TYCSA strains) or subacute sclerosing panencephalitis (SSPE) virus (Halle and Mantooth strains) were destroyed in the presence of complement by anti-measles sera as well as by sera from SSPE patients. The cytotoxic activity was demonstrated in both IgG and IgM fractions of measles convalescent sera, but only in IgG fraction of SSPE sera. Measles convalescent sera completely lost the cytotoxic activity to all the cell lines, when absorbed with any one of the cell lines, indicating that the viral surface antigens of these cell lines infected with measles or SSPE virus are identical. On the other hand, the cytotoxic activity of SSPE sera could not be readily absorbed with these cells. Thus, the affinity of SSPE sera for the viral surface antigens might be lower than that of measles convalescent sera.     

Human neonatal lymphocytes immortalized after microinjection of Epstein-Barr virus DNA.

Epstein-Barr virus (EBV) is a highly efficient acute transforming agent in human cells, provided that the intact virus is used. To investigate the ability of viral DNA alone to transform cells, we introduced the EBV genome into human lymphocytes. After microinjection of EBV DNA into neonatal B lymphocytes, we established a cell line that in early passages contained multiple viral fragments. This cell line retained sequences from the short, unique (Us) region of the EBV genome and sequences from EcoRI-E. The viral sequences were not expressed; however, the cells expressed a 2.3-kilobase polyadenylated message homologous to the c-fgr oncogene, a cellular locus believed to be activated by EBV infection [M. S. C. Cheah, T. J. Ley, S. R. Tronick, and K. C. Robbins, Nature (London) 319:238-240.]. The cell line was monoclonal with rearrangement at the immunoglobulin locus and had a reciprocal translocation t(1;7)(p34;q34) and a deletion of sequences within the locus for the beta chain of the T-cell receptor. The close proximity of the translocation to the chromosomal loci for c-fgr on chromosome 1 and the T-cell receptor beta chain on chromosome 7 suggests that structural alteration of these genes was critical to this transformation event.     

A specific viral DNA sequence is stably integrated in herpesvirus oncogenically transformed cells

The integration patterns of viral DNA sequences in three hamster embryo cell lines independently derived by transformation with equine herpesvirus type 1 (EHV-1) have been investigated by DNA blot hybridization analyses for the restriction enzymes Eco RI, Bgl II, Xba I and Bam HI with ³²P-labeled selected DNAs from a collection of cloned EHV-1 restriction enzyme fragments as probes. These EHV-1-transformed cell lines contained subgenomic portions of the viral genome in an integrated state at multiple sites in the host genome. At least one copy of a viral DNA sequence mapping colinearly from 0.32 to 0.38 map units within the EHV-1 genome was common among these three EHV-1 transformed cell lines. The 0.32–0.38 viral DNA sequence was maintained stably even after 125 cell passages, whereas sequences from other positions in the EHV-1 genome were lost progressively during continued cell passage. The significance of the findings that these oncogenically transformed cell lines harbor a specific region of the EHV-1 genome is discussed with regard to stable maintenance of the oncogenically transformed state.     

Pathogenesis of murine cytomegalovirus infection: identification of infected cells in the spleen during acute and latent infections.

Spleen cells which replicate murine cytomegalovirus (MCMV) during acute infection in vivo were identified by electron microscopy and combined immunocytochemical staining and in situ cytohybridization. Most infected cells, as defined by in situ hybridization for viral RNA with MCMV-specific probes, were shown to be positive for factor VIII-related antigen and negative for Ia, Thy-1, and F4/80 antigens. Electron microscopic ultrastructural observations indicated that the infected cells in the spleen are predominantly sinusoidal-lining cells. We also studied reactivation of MCMV from latently infected mice by cocultivation of spleen cells with mouse embryo fibroblasts. Virus was only recovered from cells in preparations of stromal (or reticular) fragments, and not from spleen cell suspensions. Neither removal of immunoglobulin-bearing cells from the stromal fragments by panning nor depletion of Thy-1- and Ia-bearing stromal cells by treatment with monoclonal antibodies and complement reduced the frequency of reactivation of MCMV. These data suggest that T lymphocytes, mature B lymphocytes, and other Ia-bearing cells are not predominant reservoirs of latent MCMV.     

Avian acute leukemia virus OK 10: analysis of its myc oncogene by molecular cloning.

Several DNAs representing the genome of the avian acute leukemia virus OK 10 were isolated by molecular cloning from a transformed quail cell line, 9C, which contained at least six OK 10 proviruses. Recombinant lambda phages harboring the OK 10 genome and additional flanking cellular DNA sequences were studied by restriction endonuclease mapping and hybridization to viral cDNA probes. Six of the clones represented complete proviruses with similar, if not identical, viral sequences integrated at different positions in the host DNA. The organization of the OK 10 genome was determined by electron-microscopic analysis of heteroduplexes formed between the cloned OK 10 DNA and DNAs representing the c-myc gene and the genomes of two other avian retroviruses, Rous-associated virus-1 and MC29. The results indicated that the OK 10 proviral DNA is about 7.5 kilobases in size with the following structure: 5'-LTR-gag-delta polmyc-delta env-LTR-3', where LTR indicates a long terminal repeat. The oncogene of OK 10, v-mycOK 10, forms a continuous DNA segment of around 1.7 kilobases between pol and env. It is similar in structure and length to the v-myc gene of MC29, as demonstrated by restriction endonuclease and heteroduplex analyses. Two of the OK 10 proviruses were tested in transfection experiments: both DNAs gave rise to virus with the transforming capacities of OK 10 when Rous-associated virus-1 was used to provide helper virus functions.     

Search for unique segments of the ectromelia virus genome by cross blot hybridization with DNA from other orthopoxviruses]

In order to identify ectromelia virus (EMV) genome regions which may contain genes responsible for the specific pathogenicity of this virus, blot cross-hybridization of EMV DNA with those of other orthopoxviruses was performed. Two hybridization schemes were employed: one of them included hybridization of labelled cloned fragments of EMV with digests of other viral DNAs, the other, reciprocal, consisted in hybridization of labelled total DNAs of various orthopoxviruses with digests of the region of EMV DNA adjacent to the right-terminal inverted repeat. It was demonstrated that the counterpart to an approximately 8-kilobase pair portion of EMV genome flanking the inverted repeat could be detected only in the cowpox virus genome but not in the genomes of vaccinia and rabbitpox viruses. XhoI-O and XhoI-K fragments of EMV DNA contained, along with genes found in other poxviruses, certain genes which appeared to be unique for EMV. It is postulated that some of these genes may determine the specific biological properties of EMV, including its pathogenicity for mice.     

Construction of fowlpox virus vectors with intergenic insertions: expression of the beta-galactosidase gene and the measles virus fusion gene.

A DNA fragment from fowlpox virus cloned on a plasmid vector was modified to contain foreign DNA inserts within an intergenic region. In a first step, a 32-base-pair intergenic region from the fowlpox virus genome corresponding to the position of the thymidine kinase locus in the vaccinia virus genome was enlarged to 55 base pairs by site-directed mutagenesis. A unique restriction endonuclease site introduced upstream of the intergenic region was then used to insert various foreign DNA fragments. The lacZ gene encoding beta-galactosidase and the measles virus gene encoding the fusion protein were positioned downstream of two vaccinia virus p7.5 promoter elements in either a direct repeat or inverted repeat orientation. Foreign DNA inserts contained within the fowlpox virus sequence were transferred to the viral genome by homologous recombination occurring in cells infected with a fowlpox virus temperature-sensitive mutant and transfected with both wild-type viral DNA and plasmid DNA. Recombinant viruses were selected for the expression of beta-galactosidase activity by screening for blue plaques in the presence of a chromogenic substrate. Stable recombinants expressing both the lacZ gene and the unselected measles gene were obtained when the p7.5 promoter was present as an inverted repeat. However, when the p7.5 promoter was in the direct repeat orientation, viral recombinants which initially expressed both gene inserts readily deleted the lacZ gene flanked by the promoter repeat. The methods described enable precise insertion and deletion of foreign genes in the fowlpox virus genome and could be applied to other intergenic regions of the same virus as well as other poxviruses.     

Sensitivity of the lymphocyte chromosomes of chronic alcoholism patients to mutagenic exposure

The level of chromosome aberrations induced by mitomycin C and cytosine arabinoside in the cultured lymphocytes from patients with chronic alcoholism is elevated, as compared to that observed in the cultured lymphocytes of healthy persons. A supposition was made that transitory instability of cell genome could cause this phenomenon.