The West Nile Virus staff report answered many of my questions. Several remain that I am very curious to have answered…I am a regular blood donor, and blood is now tested for WNV. I realize that most people who have been infected with WNV are either symptomless or have quite mild reactions. So…if I had been infected at any time (in the past) with WNV, would the antibodies still show in the blood test? Or, would only an active infection be detectable?
The staff report indicated that infection with WNV produces immunity for the ?infectee?. Would this immunity be transmitted with the transfused blood, so long as the infection was not active?
On another (viral) subject, my ob/gyn told me many years ago that almost all former or current cat owners have the antibody for toxoplasmosis in their bloods - the danger from this virus is if infection occurs during pregnancy; then the fetus is at risk…if a mother had the antibodies to toxo or WNV, is that passed onto the child?
Ah, so many questions!
orchidgal, welcome to SDMB! Your question probably will be moved to the General Questions Message Board – which is for questions that require factual information. A moderator will move it for you most likely. I hope that someone knows the answers.
It’s great that you are a regular blood donor. When I was a teacher, I rounded up high school studets for blood drives. We were the champs at donating.
Have fun at SDMB!
I agree with Zoe, so I’m moving this to General Questions forum. No biggie, orchidgal, it’s just that I think you’ll get more responses there. And welcome!
In order to have lasting immunity, you need to have the memory B cells that produce the antibodies (Abs), not just the antibodies themselves. Proteins, including Abs, have a limited half-life in the blood and break down after a certain amount of time. So any Abs present in donated blood would persist in the transfusion recipient for a while, but would ultimately vanish in the absence of the production of new Abs.
This actually ties in to your final question as well. Newborn infants’ immune systems aren’t fully developed yet so they can’t fight off infections themselves, but they are protected by maternal Abs. These are passed on both in utero where the Abs can cross the placenta and get directly into the bloodstream of the fetus, and after birth Abs are secreted in breast milk. This helps to protect babies until their own immune system develops fully, though there is usually a gap where the maternal Abs are gone but the child can’t mount a full immune response yet.
I don’t know enough about how the WNV test is done to answer your first question, but I’m sure someone else will be along shortly with that info.
Hope this helps orchidgal, and welcome to the SDMB!
The lab I work in tests for West Nile Virus by PCR. It’s only accurate for about the first five days post-infection. I’m almost positive there are tests out there that’ll work longer than that.
Thanks orchidgal (author here). There are various techniques used to detect antibodies (Smeghead mentioned one, RT-PCR, which is an excellent technique). We use a blocking ELISA (Jozan, M., Evans, R., McLean, R., Hall, R., Tangredi, B., Reed, L., Scott, J. 2003 Detection of West Nile Virus Infection in Birds by Blocking ELISA and Immunohistochemistry. Vector-borne and Zoonotic Disease, 3(3):99-110) which will detect antibodies many months after infection. We know about this long persistence since we can detect antibodies in live-caught crows during March. The crows would have most likely been infected during the previous mosquito season (although crow-to-crow transmission has been demonstrated under lab situations). We also know that crows who show antibodies during the winter months do not have virus present (or at least detectable). We don’t know how long after infections antibodies remain detectable, but that is something we’re investigating.