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M A Franco

Publications and source records attributed to M A Franco.

35 records · Page 2Linked to original sources
PubMed1997

Flagellin, a major protein present in SDS-PAGE profiles of Sarkosyl-OMP-enriched fractions from Bordetella bronchiseptica Bvg- or modulated Bvg+ strains.

The bvg or vir locus positively regulates the expression of many Bordetella virulence-associated determinants (encoded by vag genes), including cell envelope proteins, in response to environmental stimuli. On the other hand, several genes named vrg genes are negatively controlled by the bvg regulon (Knapp and Mekalanos, 1988). Flagellin is encoded by a vrg gene, which is expressed when the principal virulence factors are eliminated during antigenic modulation or in phase variants (Akerley et al., 1992). We have previously analyzed SDS-PAGE profiles of Sarkosyl-outer membrane protein (OMP)-enriched fractions from B. bronchiseptica Bvg- and modulated Bvg+ strains and reported a major band associated with the avirulent phenotype (Passerini de Rossi et al., 1995). In order to characterize this band we have purified flagellar filaments from Bvg- and modulated Bvg+ strains, and analyzed them by SDS-PAGE. These profiles revealed a single major band of 40 or 45 kDa depending on the strain. The N-terminal amino acid sequence of the putative flagellin expressed by BB7200a was identical over the first 21 residues analyzed to that of the flagellin from the modulated strain BB7865 reported by Akerley et al. (1992). Comparison of the SDS-PAGE profile of flagellar filaments with that of the OMP-enriched fraction of the corresponding strain showed that the flagellum-associated polypeptide had the same electrophoretic mobility as that of the characteristic band of the avirulent phenotype. Furthermore, this band was absent in the OMP-enriched fraction profile from a Bvg- strain subjected to a treatment that removes flagella. Our results indicate that the major protein observed in SDS-PAGE profiles of Sarkosyl-OMP-enriched fractions from B. bronchiseptica Bvg- and modulated Bvg+ strains corresponds to flagellin.

Amino Acid Sequence↗
PubMed1997

Evidence for CD8+ T-cell immunity to murine rotavirus in the absence of perforin, fas, and gamma interferon.

We recently showed that class I-restricted CD8+ T cells mediate clearance of primary rotavirus infection in mice: JHD knockout (JHD -/-) (B-cell-deficient) mice depleted of CD8+ T cells become chronically infected with murine rotavirus, and beta2 microglobulin knockout (beta2m -/-) mice have delayed but complete clearance of primary rotavirus infection. In the present work we have analyzed the mechanism used by CD8+ T cells to clear rotavirus infection. We first determined that perforin knockout (perforin -/-) mice and lpr (fas-deficient) mice clear rotavirus infection with the same kinetics as control mice. When perforin -/- or perforin +/+ mice were depleted of CD8+ T cells by administration of an anti-CD8 monoclonal antibody, they showed a delay of 1 to 2 days in the clearance of rotavirus infection compared to the clearance time for untreated control mice, indicating that CD8+ T cells in both groups of mice participate in the resolution of primary rotavirus infection. In addition, passively transferred CD8+ T cells from rotavirus-infected perforin +/+ and perforin -/- mice were able to mediate viral clearance in Rag 2 knockout (Rag 2 -/-) mice chronically infected with rotavirus with similar kinetics, suggesting that CD8+ T cells from perforin -/- mice are as efficient as CD8+ T cells from perforin +/+ mice in clearing a rotavirus infection. Gamma interferon (IFN-gamma) was also shown to be unnecessary for the antirotavirus effect of CD8+ T cells: IFN-gamma knockout (IFN-gamma -/-) mice and JHD -/-, perforin -/-, and perforin +/+ mice depleted of IFN-gamma by administration of an anti-IFN-gamma monoclonal antibody cleared rotavirus infection with the same kinetics as those for control mice. Hence, CD8+ T cells have an antirotaviral effect that is not mediated by perforin and appears to be independent of fas and the release of IFN-gamma.

Animals↗
PubMed1997

CD8+ T cells can mediate almost complete short-term and partial long-term immunity to rotavirus in mice.

We have recently shown that CD8+ T cells mediate clearance of rotavirus infection in mice. B-cell-deficient J(H)D knockout (-/-) mice depleted of CD8+ T cells become chronically infected with murine rotavirus, and beta2 microglobulin -/- and other mice depleted of CD8+ T cells have a 1- to 4-day delay in clearance of primary rotavirus infection. A role for CD8+ T cells in protection from reinfection with rotavirus was suggested by these studies, because J(H)D -/- mice rechallenged 6 to 8 weeks after primary infection shed smaller quantities of viral antigen and for fewer days than naive mice. Here we show that 8, 11, 13, and 18 days after primary infection the J(H)D -/- mice are almost completely resistant to reinfection and that they are still partially protected from reinfection 6 weeks, 5 months, and 8 months after primary infection. Protection against reinfection was dependent on CD8+ T cells, since J(H)D -/- mice depleted of CD8+ T cells by administration of an anti-CD8 monoclonal antibody became chronically infected with rotavirus upon rechallenge 13 days, 18 days, 6 weeks, and 5 months after primary infection. Thus, CD8+ T cells can actively mediate almost complete short-term and partial long-term protection from reinfection.

Animals↗
PubMed1996

Rotavirus immunity in the mouse.

Naturally attenuated animal rotaviruses have been tested as antirotavirus vaccines with moderate success. The development of improved vaccines will rely on our understanding of the immune mechanism that mediate clearance and protection from rotaviral reinfection. The mouse model of rotavirus infection is a versatile tool for studying these mechanisms: mice have a relative low cost and there is a rapidly increasing number of immunological reagents to study rotavirus immunology. This review covers recent data on the mouse model of rotavirus infection. We show that both effector arms of the immune system (CD8 + T cells and B cells) mediate anti-rotavirus effects in vivo.

Animals↗
PubMed1996

Molecular determinants of immunity and pathogenicity of rotavirus infection in the mouse model.

Rotavirus-induced diarrhea is responsible for the death of approximately 800,000 children per year. Jennerian and modified Jennerian anti-rotavirus vaccines currently being tested have a moderate protective effect against rotavirus disease. Optimization of these vaccines, development of more efficient rationally designed vaccines, and identification of other strategies to prevent or treat rotavirus disease will rely on a thorough understanding of the host-virus relationship and especially on the immune mechanisms developed by the host against rotavirus. Recent advances in our understanding of the mouse model of rotavirus infection will enhance the understanding of human rotavirus disease.

Animals↗
PubMed1995

Role of B cells and cytotoxic T lymphocytes in clearance of and immunity to rotavirus infection in mice.

The immune mechanisms involved in clearance of and immunity to rotavirus infection are poorly understood. Although mice with severe combined immunodeficiency (SCID mice) become chronically infected, nude mice have been reported to clear rotavirus infection similarly to immunocompetent controls. To better characterize the role of cytotoxic T lymphocytes (CTLs) in clearance of and immunity to rotavirus infection, we infected naive or previously infected beta 2-microglobulin (beta 2m) knockout mice with murine rotavirus. Naive beta 2m knockout mice shed rotavirus antigen 2 days longer than did normal control mice but completely resolved primary infection. beta 2m knockout naive mice treated with depleting doses of an anti-CD8 monoclonal antibody before infection shed viral antigen for an additional day. Upon rechallenge, beta 2m knockout mice, either treated with the anti-CD8 antibody or not treated, were completely resistant to reinfection. Clearance of rotavirus infection in naive beta 2m knockout mice correlated with the development of intestinal rotavirus-specific immunoglobulin A. Before rechallenge, beta 2m knockout mice had high levels of intestinal rotavirus-specific immunoglobulin A. These findings suggest that CTLs mediate rotavirus clearance but are not required for this function and that CTLs are not necessary for development of immunity to rotavirus reinfection. To further characterize the effector mechanisms involved in clearance and prevention of rotavirus infection, similar studies were performed with B-cell-deficient JHD knockout mice. After primary infection, most naive JHD mice had similar virus-shedding clearance curves as did control mice and completely resolved primary infection. However, 2 of 29 became chronically infected. All JHD mice treated with anti-CD8 antibody became chronically infected with murine rotavirus. Upon rechallenge, JHD mice which had cleared primary infection were all susceptible to reinfection. These findings suggest that B cells also play a role in clearance of primary infection but are absolutely necessary for development of immunity against rotavirus reinfection.

Animals↗
PubMed1995

Antimony oxidation states in antileishmanial drugs.

Chemical methods specific for the determination of the levels of trivalent antimony (Sb+3) and pentavalent antimony (Sb+5) were used to investigate proprietary formulas used to treat leishmaniasis. Trivalent antimony was determined by differential pulse polarography, whereas Sb+5 was determined by iodine titration. Proprietary formulas based on N-meglumine antimoniate (Glucantime) were analyzed in detail. The results showed Sb+3 in all ampules of Glucantime. In formulations said to contain either 85 or 100 mg of Sb+5/ml, we found both forms of antimony. The amount of Sb+3 ranged from 10.5 to 15.8% (10.06-18.96 mg of Sb/ml). These findings raise issues on product stability and standardization and may help to clarify resistance to antimonial drugs and the reducing effect of tissue on Sb+5.

Antimony↗
PubMed1994

Identification of cytotoxic T cell epitopes on the VP3 and VP6 rotavirus proteins.

It has been shown previously that the viral glycoprotein VP7 is a major target of cytotoxic T lymphocytes (CTLs) induced by bovine rotavirus RF in C57BL/6 mice. Here we show that these RF-specific CTLs recognize target cells infected with a recombinant vaccinia virus (rVV) expressing the SA11 (simian rotavirus) VP6 but not those infected with rVVs that express RF VP1, VP2 or VP3 core proteins. After immunization of mice with insect cells infected with recombinant baculoviruses that express the corresponding RF proteins a strong specific CTL response was generated against target cells infected with VP6 rVV and VP3 rVV, a weak one against the VP2 rVV but none against the VP1 rVV. Kb-restricted CTL epitopes were identified on VP6 and VP3 using allele-specific motifs. When peptides corresponding to these epitopes were used to restimulate in vitro the spleen cells from RF-immunized mice, CTLs specific for each peptide and its corresponding rVV were induced.

Animals↗
PubMed1993

An immunodominant cytotoxic T cell epitope on the VP7 rotavirus protein overlaps the H2 signal peptide.

C57BL/6 (H-2b) mice were primed with the bovine RF strain of rotavirus to study the induction of CD8+ cytotoxic T lymphocytes (CTLs). These rotavirus-specific CTLs were detected only after in vitro restimulation with the virus. Using a recombinant vaccinia virus we identified the RF VP7 protein as a major target of these CTLs. The response against this protein was obtained also after in vitro restimulation with simian SA11 and human WA strains of rotavirus. Using published Db and Kb allele-specific motifs to predict possible CTL epitopes in the RF VP7 protein, we synthesized and tested 18 predicted peptides of VP7. Only one peptide was able to sensitize target cells at a concentration below 5 x 10(-7) M. This CTL epitope was also induced by immunization with the RF VP7 expressed with a baculovirus vector, and was shown to be immunodominant by its capacity to inhibit, in an unlabelled target assay, the bulk response against cells infected with recombinant vaccinia virus expressing VP7. This CTL epitope overlaps the H2 signal peptide of the protein.

Amino Acid Sequence↗
PubMed1982

[Bacillus subtilis BSA 170 trp- ura-: a new nutritional mutant with absolute requirements for exogenous tryptophan and uracil for its growth].

A new Bacillus subtilis mutant was prepared, with a double nutritional requirement for uracil and tryptophan. The mutant, designed Bacillus subtilis BSA 170 trp- ura-, was constructed by transformation method, acting B. subtilis strain PB 168 trp- as recipient and B. subtilis strain PB 3308 ura- as transforming DNA donor cells. The BSA 170 trp- ura- strain was selected by replication of transformed population on nutritionally selective media. Competence development induction and genetic markers transformability were tested. The new mutant was competent by Young and Spizizen's methodology. Furthermore, both markers, uracil and tryptophan, may be transformed when B. subtilis BSA 170 trp- ura- competent cells are treated with transforming DNA isolated from B. subtilis PB 19, prototroph. Transformation frequency rate for each marker alone was far larger than that reached for both taken together.

Bacillus subtilis↗
PubMedDate not supplied

[Risperidone in the treatment of psychotic disorders associated with mental retardation].

INTRODUCTION: The safety and effectiveness of risperidone in patients with a diagnostic of mental retardation and/or psychotic and disturbance disorder was assessed in an open and observational study. MATERIAL AND METHODS: A total of 127 patients with DSM-III-R diagnoses of mental retardation together with psychotic disturbance (psychotic and/or behaviour disturbance) was included in an open label surveillance study. The study objectives were to evaluate safety and efficiency of risperidone in these patients during a six-month period. Risperidone was assessed by the Clinical Global Impression (CGI), schizophrenia subscales of Scale for Evaluating Emotional Disorders in Severely and Profoundly Mentally Retarded Persons (DASH) and Assessment and Information Rating Profile (AIRP), UKU subscale for neurological side effects and spontaneous reports. RESULTS: Ten patients (7.9%) were excluded from the statistical analysis due to protocol violation. Seventeen patients (14.5%) dropped out. Risperidone was used at a mean dosage of 2.98 (2.37 mg daily. Risperidone produced a significant reduction, vs baseline, in the mean total scores of CGI and DASH-AIRP scales from day 15 onwards. There was a significant reduction in the total UKU subscale for neurological, autonomic side effects scores and psychotic symptoms. Risperidone was generally well tolerated. During the 6 months of study period, 93.2% of the patients did not suffer any adverse event; the resting 7.7% suffered one or more side effects. DISCUSSION: In this study, risperidone was a safety and effectiveness treatment in patients with a diagnostic of mental retardation and psychotic and/or disturbance disorder associated.

Adolescent↗
PubMedDate not supplied

[Biotyping and molecular phenotypic characterization of Bordetella bronchiseptica].

In the present study biochemical tests and outer membrane protein profile (OMP) capacity for typing Bordetella bronchiseptica field isolates were evaluated. The biochemical tests were performed by API 20NE system. OMP enriched fractions were obtained from cultures under virulent and modulated conditions and were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). We have identified five patterns by differences in the bands in the 85-95 kDa region (alpha, beta, gamma, delta and epsilon) from virulent cultures; and three different patterns by the flagellin expressed isotype from modulated cultures (A: 40 kDa, B: 45 kDa, and C: 40 and 45 kD simultaneously). Isotypes alpha, beta and gamma were linked to isotpye A, isotype delta to B and C, and isotypes epsilon to B. There is no evident correlation between characterized isotypes and the origin of the isolate. Nitrate reduction was the unique variable biochemical characteristic, only observed in rabbit isolates. It was possible to differentiate seven groups with the traits included in the study. The capacity of discrimination of the traits analyzed using the Hunter and Gaston index was 0.829.

Animals↗
PubMedDate not supplied

[Viability of Bacillus subtilis auxotrophs in the absence of their essential metabolites].

The effect of tryptophan and uracil starvation on the viability of the transformant B. subtilis BSA 170 trp- ura- and its parent strains Bacillus subtilis PB 168 trp -C and Bacillus subtilis PB 3308 ura- was examined. These studies were performed at the conditions for competence development, during 16 hours. Our results showed that B. subtilis BSA 170 was resistant to tryptophan-less death during all the assay and was also resistant to uracil-less death during three hours. After this time, viability measurements revealed less colony forming units per milliliter, and decrease of the culture absorbances. The uracil-less death required the presence of tryptophan suggesting that protein synthesis is needed. The parental strains exhibit similar behavior. Bacillus subtilis PB 168 was resistant to tryptophan-less death and B. subtilis PB 3308 showed decrease of the viability after uracil starvation comparable to that of the transformant strain.

Bacillus subtilis↗
PubMedDate not supplied

[Effect of different dairy products on the growth of Listeria monocytogenes in selective media].

We have studied the influence of the incorporation of milk cream and skim milk on the growth kinetic of Listeria monocytogenes in listeria enrichment broth with 15 mg/l or 7.5 mg/l of acriflavine. Acriflavine was responsible, at least partially, for delayed growth of Listeria monocytogenes in the enrichment broths. A longer lag phase of the growth was produced by the addition of milk cream or skim milk to the enrichment broth containing 7.5 mg/l of acriflavine. However, the maximum population obtained at 48 h did not show significant differences. In the presence of 15 mg/l of acriflavine, we observed a decrease of the viable counts during the early phase of the growth cycle, which was enhanced by the addition of milk cream or skim milk. Moreover, the maximum growth rate was reduced by the addition of skim milk and maximum population was not reached at 48 h. These results suggest the need to validate the methodology of recuperation of Listeria monocytogenes from each dairy product, since its efficiency may be affected by product composition, specially when the sample biocharge is low.

Acriflavine↗
PubMedDate not supplied

[Selection of Bvg- variants of Bordetella pertussis].

Bordetella pertussis virulent strains (Bvg+) produce a wide array of virulence factors. The production of these factors is coordinately regulated by the locus bvg in response to environmental signals in a process known as antigenic modulation. Mutations in the bvg locus originate avirulent variants (Bvg-) that are unable to express virulence factors regardless of growth conditions. In this paper we have obtained spontaneous variants Bvg- of B. pertussis Tohama I and 10536, which would be useful for studying virulence markers, using the selective media Stainer-Scholte agar supplemented with 1% Casamino-acids (SSA-CAS) and Jones-Kendrick with 0.20 microgram of erythromycin per ml (JK-Ery). We have also studied the efficiency of plating of B. pertussis Tohama I, 10536 and 40103 cells (Bvg+ strains) and of Bvg- strain 347 (control of the avirulent phenotype) on SSA-CAS and Stainer-Scholte agar (SSA), and we have analyzed the phenotype of the cells recovered from these media. The bacterial phenotype was characterized by using the following virulence markers: hemolysis production, hemagglutinin production, and outer membrane protein (OMP) enriched profiles. The three Bvg+ strains showed different behaviour in these selective media. B. pertussis Tohama I and 10536 could not be recovered on SSA, whereas on SSA-CAS the efficiency of plating was poor, less than 0.001%, but nevertheless allowed the selection of stable Bvg- variants of Tohama I since the OMP profile of this stain did not change after subculture in Cyclodextrin liquid medium. By contrast, strain 10536 grown on SSA-CAS suffered the process of antigenic modulation since this strain recovered the virulent phenotype when it was subcultured in Bordet-Gengou. Stable Bvg- variants from Tohama I and 10536 were obtained on JK-Ery. On the other hand, Bvg+ strain 40103 showed a high efficiency of plating on SSA and SSA-CAS and retained the virulent phenotype in all the selective media. Bvg- strain 347, in spite of being an avirulen variant, showed a poor efficiency of plating in SSA and a scant growth in JK-Ery, in agreement with the findings of other investigators which suggest that not all avirulent strains posses the ability to grow on media that inhibit most of virulent strains.

Bacterial Outer Membrane Proteins↗