QUANTIFYING HIV-1 RNA USING THE POLYMERASE CHAIN-REACTION ON CEREBROSPINAL-FLUID AND SERUM OF SEROPOSITIVE INDIVIDUALS WITH AND WITHOUT NEUROLOGIC ABNORMALITIES

We quantified HIV-1 RNA levels (copies per milliliter) in cerebrospina l fluid (CSF) and serum from subjects at various stages of HIV-1 disea se and determined the relationship of RNA levels to clinical and neuro logic disease status (HND) and to laboratory values. Ninety-seven HIV- 1-seropositive men without CNS opportunistic infections, tumors, or ne urosyphilis and 13 high-risk seronegative controls were included in th e study. Each individual underwent a structured interview and physical and neurologic examinations, followed by standardized collection of b lood and CSF. A custom-designed, fully automated polymerase chain reac tion (PCR) system was used to perform a minimum of four separate ampli fications per specimen, using two HIV-1 gag primer pairs. Southern blo tting followed by hybridization with product-specific probes was used for post-PCR detection. The number of copies per milliliter was determ ined by relating unknowns to a built-in dilution-series standard curve using an image analysis system. HIV-1 RNA was detectable in 96% of th e sera, 78% of the concentrated CSF samples, and 54% of the unconcentr ated CSF samples. Serum RNA levels were significantly higher than in C SF. Serum RNA levels were significantly inversely correlated with CD4( +) cell counts (p = -0.34; p = 0.03): i.e., higher RNA levels in serop ositive subjects were associated with lower numbers of CD4(+) cells. S erum RNA levels correlated positively with number of AIDS-related symp toms, dysfunction scores for total neurological examination, mental st atus score, cranial nerve score, and CNS motor signs score. Serum RNA levels did not correlate significantly with length of time on zidovudi ne therapy, intrathecal IgG synthesis rate, or albumin leakage. RNA le vels in CSF significantly correlated only with intrathecal IgG synthes is rate and with serum RNA levels. These results confirm that serum le vels of HIV-1 RNA correlate with HND and inversely correlate with CD4 counts, demonstrating that HND occurs predominantly in late stages of HIV-1 disease, although HIV-1 RNA can be detected in CSF from a majori ty of HIV-1-seropositive individuals at all stages of disease, which s uggests that there can be early penetration of HIV into the CNS. Howev er, HND can occur in the absence of high levels of CSF HIV-1 RNA. We a lso found that the concentration of HIV-1 in CSF is correlated with in trathecal IgG synthesis rate.