NOVEL RETROVIRAL SEQUENCES ARE EXPRESSED IN THE EPIDIDYMIS AND UTERUSOF SYRIAN-HAMSTERS

Combined androgen and oestrogen treatment of male or female Syrian ham sters results via an unknown mechanism in the formation of leiomyosarc omas in the reproductive tract. We have examined the possibility that retroviral gene expression may play a role in tumorigenesis, Evidence of virus-like particles in epididymis and seminal fluid is shown in el ectron micrographs. We identified expressed retroviral sequences by us ing RT-PCR to amplify a conserved retroviral reverse transcriptase cod ing region in RNA isolated from epididymis, testis, clarified seminal fluid and uterus, Phylogenetic analysis allowed us to classify the seq uences into two distinct groups: (1) mammalian type-C viruses, having similarity to Moloney murine leukaemia virus, feline leukaemia virus a nd gibbon ape leukaemia virus amongst others; (2) a mixed ABCD group c ontaining, for example, Chinese hamster and murine intracisternal A-pa rticle virus sequences, mouse mammary tumour virus and human and simia n retroviral sequences. The presence of putative full-length retroviru s related to mammalian type-C viruses in the epididymis and uterus was confirmed by Northern blot analysis. However, steroid treatment did n ot alter retroviral RNA levels in the epididymis or in a uterine tumou r relative to untreated uterus, In summary, Syrian hamster reproductiv e tissues were found to express unique retroviral sequences; however, their role, if any, in hormonal carcinogenesis remains unresolved.