Survival of human enteric and respiratory viruses on plastics in soil, freshwater, and marine environments.

The public health significance of plastics and microplastics in different environmental matrices has mainly focused on the toxicological effects of human ingestion. But these pollutants can also harbour pathogenic bacteria as the surfaces of plastics in the environment quickly become colonised by microbial biofilm. This novel microbial habitat has been termed the 'plastisphere' and could facilitate the survival and dissemination of important bacterial and fungal pathogens. Importantly, however, the role of plastic pollution as a secondary pathway for the transmission of human pathogenic viruses has never been addressed. Due to the high prevalence of both enteric and respiratory viruses in the population and in the environment, there is significant potential for human viruses to become associated with the plastisphere. In this review we critically evaluate current knowledge on the interaction of human enteric and respiratory viruses with plastic surfaces and identify the main environmental conditions and plastic characteristics that could affect virus survival and persistence in the environment. Our hypothesis is that the plastisphere can enhance the adhesion, survival and dissemination of human pathogenic viruses and potentially lead to more effective transfer and transmission of viral diseases within the environment. We identify key research questions needed to more fully assess the potential human health risks associated with viruses on plastic surfaces. These include understanding, (1) the mechanisms of viral attachment to either naked or biofilm-colonised plastic (2) how the structural characteristics of viruses (e.g., enveloped, or non-enveloped), affect their persistence in the plastisphere, (3) whether the plastisphere offers protection and increases the persistence of infectious viruses in soil, freshwater, and marine environments.

Binding, recovery, and infectiousness of enveloped and non-enveloped viruses associated with plastic pollution in surface water.

Microplastics in wastewater and surface water rapidly become colonised by microbial biofilm. Such 'plastisphere' communities are hypothesised to persist longer and be disseminated further in the environment and may act as a vector for human pathogens, particularly as microplastics entering wastewater treatment plants are exposed to high concentrations of pathogenic bacteria. However, the potential for human viral pathogens to become associated with the plastisphere has never before been quantified. Here, we have used rotavirus (RV) SA11 (a non-enveloped enteric virus) and the enveloped bacteriophage Phi6 as model viruses to quantify binding and recovery from biofilm-colonised microplastic pellets in three different water treatments (filtered and non-filtered surface water, and surface water with added nutrients). Viruses associated with biofilm-colonised pellets were more stable compared to those remaining in the water. While infectious particles and genome copies of RV remained stable over the 48 h sampling period, Phi6 stability was highly impacted, with a reduction ranging from 2.18 to 3.94 log10. Virus particles were protected against inactivation factors when associated with the biofilm on microplastic surfaces, and when there was a high concentration of particulate matter in the liquid phase. Although our results suggest that the presence of an envelope may limit virus interaction with the plastisphere, the ability to recover both enveloped and non-enveloped infectious viruses from colonised microplastic pellets highlights an additional potential public health risk of surface waters becoming contaminated with microplastics, and subsequent human exposure to microplastics in the environment.

A portable reverse transcription recombinase polymerase amplification assay for rapid detection of foot-and-mouth disease virus.

Foot-and-mouth disease (FMD) is a trans-boundary viral disease of livestock, which causes huge economic losses and constitutes a serious infectious threat for livestock farming worldwide. Early diagnosis of FMD helps to diminish its impact by adequate outbreak management. In this study, we describe the development of a real-time reverse transcription recombinase polymerase amplification (RT-RPA) assay for the detection of FMD virus (FMDV). The FMDV RT-RPA design targeted the 3D gene of FMDV and a 260 nt molecular RNA standard was used for assay validation. The RT-RPA assay was fast (4-10 minutes) and the analytical sensitivity was determined at 1436 RNA molecules detected by probit regression analysis. The FMDV RT-RPA assay detected RNA prepared from all seven FMDV serotypes but did not detect classical swine fever virus or swine vesicular disease virus. The FMDV RT-RPA assay was used in the field during the recent FMD outbreak in Egypt. In clinical samples, reverse transcription polymerase chain reaction (RT-PCR) and RT-RPA showed a diagnostic sensitivity of 100% and 98%, respectively. In conclusion, FMDV RT-RPA was quicker and much easier to handle in the field than real-time RT-PCR. Thus RT-RPA could be easily implemented to perform diagnostics at quarantine stations or farms for rapid spot-of-infection detection.