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E Domingo

Publications and source records attributed to E Domingo.

At least 181 records · Page 10Linked to original sources
PubMed1991

Fitness alteration of foot-and-mouth disease virus mutants: measurement of adaptability of viral quasispecies.

We document the rapid alteration of fitness of two foot-and-mouth disease virus (FMDV) mutants resistant to a neutralizing monoclonal antibody. Both mutants showed a selective disadvantage in BHK-21 cells when passaged in competition with their parental FMDV. Upon repeated replication of the mutants alone, they acquired a selective advantage over the parental FMDV and fixed additional genomic substitutions without reversion of the monoclonal antibody-resistant phenotype. Thus, variants that were previously kept at low frequency in the mutant spectrum of a viral quasispecies rapidly became the master sequence of a new genomic distribution and dominated the viral population.

Amino Acid Sequence↗
PubMed1990

Foot-and-mouth disease virus strains isolated from persistently infected cell cultures are attenuated for mice and cattle.

It was previously reported that during serial passage of a BHK-derived cell line persistently infected with foot-and-mouth disease virus, (termed C1-BHK-Rc1) the virus became increasingly more virulent for BHK-21 cells (de la Torre et al 1988). Virus strains isolated from different cell passage levels were tested for virulence in mice and cattle. The results showed that in the course of persistence in BHK cells, FMDV became progressively less virulent for mice and cattle.

Animals↗
PubMed1990

A single amino acid substitution affects multiple overlapping epitopes in the major antigenic site of foot-and-mouth disease virus of serotype C.

Neutralizing monoclonal antibodies (nMAbs) elicited against foot-and-mouth disease virus (FMDV) of serotype C were assayed with field isolates and variant FMDVs using several immunoassays. Of a total of 36 nMAbs tested, 23 recognized capsid protein VP1 and distinguished at least 13 virion conformation-independent epitopes involved in neutralization of FMDV C. Eleven epitopes of FMDV C-S8c1 have been located in segments 138-156 or 192-209 of VP1 by quantifying the reactivity of nMAbs with synthetic peptides and with nMAb-resistant mutants of FMDV C-S8c1 carrying defined amino acid substitutions. The main antigenic site of FMDV C-S8c1 (VP1 residues 138 to 150) consists of multiple (at least 10), distinguishable, overlapping epitopes. Some amino acid replacements abolished one of the epitopes, whereas other replacements affected several epitopes in this region. The conservative substitution His(146)----Arg, found in many nMAb-resistant mutants analysed, abolished the reactivity of the virus with all nMAbs that recognized epitopes in the main antigenic site of FMDV C-S8c1. This indicates that a minimum genetic change can result in a highly amplified phenotypic effect, as regards the antigenicity of FMDV.

Amino Acid Sequence↗
PubMed1990

Unique amino acid substitutions in the capsid proteins of foot-and-mouth disease virus from a persistent infection in cell culture.

Maintenance of a persistent foot-and-mouth disease virus (FMDV) infection in BHK-21 cells involves a coevolution of cells and virus (J. C. de la Torre, E. Martínez-Salas, J. Díez, A. Villaverde, F. Gebauer, E. Rocha, M. Dávila, and E. Domingo, J. Virol. 62:2050-2058, 1988). The resident FMDV undergoes a number of phenotypic changes, including a gradual decrease in virion stability. Here we report the nucleotide sequence of the P1 genomic segment of the virus rescued after 100 passages of the carrier cells (R100). Only 5 of 15 mutations in P1 of R100 were silent. Nine amino acid substitutions were fixed on the viral capsid during persistence, and three of the variant amino acids are not represented in the corresponding position of any picornavirus sequenced to date. Cysteine at position 7 of VP3, that provides disulfide bridges at the FMDV fivefold axis, was substituted by valine, as determined by RNA, cDNA, and protein sequencing. The modified virus shows high buoyant density in cesium chloride and depicts the same sensitivity to photoinactivation by intercalating dyes as the parental FMDV C-S8c1. Amino acid substitutions fixed in VP1 resulted in altered antigenicity, as revealed by reactivity with monoclonal antibodies. In addition to defining at the molecular level the alterations the FMDV capsid underwent during persistence, the results show that positions which are highly invariant in an RNA genome may change when viral replication occurs in a modified environment.

Amino Acid Sequence↗
PubMed1989

RNA virus evolution and the control of viral disease.

RNA viruses and other RNA genetic elements must be viewed as organized distributions of sequences termed quasi-species. This means that the viral genome is statistically defined but individually indeterminate. Stable distributions may be maintained for extremely long time periods under conditions of population equilibrium. Perturbation of equilibrium results in rapid distribution shifts. This genomic organization has many implications for viral pathogenesis and disease control. This review has emphasized the problem of selection of viral mutants resistant to antiviral drugs and the current difficulties encountered in the design of novel synthetic vaccines. Possible strategies for antiviral therapy and vaccine development have been discussed.

Animals↗
PubMed1989

Implications of a quasispecies genome structure: effect of frequent, naturally occurring amino acid substitutions on the antigenicity of foot-and-mouth disease virus.

We provide evidence that the quasispecies nature (extreme genetic heterogeneity) of foot-and-mouth disease virus is relevant to the virus evading an immune response. A monoclonal antibody neutralizing the viral infectivity (clone SD6) recognizes an epitope located around a highly conserved sequence (amino acid sequence Arg-Gly-Asp-Leu-Ala at positions 141-145) in the capsid protein VP1 of foot-and-mouth disease virus of serotype C1. The amino acid substitutions Ala-138----Thr and Leu-147----Ile (or ----Val) reduced 100-fold the binding titer of monoclonal antibody SD6 to virions or to VP1. The effect of those substitutions was quantitatively reproduced with synthetic peptides representing the relevant sequences. This provides evidence that the two chemically conservative amino acids replacements--and not other substitutions present in the virus quasispecies--are responsible for the modified interaction with neutralizing monoclonal antibody SD6. The three substitutions were fixed in the viral capsid during one occurrence of foot-and-mouth disease and, furthermore, they are of a type found frequently among independent foot-and-mouth disease virus isolates. The results implicate the extreme heterogeneity of foot-and-mouth disease virus as an important element of viral pathogenesis.

Amino Acid Sequence↗
PubMed1989

A cost-effectiveness analysis of a simple micromethod for hepatitis B screening in hepatitis B virus control programmes.

We developed a simple micromethod for identifying mothers who are most likely to transmit hepatitis B infection to their infants, using reverse passive haemagglutination for detecting HBsAg (hepatitis B surface antigen) in capillary blood. This screening method was evaluated against other strategies for hepatitis B control by means of decision- and cost-effectiveness analyses. The micromethod was shown to be cost-effective when the cost of hepatitis B vaccine was high. However, with increasingly reduced costs of the vaccine, it may have a limited role in a programme of mass immunization for hepatitis B.

Carrier State↗
PubMed1989

Prognostic value of segmental contractility assessed by cross-sectional echocardiography in first acute myocardial infarction.

We prospectively studied 110 patients with a first acute myocardial infarction with cross-sectional echocardiography, between 7-10 days post-infarction, to assess the value of semiquantitative segmental contractility score for the first year post-AMI risk stratification. 87 patients had acceptable recordings (40 anterior and 47 inferior infarction). Twelve patients had severe complications (severe angina or heart failure, reinfarction or death) and 40 had non-severe complications. The total segmental score was higher in complicated than in non-complicated patients. The score also differentiated angina from heart failure. The score of necrotic area was more discriminating than that of non-necrotic area. Discriminating power was higher in anterior than in inferior acute myocardial infarction. Thus we conclude that the semiquantitative assessment of segmental contractility by cross-sectional echocardiography is useful for risk stratification following acute infarction identifying severe complications, particularly heart failure, with better discrimination in anterior acute myocardial infarction.

Adult↗
PubMed1989

Selection of antigenic variants of foot-and-mouth disease virus in the absence of antibodies, as revealed by an in situ assay.

Antigenic variants of foot-and-mouth disease virus (FMDV) of serotype C (isolate C-S8c1) were selected upon serial passage of the virus in cell culture in the absence of anti-FMDV antibodies. The variants rose from frequencies of less than 10(-2) in the initial plaque-purified FMDV C-S8c1 preparation, to 0.1 to 1 in three passaged populations. The proportion of antigenic variants was quantified using a new in situ plaque immunotest. A nitrocellulose filter is applied to the agar overlay of a FMDV plaque assay, and allows recovery of infectious virus from individual plaques. A second filter is placed directly on the cell monolayer and binds enough virus to permit colorimetric visualization of plaques by an enzyme-linked assay using monoclonal antibodies (MAbs). Either all or a fraction of plaques from passaged FMDV failed to react with MAb4G3, an antibody that recognizes an epitope located within residues 144 to 150 of capsid protein VP1. Some variants rapidly dominated the viral population, and others were maintained at low levels. RNA from unreactive viruses included mutations that resulted in amino acid substitutions at the epitope recognized by MAb 4G3. We discuss models for the selection of antigenic variants of FMDV in the absence of antibodies, and implications for the antigenic diversification of RNA viruses.

Amino Acid Sequence↗
PubMed1989

Extensive cell heterogeneity during persistent infection with foot-and-mouth disease virus.

Coevolution of viruses and the host cells occurred in BHK-21 cell cultures persistently infected with foot-and-mouth disease virus (FMDV) (J. C. de la Torre, E. Martínez-Salas, J. Diez, A. Villaverde, F. Gebauer, E. Rocha, M. Dávila, and E. Domingo, J. Virol. 62:2050-2058, 1988). In the present report we provide evidence of an extreme phenotypic heterogeneity of the cells, which was generated in the course of persistence. A total of 248 stable cell clones isolated from FMDV carrier cultures at early or late passages were analyzed. At least six distinct cell phenotypes were distinguished with regard to cell morphology, resistance to FMDV strain C-S8c1, and cell growth characteristics. No infectious FMDV or viral RNA was detected in variant cell clones, suggesting that the altered phenotypes were caused by inheritable cell modifications, selected in the course of persistence. Thus, the FMDV-BHK-21 carrier cell system must be described as a dynamic interaction between an evolving heterogeneous population of virus and multiple cell variants. We suggest that cell heterogeneity confers a selective advantage for long-term virus and cell survival by providing the cell population with a range of responses toward FMDV.

Animals↗
PubMed1989

Virus mutation frequencies can be greatly underestimated by monoclonal antibody neutralization of virions.

Monoclonal antibody-resistant mutants have been widely used to estimate virus mutation frequencies. We demonstrate that standard virion neutralization inevitably underestimates monoclonal antibody-resistant mutant genome frequencies of vesicular stomatitis virus, due to phenotypic masking-mixing when wild-type (wt) virions are present in thousandsfold greater numbers. We show that incorporation of antibody into the plaque overlay medium (after virus penetration at 37 degrees C) can provide accurate estimates of genome frequencies of neutral monoclonal antibody-resistant mutant viruses in wt clones. By using this method, we have observed two adjacent G----A base transition frequencies in the I3 epitope to be of the order of 10(-4) in a wt glycine codon. This appears to be slightly lower than the frequencies observed at other sites for total (viable and nonviable) virus genomes when using a direct sequence approach.

Animals↗
PubMed1989

Resistance to foot-and-mouth disease virus mediated by trans-acting cellular products.

Upon serial passage of BHK-21 cells persistently infected with foot-and-mouth disease virus (FMDV) C-S8c1, cells with increased resistance to the virus were selected (J. C. de la Torre, E. Martinez-Salas, J. Diez, and E. Domingo, J. Virol. 63:59-63, 1989). Two highly resistant cell clones, 74A11 and 74D12, were transformed to puromycin resistance (Purr) and were fused to BHK-21 cells transformed to neomycin resistance (Neor). The hybrid Neor Purr cells showed the specific resistance to FMDV C-S8c1 characteristic of clones 74A11 and 74D12. The results suggest that resistance to FMDV C-S8c1 is mediated by trans-acting cellular products. The possibility of engineering constitutive resistance to FMDV is discussed.

Animals↗
PubMed1989

[Evaluation of small branch occlusion and myocardial damage related to angioplasty. Usefulness of determining serum CK-MB].

In 65 consecutive cases of PTCA we prospectively looked for the appearance of myocardial necrosis during PTCA and for the presence of occlusion of collateral branches arising from the inflation area. Premedication was oral in 44 and intramuscular in 21 cases. CK-MB was abnormally increased in 6 cases: 3 with total occlusion of the dilated artery, 1 with transient coronary occlusion, and 1 with occlusion of a collateral branch greater than 1 mm diameter; in the sixth case the increased CK-MB peak was attributed to repeated defibrillations. Only 1 collateral branch less than 1 mm was occluded during PTCA though myocardial necrosis was not detected. Only collateral branches arising from the dilated stenosis were affected (occlusion and/or appearance of new stenosis) by PTCA (4/24 vs 0/162; p less than 0.01). There were no significant differences in CK-MB peak between both types of premedication. Thus we conclude that: 1) in PTCA myocardial necrosis is only induced by occlusion of coronary arteries greater than 1 mm diameter; 2) only collateral branches arising from the dilated stenosis are at risk of occlusion; 3) estimation of CK-MB pre-PTCA and 8 hours post-PTCA are sufficient for detection of myocardial necrosis.

Adult↗
PubMed1989

[Coronarography using high-flow 5F catheters. Percutaneous technic using the femoral and brachial routes].

In order to validate 5F catheters for assessing ischemic heart disease either by the femoral and the right brachial approaches, we prospectively studied with these catheters 125 patients by means of left ventriculogram and coronary artery angiograms. Twenty-five patients were studied with pigtail and Amplatz catheters using the right brachial approach (group I) and 100 patients were studied by the femoral route with pigtail and Judkins catheters (group II). Results were compared to those obtained in a control group of 100 patients prospectively studied by the femoral route with 8F catheters (group III). The following parameters were analyzed: need to change the initially elected catheter diameter or/and artery approach; technical difficulty for obtaining left ventriculogram, left coronary artery, and right coronary artery angiograms; total time of X-ray exposure; quality image of left ventriculograms; incidence of arterial puncture related hematomas or total arterial occlusion; and duration of local compression after sheath removal. There were no differences between groups I and II except for the arterial compression time (p less than 0.0001), and the X-ray exposure time (p = 0.02); both were longer in patients studied by the brachial approach (group I). Whatever the route used, 5F showed a mild increased difficulty (brachial p = 0.001; femoral p = 0.01), and a mild decreased quality image for left coronary artery (brachial p = 0.006; femoral p less than 0.05). Among patients studied by the femoral route a reduction in mild hematomas (p less than 0.05) and in the arterial compression time (p less than 0.0001) were observed in those studied with 5F catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiocardiography↗
PubMed1988

3D gene of foot-and-mouth disease virus. Conservation by convergence of average sequences.

The nucleotide sequence of the 3D (polymerase) gene of eight epidemiologically related isolates of foot-and-mouth disease virus of serotype C1 is reported. The genetic heterogeneity of 3D RNA is compared with that of the VP1-coding RNA of the same viruses. Regression lines of substitutions per nucleotide that distinguish any pair of viruses as a function of the time interval between the corresponding isolations show: (1) the slope (substitutions/nucleotide per month) is 2.1 times larger for the VP1 RNA than for the 3D RNA region; (2) the intercept with the ordinate (substitutions/nucleotide) for VP1 RNA is indistinguishable from that for 3D RNA. Thus, the average heterogeneity of the VP1-coding region is very similar to that of the 3D-coding region only among co-circulating viruses. Nine mutations and points of heterogeneity occurred within nucleotide residues 883 to 1026, which encode an amino acid segment, extremely conserved among many different RNA viruses. The results suggest that, rather than due to inherently lower mutability, the conservation of 3D genes is caused by a limitation in the fixation of substitutions in viable genomes.

Base Sequence↗