Host Plants Indirectly Influence Plant Virus Transmission by Altering Gut Cysteine Protease Activity of Aphid Vectors.

The green peach aphid, Myzus persicae, is a vector of the Potato leafroll virus (PLRV, Luteoviridae), transmitted exclusively by aphids in a circulative manner. PLRV transmission efficiency was significantly reduced when a clonal lineage of M. persicae was reared on turnip as compared with the weed physalis, and this was a transient effect caused by a host-switch response. A trend of higher PLRV titer in physalis-reared aphids as compared with turnip-reared aphids was observed at 24 h and 72 h after virus acquisition. The major difference in the proteomes of these aphids was the up-regulation of predicted lysosomal enzymes, in particular the cysteine protease cathepsin B (cathB), in aphids reared on turnip. The aphid midgut is the site of PLRV acquisition, and cathB and PLRV localization were starkly different in midguts of the aphids reared on the two host plants. In viruliferous aphids that were reared on turnip, there was near complete colocalization of cathB and PLRV at the cell membranes, which was not observed in physalis-reared aphids. Chemical inhibition of cathB restored the ability of aphids reared on turnip to transmit PLRV in a dose-dependent manner, showing that the increased activity of cathB and other cysteine proteases at the cell membrane indirectly decreased virus transmission by aphids. Understanding how the host plant influences virus transmission by aphids is critical for growers to manage the spread of virus among field crops.

N-acetyl cysteine and mushroom Agaricus sylvaticus supplementation decreased parasitaemia and pulmonary oxidative stress in a mice model of malaria.

BACKGROUND: Malaria infection can cause high oxidative stress, which could lead to the development of severe forms of malaria, such as pulmonary malaria. In recent years, the role of reactive oxygen species in the pathogenesis of the disease has been discussed, as well as the potential benefit of antioxidants supplementation. The aim of this study was to investigate the effects of N-acetyl cysteine (NAC) or mushroom Agaricus sylvaticus supplementation on the pulmonary oxidative changes in an experimental model of malaria caused by Plasmodium berghei strain ANKA. METHODS: Swiss male mice were infected with P. berghei and treated with NAC or AS. Samples of lung tissue and whole blood were collected after one, three, five, seven or ten days of infection for the assessment of thiobarbituric acid reactive substances (TBARS), trolox equivalent antioxidant capacity (TEAC), nitrites and nitrates (NN) and to assess the degree of parasitaemia. RESULTS: Although parasitaemia increased progressively with the evolution of the disease in all infected groups, there was a significant decrease from the seventh to the tenth day of infection in both antioxidant-supplemented groups. Results showed significant higher levels of TEAC in both supplemented groups, the highest occurring in the group supplemented with A. sylvaticus. In parallel, TBARS showed similar levels among all groups, while levels of NN were higher in animals supplemented with NAC in relation to the positive control groups and A. sylvaticus, whose levels were similar to the negative control group. CONCLUSION: Oxidative stress arising from plasmodial infection was attenuated by supplementation of both antioxidants, but A. sylvaticus proved to be more effective and has the potential to become an important tool in the adjuvant therapy of malaria.

Nutritional supplementation with the mushroom Agaricus sylvaticus reduces oxidative stress in children with HIV.

BACKGROUND: The involvement of free radicals and oxidative stress in HIV infection has been extensively studied, and the benefits of antioxidant supplementation in animal studies have been demonstrated. However, few studies have demonstrated a benefit in clinical studies. OBJECTIVE: To verify the effects of dietary supplementation with Agaricus sylvaticus, a mushroom rich in antioxidants, on the oxidative profile of children born with HIV undergoing antiretroviral therapy. DESIGN: The sample included 24 children (both boys and girls) between two and eight years of age, of whom 10 were HIV positive and received supplementation with Agaricus sylvaticus for a three-month period, and 14 were HIV negative and received no supplementation. At the beginning and conclusion of the study, thiobarbituric acid-reactive substances (TBARS), nitrite and nitrate (NN), Trolox equivalent antioxidant capacity, and the antioxidant capacity of inhibition of diphenyl-picrilhidrazil (DPPH) free radicals were analyzed. RESULTS: Before supplementation, significantly higher values of TBARS and NN, but decreased values of DPPH, were observed in infected subjects when compared with HIV-negative subjects. After supplementation, a reduction of TBARS and NN values and an increase in DPPH and Trolox equivalent antioxidant capacity values were observed in HIV-positive subjects. CONCLUSIONS: The results of the present study suggest the involvement of oxidative stress in HIV infection, with the participation of NN synthesis. Additionally, supplementation reversed oxidative alterations and improved antioxidant defense in infected individuals, and may become a complementary strategy in the treatment of these patients.

HISTORIQUE: L'activité des radicaux libres et du stress oxydatif dans l'infection par le VIH a fait l'objet de nombreuses études, et les bienfaits des suppléments d'antioxydants ont été démontrés dans des études sur des animaux. Cependant, peu d'études en ont confirmé les avantages dans des études cliniques. OBJECTIF: Vérifier les effets de suppléments alimentaires contenant de l'Agaricus sylvaticus, un champignon riche en antioxydants, sur le profil oxydatif des enfants nés avec le VIH sous thérapie antirétrovirale. MÉTHODOLOGIE: L'échantillon se composait de 24 enfants (garçons et filles) de deux à huit ans, dont dix étaient positifs au VIH et ont reçu des suppléments d'Agaricus sylvaticus pendant trois mois, et 14 étaient négatifs au VIH est n'ont pas reçu de suppléments. Au début et à la fin de l'étude, les chercheurs ont analysé les substances réactives à l'acide thio-barbiturique (SRATB), les nitrites et les nitrates (NN), la capacité antioxydante en équivalent Trolox et la capacité antioxydante de l'inhibition des radicaux libres diphényl-picrylhydrazyl (DPPH). RÉSULTATS: Avant la prise de suppléments, les sujets infectés présentaient des valeurs considérablement plus élevées de SRATB et de NN, mais plus faibles de DPPH, que les sujets négatifs au VIH. Après la prise de suppléments, les valeurs de SRATB et de NN diminuaient tandis que celles de DPPH et de la capacité antioxydante en équivalent Trolox augmentaient chez les sujets positifs au VIH. CONCLUSIONS: D'après les résultats de la présente étude, le stress oxydatif est actif dans l'infection par le VIH, avec la participation de la synthèse des NN. De plus, des suppléments renversaient les altérations oxydatives et accroissaient la défense assurée par les antioxydants chez les sujets infectés. De tels suppléments pourraient devenir une stratégie complémentaire au traitement.