SARS-CoV-2 surrogate (Phi6) environmental persistence within free-living amoebae

Abstract

The reported persistence of SARS-CoV-2 virions in aquatic environments highlights the need to better understand potential mechanisms that may prolong its dissemination. We evaluated the possibility that amoebae might serve as transport hosts by studying the interaction of the enveloped bacteriophage Phi6, as a potential surrogated along with one of the most common amoebae in engineered aquatic environments, Vermamoeba vermiformis. Using microscopy, imaging flow cytometry and bacteriophage cell culture, our results imply that the SARS-CoV-2 surrogate triggers amoebic mitochondria and induced apoptosis to promote viral persistence in trophozoites. Furthermore, virus-infected amoebae were still infectious after 2 months within FLA cysts. These results suggest that amoebae could contribute to the environmental persistence of SARS-CoV-2, including disinfection processes. In addition, amoebae could be a successful model system for understanding respiratory virus-eukaryotic biology at the cellular and molecular levels.

The role of free-living amoebae in the persistence of viruses in the era of severe acute respiratory syndrome 2, should we be concerned?

“…In addition, to FLA live and be abundant in the sewer, a relatively short time (one hour) of interaction between FLA and viruses has been reported to be sufficient to internalize a considerable number of viral particles (4 × 10 2 ), as shown for human norovirus (HuNoV) surrogates (Murine norovirus type 1 and Feline calicivirus) 11 . FLA usually disperse internalized viruses by releasing respirable-sized vesicles (2-3 µm) filled with viral particles (Figure 1), as shown for RSV and Coxsackievirus B5 12 . This may increase the resistance, viability time, and range of dispersion of SARS-Cov-2 in the environment since the vesicles provide protection against biocidal factors until they reach a new host or less unfavorable environments 8,12 .…”

“…FLA usually disperse internalized viruses by releasing respirable-sized vesicles (2-3 µm) filled with viral particles (Figure 1), as shown for RSV and Coxsackievirus B5 12 . This may increase the resistance, viability time, and range of dispersion of SARS-Cov-2 in the environment since the vesicles provide protection against biocidal factors until they reach a new host or less unfavorable environments 8,12 . The public health concern raised by this possibility is more significant for rural areas of developing countries, where sanitation is critical, and people's exposure to contaminated water is greater.…”

“…Recently, it has been demonstrated that infectious viral particles of the SARS-Cov-2 surrogate (Phi6 phage) can be recovered from infected FLA (V. vermiformis), including infected cysts stored for up to 20 days 12 .…”

Editorial: SARS-CoV-2 in water

“…Of course, scientific evidence grows rapidly with ongoing research efforts and there is a need to stay alert and open-minded should there be a need to revisit. With that in mind, we commend to you a study from Dey et al (2022) investigating the potential role of amoebae in the environmental persistence of SARS-CoV-2 virus. Understanding the microbial ecology of water systems and the interaction between different microorganisms is of great value and is important for managing the waterborne risk of several pathogens (from SARS-CoV-2 or other RNA viruses) in the future.…”

Longer amplicons provide better sensitivity for electrochemical sensing of viral nucleic acid in water samples using PCB electrodes

“…Phi6 phage is comparable to SARS-CoV-2 in size (80–100 nm), and also possesses lipid membrane and spike proteins. Because of these reasons, phage Phi6 is a popular surrogate for SARS-CoV-2 and other enveloped pathogenic RNA viruses 14 , 15 . RNA isolated from the phage particles was used as template for cDNA synthesis, that was then used as template for PCR to obtain two DNA fragments of lengths 117 and 503 base pairs.…”