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Biomedical subjects

C E Coto

Publications and source records attributed to C E Coto.

At least 19 recordsLinked to original sources
PubMed2001

Involvement of vacuolar proton ATPase in Junin virus multiplication.

The role of vacuolar-proton ATPase (V-H+ ATPAse) on Junin virus (JV) replication was evaluated by analyzing the effect of specific inhibitors of the enzyme activity on different steps of virus multiplication cycle. The presence of the macrolide antibiotics bafilomycin A1 and concanamycin A during the first two hours of infection caused a significant reduction of extracellular infectious virus production and viral protein expression in Vero and BHK-21 cells. The inhibitory action of the compounds was mainly exerted at an early stage of the JV multiplication cycle, without affecting virus attachment to the cell but preventing virus penetration. A correlation between the inhibitory action of the compounds on intracellular compartments acidification and the reduction of JV yield was observed. The addition of concanamycin A at different times after infection indicated that the compound also interferes with the release of infectious particles to the extracellular medium. Although, intracellular transport of JV glycoproteins to the cell membrane, seems not to be affected as revealed by immunofluorescence staining. The results confirm that JV enters into the cell through the endocytic pathway as previously suggested by using lysosomotropic compounds.

Adsorption↗
PubMed2000

Antiviral effect of brassinosteroids against herpes virus and arenaviruses.

A natural brassinosteroid and a series of synthetic derivatives were found to be good inhibitors of herpes simplex virus type 1 (HSV-1) and arenavirus replication in cell culture. The synthetic compounds tested were analogues of the 24(S) ethylbrassinone. Compounds (22 R,23 R,24S)-2alpha, 3alpha,5alpha,22,23-pentahydroxy-stigmastan-6-one and (22R,23R,24S)-3beta-bromo-5alpha,22,23-trihydroxy stigmastan-6-one were cytotoxic at concentrations of 20-40 microM. (22S,23S,24S)-2alpha,3alpha,22,23-tetrahydroxy-5alpha, stigmastan-6-one, (22R,23R,24S)-3beta-acetoxy-22,23-dihydroxy-5alpha-choles tan-6-one, (22S,23S,24S)-3beta-bromo-22,23-dihydroxy-5alpha-cholestan-6 -one and (22S,23S,24S)-3beta-bromo-5alpha,22,23-trihydroxy-stigmastan -6-one were the most active of the series against HSV-1, with selectivity index (SI) values (CC50/EC50) ranging from 10.6 to 16.5. The majority of the compounds were potent inhibitors of arenaviruses, (22S,23S,24S)-3beta-bromo-5alpha,22,23-trihydroxy-stigmastan -6-one being the most active, with SI values of 307.8 and 692.5 for Tacaribe and Junin viruses, respectively. The antiviral activity of brassinosteroid derivatives was not because of direct inactivation; time-of-addition experiments suggested that a late step in HSV-1 multiplication was affected, whereas arenaviruses remained susceptible to the compounds throughout the replicative cycle.

Animals↗
PubMed2000

Treatment with meliacine, a plant derived antiviral, prevents the development of herpetic stromal keratitis in mice.

Herpetic stromal keratitis is caused by ocular infection with herpes simplex virus type 1 (HSV-1) and constitutes a leading cause of human blindness. The effect of meliacine, an antiviral compound isolated from leaves of Melia azedarach L. that inhibits HSV-1 replication in vitro, was examined on experimental corneal HSV-1 inoculation in Balb/c mice. Mice were inoculated with HSV-1 strain KOS at their corneas after abrasion. Meliacine was administered topically 3 times a day for 4 days beginning 1 day before inoculation. Infected animals treated or not with meliacine were observed carefully for the development of stromal keratitis and the clinical scoring was done 14 days post-infection. Histological examination of corneas and viral isolation from eyes from HSV-1 infected mice treated or not with meliacine were also carried out. It was found that the treatment of HSV-1-induced ocular disease in Balb/c mice with meliacine reduced significantly the development of clinical disease, as well as the histological damage in corneas. The viral titers detected in eyes of infected and treated mice were 2-orders-of-magnitude lower than those corresponding to HSV-1 infected control animals. Mock-infected and treated mice did not reveal any corneal alteration due to the administration of the compound. Meliacine was found to exert a strong antiviral action on HSV-1-induced ocular disease in mice with no evidence of toxic effects.

Animals↗
PubMed1999

Antiviral activity of enterocin CRL35 against herpesviruses.

Enterocin CRL35 is an antibacterial polypeptide of 3.5 x 10(3) Da produced by Enterococcus faecium CRL35. A series of experiments are described that show the enterocin also had antiviral activity against thymidine-kinase positive (tk+) and deficient (tk-) strains of herpes simplex (HSV) type 1 and 2 in Vero and BHK-21 cells. This activity was observed at 100 microg/ml, 15-fold lower than the cytotoxic concentration. In both cell lines there was a 2 log inhibition of infectivity. The compound inhibited viral multiplication in a dose-dependent manner and had no virucidal effect. Enterocin CRL35 also inhibited the virion-associated host shutoff in infected Vero cells showing that intracellular viral multiplication was affected.

Acyclovir↗
PubMed1998

Inhibition of foot and mouth disease virus (FMDV) uncoating by a plant-derived peptide isolated from Melia azedarach L leaves.

Meliacine (MA), a peptide isolated from leaves of the high plant Melia azedarach L inhibited the multiplication of foot and mouth disease virus (FMDV) in BHK-21 cells. In this report, we establish that the MA-inhibitable process takes place within the first hour of the viral reproductive cycle. MA had no virucidal effect and did not affect adsorption and penetration of the virus in cells. In experiments with neutral red-labeled virus, it was found that MA significantly suppressed the development of photoresistance of the virus in infected cells. In untreated cultures nearly all virus which adsorbed to cells was uncoated within 1 h at 37 degrees C, whereas in treated cultures, even after 3 h only 3% of the virus was uncoated. Labeling of BHK-21 cells with acridine orange showed that MA affects the pH of intracellular acidic vesicles. Therefore, it is concluded that MA prevents the process of uncoating of FMDV in BHK-21 cells by inhibiting vacuolar acidification.

Animals↗
PubMed1998

In vitro anti-Junin virus activity of a peptide isolated from Melia azedarach L. leaves.

Meliacine, a peptide isolated from leaves of Melia azedarach L. inhibited the multiplication of Junin virus in Vero cells treated with the compound before infection (pre-treatment) or immediately after virus adsorption. Analysis of early events following infection demonstrated that meliacine blocks virus penetration by preventing the uncoating step. The addition of meliacine at different times after infection indicated that meliacine also interferes with the release of infectious particles to the extracellular medium and inhibits the low-pH-induced fusion of infected cells. Intracellular transport of viral glycoproteins to the cell membrane was not affected by meliacine, as revealed by immunofluorescence staining. Taken together, these results suggest that meliacine affects two events of the virus replicative cycle that require membrane fusion: uncoating and budding.

Animals↗
PubMed1994

In vitro antiphagocytic effect of Melia azedarach leaf extracts on mouse peritoneal exudate cells.

The effect of Melia azedarach L. (Meliaceae) leaf extract on the phagocytic capability and respiratory burst of mouse peritoneal exudate cells was studied. The extract inhibited the phagocytosis of opsonized sheep erythrocytes. This inhibition was both dose- and time-dependent and reverted 48 h after removing the extract from the culture medium. Furthermore, chemiluminescence in treated cells was also impaired using either receptor (opsonized zymosan) or post-receptor (PMA) stimuli.

Animals↗
PubMed1994

A simple method to eliminate mycoplasma from cell cultures.

The efficacy of several antibiotic treatments to eliminate mycoplasma from Vero cells contaminated chronically with Mycoplasma orale II were tested. Minocyclin, Kanamycin, Tylosine and Roxitromycin, at non cytotoxic concentrations, were assayed alone or in different combinations. Mycoplasma contamination was effectively eradicated without recurrence once the following regimen was applied: Incubation of contaminated cells with Tylosine (250 micrograms/ml) for 12 days followed by incubation with Minocycline (5 micrograms/ml) for 10 days. This treatment was not deleterious for cell growth, it was effective after only one application and it was successful to eradicate mycoplasma from other contaminated eukaryotic continuous cell lines.

Animals↗
PubMed1993

In vitro selection of Junin virus antigenic variants.

The establishment of an experimental persistent infection with Junin virus, the aetiological agent of argentine hemorrhagic fever, involves the emergence of antigenic variants in brain and blood of the cricetid Calomys musculinus. We demonstrate that antigenic variants can also be isolated in vitro under the selective pressure of polyclonal antibodies and from a long-term infected C. musculinus primary embryo fibroblast culture. The participation of neutralizing antibodies and host cells in the appearance of viral variants in vivo is discussed.

Animals↗
PubMed1991

Characteristics of an inulinase produced by Bacillus subtilis 430A, a strain isolated from the rhizosphere of Vernonia herbacea (Vell Rusby).

Bacillus subtilis 430A, isolated from the Vernonia herbacea (Vell Rusby) rhizosphere, produced an exocellular inulinase that fits the requirements for the production of syrups on an industrial scale. The partially purified enzyme, obtained by acetone precipitation, displayed a higher specificity for inulin (Km, 8 mM) than for sucrose (56 mM) and a total invertase/total inulase ratio of 0.62. In addition, it is stable at an optimal temperature of 45 to 50 degrees C for at least 7 h and is inhibited by the end product, fructose, at 14 mM.

Bacillus subtilis↗
PubMed1990

Meliacine, an antiviral compound from Melia azedarach L., inhibits interferon production.

A glycopeptide isolated from the high plant Melia azedarach L. (meliacine) inhibits the in vitro replication of several RNA and DNA animal viruses. Interferon (IFN) production was depressed greatly in meliacine treated L929 cells and primary mouse embryo fibroblast cultures (MEF) induced with Newcastle disease virus (NDV) or poly(rI).poly(rC). This action was observed when meliacine was added before, simultaneously or early after induction with poly(rI).poly(rC) or NDV. In addition, accumulation of acid-resistant IFN was strongly diminished in adult mice treated intraperitoneally with meliacine. Though meliacine causes a strong inhibition of IFN both in vitro and in vivo, we do not know how selectively it affects the IFN system.

Animals↗
PubMed1990

[Blood parameters variation in Calomys musculinus infected with Junin virus, strain XJCl3].

The aim of this study was to analyze the alterations in homeostasis induced by Junin virus during acute and persistent infection of C. musculinus. Virus presence in brain, hematological response and glycemia levels were evaluated. Newborn C. musculinus inoculated with 4000 DL50 of Junin virus, strain XJCl3 by intraperitoneal route developed a typical acute disease, with 50-70% mortality. Virus was isolated from brain starting day 6 post-infection (Fig. 1) and the peak titer (10(8) DL50/ml) was reached at 12 days post-infection. Neutralizing anti-Junin virus antibodies were detected from day 11 post-infection and all chronically infected animals developed persistent levels of neutralizing antibodies. In the acute stage of infection, 40% of the animals developed lymphopenia and neutrophilia (Fig. 2) while a slight variation was observed in the monocyte population. An important hypoglycemia was also seen in the acute infection (mean = 3.52 mmol/l) in comparison with control values (mean = 6.21 mmol/l), p less than 0.01 (Fig. 3). By contrast during the chronic stage of infection, neither hematological parameters (Table 2) varied between infected and control animals.

Analysis of Variance↗
PubMed1989

Antigenic relationships between attenuated and pathogenic strains of Junin virus.

Antigenic relationships between attenuated and pathogenic strains of Junin virus (JV) were investigated. Five strains of either human or rodent origin were tested by cross-neutralization assay with hyperimmune antisera, raised in rabbits, against each strain. Polyclonal antisera could be used to distinguish among these JV strains, as the titer values differed significantly with ratios of homologous to heterologous titers, which ranged from 1.3 to 22.3. This demonstrates, independent of their virulence, a heterogeneity among the JV strains tested. The relatedness among JV strains was expressed quantitatively through a dendrogram based on taxonomic distance coefficients. The field strains of JV were grouped into two clusters, according to their geographic origin.

Animals↗
PubMed1988

Induction of a refractory state to viral infection in mammalian cells by a plant inhibitor isolated from leaves of Melia azedarach L.

A partially purified plant inhibitor (Meliacin) isolated from Melia azedarach L induced in cells a refractory state to virus infection. Meliacin was active in a large variety of continuous and/or primary cell cultures. A state of maximum virus resistance was achieved after 2 h of incubation and was maintained for at least 15 h; later on it declined but it was fully regained after a second pulse of Meliacin. Interferon was not detected in the supernatant of cells treated with Meliacin and a measurable increase in ds-RNA dependent protein kinase activity was not observed in extracts of Meliacin-treated cells. The antiviral state was not transferred by either extracellular fluid or direct cell-to-cell contact. An active cell metabolism was required for Meliacin action, which was partially reversed in the presence of actinomycin D. It appears that Meliacin is not an interferon-like substance, which induces an antiviral state based on a still unexplained mechanism.

Animals↗
PubMed1988

Differentiation of Junin virus and antigenic variants isolated in vivo by kinetic neutralization assays.

The major natural reservoir of Junin virus, the aetiological agent of Argentine haemorrhagic fever, is the cricetid Calomys musculinus. Neonatal animals experimentally infected with Junin virus (XJCl3 strain) developed typical disease and approximately 80% of them died. Most survivors become persistently infected. Antigenically variant viruses were isolated from the blood and brain of infected cricetids during the acute and chronic stages of the disease. These variants could be distinguished from the parental strain by kinetic neutralization assays using polyclonal antibodies. Some biological properties were shared with the parental virus strain including its virulence for newborn C. musculinus. These variant viruses may play a major role in chronic disease since we have shown that a viral isolate from an infected brain was poorly neutralized by serum obtained from the same animal.

Animals↗
PubMed1987

Antiviral effects of Melia azedarach L. leaves extracts on Sindbis virus-infected cells.

Partially purified extracts from leaves of Melia azedarach L. (MA) exert a broad range of antiviral effects on DNA and RNA viruses. The effect of MA on different stages of Sindbis virus replicative cycle in BHK cells was investigated. Under one-step growth conditions MA afforded a greater than 90% inhibition in virus yield if added to the cell cultures 2 h before or after infection, and when added 4 h after infection MA still caused a greater than 80% inhibition. Analysis of early events following Sindbis virus infection showed that MA did not affect viral adsorption to or penetration in BHK cell. In contrast, viral RNA and protein synthesis was almost totally inhibited in cells pretreated with MA 2 h before infection, while cellular macromolecular synthesis was similar in MA-treated and untreated cell cultures.

Antiviral Agents↗