Human endogenous retrovirus-R (ERV 3) env-like antigens expressed in baboon testes and epididymides.

BACKGROUND: A substantial component of the vertebrate genome comprise of retrovirus-related sequences named as endogenous retroviruses (ERVs). The role of these ERV-related sequences in the biological processes of the host species is still unknown. However, they have been associated with tumourigenesis, autoimmune diseases and placental morphogenesis in primates. OBJECTIVE: To determine the expression of ERVs in male baboon reproductive tissues. DESIGN: The testes and other reproductive tissues from sexually immature and mature male olive baboons (Papio anubis) were investigated for the expression of endogenous retrovirus-related particles. Immunohistochemical staining was performed using antibodies raised against human immunodeficiency virus (HIV)-1/2, simian immunodeficiency virus (SIV) and human ERVs. Biochemical properties were determined by western blot, and reverse transcriptase (RTase) activity in epididymal spermatozoa, ejaculate spermatozoa and seminal fluid was evaluated. SETTING: Institute of Primate Research, Nairobi, Kenya. RESULTS: ERV3 env-like antigens were detected on spermatogenic cells in mature baboon testes and on epididymal spermatozoa. Similarly, antigens cross-reactive with antibodies to HIV structural and envelope glycoproteins were expressed in mature and juvenile baboon testes. In addition, reverse transcriptase activity was detected in ejaculate spermatozoa, seminal fluid and epididymal spermatozoa. CONCLUSION: These results indicate that retroviral-related genes were expressed in normal male baboon testes and spermatozoa, similar to humans. The functions of these ERVs in vertebrates remains unclear.

Endogenous retrovirus sequences expressed in male mammalian reproductive tissues: a review.

OBJECTIVES: To review the research findings on the expression of endogenous retroviruses and retroviral-related particles in male mammalian reproductive tissues, and to discuss their possible role in normal cellular events and association with disease conditions in male reproductive tissues. DATA SOURCES: Published findings on endogenous retrovirus (ERV) expression in vertebrate reproductive tissues. STUDY SELECTION: Relevant citations on ERVs and male reproduction by research groups worldwide. DATA EXTRACTION: Literature search on Medline and Pubmed upto the year 2000, and retrieval of relevant articles cited from international and local journals. DATA SYNTHESIS: Most of the studies demonstrated integrated retroviruses and retroviral-related sequences in human and mouse testis, epididymis and vas deferens. Endogenous retroviruses in human and mice may be associated with normal cellular differentiation and development, and carcinogenesis. In humans, one ERV family, human endogenous retrovirus-K (HERV-K) is abundantly expressed, and is associated with germ cell tumours, while ERV3 env is expressed in normal human testis. CONCLUSION: The expression of ERVs in male reproductive tissues suggests a possible role in normal and disease conditions involving the testis and epididymis. These speculative functions may include among others spermatogenesis and or sperm maturation or tumour formation. However, further studies need to be carried out to investigate specific roles of ERVs in male reproductive events.

Evaluation of Non-radioactive ELISA assay Kits for Detection of Retroviral Reverse Transcriptase (RT) Activity Associated with Retroviral SIV and HIV.

Reverse transcriptase (RT) assay is commonly used to detect enzyme activity associated with retroviral-like particles. Previously, detection of RT activity in virus-infected cultures was done using a radioisotope-based assay system. However, assay systems, which detect the antigen directly(as opposed to antibody ELISA assays), have been developed. For diagnostic purposes, RT activity and p24 antigen capture assays are the two most commonly used methods for detection of retroviral infection. More recently, new non-radioactive assay systems have been developed. In this study, four non-radioactive reverse transcriptase kits were evaluated using samples obtained from a chimeric virus, simian/human immunodeficiency virus (SHIV) and SIV-infected cell cultures. The results showed that the magnesium kit was the most appropriate for detection of SIV and SHIV infection in cell culture supernatants.

The prevalence of antibodies to simian T-cell leukaemia/lymphotropic virus (STLV-I) in non-human primate colonies in Kenya.

Retroviruses closely related to the human T-cell leukaemia/lymphotrophic virus type I (HTLV-I) have been detected in several, non-human, primate species. These retroviruses are called simian T-lymphotrophic virus type I (STLV-I). Infection with STLV-I has been associated with lymphoma and leukaemia in macaques, baboons, African green monkeys and gorillas. However, no STLV-I infection has been detected in New World primates, although STLV-II has been detected in spider monkeys. When sera from 10 species of non-human primates maintained at the Institute of Primate Research were screened for STLV-I infection, anti-STLV-I antibodies were detected in 12%, 12%, 23% and 38% of the olive baboons, yellow baboons, African green monkeys and lowland Sykes' monkeys, respectively. Western-blot studies confirmed these results. To date, no clinical disease has been linked with STLV-I infection in these colonies. The relatively high prevalence of anti-STLV-I antibodies in these non-human primates offers an opportunity for studies on the transmission, phylogenetic relationships and natural history of STLV-I in primate colonies.