Analysis of endogenous retrovirus-like particle expression in normal male olive baboon (papio anubisj reproductive tissues.'

Abstract

Endogenous retrovirus- Iike sequences (ERV s) represent a substantial component of most vertebrate genomes. Majority share morphological features with type-C retroviruses. To date, the significance of ERV -related sequences in primate reproductive processes is sti11 unknown. In this study, testicular, epididymal and vasa deferentia tissues from sexually immature (n=2) and mature (n=4) male olive baboons were investigated for the expression of endogenous retrovirus-like particles. Immunohistochemical staining was done using antibodies raised against human immunodeficiency virus (HIV)-1I2, simian immunodeficiency virus (SIV) and ERVs. In addition sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-P AGE), and Western blot was done on homogenized sperm pellet and seminal plasma. Reverse transcriptase (RTase) activity in epididymal and ejaculated spermatozoa, and seminal fluid was evaluated. This study demonstrated ERV3 env-like antigens on early phases of spermatogenic ce11s in mature baboon testes (n=4) and on epididymal spermatozoa (n=4). Similarly, HIV-l p24/25 gag and HIV-2 gp120-like antigens were expressed in mature and juvenile baboon testes. In addition, reverse transcriptase activity was detected in ejaculated spermatozoa, seminal fluid and epididymal spermatozoa. Proteins of approximately 49, 58 and 80 kDa were detected in seminal fluid, 58 and 32 kDa in sperm pe11et from ejaculum and epididymis respectively. Antibodies reactive with the testes and epididymis did not cross-react with any of the proteins from semen samples including epididymal spermatozoa on immunoblot. These results indicate that retroviral-Iike antigens are expressed in normal male baboon testes and spermatozoa.