Biodiversity from a global health approach through molecular biology and massive sequencing strategiesParticular cases of Perkinsus olseni and SARS CoV2

Abstract

The marine ecosystem contains a great diversity of prokaryotic, eukaryotic and virus organisms that are still completely unknown, and varies depending on each environmental compartment. At the ecological level, each organism fulfils a series of fundamental functions that result in the interaction of some organisms with others, thus obtaining the balance of an ecosystem. However, several factors such as changes in environmental parameters (temperature, salinity, etc.) or the introduction of species in new geographical areas, mostly caused by human activity, can favour the proliferation of pathogenic organisms that cause, in very severe cases, massive mortalities. This can lead to the ecological alteration of the composition and balance of the ecosystem, economical losses in the aquaculture sector. This, added to the lack of knowledge about the biology of certain pathogens, makes the total eradication of diseases very complex, and that the fight against diseases is based on the application of preventive monitoring measures, in order to detect pathogens and predict the possible occurrence of diseases. The doctoral thesis will address the study of the biodiversity of a coastal ecosystem (Ría de Vigo) that is significantly affected by the effect of humans. For this reason, we will also carry out a study of the diversity of bacteria found in wastewater and that are discharged into the marine ecosystem after wastewater treatment. The health of people is therefore related to the health of animals and the environment in a broad concept of “global health”. In this study, methodologies based on molecular biology and next-generation massive sequencing (NGS) will be applied. In addition to the study of the biodiversity of the coastal marine ecosystem and the wastewater discharged into it, with special emphasis on potential pathogens, we will focus our study on the distribution of two pathogens: Perkinsus olseni (pathogen in bivalve aquaculture) and SARS-CoV- 2 (virus which has caused the COVID-19 pandemic). The pathogen Perkinsus olseni is a protozoan that affects a wide variety of bivalve molluscs throughout the world and generates severe economic losses in the aquaculture sector. Due to its great impact, this parasite has been included in the list of mandatory notifiable organisms by the World Organization for Animal Health (OIE, 2019), so it is necessary to develop and validate new diagnostic methodologies that allow an early and effective detection of the disease. The SARS-CoV2 virus is a type 2 coronavirus that causes severe acute respiratory syndrome and whose worldwide expansion has caused the current COVID-19 pandemic which has been officially declared in January 2020 by the World Health Organization (WHO). In addition to respiratory symptoms, the virus can also cause gastrointestinal symptoms and be released in the feces (Cheung et al., 2020, Randazzo et al., 2020). Currently, several studies have detected SARs-CoV2 RNA in wastewater by quantitative PCR (La Rosa et al., 2020; Randazzo et al., 2020) and have suggested that detection of the virus in wastewater by PCR could be a non-invasive method for an early detection of the disease, allowing authorities to establish accurate coordination strategies (Daughton, 2020).