Antibodies

So I'm confused. How do you have antibodies for hsv1 and 2 but still be considered negative due to the low index value? Please shed some light for me.

From my (non-expert) understanding, the simple answer is that the tests are good, but they're imperfect. The way the blood test is done, virtually no one gets a zero. It's almost unheard of. An index value of 0 to 0.9 is considered negative, 0.9 to 1.1 is considered equivocal (unclear), and over 1.1 is considered positive. Smart people through research and clinical practice found that a fair number of people with index values between 1.1 and 3.5 are actually negative. Sometimes when the answer isn't clear with the IgG blood test, a much more sensitive test, called the western blot, is needed for confirmation.