Game as a potential driver of disease emergence

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A study published on the bioRxiv* The preprint server characterized the total virome of game animals from five orders of mammals using the total RNA sequencing technique. Of the 71 mammal species discovered, the study found that 18 posed a potential risk to humans.

Study: Characterizations of the total game virome in China reveal a spectrum of emerging viral pathogens. Image Credit: teekayu / Shutterstock

In addition to finding human viruses in these animals, it’s interesting to note that the study researchers identified a species of alphacoronavirus that passes from bats to civets. They also detected the H9N2 influenza virus in a civet and an Asian badger.

These data underscore the importance of game as a potential driver of disease emergence. The study reports that many species were first studied using the metagenomic framework.

introduction

In the context of the ongoing 2019 coronavirus disease (COVID-19) pandemic, caused by the severe acute respiratory syndrome virus (SARS-CoV-2), and previous viral epidemics caused by the influenza virus, SARS-CoV and the Middle East Respiratory Coronavirus (MERS-CoV), scientists are continuing their research on the zoonotic origin of human pathogens and the interspecies jump.

Game, wildlife or semi-wild species traded and consumed as exotic foods in China and other Asian countries are potential reservoirs of viruses, such as SARS-CoV and SARS-CoV-2. They include rodents (porcupines, bamboo rats, and groundhogs), carnivores (civets, badgers, and foxes), pangolins, hedgehogs, and rabbits.

Markets for live or wet animals where these animals are imported for trade have developed into commercial farms for breeding wild animals and for the diversity of their species. Due to poor hygienic conditions and close contact between animals and humans, these markets provide an ideal breeding ground for emerging infectious diseases.

Several outbreaks of infectious diseases are linked to these markets. Cases of SARS-CoV and SARS-CoV-2 have been identified in these markets, and related species have also been found in civets, raccoon dogs and pangolins.

In this context, it is important to identify existing and potential human pathogens in game. This will help trace the origin of outbreaks and provide a risk assessment of probable future outbreaks.

Using techniques such as consensus PCR and Sanger sequencing approaches on isolated viruses and next-generation metagenomic sequencing (mNGS), scientists recently discovered several infectious human pathogens from animals. However, there are few such systematic surveys, especially in China, where wet markets are predominant.

Due to the few surveys done on game for their virome, the researchers of the present study performed a systematic study of the meta-transcriptomic virome (i.e. the sequencing of total RNA) of 16 species. game representing five orders of mammals sampled across China. Researchers are trying to assess which species have the greatest potential for carrying viruses that could eventually emerge in human populations.

Study results

In this study, researchers collected samples from 1,725 ​​game animals from 16 species commonly eaten as exotic foods across China between 2017 and 2021. They collected most animal samples after 2020, coinciding with the pandemic. of COVID-19.

These species represented five orders of mammals: Rodentia, Pholidota, Carnivores, Eulipotyphe, and Lagomorpha, including civets (P. larvata) that were implicated in the emergence of SARS-CoV. These animals were obtained from artificial breeding sites that supply animal markets and zoos, and natural habitats.

The researchers collected respiratory and fecal samples from 19 Chinese provinces. Subsequently, they organized them into 181 pools based on species, location, health, and feeding (living) conditions for RNA extraction and library construction – the meta-transcriptomic sequencing. They reported that this process produced 172.36 billion nucleotide bases of sequence reads for virus discovery and characterization.

They pre-identified viruses, in particular vertebrate-specific viruses and vector-borne vertebrate viruses, based on taxonomic lineage information from blastx results, and then confirmed them by phylogenetic analyzes.

Researchers have identified a wide variety of virus species (both previously described and new). Interestingly, they did not find any SARS-CoV or SARS-CoV-2-like sequences, even in Malaysian pangolins. Indeed, most likely, the positive samples for SARS were confiscated by the customs authorities of the provinces.

The study found that civets (Paguma larvae) carried the greatest number of potentially high-risk viruses.

Researchers have identified the transmission of Coronavirus bat HKU8 from a bat to a civet. Likewise, they identified birds Influenza A virus H9N2 in Asian civets and badgers. These observations confirmed inter-species jumps from bats to hedgehogs and from birds to porcupines, “which could trigger an epidemic.”

In addition, the researchers presented the first evidence of human pathogens in various game animals, such as Influenza B virus, Human parainfluenza virus 2, and Norovirus GII.17 in bamboo rats, Malaysian pangolins and civets – indicating human-to-wildlife transmission.

Importantly, the study showed that these viruses were present in apparently healthy animals, and that there is continuous transmission between species of the virus among game animals.

Conclusion

Carry out a large-scale investigation of viral pathogens, this study reveals the diversity and abundance of viruses in game using metatrancriptomic techniques. He confirms that game is important hosts for these viruses which pose a health risk to humans and domestic animals.

This is an important study with information on viruses in game that could lead to the next pandemic.

*Important Notice

bioRxiv publishes preliminary scientific reports which are not peer reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.

Journal reference:

  • Wan-Ting He, Xin Hou, Jin Zhao, Jiumeng Sun, Haijian He, Wei Si, Jing Wang, Zhiwen Jiang, Ziqing Yan, Gang Xing, Meng Lu, Marc A. Suchard, Xiang Ji, Wenjie Gong, Biao He, June Li, Philippe Lemey, Deyin Guo, Changchun Tu, Edward C. Holmes, Mang Shi, Shuo Su. bioRxiv. 2021. do I: https://doi.org/10.1101/2021.11.10.467646 https://www.biorxiv.org/content/10.1101/2021.11.10.467646v1

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