• Proportion of mother with plasma HIV1 below 200 copies per ml after 8 weeks of treatment
  

• Proportion of women maintained with monotherapy until delivery,
  
• Proportion of women with a VL below 50 copies per ml at delivery,
  
• Proportion of women harbouring resistant HIV strains four weeks after delivery,
  
• Concentrations of studied drug in plasma and in cord-blood,
  
• HIV-1 detection in vaginal secretion before and after treatment and in the new born gastric fluid, HIV diagnostic in infant (criteria for stopping the trial at second infection)
  

Recent data from the French perinatal cohort and others indicate that HIV-RNA levels at delivery correlate with risk of transmission among women treated with antiretroviral agents. Most of these treatments include zidovudine alone or in combination. Mitochondrial toxicity related to nucleoside analogues exposure (zidovudine and lamivudine) has been reported in adults and in infants with in utero exposure to these drugs. In addition, biological markers of genotoxicity on nuclear DNA have recently been shown in exposed newborn. These issues raised the concern of the risk/benefit of multiple therapy in the context of mother to child transmission for women who do not meet the standard criteria for antiretroviral therapy. In women with CD4≥350 and VL<30 000 copies/ml a treatment with lopinavir/ritonavir should achieve a rapid control of HIV1 viremia below 1000 copies/ml without harm in term of resistance. In this study we would like to assess under strict control, the safety and efficacy of such regimen compared to the same boosted PI + zidovudine and lamivudine as standard regimen. The treatment will start at 26 weeks of gestation, and the follow up will include safety and efficacy parameters as well as pharmacokinetics in plasma and genital tract for the women, blood/cord ratio, testing for ARV resistance. Women will stop their treatment after delivery. Infants will be closely monitored up to 24 months with HIV DNA and HIV.RNA-PCR for HIV testing and biochemical and haematology usual safety evaluation. In addition frozen samples will be collected for specific evaluation of nucleoside analogue foetal mitochondrial and nuclear DNA interactions.

In term of transmission safety, the end point would be to reach a viral load below 200 copies after 8 weeks of treatment. In case of failure, this would allow a sufficient delay for a treatment modification: i.e. addition of NRTI and an elective caesarian could be programmed.