The antiviral role of zinc and metallothioneins in hepatitis C infection

Metallothioneins (MTs) are small, cysteine-rich proteins characterized by a high affinity for monovalent and divalent cations, such as copper and zinc. Of the four known MT isoforms, only, members of the MT 1 and 2 subfamilies are widely expressed, acting as metal chaperones whose primary role is to mediate intracellular zinc homoeostasis. Metallothioneins are potently induced by heavy metals and other sources of oxidative stress where they facilitate metal binding and detoxification as well as free radical scavenging. Metallothionein expression is well documented in the context of viral infection; however, it remains uncertain whether MTs possess specific antiviral roles or whether induction is merely a consequence of cellular stress. To better understand the role of MTs following hepatitis C virus (HCV) infection, we examined MT expression and localization in vitro and in vivo and used a siRNA knockdown approach to ascertain their antiviral efficacy. We confirmed HCV-driven MT induction in vitro and demonstrated MT accumulation in the nucleus of HCV-infected hepatocytes by immunofluorescence. Using a pan-MT siRNA to knock down all members of the MT1 and MT2 subfamilies, we demonstrate that they are mildly antiviral against the JFH1 strain of HCV in vitro (~1.4 fold increase in viral RNA, P < .05). Furthermore, the antiviral effect of zinc treatment against HCV in vitro was mediated through MT induction (P < .05). Our data suggest a potential benefit of using zinc as a low-cost adjunct to current HCV antiviral therapies and suggest that zinc may facilitate the antiviral role of MTs against other viruses

Seasonal variations in time and space utilization by radio-tagged yellow eels Anguilla anguilla (L.) in a small stream

Seven yellow eels (572–643 mm, 318–592 g) Anguilla anguilla (L.) were tagged with surgically implanted radio transmitters (activity circuit, 1.6–1.7 g) and tracked in the Awirs stream, a small (width <5 m, depth from 0.1 to 1.2 m), densely populated (ca. 250 kg of eel ha−1) tributary of the Belgian River Meuse. The eels were positioned daily from late April to mid-August, and their diel activity was studied during twenty four 24-h cycles. During day-time, the eels were resting in rootwads or in crevices inside stone walls or in crevices in between rocks. They became more active in the late afternoon but generally did not leave their residence before sunset, except under overcast weather. Activity peaked during the first part of the night then progressively vanished, and always ended before sunrise. The area exploited during night-time never extended over more than 40 m2, except when the eel changed its residence. The intensity and timing of nocturnal activity and the extent of the daily activity area were dependent on water temperature (respectively P<0.0001, P<0.05 and P<0.0005), with eels showing little or no activity when the diurnal temperature did not exceed 13 _C. Eels showed higher agitation under full moon and maintained their activity later in the night (P<0.05). The eels showed restricted mobility, and occupied small stream areas (from 0.01 to 0.10 ha) in a non sequential mode, except for two fish which were displaced to the River Meuse by a spate in early June and were never recovered. The length and frequency of net daily journeys were higher (P = 0.005) at water temperatures above 16 _C in late May and June, which also corresponded to the period of immigration of eels from the River Meuse. This study thus shows that large yellow eels may adopt a highly sedentary lifestyle in a continental, fast flowing and densely populated environment, even at periods of the year when these stages usually show upstream migrations