We have recently constructed a series of novel human immunodeficiency viruses (HIV-1s) that are tropic for a macaque cell line (mt; macaque cell-tropic) to generate and establish a primate experimental system for HIV-1/AIDS study. In order to determine biological properties of these viruses effectively, several other macaque cell lines with distinct characteristics that can be routinely and easily used, instead of primary cells, for infection experiments are required. In this study, we have examined four macaque cell lines for their surface expression of virus receptor molecules and for their genotype of a major anti-viral capsid gene. Furthermore, we monitored the susceptibility of the cell lines to a standard simian immunodeficiency virus (SIV) clone and three representative basic mt HIV-1 clones. Results obtained here have clearly indicated that these cell lines are exquisitely useful to characterize various SIVs and more importantly, mt HIV-1s. J. Med. Invest. 57: 284-292, August, 2010