Developing lateral-flow devices for the fast and cheap detection of SARS-cov-2 in wastewater: a potential tool to monitoring local virus outbreaks by wastewater based epidemiology

Abstract

The SARS-CoV-2 virus generates severe respiratory tract complications such as pneumonia and bronchitis and mild symptoms such as common colds or asymptomatic conditions. The SARS-CoV-2 presence in human feces and in treated/untreated wastewater suggests a transmission way that could generate local outbreaks, in addition to other type of diseases or disorders. Based on the above, in this work it was proposed the assembly of a lateral flow device (LFD) to determine the SARS-CoV-2 presence in wastewater samples. In the LFD a wastewater sample capillary flowed through four membranes: sample zone, conjugate delivery zone, reaction zone and the reactive adsorption zone. The virus amplification was achieved by the novel reverse transcription loop-mediated isothermal amplification (RT-LAMP) at the sampling point. The membranes preconditioning processes and the use of membranes with 5-20 nm porous size increased the capillary flow rate and it was promoted the interaction of the gen of SARS-CoV-2 with the capture agents in the reactive adsorption zone. Additionally, the sensibility of the detection was improved using several methods for the immobilization of the capture agents on the reaction zone membrane. The RT-LAMP method combined with the assembled LFD allowed an efficient SARS-CoV-2 detection at the sampling point in a simple way, cheap and fast compared to conventional and expensive RT-PCR.