HIV is inactivated after the drying of biological fluid in the environment according to the CDC. How rapidly does inactivation actually occur? Would a small quantity of infected blood remain infectious after 1 minute, 5 minutes, or until it has completely dried?
(I have read one belief that HIV can remain viable hours after drying of infected blood in air, though contradicts the CDC statement).

My colleugues have done some experiments to check the decay of HIV. They found out even after 24 hours drying in the hood without UV, without bleach, HIV can still recover if they put them back into tissue culture.
But HIV is very sensitive to the UV light, bleach, alcohol and etc.

To what would you contribute the low incidence of seroconversion of healthcare workers resulting from percutaneous injuries of sharps (especially scalpels)? Inactivation from UV light or low inoculum? Also, the extreme rarity of infection from exposure to contaminated environmental surfaces (if ever documented at all)?

There could be many reasons. The most frequently used is the "blood bleeds out not in". An injury with, say a blade is quite unlikely to result in virus from the blade's surface intering past the protective barrier formed by the skin. With a needle the same would apply unless the individual involved actuall discharges the contents of the syringe.

Even here there is a low rate of infection because a) you have an immune system, and b) the most efficient transmission of retro and lentiviruses occurs when there is contact between a virus-infected cell and a neighbouring cell. ie. The virus buds from the infected cell straight into the neighbouring cell. Free virus is less likely to produce an infection and will require a much higher M.O.I. to be as effective as the cell-cell contact mechanism.

When you work with these viruses in vitro it can often be hard to get good infection rates and that's without the action of any immune system.

So overall, how accurate do you feel the CDC's statement is regarding drying of biological fluid and inactivation in the environment? (and if not solely due to drying, possibly considering any other factors contributing to timely inactivation when not in a laboratory setting).

http://www.cdc.gov/hiv/pubs/facts/transmission.htm

It looks pretty unambiguous to me:

"Since the HIV concentrations used in laboratory studies are much higher than those actually found in blood or other specimens, drying of HIV-infected human blood or other body fluids reduces the theoretical risk of environmental transmission to that which has been observed--essentially zero."

Viruses with lipid coats (and ssRNA genomes) are always going to be more sensitive than DNA viruses with tougher protein coats.

I am glad to see you agree with their statement. I had read something another virologist wrote that concerned me, that a biological fluid retains a high level of HIV infectiousness even after drying in the natural environment (back in my original post). Thanks for your assistance.

parvoman said:

There could be many reasons. The most frequently used is the "blood bleeds out not in". An injury with, say a blade is quite unlikely to result in virus from the blade's surface intering past the protective barrier formed by the skin. With a needle the same would apply unless the individual involved actuall discharges the contents of the syringe. Even here there is a low rate of infection because a) you have an immune system, and b) the most efficient transmission of retro and lentiviruses occurs when there is contact between a virus-infected cell and a neighbouring cell. ie. The virus buds from the infected cell straight into the neighbouring cell. Free virus is less likely to produce an infection and will require a much higher M.O.I. to be as effective as the cell-cell contact mechanism. When you work with these viruses in vitro it can often be hard to get good infection rates and that's without the action of any immune system.

Thank you for all of your discussions.

Does Hiv lose it's infectiousness if it is stored in water or another outside liquid? ie. blood or semen mixed with water...