Nanoplastics Increase Fish Susceptibility to Nodavirus Infection and Reduce Antiviral Immune Responses.

Carmen González-Fernández,Alberto Cuesta

doi:10.3390/ijms23031483

Carmen González-Fernández, Alberto Cuesta

Open Access

https://doi.org/10.3390/ijms23031483

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Abstract

Nanoplastics (NPs) might cause different negative effects on aquatic organisms at different biological levels, ranging from single cells to whole organisms, including cytotoxicity, reproduction, behavior or oxidative stress. However, the impact of NPs on disease resistance is almost unknown. The objective of this study was to assess whether exposure to 50 nm functionalized polystyrene NPs impacts fish susceptibility to viral diseases both in vitro and in vivo. In particular, we focused on the nervous necrosis virus (NNV), which affects many fish species, producing viral encephalopathy and retinopathy (VER), and causes great economic losses in marine aquaculture. In vitro and in vivo approaches were used. A brain cell line (SaB-1) was exposed to 1 μg mL−1 of functionalized polystyrene NPs (PS-NH2, PS-COOH) and then infected with NNV. Viral titers were increased in NP-exposed cells whilst the transcription of inflammatory and antiviral markers was lowered when compared to those cells only infected with NNV. In addition, European sea bass (Dicentrarchus labrax) juveniles were intraperitoneally injected with the same NPs and then challenged with NNV. Our results indicated that NPs increased the viral replication and clinical signs under which the fish died although the cumulate mortality was unaltered. Again, exposure to NPs produced a lowered inflammatory and antiviral response. Our results highlight that the presence of NPs might impact the infection process of NNV and fish resistance to the disease, posing an additional risk to marine organisms.

Highlights

IntroductionPlastic debris in the environment continues increasing as consequence of plastic production (estimated around 359 million tons of plastics per year; [1]), being an emerging concern
Plastic debris in the environment continues increasing as consequence of plastic production, being an emerging concern
SaB-1 cells were exposed to NPs for 24 h and infected with nervous necrosis virus (NNV), determining the cell cytopathic effect daily and the viral titer after 10 days of infection

Summary

Introduction

Plastic debris in the environment continues increasing as consequence of plastic production (estimated around 359 million tons of plastics per year; [1]), being an emerging concern. Unlike MPs, particles with lower sizes such as NPs have the capability to cross cellular membranes, resulting in high toxicity [8,9]. In addition to their own toxicity, the presence of MP/NPs in natural environments promotes their interaction with other factors. Plastic particles are able to sorb or be colonized by microorganisms, including pathogens, forming a biofilm, which has been called a “plastisphere” [14] This plastisphere can include bacteria and viruses, which makes them a potential vector for diseases [15]. Further studies are still needed to ascertain if the observed impaired immunity to mount an effective response might be linked to extended susceptibility to disease, as suggested

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