Why people could test negative for a HGRV but still be infected
(HGRV - Human Gamma Retro Virus)
One amino acid difference in the virus in your body compared to others used to calibrate the serology would mean that you could be negative for serology
Previous studies from this laboratory have described two antigenicsubclasses of polytropic virus isolates based on their reactivitieswith two different monoclonal antibodies termed Hy 7 and MAb516 (28). Virtually all of the polytropic isolates were reactivewith either Hy 7 or MAb 516; however, none of the viruses werereactive with both antibodies.
We mapped a major determinant of the epitopes for both antibodies to a single amino acid residue in the receptor-binding region of the polytropic SU protein.Hy 7-reactive viruses contained a lysine at that position, andMAb 516-reactive viruses contained a glutamine.
One base change is sufficient for host range conversion of murine leukemia virus from B to NB tropism
Tropism is the type of cell or host that a virus can infect
What this means is that if you have blood taken and PCR follows culture you may be negative just because your version of a hgrv does not infect T or B cells.
That does not mean that it is not in your thymus or spleen or indeed in the endothelial cells of the brain wreaking havok with your immune system