Tal­mu­dic Ques­tion #79

42?

as good a guess as any.
Thanks,
Elio

Too broad a ques­tion, I believe...I can't an­swer that ques­tion as it has been presently for­mu­lated to this faith­ful small­thinger. I think that would be bet­ter to spec­ify which type of or­gan­ism are we speak­ing of: species of prokary­otes? Or are we in­clud­ing too eu­kary­otes? And if we in­clude eu­kary­otes, only uni­cel­lu­lar ones or also pluri­cel­lu­lar. As we know, in the last case, things get com­pli­cated be­cause the dif­fer­ent kinds of cells of a pluri­cel­lu­lar eu­kary­ote have, each type, a va­ri­ety of viruses able to in­fect them...
Go­ing fur­ther than I should go be­cause I am not the per­son who has ad­dressed the ques­tion, let us as­sume we're speak­ing only of prokary­otic species. But here too, things get also com­pli­cated be­cause the prokary­otic species ‑as we usu­ally ac­cept be­ing defined‑,includes a lot of dif­fer­ent strains, and that "a lot" can be an aw­ful "a lot". And each strain may have, and usu­aly has,a spe­cific com­ple­ment of viruses able to at­tack it. So... What do we do: do we re­strict the whole thing to a sin­gle strain ? But even if we do so, we must take the time di­men­sion out of the story, be­cause prokary­otic strains have a well known and ac­tive ge­netic dy­nam­ics that with­out doubt af­fects its vi­ral sus­cep­ti­bil­ity.
And last but not least: What do we mean when we say "dif­fer­ent kinds of viruses"? I mean: con­sid­er­ing e.g. bac­te­rio­phages, there may be lots and lots of dif­fer­ent lamb­doids, or of dif­fer­ent my­oviri­dae, or of dif­fer­ent podoviri­dae, etc. Just think about the hy­po­thet­i­cal dif­fer­ent ds­DNA se­quences "us­ing" a spe­cific vi­ral mor­phol­ogy, not to men­tion ss­DNA ones, and the RNA ones.
Con­sid­er­ing all of the above my guess is that the num­ber of dif­fer­ent kinds of viruses of a prokary­otic species may be a num­ber very very big and in con­stant change, par­tic­u­larly if we in­clude into the equa­tion the time (+ the en­vi­ron­ment of course) and with the time, the in­trin­sic ge­netic dy­nam­ics of the prokary­otic "species".
In that area of think­ing, would it have sense ask­ing how many dif­fer­ent prokary­otic "species" a pleiotropic virus could in­fect? The an­swer to that ques­tion has a lot to do with all of the above. I think.
Fran­cisco T.

Per­haps an eas­ier ques­tion to an­swer would be what is the largest num­ber of viruses that can in­fect a given species at one time. Again, of course, it would de­pend on what kind of host or­gan­ism we are talk­ing about. But for adult hu­mans, it is ex­tremely com­mon for an av­er­age healthy in­di­vid­ual to be chron­i­cally in­fected with at least 6 her­pesviruses, sev­eral torque ten­oviruses, poly­omaviruses JC and BK, pa­pil­lo­maviruses that come and go, and of course sev­eral hun­dred hu­man en­doge­nous retro­viruses. Add to that the not so un­usual HIV, he­pati­tis B, he­pati­tis C virus co-in­fec­tion and tran­sient res­pi­ra­tory viruses and you have a rather crowded host.

Al­i­cen,
Be­ing good or bad at math has lit­tle to do with this, so you are en­ti­tled to pipe in as much as an ad­vanced math­e­mati­cian.  So your guess is as good as any.
Elio