Capsid integrity detection of pathogenic viruses in waters: Recent progress and potential future applications

Abstract

Waterborne diseases caused by pathogenic human viruses are a major public health concern. To control the potential risk of viral infection through contaminated waters, a rapid, reliable tool to assess the infectivity of pathogenic viruses is required. Recently, an advanced approach (i.e., capsid integrity (RT-)qPCR) was developed to discriminate intact viruses (potentially infectious) from inactivated viruses. In this approach, samples were pretreated with capsid integrity reagents (e.g., monoazide dyes or metal compounds) before (RT -)qPCR. These reagents can only penetrate inactivated viruses with compromised capsids to bind to viral genomes and prevent their amplification, but they cannot enter viruses with intact capsids. Therefore, only viral genomes of intact viruses were amplified or detected by (RT-)qPCR after capsid integrity treatment. In this study, we reviewed recent progress in the development and application of capsid integrity (RT-)qPCR to assess the potential infectivity of viruses (including non-enveloped and enveloped viruses with different genome structures [RNA and DNA]) in water. The efficiency of capsid integrity (RT-)qPCR has been shown to depend on various factors, such as conditions of integrity reagent treatment, types of viruses, environmental matrices, and the capsid structure of viruses after disinfection treatments (e.g., UV, heat, and chlorine). For the application of capsid integrity (RT-)qPCR in real-world samples, the use of suitable virus concentration methods and process controls is important to control the efficiency of capsid integrity (RT-)qPCR. In addition, potential future applications of capsid integrity (RT-)qPCR for determining the mechanism of disinfection treatment on viral structure (e.g., capsid or genome) and a combination of capsid integrity treatment and next-generation sequencing (NGS) (capsid integrity NGS) for monitoring the community of intact pathogenic viruses in water are also discussed. This review provides essential information on the application of capsid integrity (RT-)qPCR as an efficient tool for monitoring the presence of pathogenic viruses with intact capsids in water.

Keywords: Capsid integrity (RT-)qPCR; Pathogenic viruses; Virus infectivity and water.