Pineau, P. | bioRxiv Science

bioRxiv2020

Anti-COVID-19 efficacy of ivermectin in the golden hamster

The devastating coronavirus disease 2019 (COVID-19) pandemic, due to SARS-CoV-2, has caused more than 47 million confirmed cases and more than 1.2 million human deaths around the globe1, and most of the severe cases of COVID-19 in humans are associated with neurological symptoms such as anosmia and ageusia, and uncontrolled inflammatory immune response2-5. Among therapeutic options6-8, the use of the anti-parasitic drug ivermectin (IVM), has been proposed, given its possible anti-SARS-CoV-2 activity9. Ivermectin is a positive allosteric modulator of the -7 nicotinic acetylcholine receptor10, which has been suggested to represent a target for the control of Covid-19 infection11, with a potential immunomodulatory activity12. We assessed the effects of IVM in SARS-CoV-2-intranasally-inoculated golden Syrian hamsters. Even though ivermectin had no effect on viral load, SARS-Cov-2-associated pathology was greatly attenuated. IVM had a sex-dependent and compartmentalized immunomodulatory effect, preventing clinical deterioration and reducing olfactory deficit in infected animals. Importantly, ivermectin dramatically reduced the Il-6/Il-10 ratio in lung tissue, which likely accounts for the more favorable clinical presentation in treated animals. Our data support IVM as a promising anti-COVID-19 drug candidate.

immunology↗

bioRxiv2020

Diapause regulation in newly invaded environments: termination timing allows matching novel climatic constraints in the box tree moth, Cydalima perspectalis (Lepidoptera: Crambidae)

The association between indirect environmental cues that modulate insect diapause and the actual stressors is by no means granted when a species encounters new environments. The box tree moth, Cydalima perspectalis, is an Asian pest whose rapid invasion in Europe cause considerable economic and ecological impacts. Larvae enter a winter diapause induced by photoperiod in both native and invaded ranges, but factors that trigger the return to an active phase are still unknown. Yet, identifying them is crucial to understand how diapause end synchronizes with the end of the winter stress encountered in Europe. To test whether activity resumption is regulated by thermal and/or photoperiodic thresholds, or additive effects between these factors often involved in diapause termination, diapausing caterpillars from an invaded area were exposed to crossed treatments at the laboratory. The evolution of diapause rate was monitored over time and compared to that of nearby field sites invaded. A strong positive effect of increasing temperature was found on the rate and dynamics of diapause termination, whereas no compelling effect of photoperiod appeared. Resuming development directly when main stressors fade, not in response to indirect photoperiodic cues that could be mismatched outside native areas, likely contributes to the good match observed between diapause and the new climates this pest encountered in the invaded range.

zoology↗