Criterion for positivity usually reaction with all three major HIV protein antigens, gag, pol and env. Desired feature of secondary screen is high specificity. PCR based diagnosis is more effective and less ambiguous than antibody. Ability to detect minute amounts of virus a definite plus. Primers designed for gag, pol or env genes of the virus.
Advantage is detection of infection prior to mounting immune response and extreme sensitivity.
Later see use of PCR to define carrier state of AIDS patients without symptoms. Hybridization procedures are up to 1000 times more sensitive. PCR methods reduce detection level to a few copies of hepatitis B virus. Cytomegalovirus and Enteroviruses Covered in your text, chapter 5. The boy had been born of an uncomplicated full-term pregnancy and delivery, with a birth weight of 3.5 kg.