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Biomedical subjects

L Enjuanes

Publications and source records attributed to L Enjuanes.

At least 91 records · Page 5Linked to original sources
PubMed1987

Reactivity with monoclonal antibodies of viruses from an episode of foot-and-mouth disease.

A panel of 12 monoclonal antibodies (MAbs) raised against foot-and-mouth disease virus (FMDV) of serotype C1 (FMDV C-S8c1) and 11 MAbs raised against other FMDVs have been used to evaluate the reactivity of 14 isolates of FMDV of serotype C1 (series FMDV C-S), 12 of them from one disease episode (Spain 1979-1982). The assays used were immunoelectrotransfer blot, immunodot and neutralization of infectivity. None of the isolates could be clearly distinguished by its reactivity with 6 non-neutralizing and 2 neutralizing MAbs raised against FMDV C-S8c1. In contrast, the isolates were distinguished in two groups by a 10(2)-fold difference in their reactivity with 6 neutralizing MAbs. The reactivity of MAbs with synthetic peptides indicated that conserved and non-conserved epitopes recognised respectively by neutralizing MAbs 4G3 and SD6 are localized in the immunogenic region (amino acids 138-156) of VP1. Thus, epidemiologically related FMDVs differ in at least one epitope critical for virus neutralization.

Amino Acid Sequence↗
PubMed1987

Synthesis of African swine fever (ASF) virus-specific antibodies in vitro in a porcine leucocyte system.

We have developed a system of porcine peripheral blood mononuclear cells for the synthesis of antibodies in vitro, induced by partially purified African swine fever virus particles inactivated with formaldehyde. The antibodies synthesized were detected by a radioimmunoassay with a sensitivity of 3 ng of immunoglobulin. Primary responses were dependent on supernatants from peripheral blood mononuclear cells incubated with concanavalin A, macrophages and T lymphocytes. Secondary responses did not require concanavalin A-conditioned medium. The kinetics of antibody synthesis was similar in both primary and secondary responses, but the extent of synthesis was four to five times larger in the secondary than in the primary response. The antibodies synthesized in vitro were specific for African swine fever virus antigens (and did not react with viral antigen other than that from African swine fever virus particles), in contrast to pokeweed mitogen-induced antibodies, which reacted with all the antigens tested. African swine fever virus-induced antibodies did not neutralize the virus. These results and the inability of the virus to stimulate a primary response in the absence of concanavalin A supernatants indicate that inactivated African swine fever virus is not a polyclonal stimulator.

African Swine Fever Virus↗
PubMed1986

Localization of structural proteins in African swine fever virus particles by immunoelectron microscopy.

Seven African swine fever virus structural proteins were localized in the virion by immunoelectron microscopy. African swine fever virus-infected cells were incubated, before or after embedding and thin sectioning, with monoclonal antibodies specific for different structural proteins, and after labeling with protein A-gold complexes, the samples were examined in the electron microscope. Proteins p14 and p24 were found in the external region of the virion, proteins p12, p72, p17, and p37 were found in the intermediate layers, and protein p150 was found in the nucleoid and in one vertex. A monoclonal antibody that recognized protein p150 as well as p220, a virus-induced, nonstructural protein, could also bind to a component present in the nucleus of both uninfected and virus-infected cells.

African Swine Fever Virus↗
PubMed1986

Monoclonal antibodies of African swine fever virus: antigenic differences among field virus isolates and viruses passaged in cell culture.

An analysis of the binding properties of a collection of monoclonal antibodies to African swine fever virus particles showed that virus field isolates passaged in porcine macrophages changed antigenically more than a strain of a cell-adapted virus passaged in Vero cells. From seven clones isolated from the spleen of a field-infected pig, we found four clones that had the same antigenic properties, one clone that had large changes in proteins p150 and p27 and small changes in proteins p37 and p14, and two clones that had minor changes in proteins p150 and p27, respectively. An analysis of the binding properties of the monoclonal antibodies to 23 field isolates from Africa, Europe, and America showed that the African isolates differed among themselves more than the European and the American isolates; in this study we found changes in 8 of the 10 virus proteins tested. The most variable proteins in the African isolates were p150, p27, p14, and p12. In contrast to the African isolates, protein p12 from the non-African viruses did not change. The clustering of the field virus isolates in six antigenic homology groups indicated the existence of a complex variety of African swine fever virus serotypes.

Africa↗
PubMed1986

Critical epitopes in transmissible gastroenteritis virus neutralization.

Purified transmissible gastroenteritis (TGE) virus was found to be composed of three major structural proteins having relative molecular weights of 200,000, 48,000, and 28,000. The peplomer glycoprotein was purified by affinity chromatography with the monoclonal antibody (MAb) 1D.G3. A collection of 48 MAbs against TGE virus was developed from which 26, 10, and 3 were specific for proteins E2, N, and E1, respectively. A total of 14 neutralizing MAbs of known reactivity were E2 protein specific. In addition, MAb 1B.C11, of unknown specificity, was also neutralizing. These MAbs reduced the virus titer 10(2)- to 10(9)-fold. Six different epitopes critical in TGE virus neutralization were found, all of which were conformational based on their immunogenicity and antigenicity. Only the epitope defined by MAb 1G.A7 was resistant to sodium dodecyl sulfate treatment, although it was destroyed by incubation in the presence of both the detergent and beta-mercaptoethanol. The frequency of MAb-resistant (mar) mutants selected with four MAbs (1G.A7, 1B.C11, 1G.A6, and 1E.F9) ranged from 10(-6) to 10(-7), whereas the frequency of the putative mar mutant defined by MAb 1B.B11 was lower than 10(-9). Furthermore, the epitopes defined by these MAbs and by MAbs 1H.C2 and 1A.F10, were present in 11 viral isolated with different geographical locations, years of isolation, and passage numbers (with the exception of two epitopes absent or modified in the TOY 56 viral isolate), suggesting that the critical epitopes in TGE virus neutralization were highly conserved.

Antibodies, Monoclonal↗
PubMed1985

Monoclonal antibodies specific for African swine fever virus proteins.

We have obtained 60 stable hybridomas which produced immunoglobulins that recognized 12 proteins from African swine fever virus particles and African swine fever virus-infected cells. Most of the monoclonal antibodies were specific for the three major structural proteins p150, p72, and p12. The specificity of some monoclonal antibodies for the structural proteins p150 and p37 and the nonstructural proteins p220 and p60 indicated that proteins p150 and p220 are antigenically related to proteins p37 and p60. The association of some viral antigens to specific subcellular components was determined by immunofluorescence and analysis of the binding of monoclonal antibodies to infected cells. A host protein (p24) seemed to be associated with the virus particles.

Animals↗
PubMed1984

Porcine leukocyte cellular subsets sensitive to African swine fever virus in vitro.

African swine fever virus infected most, if not all, of the macrophages (monocytes) and ca. 4% of the polymorphonuclear leukocytes from porcine peripheral blood. B and T lymphocytes, either resting or stimulated with phytohemagglutinin, lipopolysaccharide, or pokeweed mitogen, were not susceptible to the virus. All of the mitogens used inhibited African swine fever multiplication in susceptible cells. The number of virus passages in vitro and the virulence degree of the virus did not affect the susceptibility of porcine B or T lymphocytes to African swine fever virus.

African Swine Fever↗
PubMed1981

Resistance of cultures of normal T cells to infection with murine type C viruses.

Long-term continuous cultures of normal T cells were established from C57BL/6 and BALB/c mice by using conditioned medium from concanavalin A-stimulated lymphocytes. The ability of various murine type C viruses to infect these normal T cell cultures was examined and compared with their ability to infect transformed T cells. All of the viruses examined, including a thymotropic radiation leukemia virus, were unable to infect and replicate in normal T cells but readily did so in transformed T cells.

Animals↗
PubMed1981

T cell recognition of Moloney sarcoma virus proteins during tumor regression. I. Lack of a requirement for macrophages and the role of blastogenic factors in T cell proliferation.

The characteristics of the T cell blastogenic response of lymphocytes from Moloney leukemia/sarcoma virus inoculated mice against the virion proteins gp71 and p12 were examined. The proliferative responses to both antigens were independent of a requirement for macrophages as determined by macrophage-depletion experiments, the lack of an effect of antisera against Ia on proliferation and by analysis of the number of cell interactions required for proliferation. The kinetics of antigen-lymphocyte interaction were examined and found to require only 4 to 6 hr for half-maximal activation. Proliferation in response to gp71 or p12 was found to be due to the production of blastogenic factor(s), and using additivity experiments, little if any proliferation appears to be associated with antigen-specific lymphocytes. The production of blastogenic factor(s) does not require proliferation and is temporally displaced from antigen-lymphocyte interaction by 8 to 10 hr.

Animals↗
PubMed1981

T cell recognition of Moloney sarcoma virus proteins. II. Phenotypes of the different lymphocyte subpopulations producing and responding to blastogenic factors and their relative frequencies during tumor regression.

The characteristics of the blastogenic response of splenic lymphocytes from MoLV/MSV immune mice was examined. Splenic lymphocytes from immune mice proliferate in vitro in response to the major virion envelope glycoprotein, gp70. Associated with this response is production of blastogenic factors that induce the proliferation of nylon wool-purified lymphocytes from either normal or immune mice. The phenotype of antigen-specific lymphocytes essential for the production of blastogenic factors was found to be Thy 1.2+, Lyt 1+, 2-. The induction of proliferation by blastogenic factors does not require the presence of antigen. Using splenic lymphocytes from either normal or immune mice, blastogenic factors predominantly induce the proliferation of a Thy 1.2-, Lyt 1-, 2- lymphocyte. As a consequence of responding to blastogenic factors, in vitro, approximately 50% of this lymphocyte population becomes Thy 1.2+, Lyt 1+ over a period of 3 days. The frequencies of lymphocytes producing and responding to blastogenic factors were found to show characteristic changes during the course of tumor growth and regression.

Animals↗
PubMed1980

Characterization of a unique defective type C virus associated with a Moloney leukemia virus-induced splenic T-cell lymphoma cell line.

Moloney leukemia virus (MoLV) induces lymphomas in BALB/c mice which either involve an immature thymic T-cell subpopulation or a splenic mature T-cell subpopulation. To investigate further the possible virological and immunological differences in these lymphomas, several lymphoma cell lines were derived. Although the majority of these cell lines expressed only the parental MoLV, one lymphoma cell line (5F4) was found which expressed only a defective virus. 5F4 virions lacked detectable reverse transcriptase activity and by immunoprecipitation lacked a serologically detectable reverse transcriptase. The lack of reverse transcriptase did not appear to be due to a deletion in the viral genome. Intracellularly 5F4 cells synthesized normal gag gene precursors but had little, if any, detectable Pr180gag-pol or an altered precursor. These results suggest that the defect of the 5F4 virus is associated with the inability to translate the appropriate precursor for reverse transcriptase. The possible origin of the detective 5F4 virus was also examined by competition radioimmunoassays. These results demonstrate that the type-specific proteins, gp71 and p12, are serologically identical to those of the endogenous ecotropic virus and distinct from the MoLV proteins. Competition assays of 5F4 cell extracts further demonstrated the lack of any detectable MoLV type-specific proteins, although the tumor was presumably induced by MoLV. The significance of these observations to leukemogenesis is discussed.

Animals↗
PubMed1979

Cross-links in African swine fever virus DNA.

African swine fever virus DNA sediments in neutral sucrose density gradients as a single component with a sedimentation coefficient of 60S. In alkaline sucrose density gradients, this material shows two components with sedimentation coefficients of 85S and 95S, respectively. The sedimentation rate value of alkali-denatured virus DNA in neutral sucrose density gradients and the renaturation velocity of denatured DNA show that is reassociated much faster than expected from its genetic complexity. This behavior is compatible with the existence of interstrand cross-links in the molecule. We also present results which suggest that there are only a few such cross-links per molecule, that they are sensitive to S1 nuclease digestion, and that they are probably located next to the ends of the DNA.

African Swine Fever Virus↗
PubMed1977

Sensitivity of macrophages from different species to African swine fever (ASF) virus.

The swine white blood cells sensitive to African swine fever (ASF) virus are monocytes differentiated in vitro to macrophages. These cells have been characterized by their morphology, phagocytic capacity and the presence of receptors for swine immunoglobulin G in their membranes. ASF virus does not produce any detectable effect on macrophages from humans, rabbits, guinea pigs, hamsters or rats, whereas ASF virus-infected chicken macrophages show an enhancement of cellular DNA synthesis and an intense cytopathic effect. ASF virus, adapted to grow in VERO cells, produces a strong cytopathic effect in human macrophages leading to cell destruction. This effect is not associated with the synthesis of infectious virus, cellular or virus DNA nor with the formation of detectable virus-related structures.

African Swine Fever Virus↗
PubMed1976

Titration of African swine fever (ASF) virus.

A haemadsorption microtest for African swine fever (ASF) virus is described. This assay is as sensitive and its response is faster than the conventional assay which uses buffy coat cultures in Leighton tubes. The method can also process a larger number of samples by using smaller amounts of swine blood and laboratory space. A plaque assay for ASF virus adapted to grow in VERO cells gives a titre similar to that obtained using the haemadsorption microtest. In both the micromethod and the plaque assay infection may be produced by a single infective particle.

African Swine Fever Virus↗