DIAGNOSIS OF HIV INFECTION

Use of "less sensitive" HIV Ab test to diagnose early HIV-1 infection:

• During acute infection (i.e. before detectable HIV Ab is produced), HIV RNA, proviral DNA, culturable virus, and viral p24 Ag can be detected in the blood
• HIV RNA is most sensitive for acute infection but false-positives do occur
• Some labs offer an "Acute/Early HIV-1 Panel" consisting of HIV Ab-standard EIA, HIV Ab-less-sensitive EIA, & HIV-RNA; if the standard EIA is positive, the less-sensitive EIA is done. Since the mean time-to-conversion for the less-sensitive EIA is 130d (compared with 30-60d for the standard EIA), so if the standard EIA is positive and the less-sensitive EIA is negative that suggests infection occurred < 130d prior
• Note that the less-sensitive EIA may become negative in late-stage HIV infection

p24 Antigen testing can identify many, but not all, cases of primary HIV infection; more specific than HIV RNA testing (Ann. Int. Med. 134:25, 2001--JW)

HIV-1 Quantitative RNA testing--useful in determining "viral load"; both sensitive to 50 RNA copies/mL (thought the Amplicor requires a special centrifugation step to attain that level of sensitivity)

• Branched-chain DNA (Quantiplex)
• RT/PCR amplification (Amplicor)