Hamster polyomavirus-encoded proteins: gene cloning, heterologous expression and immunoreactivity.

The hamster polyomavirus (HaPV) is associated with spontaneously appearing skin epithelioma of the Syrian hamster Z3 strain. Virus particles prepared from the skin epithelioma cause lymphoma and leukemia when injected into newborn hamsters from a distinct Syrian hamster colony (HaP); in contrast to the skin epithelioma the hemopoietic tumors are virus free but accumulate viral DNA. To study the humoral immune response of HaPV-infected Z3 hamsters we produced recombinant HaPV proteins in Escherichia coli as β-galactosidase-, TrpE-and dihydrofolate reductase-fusion proteins or as non-fused proteins. Recombinant plasmids carried segments of all putative early and late HaPV proteins. The recombinant proteins were detected in stained SDS polyacrylamide gels and in Western blots using monoclonal anti-TrpE and anti-β-galactosidase antibodies and sera of HaPV-infected hamsters.