The apolipoprotein A-IMilano (apoA-IM) is a molecular variant of apoA-I characterized by the Arg173-->Cys substitution, resulting in the formation of homodimers (A-IM/A-IM) and heterodimers with apoA-II. In order to examine the effects of the introduction of an interchain disulfide bridge on the lipid-binding properties of apoA-I, the present studies compare the kinetics of association of A-IM/A-IM and apoA-I with dimyristoylphosphatidylcholine (DMPC), and the structure and properties of reconstituted HDL containing palmitoyloleoylphosphatidylcholine (POPC) and either A-IM/A-IM or apoA-I. The results show that apoA-I dimerization does not affect the rate of association with DMPC. Apolipoprotein-POPC complexes instead, when analyzed by nondenaturing gradient gel electrophoresis, demonstrate that, differently from apoA-I, A-IM/A-IM forms only two species of rHDL particles despite a wide range of initial lipid to protein ratios. These two rHDL species contain one or two A-IM/A-IM molecules and have a diameter of 7.8 nm and 12.5 nm. Investigations of the A-IM/A-IM structure in these two rHDL, by circular dichroism, fluorescence, and second-derivative UV spectroscopy, suggest that the secondary and tertiary structures of A-IM/A-IM are remarkably similar in both small and large particles. These results suggest that the introduction of an interchain disulfide bridge does not affect the association of apoA-I with lipids but restricts HDL particle size heterogeneity, thus possibly affecting HDL function in lipid metabolism and atherosclerosis protection.

BackgroundUnderstanding the dispersal dynamics of invasive mosquito species is fundamental to improve vector surveillance and to target control efforts. Aedes albopictus has been deemed a poor flyer as its range of active dispersal is generally assumed to be limited to a few hundred metres, while laboratory studies suggest this mosquito could actually fly several kilometres. The discrepancy may be due to differences in the local environment or to the methodological approach. In Switzerland, Ae. albopictus has been present since 2003 and has since then expanded its range. While passive dispersal is a key driver, it remains unclear how far this mosquito spreads through active flight and what the age structure and size of the local population are, all important parameters for vector surveillance and control.MethodWe investigated the active dispersal, daily survival rate and population size of Ae. albopictus in mark-release-recapture studies in Coldrerio and Lugano, two areas of intensive control in Switzerland. To mark mosquitoes emerging from breeding sites, we used self-marking units with fluorescent pigment that have minimal impact on mosquito survival and behaviour. We recaptured the adult mosquitoes with BG-Sentinel traps within a radius of 1 km from the marking units over 22 consecutive days.ResultsWe found that 77.5% of the recaptured Ae. albopictus individuals flew further than 250 m, the limit that is usually deemed sufficient for vector containment. The average age of females and males was 8.6 days and 7.8 days in Coldrerio and Lugano, respectively, while the estimated mosquito population densities were 134 mosquitoes/ha in Coldrerio and 767 mosquitoes/ha in Lugano.ConclusionsSelf-marking units are an effective tool to mark wild mosquitoes. Using this approach, we found that mosquitoes survive long enough to potentially transmit arboviral disease in our study area and that host-seeking Ae. albopictus females may travel further than previously assumed for European mosquito populations. This finding has direct implications for vector control as emergency treatments around positive cases, as well as surveillance and control around detections of new infestations, might need to be extended beyond the usual recommended range of just a few hundred metres.

Over the past three decades, Europe has witnessed an increased spread of invasive aedine mosquito species, most notably Aedes albopictus, a key vector of chikungunya, dengue and Zika virus. While its distribution in southern Europe is well documented, its dispersal modes across the Alps remain poorly investigated, preventing a projection of future scenarios beyond its current range in order to target mosquito control. To monitor the presence and frequency of invasive Aedes mosquitoes across and beyond the Alps we set oviposition and BG-Sentinel traps at potential points of entry with a focus on motorway service areas across Switzerland. We placed the traps from June to September and controlled them for the presence of mosquitoes every other week between 2013 and 2018. Over the six years of surveillance we identified three invasive Aedes species, including Ae. albopictus, Ae. japonicus and Ae. koreicus. Based on the frequency and distribution patterns we conclude that Ae. albopictus and Ae. koreicus are being passively spread primarily along the European route E35 from Italy to Germany, crossing the Alps, while Ae. japonicus has been expanding its range from northern Switzerland across the country most likely through active dispersal.