Testing specificity and sensitivity of wastewater-based epidemiology for detecting SARS-CoV-2 in four communities on Vancouver Island, Canada

We report wastewater surveillance of the spread of SARS-CoV-2 based upon 24-h composite influent samples taken weekly from four wastewater treatment plants (WWTP) on Vancouver Island, BC, Canada between January 3, 2021 and July 10, 2021. Samples were analyzed by reverse transcription quantitative polymerase chain reaction targeting the N1 and N2 gene fragments of SARS-CoV-2 and a region of the replication associate protein of the pepper mottle mosaic virus (PMMoV) serving as endemic control. Only a small proportion of samples had quantifiable levels of N1 or N2. Overall case rates are weakly correlated with the concentration (gene copies/L) and with the flux of viral material influent to the WWTP (gene copies/day); the latter accounts for influent flow variations. Poisson multimodal rank correlation accounts for differences between the four WWTP and shows a significant correlation with a significant positive intercept. Receiver operator characteristics (ROC) analysis confirms a cut-off of cases based on amplified/not-amplified experimental data. At the optimal cut point of 19 (N1) or 17 (N2) cases/week/100,000 the sensitivity and specificity is about 75% for N1 and 67% for N2.

Amino acid and 22Na+ uptake in membrane vesicles from confluent simian virus 40 transformed Balb/c3T3 and Balb/c3T3

The studies reported here were carried out to characterize further previously described changes in membrane localized amino acid transport associated with simian virus 40 transformation of the mammalian cell line, Balb/c3T3. Membrane vesicles were prepared from confluent cultures of both simian virus 40 transformed Balb/c3T3 (SV3T3) and the untransformed parent line, Balb/c3T3 (3T3). An initial, externally imposed out greater than in, 100 mM a+ gradient produces acceleration of early ingress of alpha-aminoisobutyric acid (AlB) in vesicles from both cell lines, but transient, concentrative uptake (overshooting) only in SV3T3 vesicles. Early ingress of L-leucine is also accelerated in SV3T3 vesicles by a Na+ gradient, and overshooting is also demonstrable. Na+-gradient independent AIB permeability of SV3T3 and 3T3 membranes was estimated using uptake data, a first order rate equation and measurements of vesicle size derived from quasi-elastic light-scattering studies. AIB permeability of SV3T3 membranes is greater than that of 3T3 membranes (113 A/min and 43 A/min, respectively), suggesting that overshooting in 3T3 vesicles is not attenuated by a Na+-independent AIB "leak". Na+ permeability of the two membranes is similar, ruling out the possibility that a slower rate of Na+ equilibration across the SV3T3 membrane allows development of the overshoot. In SV3T3 vesicles the height of a Na+-gradient dependent overshoot varies with the initial [Na+]o/[Na+]i ratio, and ln[Na+]o/[Na+]i is linearly related to ln AIB uptake at overshoot peak/AIB uptake at equilibrium, consistent with the possibility that for [Na+]o/[Na+]i ratios in the range studied, AIB overshoot is energized by a constant proportion of the energy available from the initial electrochemical gradient for Na+. These results are consistent with the possibility that Na+-gradient dependent overshooting in SV3T3 vesicles is produced by Na+-amino acid carrier interactions resulting in either an increase in maximum transport velocity or an increase in carrier affinity for AIB.