Carla Sánchez-Hernández

Respiratory syncytial virus glycoproteins uptake occurs through clathrin-mediated endocytosis in a human epithelial cell line

Cell-surface viral proteins most frequently enter the cell through clathrin or caveolae endocytosis. Respiratory syncytial virus antigen internalization by immune cells is via caveolin, however, uptake of paramyxovirus cell membrane proteins by non-immune cells is done through clathrin-coated pits. In this work, the uptake of respiratory syncytial virus cell surface glycoproteins by non-immune human epithelial cells was investigated through indirect immunofluorescence with polyclonal anti-RSV antibody and confocal lasser-scanner microscopy. Clathrin and caveolae internalization pathways were monitored through specific inhibitors monodansylcadaverine (MDC) and methyl-beta-cyclodextrin (MBCD), respectively. Internalization of RSV antigens was inhibited by MDC but not by MBCD, implying that clathrin-mediated endocytosis is the major uptake route of RSV antigens by an epithelial human cell line.

Foraging behaviour of the parasitoid Eretmocerus eremicus under intraguild predation risk by Macrolophus pygmaeus.

BACKGROUND Intraguild predation (IGP), predation between species that use a common resource, can affect the populations of a pest, of the pests natural enemy (IG prey) and of the predator of the pests natural enemy (IG predator). In this study, we determined whether the parasitoid Eretmocerus eremicus (Hymenoptera: Aphelinidae) (IG prey), modifies its foraging behaviour under the risk of IGP by Macrolophus pygmaeus (Hemiptera: Miridae) (IG predator). Parasitoid behaviour was analysed using two bioassays (choice and no-choice) with the following treatments: (i) control, tomato leaf infested with whitefly nymphs; and (ii) PEP, tomato leaf infested with whitefly nymphs and previously exposed to the IG predator; and (iii) PP, tomato leaf infested with whitefly nymphs, with both, the IG predator and the IG prey present. RESULTS In both bioassays, we found that E. eremicus did not significantly modify the number of ovipositions, time of residence, duration of oviposition or behavioural sequence. However, in the no-choice bioassay, the number of attacks was higher and their duration shorter in the PEP treatment than in the control. CONCLUSION Our results indicate that the parasitoid may detect IGP risk to a certain extent, but it did not significantly modify its foraging behaviour, suggesting that simultaneous release of the two natural enemies can be successfully employed.

Virus-like particles from Escherichia Coli-derived untagged papaya ringspot virus capsid protein purified by immobilized metal affinity chromatography enhance the antibody response against a soluble antigen.

There is a growing interest in using virus-like particles (VLPs) as scaffolds for the presentation of antigens of choice to the immune system. In this work, VLPs from papaya ringspot virus capsid protein expressed in Escherichia coli were evaluated as enhancers of antibody response against a soluble antigen. Interestingly, although the capsid protein lacks a histidine tag, its purification by immobilized metal affinity chromatography was achieved. The formation of VLPs was demonstrated by electron microscopy for the first time for this capsid protein. VLPs were enriched by polyethylene glycol precipitation. Additionally, these VLPs were chemically coupled to green fluorescent protein in order to evaluate them as antigen carriers; however, bioconjugate instability was observed. Nonetheless, the adjuvant effect of these VLPs on BALB/c mice was evaluated, using GFP as antigen, resulting in a significant increase in anti-GFP IgG response, particularly, IgG1 class, demonstrating that the VLPs enhance the immune response against the antigen chosen in this study.

Extracts from green and brown seaweeds protect tomato (Solanum lycopersicum) against the necrotrophic fungus Alternaria solani

Several reports have shown that crude or purified extracts of green, brown, and red seaweeds induce protection against fungal, bacterial, and viral pathogens in plants. In this work, we report that polysaccharide-enriched seaweed extracts obtained from green, Ulva lactuca and Caulerpa sertularioides, and brown algae, Padina gymnospora and Sargassum liebmannii, induced protection against the necrotrophic fungus Alternaria solani in tomato plants (Solanum lycopersicum). Protein activity of defense-related proteins polyphenol oxidase, guaiacol peroxidase and proteinase inhibitors together with expression levels of systemic wound response (SWRP) genes were also measured in leaf samples after algal extract treatment. All extracts were shown to reduce necrotic lesions induced by A. solani, particularly those obtained from U. lactuca and P. gymnospora. U. lactuca extracts induced the expression of SWRP genes, including defense, signal pathway, and protease genes, whereas those obtained from C. sertularioides, P. gymnospora and S. liebmannii showed almost no induction of SWRP genes, suggesting that extracts from the latter, whose carbohydrate composition varied from that of U. lactuca, may act through mechanisms other than the jasmonic acid/systemin wound-response pathway.

In vivo activity of plant-based interleukin-12 in the lung of Balb/c mouse

BackgroundIn the last years, plants are being used for the production of a wide variety of biopharmaceuticals, including cytokines, and have the potential to serve as vehicles for mucosal administration of these molecules. We had previously reported the expression of a cytokine, interleukin-12 (IL-12), in transgenic tomato plants and had demonstrated that it retained its biologic activity in vitro.FindingsIn this work, we administered crude extracts of IL-12-containing tomato fruits to mice through the intratracheal route, measuring endogenous IL-12 and determining biologic activity by quantification of interferon-gamma (IFN-γ) in lungs and by histological analysis. IFN-γ expression in lungs, as well as histological analysis, indicate that tomato-expressed IL-12 retains its biologic activity and, most importantly, its effects are restricted to the site of administration.ConclusionOur results indicate that the functional activity of tomato-expressed IL-12 is comparable to that of commercial recombinant IL-12 when given via the mucosal route. This opens the possibility of using crude extracts prepared from tomatoes expressing IL-12 for certain immunotherapies.

Intraguild predation of Geocoris punctipes on Eretmocerus eremicus and its influence on the control of the whitefly Trialeurodes vaporariorum.

BACKGROUND Geocoris punctipes (Hemiptera: Lygaeidae) and Eretmocerus eremicus (Hymenoptera: Aphelinidae) are whitefly natural enemies. Previously, under laboratory conditions, we showed that G. punctipes engages in intraguild predation (IGP), the attack of one natural enemy by another, on E. eremicus. However, it is unknown whether this IGP interaction takes place under more complex scenarios, such as semi-field conditions. Even more importantly, the effect of this interaction on the density of the prey population requires investigation. Therefore, the present study aimed to establish whether this IGP takes place under semi-field conditions and to determine whether the predation rate of G. punctipes on the whitefly decreases when IGP takes place. RESULTS Molecular analysis showed that, under semi-field conditions, G. punctipes performed IGP on E. eremicus. However, although IGP did take place, the predation rate by G. punctipes on the whitefly was nevertheless higher when both natural enemies were present together than when the predator was present alone. CONCLUSION While IGP of G. punctipes on E. eremicus does occur under semi-field conditions, it does not adversely affect whitefly control. The concomitant use of these two natural enemies seems a valid option for inundative biological control programmes of T. vaporariorum in tomato.