Interleukin-13 associates with life-threatening rhinovirus infections in infants and young children.

OBJECTIVE: Delineate risk factors associated with severe hypoxemia (O2 sat ≤87%) in infants and children younger than 2 years hospitalized with single pathogen HRV infection. STUDY DESIGN: Prospective study in a yearly catchment population of 56 560 children <2 years old between 2011 and 2013 in Argentina. All children with respiratory signs and O2 sat <93% on admission were included. HRV infections were identified by reverse transcriptase-polymerase chain reaction. Epidemiologic, clinical, viral, and immunological risk factors were assessed. RESULTS: Among 5012 hospitalized patients, HRV was detected as a single pathogen in 347 (6.92%) subjects. Thirty-two (9.2%) had life-threatening disease. Traditional risk factors for severe bronchiolitis did not affect severity of illness. HRV viral load, HRV groups, and type II and III interferons did not associate with severe hypoxemia. Interleukin-13 Levels in respiratory secretions at the time of admission (OR = 7.43 (3-18.4); P < 0.001 for IL-13 >10 pg/mL) predisposed to life-threatening disease. CONCLUSIONS: Targeted interventions against IL-13 should be evaluated to decrease severity of HRV illness in infancy and early childhood.

TLR4 genotype and environmental LPS mediate RSV bronchiolitis through Th2 polarization.

While 30%-70% of RSV-infected infants develop bronchiolitis, 2% require hospitalization. It is not clear why disease severity differs among healthy, full-term infants; however, virus titers, inflammation, and Th2 bias are proposed explanations. While TLR4 is associated with these disease phenotypes, the role of this receptor in respiratory syncytial virus (RSV) pathogenesis is controversial. Here, we evaluated the interaction between TLR4 and environmental factors in RSV disease and defined the immune mediators associated with severe illness. Two independent populations of infants with RSV bronchiolitis revealed that the severity of RSV infection is determined by the TLR4 genotype of the individual and by environmental exposure to LPS. RSV-infected infants with severe disease exhibited a high GATA3/T-bet ratio, which manifested as a high IL-4/IFN-γ ratio in respiratory secretions. The IL-4/IFN-γ ratio present in infants with severe RSV is indicative of Th2 polarization. Murine models of RSV infection confirmed that LPS exposure, Tlr4 genotype, and Th2 polarization influence disease phenotypes. Together, the results of this study identify environmental and genetic factors that influence RSV pathogenesis and reveal that a high IL-4/IFN-γ ratio is associated with severe disease. Moreover, these molecules should be explored as potential targets for therapeutic intervention.

Emergence of herpes simplex virus-1 syncytial variants with altered virulence for mice after selection with a natural carrageenan.

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.

Galactan sulfate of Grateloupia indica: Isolation, structural features and antiviral activity.

Natural compounds offer interesting pharmacological perspectives for antiviral drug development with regard to broad-spectrum antiviral properties and novel modes of action. In this study, we have analyzed polysaccharide fractions isolated from Grateloupia indica. The crude water extract (GiWE) as well as one fraction (F3) obtained by anion exchange chromatography had potent anti-HSV activity. Their inhibitory concentration 50% (IC50) values (0.12-1.06 microg/ml) were much lower than cytotoxic concentration 50% values (>850 microg/ml). These fractions, which were effective antiviral inhibitors if added only during the adsorption period, had very low anticoagulant activity. Furthermore, they had no direct inactivating effect on virions in a virucidal assay. Chemical, chromatographic and spectroscopic methods showed that the active polysaccharide, which has an apparent molecular mass of 60 kDa and negative specific rotation [alpha]D(32) -16 degrees (c 0.2, H2O), contains alpha-(1-->4)- and alpha-(1-->3)-linked galactopyranose residues. Sulfate groups, if present, are located mostly at C-2/6 of (1-->4)- and C-4/6 of (1-->3)-linked galactopyranosyl units, and are essential for the anti herpetic activity of this polymer.

Structure and antiviral activity of sulfated fucans from Stoechospermum marginatum.

A sulfated fucan containing fraction (SmWE) was isolated from water extract of the brown seaweed Stoechospermum marginatum collected from the Arabian Sea. Anion exchange chromatography of the crude fraction results in the production of a sulfated fucan (F3) having a molecular mass of 40 kDa and specific rotation [alpha]D(30) - 124 degrees (c 0.5, H2O). NMR spectroscopic studies and methylation analysis suggested that the polymer consists of a backbone of (1-->4)- and (1-->3)-linked-alpha-L-fucopyranosyl residues that are substituted at C-2 and C-3, and that fucosyl residues are sulfated mostly at C-2 and/or C-4. SmWE and F3 were selective inhibitors of herpes simplex virus type 1 (strain F, thymidine kinase-deficient strains field and B2006 and syncytial variants arising after selection with a natural carrageenan syn 13-8 and 14-1) and type 2 (strain MS) in Vero cells, with antiviral effective concentration 50% (EC50) values in the range 0.63-10.0 microg/ml. The compounds were highly selective due to the lack of cytotoxicity. The antiviral activity was dependent on the presence of the sulfated fucans during the adsorption period. No direct inactivating effect on virions was observed in a virucidal assay. The absence of anticoagulant activity at concentrations near EC50 confirmed that there was no correlation between the antiviral and anticoagulant properties.