Blastp against (only) human Sars-cov1 : which taxid?

Question

[guillaume.rbt]

Hi all,

I'm trying to blast peptides against human Sars-cov1 with blastp.

I'm not quite sure which taxid I should use to keep only results from Sars-cov1. When I search the term "sars" in the organism field, it proposes "HCoV-SARS (taxid:694009)", but this taxid includes a lot of different coronaviruses strains, including the sars-cov2 and bat strains, which I don't want to keep. Is there a reference strain with a taxid for sars-cov1 that I could use?

Any advices would be very useful !

Thanks

[manaswwm]

I think you have the correct taxid, you can double check on this by going to Taxonomy section of NCBI and putting in this id and it will return the following : https://www.ncbi.nlm.nih.gov/taxonomy/?term=694009. Have you tried doing the following: when you enter organism taxid in blastp settings, click the add button to enter info on another organism and enter the taxid of sars-cov2 in the textarea below and tick the exclude option?

[guillaume.rbt]

Thank for your help. I've indeed checked this taxid on the taxonomy section of NCBI. It includes sequences from a lot of strains, including Bat coronavirus strains, and I would like to focus on human strains. Even when I exclude sars-cov2 I will still have all the bat strains (if I understand correctly) ?

Answer 1

[GenoMax]

I would say 333387 entry should be the correct one.

RefSeq genome for original SARS virus seems to cross-reference top level taxID that you have in your post so you may just want to use this genome.

[guillaume.rbt]

Thank for your input. Is 333387 a bat strain? I would like to blast againt a human sars-cov1 strain.

[GenoMax]

Then use the RefSeq reference I linked above. Unfortunately it seems to be given a taxID of 694009 which is the generic ID for SARS like corona viruses. As for the bat/human issue the strain originated in bats correct? Human coronaviruses come in many categories.

[guillaume.rbt]

Yes it seems to come from bats, but if I could I would like to focus on human strains. I'm a bit confused by the fact that the taxid is the generic ID for SARS like coronaviruses, which seems to include bat strains (https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=694009). But at the same time, it is described here as human coronavirus. If I blast againts this taxid, will it use the 50,013 protein sequences referenced? And will those sequences include those from bat strains?

[GenoMax]

If you want to be strict then use these 14 proteins from the RefSeq genome linked above.

If I blast againts this taxid, will it use the 50,013 protein sequences referenced?

It probably will since you are limiting at taxID level.

[guillaume.rbt]

Ok thanks! FYI I tried to blast with a sequence coming from a bat strain, specifyin the 694009 taxid, and I didn't get a perfect match. The best match being a sequence from the human reference. Which lead me to think that sequences from bat strains are not included in the blast search.

[GenoMax]

That is curious since the top few entries seem to be from Bats for that taxID.

Severe acute respiratory syndrome-related coronavirus     Click on organism name to get more information.

    Bat coronavirus Cp/Yunnan2011   
    Bat coronavirus RaTG13   
    Bat coronavirus Rp/Shaanxi2011   
    Bat SARS coronavirus HKU3   
        Bat SARS coronavirus HKU3-1   
        Bat SARS coronavirus HKU3-10

[guillaume.rbt]

I think I understand, I was using refseq and not nr as database, and it didn't include the bat strains sequences.