RESUMO
The interactions between bovine serum albumin (BSA) and mycophenolic acid (MPA) were investigated in silico through molecular docking and in vitro, using fluorescence spectroscopy. Dynamic light scattering and scanning electron microscopy were used to figure out the structure of MPA-Complex (MPA-C). The binding affinity between MPA and BSA was determined, yielding a Kd value of (12.0 ± 0.7) µM, and establishing a distance of 17 Å between the BSA and MPA molecules. The presence of MPA prompted protein aggregation, leading to the formation of MPA-C. The cytotoxicity of MPA-C and its ability to fight Junín virus (JUNV) were tested in A549 and Vero cell lines. It was found that treating infected cells with MPA-C decreased the JUNV yield and was more effective than free MPA in both cell line models for prolonged time treatments. Our results represent the first report of the antiviral activity of this type of BSA-MPA complex against JUNV, as assessed in cell culture model systems. MPA-C shows promise as a candidate for drug formulation against human pathogenic arenaviruses.
Assuntos
Vírus Junin , Soroalbumina Bovina , Humanos , Ácido Micofenólico , Simulação de Acoplamento Molecular , Replicação Viral , Antivirais/farmacologiaRESUMO
Our perspective on nature has changed throughout history and at the same time has affected directly or indirectly our perception of biological processes. In that sense, the "fluxus" of information in a viral population arises a result of a much more complex process than the encoding of a protein by a gene, but as the consequence of the interaction between all the components of the genome and its products: DNA, RNA, and proteins and its modulation by the environment. Even modest "agents of life" like viruses display an intricate way to express their information. This conclusion can be withdrawn from the huge quantity of data furnished by new and potent technologies available now to analyze viral populations. Based on this premise, evolutive processes for viruses are now interpreted as a simultaneous and coordinated phenomenon that leads to global (i.e., not gradual or 'random') remodeling of the population. Our system of study involves the modulation of herpes simplex virus populations through the selective pressure exerted by carrageenans, natural compounds that interfere with virion attachment to cells. On this line, we demonstrated that the passaging of virus in the presence of carrageenans leads to the appearance of progeny virus phenotipically different from the parental seed, particularly, the emergence of syncytial (syn) variants. This event precedes the emergence of mutations in the population which can be readily detected five passages after from the moment of the appearance of syn virus. This observation can be explained taking into consideration that the onset of phenotypic changes may be triggered by "environmental-sensitive" glycoproteins. These "environmental-sensitive" glycoproteins may act by themselves or may transmit the stimulus to "adapter" proteins, particularly, proteins of the tegument, which eventually modulate the expression of genomic products in the "virocell." The modulation of the RNA network is a common strategy of the virocell to respond to environmental changes. This "fast" adaptive mechanism is followed eventually by the appearance of mutations in the viral genome. In this paper, we interpret these findings from a philosophical and scientific point of view interconnecting epigenetic action, exerted by carragenans from early RNA network-DNA interaction to late DNA mutation. The complexity of HSV virion structure is an adequate platform to envision new studies on this topic that may be complemented in a near future through the analysis of the genetic dynamics of HSV populations.
RESUMO
The structures of two sulfated xylomannans extracted from the red alga Nemalion helminthoides were determined. These two fractions plus a sulfated mannan, isolated from the same alga and whose structure was previously reported, were subjected to chemical modification. The mannan was oversulfated with SO(3)-pyridine in dimethyl sulfoxide at 60 °C during two and three hours and the xylomannans were subjected to Smith degradation in order to eliminate xylose side-chains. Structural analysis of all derivatives was carried out by methylation analysis and (13)C NMR spectroscopy. Antiviral activity against herpes simplex virus type 1 and 2, and dengue virus type 2 of native and modified mannans and xylomannans was estimated. Anticoagulant effect of the active fractions was also determined.
Assuntos
Anticoagulantes/isolamento & purificação , Anticoagulantes/farmacologia , Antivirais/isolamento & purificação , Antivirais/farmacologia , Mananas/isolamento & purificação , Mananas/farmacologia , Rodófitas/química , Ésteres do Ácido Sulfúrico/isolamento & purificação , Ésteres do Ácido Sulfúrico/farmacologia , Anticoagulantes/química , Antivirais/química , Vírus da Dengue/efeitos dos fármacos , Herpesvirus Humano 1/efeitos dos fármacos , Herpesvirus Humano 2/efeitos dos fármacos , Mananas/química , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Ésteres do Ácido Sulfúrico/química , Xilose/química , Xilose/farmacologiaRESUMO
BACKGROUND: Antiviral therapy against herpes simplex virus based on sulfated polysaccharides, like carrageenans, represents a new alternative for genital herpes infections treatment and arises the concern about the appearance of resistant viral populations. METHODS: We characterized the F strain of herpes simplex virus-1 passaged in the presence of a natural carrageenan isolated from the red seaweed Gigartina skottbergii in view of the virulence for mice of isolated viral clones. RESULTS: Viral clones (syn14-1 and syn17-2) showed a syncytial phenotype and a mild resistance to carrageenan, heparin, acyclovir, and brivudine. Both clones were avirulent for BALB/c mice when inoculated intravaginally, whereas F strain produced high mortality. Attenuation correlated with low levels of TNF-[alpha], interleukin-6, and IFN-[gamma] in vaginal lavages although virus titers were similar to those obtained for F strain. On the contrary, they showed a marked virulence when inoculated intranasally leading to a generalized spreading of virus. CONCLUSIONS: Results confirm the hypothesis that selection of herpes simplex virus-1 with a carrageenan in vitro leads to the emergence of variants with a differential virulence when compared to the original virus. This finding should be addressed when an antiviral therapy against genital herpes infection employing a natural carrageenan is under consideration.
Assuntos
Antivirais/farmacologia , Carragenina/farmacologia , Variação Genética , Células Gigantes/fisiologia , Herpesvirus Humano 1/patogenicidade , Seleção Genética , Animais , Chlorocebus aethiops , Feminino , Herpes Genital/patologia , Herpes Genital/virologia , Herpes Simples/patologia , Herpes Simples/virologia , Herpesvirus Humano 1/classificação , Herpesvirus Humano 1/efeitos dos fármacos , Herpesvirus Humano 1/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Rodófitas/química , Alga Marinha/química , Células Vero , VirulênciaRESUMO
Nemalion helminthoides, collected in the Argentine South Atlantic coast, was extracted with hot water and the crude product fractionated using cetrimide. The complexed material was subjected to fractional solubilization in solutions of increasing sodium chloride concentration and seven fractions were separated and analyzed. Structural analysis of the main fractions, those soluble in 3.0 and 4.0 M NaCl (yields 21.0% and 13.8%, respectively) and those insoluble in 4.0 M NaCl (yield 20.0%), indicated that this seaweed biosynthesizes (1-->3)-linked alpha-D-mannans that are sulfated at positions 4 and 6. Three mannan fractions comprising considerable amounts of xylose were also isolated in very low total yield (2.0%). The fractions that were soluble in 3.0 and 4.0 M NaCl showed low antiherpetic activity whereas this activity was considerable for the fraction solubilized in 2.0 M NaCl (yield 0.5%) which contained single stubs of beta-D-xylose. A xylan, soluble in cetrimide solution, containing (1-->3, 1-->4)-linked beta-D-xylose residues, was also isolated in minor amount.