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SARS-CoV-2: as evidências genéticas da sua origem
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Em dezembro de 2019 foi identificado pela primeira vez o novo agente viral Síndrome Respiratória Aguda Grave Coronavírus 2 (SARS-CoV-2), em Wuhan na China. Desde então, o vírus propagou-se rapidamente pelo mundo, resultando na pandemia da Doença por Coronavírus 2019 (COVID-2019) a qual já conta com um número de mortes superior a 4 milhões.
Este é um vírus da família Coronaviridae do género Betacoronavirus e do subgénero Sarbecovirus. Atualmente já foram descritos sete coronavírus que infetam humanos sendo que, em menos de 20 anos esta família já foi responsável por duas epidemias: a Síndrome Respiratória Aguda Grave, em 2002, e a Síndrome Respiratória do Médio Oriente, em 2012.
O morcego é o reservatório principal de Betacoronavirus, sendo a sequência mais próxima detetada até ao momento de uma amostra viral de morcego (Rhinolophus affinis), com homologia de 96.2%. Contudo sugerem-se a existência de hospedeiros intermediários, como o pangolim de Guangdong, devido à sua semelhança no domínio de ligação ao recetor.
Embora existam várias hipóteses sobre a origem deste vírus, neste trabalho procurou-se abordar as principais características genéticas e, com base na evidência disponível, fazer uma análise das suas quatro hipóteses de origem: transmissão zoonótica direta; transmissão alimentar pela cadeia de frio; introdução através de uma espécie hospedeira intermediária; e introdução através de um incidente laboratorial.
In December 2019, the new viral agent Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV-2) was identified for the first time in Wuhan, China. Since then, the virus has been spreading rapidly around the world, resulting in the current Coronavirus Disease 2019 (COVID-2019) pandemic which has already caused more than 4 million deaths. This virus is a member of the family Coronaviridae, genus Betacoronavirus and of the subgenus Sarbecovirus. So far, seven coronaviruses that infect humans have been described, and in less than 20 years this family has already been responsible for two epidemics: Severe Acute Respiratory Syndrome, in 2002, and the Middle East Respiratory Syndrome, in 2012. The bat is the main reservoir of Betacoronavirus, being it the closest sequence detected so far from a bat viral sample (Rhinolophus affinis), having 96.2% homology. However, the existence of intermediate hosts, such as the Guangdong pangolin, is suggested due to its similarity in the receptor binding domain. Although there are several hypotheses about the origin of this virus, the purpose of this research was to approach the main genetic characteristics and, based on the available evidence, make an analysis of its four origin hypotheses: direct zoonotic transmission to humans (spillover); food transmission through the cold food chain; introduction through an intermediate host species; and introduction through a laboratory incident.
In December 2019, the new viral agent Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV-2) was identified for the first time in Wuhan, China. Since then, the virus has been spreading rapidly around the world, resulting in the current Coronavirus Disease 2019 (COVID-2019) pandemic which has already caused more than 4 million deaths. This virus is a member of the family Coronaviridae, genus Betacoronavirus and of the subgenus Sarbecovirus. So far, seven coronaviruses that infect humans have been described, and in less than 20 years this family has already been responsible for two epidemics: Severe Acute Respiratory Syndrome, in 2002, and the Middle East Respiratory Syndrome, in 2012. The bat is the main reservoir of Betacoronavirus, being it the closest sequence detected so far from a bat viral sample (Rhinolophus affinis), having 96.2% homology. However, the existence of intermediate hosts, such as the Guangdong pangolin, is suggested due to its similarity in the receptor binding domain. Although there are several hypotheses about the origin of this virus, the purpose of this research was to approach the main genetic characteristics and, based on the available evidence, make an analysis of its four origin hypotheses: direct zoonotic transmission to humans (spillover); food transmission through the cold food chain; introduction through an intermediate host species; and introduction through a laboratory incident.
Descrição
Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, 2021, Universidade de Lisboa, Faculdade de Farmácia.
Palavras-chave
SARS-CoV-2 COVID-19 Origem Genoma Proteína spike Mestrado integrado - 2021