Correlation between HIV provirus burden and in utero transmission

Objective: No predictive parameters of in utero or perinatal vertical transmission of HIV to newborns are known at present. Vertical transmission may be related to several biological parameters of maternal HIV infection: (1) immunological parameters (neutralizing antibodies); (2) the concentration of viral particles and/or infected cells; and (3) the selection of HIV subspecies of particular cellular tropism. The present study was designed to examine the relationship between cellular viral burden and transmission, and between maternal viral burden and CD4+ cell count and clinical status at delivery. Method: We investigated mother-to-infant HIV-1 transmission at delivery in a cohort of 51 pairs of mothers and newborns. Twelve infants were HIV-infected, as determined by successive polymerase chain reaction and culture determinations within the first 6 months of life, and nine of these were diagnosed as HIV-infected during the first week of life. We determined peripheral blood mononuclear cell proviral DNA burden using a quantitative polymerase chain reaction assay. Polymerase chain reaction was performed in the HIV-1 gag gene, using [32P]-end-labelled primers. External standard DNA samples were from the 85-14 F2 cell line, which contains a unique defective proviral DNA genome. Results: There was a linear relationship between the logarithms of c.p.m. and the number of HIV-1 DNA copies. Conclusion: We have previously reported that the number of HIV provirus copies in maternal blood cells is related to transmission of the virus. Quantification of the HIV provirus by polymerase chain reaction may be used as a predictive parameter of vertical transmission if accompanied by an exhaustive clinical and biological follow-up during pregnancy.