HIV Database and Analysis Group (T10), Los Alamos National Laboratory, Mail stop K710, Los Alamos, NM 87545, USA. bkg@lanl.gov|HIV Database and Analysis Group (T10), Los Alamos National Laboratory, Mail stop K710, Los Alamos, NM 87545, USA. bkg@lanl.gov|HIV Database and Analysis Group (T10), Los Alamos National Laboratory, Mail stop K710, Los Alamos, NM 87545, USA. bkg@lanl.gov|HIV Database and Analysis Group (T10), Los Alamos National Laboratory, Mail stop K710, Los Alamos, NM 87545, USA. bkg@lanl.gov