[Nature of the endogenous retrovirus-like particles of the rat liver]

Previously virus-like particles (VLP) with properties resembling retroviruses were isolated from the liver of Wistar rats. Molecular hybridization and CRIA test were used for further analysis of the VLP. The CRIA method showed that VLP preparation lacked antigenic determinants of the major internal protein of C-type virus. By the dot hybridization technique no homology was detected between VLP and Mo-MuLV DNA, however VLP RNA was found to be homologous to IAP (interstitial A particles) DNA of mice. VLP proviral DNA was detected in the rat genome by the blot hybridization technique. Thus, it was concluded that VLP resemble IAP. A possible role of rat IAP expression is discussed.