The HIV reverse transcriptase and protease sequence database (HIVRT&PrDB) is an online relational database that catalogs evolutionary and drug-related sequence variations in HIV-1 reverse transcriptase (RT) and protease enzymes, which are molecular targets of antiretroviral therapy. The database contains nearly all published HIV RT and protease sequences, including those from GenBank, journal articles, and clinical trial participants. Sequences are linked to data about the source, antiretroviral treatment history, and in vitro drug susceptibility testing results. In 2003, the database will include sequences for two new molecular targets: gp41 (cell fusion) and integrase. The database is designed to assist scientists developing new HIV-1 drugs, clinical investigators studying drug resistance, and clinicians using genotypic resistance tests. It links sequence changes in molecular targets to treatment history and phenotypic data. The database includes data from over 420 published papers, sequences from over 7000 individuals and 500 laboratory isolates, and over 20,000 drug susceptibility results from over 2000 virus isolates. It provides composite alignments showing mutations present in HIV-1 isolates from treated and untreated individuals. The database allows users to retrieve sequences and data based on specific criteria, including drug treatment, mutations, and resistance profiles. It also provides access to raw sequence data in various formats. The database includes three sequence interpretation programs: HIVseq, HIVdb, and HIValg. HIVseq compares user-submitted sequences to a reference sequence and allows users to examine new sequences in the context of previously published sequences. HIVdb infers resistance levels to 16 FDA-approved antiretroviral drugs based on mutations. HIValg compares the output of different drug-resistance algorithms on the same sequence. The database is planned to include gp41 sequences and resistance data to fusion inhibitors, as well as integrase sequences.The HIV reverse transcriptase and protease sequence database (HIVRT&PrDB) is an online relational database that catalogs evolutionary and drug-related sequence variations in HIV-1 reverse transcriptase (RT) and protease enzymes, which are molecular targets of antiretroviral therapy. The database contains nearly all published HIV RT and protease sequences, including those from GenBank, journal articles, and clinical trial participants. Sequences are linked to data about the source, antiretroviral treatment history, and in vitro drug susceptibility testing results. In 2003, the database will include sequences for two new molecular targets: gp41 (cell fusion) and integrase. The database is designed to assist scientists developing new HIV-1 drugs, clinical investigators studying drug resistance, and clinicians using genotypic resistance tests. It links sequence changes in molecular targets to treatment history and phenotypic data. The database includes data from over 420 published papers, sequences from over 7000 individuals and 500 laboratory isolates, and over 20,000 drug susceptibility results from over 2000 virus isolates. It provides composite alignments showing mutations present in HIV-1 isolates from treated and untreated individuals. The database allows users to retrieve sequences and data based on specific criteria, including drug treatment, mutations, and resistance profiles. It also provides access to raw sequence data in various formats. The database includes three sequence interpretation programs: HIVseq, HIVdb, and HIValg. HIVseq compares user-submitted sequences to a reference sequence and allows users to examine new sequences in the context of previously published sequences. HIVdb infers resistance levels to 16 FDA-approved antiretroviral drugs based on mutations. HIValg compares the output of different drug-resistance algorithms on the same sequence. The database is planned to include gp41 sequences and resistance data to fusion inhibitors, as well as integrase sequences.