Define "minimum infecting dose" - (Feb/14/2006 )

"Minimum Infecting Dose" means:

1) The minimum number of (say, influenza virions) required to produce infection (in the average member of a given species).

or

2) A number of (say, number of influenza virions) guaranteed to produce infection (in same as above).

or

3) The number of (say, influenza virions) that will produce infection in 50% of (same as above).

I know this is probably a dumb question, but I can't seem to find a reliable reference.

Now that I've realized that I was assuming #1, without even realizing I was making an assumption by doing so, I'm logically more attracted to #3, which might be more crisply expressed as: "median minimum infecting dose", but I don't get any google hits on that phrase (plus it still subsumes the ambiguity of the choice between #1 and #2), so I'm still not clear on what "minimum infecting dose" commonly refers to.

See what I'm saying?

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The minimum infecting dose is the inoculum size necessary to initiate the viral production process.

Hope this helps.

vetticus

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Er, yes, well... shall I take it from your use of the word "necessary" that you find #1 above to be the closest? If so, have to say that (now that I've thought about it) I can't see any theoretical barrier to a single virion initiating such a process -- which would seem to render the term "minimum infecting dose" so weak as to be essentially useless. Any explanatory power it has would have to derive from some assumptions that there is a difference between the way this works in theory and the way it works in the real world.

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My experience is primarily with bacteria, but if the rules are the same then I would say theoretical minimum dose is, of course, one virion...

however, if viruses are measured the same way as pathogenic bacteria, then a standard minimal infectious dose would be based on clinical tests and experimentation, and would reflect an average across a given species population. Theoretically, under proper conditions, it only ever takes one organism or virion to cause illness...but that is not really what you see or we would all be much sicker all of the time

I do think #3 refers to ID50, not to be confused with LD50...

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Yes, that's just what I had in mind (and that's what I think it should mean). While LD50 and ID50 are both nice, crisp terms, "minimum infecting dose" seems ambiguous. I'd like it best if what it referred to was essentially the same as ID50, but I don't want to assume that wherever I see the phrase, that's what it refers to; if the term is inherently ambiguous, and its usage subject to the whim of the individual user, then I want to know to ask each user for clarification -- but if everybody but me knows what it means, I don't want to embarass myself by asking. I was hoping to get that out of the way here.

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I do believe, that its the amount required, not guaranteed. I don't think you could ever guarantee anything in virology.

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