I believe I was exposed to HIV several days ago. Since, I have begun a post exposure prophylaxis regiment of combivir and kaletra (begun 30 hours after potential exposure). I am wondering: if I have a PCR RNA viral load test done 1 week after exposure, what can I expect from the reliability of the results? If I get a negative is it actually the cases that I very likely did not contract the virus or might the retrovirals just suppress the viral load to an undetectable level?