In a research article written in early-mid November of 2022, Smriti Mallapaty conducts and evaluates the bat ancestry in SARS CoV-2. Over the few years of COVID research, scientists discovered that COVID shares ancestry with bats more recently than they believed. However, recent findings suggest that finding that ancestor is unlikely.
In a recent presentation at the 7th World One Health Congress in Singapore, scientists compared portions of the coronavirus set of genes, which led to the discovery that COVID and bats shared genes as recently as 2016. In addition, it narrowed down the time between SARS-CoV-2 jumping from bats to humans. According to the Bat Conservation Trust, the reason for the transmission of COVID from bats to humans is due to deforestation and livestock farming on the cleared land brought wildlife into much closer contact with humans providing the opportunity for a spillover event.
This study conducted by Mallapaty highlighted the difficulty of finding the direct ancestor of the coronavirus. However, this led to research efforts in Asia. Many southeastern Asian scientists have come together to test the sequencing of viruses in different tissues to identify the ancestor. But, due to their struggle to find their ancestors’ people began to believe that the virus came from a Wuhan Virology facility. In the Wuhan Virology facility, according to the United States Senate, researchers and their collaborators collected virus expeditions on large scales to Southern China and Southeast Asia, where bats naturally harbor SARS-related viruses, on an annual basis from 2004 onwards. Scientists collected samples of bat blood, urine, and saliva. The bats and or samples from the bats transmitted covid to humans beginning of the COVID-19 pandemic.
This passage relates to the AP Biology Curriculum, specifically the Immune system and Adaptive immunity. In adaptive immunity, the body uses Pathogen Specific Recognition to target infected cells through a cell-mediated response. The MHC protein on macrophages and dendritic cells displays the foreign antigen and releases cytokine. The cytokines activate the T helper cells to recognize the antigen and start the cell-mediated response. The T helper cells stimulate other T cells to divide into Killer T and T memory cells. The T-killer cells kill infected cells, and T-plasma cells block off and remember the antigen to cause a faster immune response if exposed again. In addition, one can be further protected by receiving the mRNA vaccine. The mRNAs vaccine blocks the spike protein surrounding COVID cells so it can bind to the receptor on human cells that would allow it in.
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Overall, from their rigorous research, these scientists were able to find that SARS-CoV-2’s closest known relative is a bat virus found in Laos called BANAL-52, whose genome is 96.8% identical to SARS-CoV-2. In addition, another virus = is called RaTG13, which is 96.1% identical. They did this using a method of isolating viruses from bats and comparing their genomes. All these percentages reveal that the virus has undergone between 40-70 years of evolution. On the other hand, some researchers say that comparing whole-genome sequences ignores the role of recombination in virus evolution. Recombination is a description of DNA made by combining genetic material from 2 different sources. In this process, pieces of RNA could be very different from SARS-CoV-2, suggesting they are more distantly related, whereas other fragments that are much more similar imply a closer relationship. Therefore to account for recombination, researchers compared bat and pangolin genes and split them into segments and smaller nucleotide segments. At that point, each segment was evaluated with a subset to estimate how recently SARS-CoV-2 shared a common ancestor with a bat or animal virus.
This topic grabbed my attention because I was reflecting on my interactions with animals. Besides domesticated animals, the only animals I have had true interactions with are bats and birds. In addition, since the pandemic, I heard about the role bats play in the spread of COVID but never took the time to understand their involvement. In short, I took this opportunity to educate myself on these creatures that hang upside down and turned our world upside down.
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