A new international collaborative study has identified wildlife species present at the market from which SARS-CoV-2, the virus responsible for the COVID-19 pandemic, most likely originated in late 2019. The study is based on an analysis of metatranscriptomic data released by the Chinese Center for Disease Control and Prevention (CDC), collected in and around the Huanan Seafood Wholesale market. Researchers analyzed the data and viral genomes reported from early COVID-19 patients to piece together the origins of the pandemic. The research, published in the journal Cell, provides crucial insights into how the virus may have been introduced into the market.
Investigators from the Chinese CDC collected samples from the market on January 1, 2020, after the animals were removed and the market was closed. They swabbed various surfaces in the stalls, focusing on those selling wildlife, and also collected samples from drains and sewers. Metatranscriptomic sequencing was performed on these samples to detect RNA sequences from viruses, bacteria, plants, animals, and humans present at the market. The data were then analyzed by an international team to uncover the identities of animal species that could have served as intermediate hosts for the virus.
The study found evidence of SARS-CoV-2 in stalls where wildlife was sold, including raccoon dogs and civet cats. Genetic material from the virus and these animals was detected on the same swabs, indicating a potential link between the animals and the virus. The researchers were able to identify these animal species by genotyping their mitochondrial genomes in the samples. While direct proof of infected animals was lacking due to animals being cleared out before sampling, the findings suggest a likely scenario where infected animals were introduced into the market.
Evolutionary analysis of the earliest viral genomes reported in the pandemic supported the theory of market emergence of SARS-CoV-2. The results indicated that very few, if any, humans were infected prior to the market outbreak, suggesting spillovers from animals to humans within the market. The presence of various animal species in the market, including raccoon dogs, masked palm civets, Hoary bamboo rats, and Malayan porcupines, raises questions about potential intermediate hosts for the virus. While the data cannot definitively pinpoint the source of the virus, it provides valuable information for tracing its origins.
The findings underscore the importance of understanding the origins of the COVID-19 pandemic to prevent future zoonotic events. With recent spillovers like avian flu viruses in cattle, the researchers emphasize the need for accurate information to enhance national security and public health measures worldwide. The study highlights the critical role of wildlife trade and human-animal interactions in the emergence of novel pathogens and the importance of mitigating risks to prevent future pandemics. By analyzing data from early in the pandemic, the researchers shed light on the initial spread of SARS-CoV-2 and the potential implications for future disease outbreaks.
Overall, the collaborative study provides valuable insights into the origins of the COVID-19 pandemic and the potential role of wildlife species in the transmission of the virus. By analyzing metatranscriptomic data from the market where the virus likely originated, the researchers identified key animal species that may have served as intermediate hosts for SARS-CoV-2. The study contributes to our understanding of zoonotic events and underscores the importance of surveillance and prevention measures to reduce the risk of future pandemics.
