Coronavirus Latest: Brazilian Study Indicates That SARS-CoV-2 Coronavirus Could Affect Aquatic Animals
: Scientists from Brazil in a new study led by the University of Sao Paulo and involving numerous other research institutions have found that oxidative stress and neurotoxicity biomarkers increased in tadpoles exposed to synthetic SARS-CoV-2 spike protein peptides.
Aquatic animlas like prawns, not only tadpoles could be affected
by the SARS-CoV-2 coronavirus. Image Credit: iStock
The Spike protein (S protein) is a critical component in the infection of the new SARS-CoV-2 virus. The objective of this study was to evaluate whether peptides from S protein could cause negative impact in the aquatic animals.
The aquatic toxicity of SARS-CoV-2 spike protein peptides derivatives has been evaluated in tadpoles (n = 50 tadpoles / 5 replicates of 10 animals) from species Physalaemus cuvieri (Leptodactylidae). After synthesis, purification, and characterization of peptides (PSDP2001, PSDP2002, PSDP2003) an aquatic contamination has been simulatedwith these peptides during 24 hours of exposure in two concentrations (100 and 500 ng/mL). The control group (C) was composed of tadpoles kept in polyethylene containers containing de-chlorinated water.
Oxidative stress, antioxidant biomarkers and neurotoxicity activity were assessed. In both concentrations, PSPD2002 and PSPD2003 increased catalase and superoxide dismutase antioxidants enzymes activities, as well as oxidative stress (nitrite levels, hydrogen peroxide and reactive oxygen species). All three peptides also increased acetylcholinesterase activity in the highest concentration. These peptides showed molecular interactions in silico with acetylcholinesterase and antioxidant enzymes. Aquatic particle contamination of SARS-CoV-2 has neurotoxics effects in P. cuvieri tadpoles. These findings indicate that the COVID-19 can constitute environmental impact or biological damage potential.
The study findings were published on a preprint server and have yet to be peer reviewed. https://www.biorxiv.org/content/10.1101/2021.01.11.425914v1
The SARS-CoV-2 virus, the causative pathogen of coronavirus disease 2019 (COVID-19), spreads mainly by the airborne transmission of virus droplets from an infected person. However, the virus can stay alive on various surfaces (also known as 'fomites') for several days. Coming in contact with such contaminated surfaces can also cause virus transmission.
Also environmental transmission of the virus can also occur through indirect contact with urine or stool of infected individuals. Studies around the globe have detected the presence of the virus's ribonucleic acid (RNA) in sewage and wastewater. Household waste from hospitals and large buildings can thus harbor the virus and its ecotoxicological effects are yet unknown.
Studies have also shown that the SARS-CoV-2 coronavirus can survive in water for up to 25 days and can also be water-borne. https://www.thailandmedical.news/news/breaking-news-c
Hence, there is an urgent need to investigate the effect of the virus on aquatic organisms that live near discharges from such places. However, there are almost no aquatic animal models to conduct trials on and understand the virus's effect on aquatic vertebrates.
In order to study how SARS-CoV-2 affects aquatic animals, the study team used previously developed synthetic peptides of the SARS-CoV-2 spike protein to study its effect on a tadpole Physalaemus cuvieri.
This tadpole is commonly found in freshwater throughout Brazil and South America and has a stable and abundant population. Previous studies have used this animal to study the effects of water pollution.
The study team divided the tadpoles into seven groups of 50 animals each, including a control group. They added two different concentrations of the three synthetic spike protein peptides into water and kept the tadpoles in the spiked water for a day.
Utilizing biomarkers for oxidative stress and neurotoxicity, the study team assessed the toxic effects of the virus on the tadpoles. The team also estimated the binding affinity and mode of the synthesized peptides with the oxidative stress and neurotoxic biomarkers using chemoinformatic screens and molecular docking simulations.
The researchers found significant biochemical changes in the tadpoles exposed to two of the peptide after 24 hours. They found an increase in the production of nitrite and hydrogen peroxide, indicating an increase in the oxidative stress processes in the animals. They also found an increase in the amounts of the enzymes catalase and superoxide dismutase, which are antioxidants produced against oxidative stress.
The study findings are in agreement with previous studies that have shown that SARS-CoV-2 can induce oxidative stress upon infection and show the peptides can induce metabolic changes in the tadpoles.
However the antioxidant levels produced were not enough to counter the oxidative stress. The study team thinks this could be because the peptides induced functional changes in and had an affinity to the antioxidant enzyme; this idea being supported by molecular docking simulations.
The increase in nitrite could be because of a standard response to SARS-CoV-2 by the innate immune system, and hence an increase in the proinflammatory cytokines.
The stud team also evaluated neurotoxicity in the animals by measuring acetylcholinesterase (AChE), a marker for cholinergic function. At the higher concentration, all the peptides caused increased production of AChE, between 200% and 700%.
These findings are different from previous studies, which reported suppression in AChE production, possibly because of the degradation in neurotransmission and oxidation damage. The results seen in the tadpoles may be because of an activation of the cholinergic anti-inflammatory pathway. This is seen to aid the prevention of inflammatory conditions in animal models and the pathway can control inflammation by releasing the neurotransmitter acetylcholine. This mechanism has also been reported in COVID-19 patients.
Significantly the activation of the tadpoles' cholinergic system could also be because of the direct interaction of the peptides with AChE.
Molecular docking analysis showed a strong affinity between the two. However, more studies are needed to determine if this interaction changed the association and catalysis mechanism or increased enzyme efficiency because of increased substrate affinity with the active site.
Hence, the results indicate that SARS-CoV-2 protein fragments have a strong detrimental effect on tadpoles. However, there are still many questions about the effect of the virus in the aquatic environment, such as the effect of longer exposure, the effect on other animal models, and other toxicity biomarkers, which can be addressed in future studies. This knowledge can help in understanding the impact of SARS-CoV-2 on the environment and the ecosystem.
The study team concluded, “From a systemic approach that included the synthesis, cleavage, purification, and alignment of peptides to P. cuvieri tadpoles’ exposure to peptide fragments of Spike protein, we gathered evidence that confirms the toxicity of viral constituents in the evaluated animal model. The increase in predictive biomarkers of REDOX imbalance and neurotoxic action is, therefore, an insight into how aquatic particle contamination of SARS-CoV-2 can constitute additional environmental damage to the COVID-19 pandemic. In this sense, we strongly suggest conducting further studies necessary to understand the real magnitude of the biological/environmental impact of COVID-19.”
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