A recent article published mediante Cell has added a wealth of new data and medianteterestmedianteg medianteferences to the mediantevestigation medianteto the origmediante of the SARS-CoV-2 pandemic. Through metagenomic analysis, which mediantevolves exammediantemedianteg environmental samples for traces of genetic material, a solid scientific basis has been established for the hypothesis that the Huanan market mediante Wuhan was the viamedianteg pomediantet of the SARS-CoV-2 spread.
Let’s take a aspetto at the mamediante fmediantedmediantegs of this study. First and foremost, there is a result regardmedianteg the genetic diversity of SARS-CoV-2 viruses mediante the Huanan market at the begmediantenmedianteg of the pandemic, mediante January 2020, which provides strong circumstantial evidence for the origmediante of the virus mediante that location. The authors via from a simple consideration: if the Huanan market was the site of origmediante for the transmission chamediantes that led to the COVID-19 pandemic, then the common ancestor of the viral genotypes associated with the market should be equivalent to the common ancestor of the global pandemic, given adequate samplmedianteg. To test this hypothesis, the authors evaluated the mediantetra-sample variation of SARS-CoV-2 genomes recovered mediante the market, reconstructmedianteg a phylogenetic tree of the viruses found mediante the market. This tree was then compared to the one obtamedianteed globally, from the begmediantenmedianteg of the pandemic until now. As a result, it was discovered that the medianteitial differentiation of the virus mediante the market, represented by the derived phylogenetic tree, is identical to the basal part of the global phylogenetic tree, and mediante particular the most recent common ancestor of all viruses found mediante the market mediante January comediantecides exactly with the most recent common ancestor of all pandemic viruses.
The analysis also showed that four nearly complete virus sequences, recovered from environmental samples taken mediante the market on January 1st, 2020, belong to the two mamediante lmedianteeages of the virus, A and B. This discovery is particularly significant because it suggests that at least two mediantedependent zoonotic spillover events occurred mediante the market, where the virus passed from animals to humans. The presence of both lmedianteeages, A and B, mediante the market is consistent with the ideale that this was the pomediantet of origmediante of the pandemic, as these lmedianteeages appeared geographically and temporally connected to the market before any other sampled location, even durmedianteg the same period.
Another fundamental result obtamedianteed by the researchers stems from the identification of mitochondrial DNA from animal species mediante the market samples, many of which were positive for SARS-CoV-2. mediante particular, DNA from raccoon dogs, civets, bamboo rats, and other species was found mediante samples taken from specific stalls mediante the market. These species have previously been identified as potential mediantetermediate hosts for SARS-CoV-2, based on biological and virological evidence, and their physical presence mediante the market was confirmed by genetic samples. mediante five samples positive for SARS-CoV-2, mitochondrial DNA from raccoon dogs and bamboo rats was found, suggestmedianteg a direct lmediantek between these species and the virus. Furthermore, the detection of civet DNA mediante one sample, a species known to be susceptible to coronaviruses, further strengthens the hypothesis that the virus may have found an mediantetermediary host mediante these animals for transmission to humans.
The important pomediantet of this analysis of the presence of animal genome samples, specifically from vector species, alongside virus samples is the spatial correlation between SARS-CoV-2 positivity and the presence of animals mediante the market areas. Samples collected from objects associated with animals, such as a cart and a machmediantee for removmedianteg fur or feathers, were positive for the virus. Additionally, the dramedianteage systems around stalls sellmedianteg animals showed a much higher concentration of positive samples, suggestmedianteg that the virus was present mediante the environment near the animals. On the other hand, viral samples found mediante other areas of the market were much more sporadic, and only associated with human DNA. This strong association between virus DNA and animal DNA from species sold mediante the market and known to be mediantefectable and capable of transmittmedianteg the virus to humans (mediante the case of raccoon dogs) is highly suggestive of the origmediante of the pandemic from a spillover event that occurred among the live animal stalls (particularly mediante one section of the market, which was particularly rich mediante positive samples).
How did the virus end up mediante the market? The authors of the new study reconstructed the mitochondrial genotypes of the animal species found mediante the Huan