In silico detection of (CRISPR) spacers matching Betacoronaviridae genomes in gut metagenomics sequencing data
Leoni G.1,2, Petrillo M.2, Puertas-Gallardo A.2, Sanges R.1, Patak A.2
1. Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste (Italy);
2. Joint Research Center (JRC), Ispra (Italy).
The CRISPR-Cas system is the major component of the prokaryotic adaptive immune system (Horvath
& Barrangou, 2010). CRISPR, which stand for “Clustered Regularly Interspaced Short Palindromic
Repeats”, are genomics arrays found in the DNA of many bacteria. They consist in short repeated
sequences (size 23-47 base pairs), separated by unique sequences of similar length (spacers), that often
derives from phages and viral infections, plasmids or mobile genetic elements (Shmakov et al., 2017).
CRISPRs are coupled to specific “CRISPR-associated genes” (Cas) to form the so called CRISPR-Cas
system. This system has the primary role to protect prokaryotes from virus and other mobile genetic
elements activity by conferring immunological memory from past infections (Garneau et al., 2010;
Nussenzweig & Marraffini, 2020).
Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a single-stranded RNA virus that
rapidly emerged in 2019. In humans, it causes coronavirus disease 2019 (COVID-19), an influenza-like
disease that is primarily thought to infect the lungs with transmission through the respiratory route.
However, clinical evidence suggests that the intestine may present another viral target organ, a potential
hiding place for the virus, which may explain the persistence of COVID-19 symptoms after months
from patients recovery (Lamers et al., 2020). Furthermore, extra-pulmonary clinical manifestations of
COVID-19 are reported. Nonetheless, although a link between SARS-CoV-2 infection and the misregulation
of the gut microbiome was suggested, its involvement remains largely unexplored (Brooks
& Bhatt, 2021).
To simultaneously verify both the potential existence of SARS-CoV-2 in gut and to test whether the
human gut microbiome may be stressed by SARS-CoV-2 infection, we developed a bioinformatic
workflow based on the detection of Betacoronaviridae-specific CRISPR spacers from ~28,000 public
available gut metagenomics data. To process such “Big Biological Data” in a reasonable CPU time, we
relied on a HTCondor High Throughput Computing System, characterized by 10 Tflops of computing
capacity and more than 80 Tbytes of storage. Computing block was composed by 8 Nodes IBM x3550
with two Intel Xeon processor E5-2600 v3 product family CPUs with10 cores 2.6 GHz, two QPI links
up to 9.6 GT/s each and 256 GB of RAM. While our work is still ongoing, preliminary results revealed
the presence of some Betacoronavirus-specific spacers in the human gut metagenomics data, proving
that SARS-like viruses can target human gut and suggesting that the human microbiome can be
stressed by the systemic viral infection. By collecting further data, we aim to strengthen our results as
well as to investigate the effects of the SARS-COV-2-induced microbiome stress to the host.
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