I have a question about virus transportation inside, say, blood. I did a rough estimate of the average virus Reynolds Number and it turned out to be around .0051. So aside from some good old Brownian Motion, those viruses aren’t really going anywhere without some sort of flagella or what-have-you. Do any viruses have a propulsion mechanism or do they all just loaf around wait for stuff to bump into them?
Short answer- No, viruses dont have their own propulsion systems That would require ATP and a means to generate ATP, ie metabolism. Viruses dont have that (they steal everything from their hosts).
But that doesnt mean viruses are at the mercy of Brownian Motion!
Viruses are the masters of mind control– they might not be able to move on their own, but they can take control of our cells!
To use HIV-1 as an example, HIV-1 doesnt just hang out in your vagina waiting for a CD4+ T-cell. to wander by (which is good, cause thats not going to happen). Vaginas have sentinal dendritic cells that pick up HIV-1 viruses (like a friggen chauffeur) and carry them to lymph nodes. Lymph nodes full of nommy, nommy CD4+ T-cells.
Mission accomplished, no viral locomotion needed.
Other viruses, like vaccinia, hijack cellular processes to help them infect more cells. It creates an actin ‘rocket pack’ to propel itself into nearby cells. Yeah. Actin shoots out the infected cells membrane like Wolverines claws, and into cells ‘next door’, infecting them. Im not lying (green dots are the virus, red tails the actin):
Those were two examples of viral ‘movement’ that I could think of off the top of my head– Ill try to think of some more (just cause its cool). Now randomness certainly plays a part in viral infection (you can be exposed to HIV-1 without being permanently infected), but viruses are not at the mercy of randomness just because they dont have their very own perfectly designed propulsion systems