The project will be performed in collaboration with the Israeli National HIV Reference Center Laboratory, which maintains a national bank of HIV-positive blood samples, and with HIV/AIDS treatment centers located throughout Israel. An initial survey will identify retrospectively those HIV+ women who were given antiretroviral therapy while pregnant and stopped treatment after delivery. The list of HIV+ deliveries over the past five years in each participating hospital will be reviewed, and all HIV-positive women who received antiretroviral treatment during pregnancy will be invited to participate in the study project. Women who are currently pregnant, or become pregnant during the study, will be invited to participate when pregnancy is diagnosed. After obtaining informed consent, two blood samples will be obtained: one before the initiation of perinatal treatment, and the other following delivery. (Due to technical limitations, only samples with viral loads above 1000 cp/ml can be genotyped. It is expected that HIV loads will rise following cessation of antiretroviral treatment, and that almost all samples will be eligible for resistance testing.)

In addition, after obtaining maternal informed consent, samples from newborns infected perinatally with HIV will also be tested for resistance mutations, and these will be compared with the resistance pattern found in the mother.

The samples obtained will be tested for genotypic resistance mutations. The results will be transmitted to the treating physician to assist in choice of antiretroviral therapy for the women and their children, if needed. The data will also be used to establish a national database to evaluate and improve existing protocols for perinatal antiretroviral treatment, and will be used to contribute to international databases of HIV resistance. All resistance data, except that given to the health care provider(s), will be transmitted without additional identifying information.