oronavirus disease 2019 (COVID-19) is a complex clinical syndrome caused by SARS-CoV-2. Despite extensive research into severe disease of hospitalized patients 1 and many large studies leading to approval of vaccines and antivirals 2-4 , the global spread of SARS-CoV-2 continues and is, indeed, accelerating in many regions. Infections are typically mild or asymptomatic in younger people, but these likely drive community transmission 5 , and the detailed time course of infection and infectivity in this context has not been fully elucidated 6,7 . Deliberate human infection of low-risk volunteers enables the exact longitudinal measurement of viral kinetics, immunological responses, transmission dynamics and duration of infectious shedding after a fixed dose of

-Adult drone honey bees from 4 Australian breeding lines were reared under similar conditions and examined for semen and sperm production when 14, 21 and 35 days old, during spring, summer and autumn. Almost half (40.5%) of all drones examined did not release any semen when manually everted. For those that released semen, the average volume released per drone was 1.09 μL (range 0.72 (±0.04)-1.12 (±0.04) μL) and the average number of sperms in the semen per drone was 3.63 × 10 6 (range 1.88 (±0.14)-4.11 (±0.17) × 10 6 ). The release of semen was dependent on breeding line and age (P < 0.05), but not on the rearing season. The volume of semen released per drone was dependent on season, age, and breeding line (P < 0.05), while the concentration of sperm in the semen was dependent on season and breeding line (P < 0.05). Hence our data indicate that genetics underpins the maturation of drone honey bees as well as the volume of semen they release and the concentration of sperm in that semen.Apis mellifera / drones / semen production / sperm

BackgroundMatrix-metalloproteinases (MMPs) are proteolytic enzymes that can degrade the extra cellular matrix and drive tissue remodelling, key processes in the pathogenesis of COPD. The development of small airway disease has been identified as a critical mechanism in the early development of airflow obstruction but the contribution of MMPs in human disease is poorly characterised.

To establish a novel SARS-CoV-2 human challenge model, 36 volunteers aged 18-29 years without evidence of previous infection or vaccination were inoculated with 10 TCID50 of a wild-type virus (SARS-CoV-2/human/GBR/484861/2020) intranasally. Two participants were excluded from per protocol analysis due to seroconversion between screening and inoculation. Eighteen (~53%) became infected, with viral load (VL) rising steeply and peaking at ~5 days post-inoculation. Virus was first detected in the throat but rose to significantly higher levels in the nose, peaking at ~8.87 log10 copies/ml (median, 95% CI [8.41,9.53). Viable virus was recoverable from the nose up to ~10 days post-inoculation, on average. There were no serious adverse events. Mild-to-moderate symptoms were reported by 16 (89%) infected individuals, beginning 2-4 days post-inoculation. Anosmia/dysosmia developed more gradually in 12 (67%) participants. No quantitative correlation was noted between VL and symptoms, with high VLs even in asymptomatic infection, followed by the development of serum spike-specific and neutralising antibodies. However, lateral flow results were strongly associated with viable virus and modelling showed that twice-weekly rapid tests could diagnose infection before 70-80% of viable virus had been generated. Thus, in this first SARS-CoV-2 human challenge study, no serious safety signals were detected and the detailed characteristics of early infection and their public health implications were shown. ClinicalTrials.gov identifier: NCT04865237.

Background-Characterization