Hi SadTex,
I think I can answer this from personal experience.
An IgG test for antibodies. Antibodies are produced by the body as a response to pathogens. Therefore, when you are exposed to a pathogen such as the common cold your body does not have its little soliders (antibodies) ready to prepare for an attack.
However, once exposed, the body is able to make antibodies to fight the pathogen and it is said you never catch the same strain of the common cold twice. A second exposure to the same common cold, the body can deal with it and eliminate it.
An IgG test will let you know if you have had exposure to HSV and it has an index as follows.
1. Less than 0.9= NEG
2. 0.9-1.1= Maybe/maybe not....re-test
3. More than 1.1= POS
Also, it is recommended to wait 12-16 weeks if its a primary exposure. Like HIV you need to wait at least 90 days for an accurate result. Testing before the recommended time can give you a false negative.
Does that make sense?
A PCR tests for DNA (the DNA of a pathogen). So a PCR is the test that detects what-ever-it-is-your-looking-for.
Yes, the PCR is said to be the gold standard test for herpes. However, herpes is a latent and dormant virus that hides in the nerves. Your own body cannot get to it as the immune system is not designed to attack the nerves, the nervous system or the body itself.
When the immune system attacks the body you are said to have an auto immune disorder. An auto immune disorder is when ones body is attacking itself and it is manifested in deliberating conditions. Please google 'auto immune disorders'.
Herpes is not like HIV so it not in the blood when it is latent, dormant or hiding in the nerves. So a PCR blood test may not detect HSV if it is hiding in the nerves.
Does that make sense so far?
Therefore, it is best, in my opinion, to have different tests to ascertain your status.
I was recently exposed to HSV and I had to wait the recommended time to have an IgG, which is negative and I also took the PCR (at the same time of the IgG) which is also negative.
My ex tested positive for HSV in March 2012 and again in June 2012 on an IgG from two different labs.
He took a PCR blood test 7 days after his second positive IgG and it was negative.
So, I understand your confusion from personal experience. I have seen with my own two eyes two positive IgG's and one negative PCR, within a week of each other.
So to be sure, absolutely sure, it is is best to retest with an IgG after a negative PCR at a later date. Also, there are many vaccinations that need to be taken every 2 or more years. WHY IS THIS?
According to the medical profession, the antibodies fall and die off and you need to top up with another jab. I don't know if this is true for HSV antibodies but I'm kinda going by this theory.
*Disclaimer
The above is my opinion. I have no medical training. If I have made mistake, I invite anyone to correct me and set the record straight.