Predictive potential of SARS-CoV-2 RNA concentration in wastewater to assess the dynamics of COVID-19 clinical outcomes and infections.

Coronavirus disease 2019 - caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) -, has triggered a worldwide pandemic resulting in 665 million infections and over 6.5 million deaths as of December 15, 2022. The development of different epidemiological tools have helped predict new outbreaks and assess the behavior of clinical variables in different health contexts. In this study, we aimed to monitor concentrations of SARS-CoV-2 in wastewater as a tool to predict the progression of clinical variables during Waves 3, 5, and 6 of the pandemic in the Spanish city of Xátiva from September 2020 to March 2022. We estimated SARS-CoV-2 RNA concentrations in 195 wastewater samples using the RT-PCR Diagnostic Panel validated by the Center for Disease Control and Prevention. We also compared the trends of several clinical variables (14-day cumulative incidence, positive cases, hospital cases and stays, critical cases and stays, primary care visits, and deaths) for each study wave against wastewater SARS-CoV-2 RNA concentrations using Pearson's product-moment correlations, a two-sided Mann-Whitney U test, and a cross-correlation analysis. We found strong correlations between SARS-CoV-2 concentrations with 14-day cumulative incidence and positive cases over time. Wastewater RNA concentrations showed strong correlations with these variables one and two weeks in advance. There were significant correlations with hospitalizations and critical care during Wave 3 and Wave 6; cross-correlations were stronger for hospitalization stays one week before during Wave 6. No association between vaccination percentages and wastewater viral concentrations was observed. Our findings support wastewater SARS-CoV-2 concentrations as a potential surveillance tool to anticipate infection and epidemiological data such as 14-day cumulative incidence, hospitalizations, and critical care stays. Public health authorities could use this epidemiological tool on a similar population as an aid for health care decision-making during an epidemic outbreak.

Insulin-like peptides involved in photoperiodism in the aphid Acyrthosiphon pisum.

Aphids were the first animals reported as photoperiodic as their life cycles are strongly determined by the photoperiod. During the favourable seasons (characterised by long days) aphid populations consist exclusively of viviparous parthenogenetic females (known as virginoparae). Shortening of the photoperiod in autumn is perceived by aphids as the signal that anticipates the harsh season, leading to a switch in the reproductive mode giving place to the sexual morphs (oviparae females and males) that mate and lay winter-resistant (diapause-like) eggs. The molecular and cellular basis governing the switch between the two reproductive modes are far from being understood. Classical experiments identified a group of neurosecretory cells in the pars intercerebralis of the aphid brain (the so called group I of neurosecretory cells) that were essential for the development of embryos as parthenogenetic females and were thus proposed to synthesise a parthenogenesis promoting substance that was termed "virginoparin". Since insulin-like peptides (ILPs) have been implicated in the control of diapause in other insects, we investigated their involvement in aphid photoperiodism. We compared the expression of two ILPs (ILP1 and ILP4) and an Insulin receptor coding genes in A. pisum aphids reared under long- and short-day conditions. The three genes showed higher expression in long-day reared aphids. In addition, we localised the site of expression of the two ILP genes in the aphid brain. Both genes were found to be expressed in the group I of neurosecretory cells. Altogether, our results suggest that ILP1 and ILP4 play an important role in the control of the aphid life-cycle by promoting the parthenogenetic development during long-day seasons while their repression by short days would activate the sexual development. Thus we propose these ILPs correspond to the so called "virginoparin" by early bibliography. A possible connection with the circadian system is also discussed.