Abstract
Sera were produced by injection of a particular rat cell line (HLBRK EcoC1), produced by transformation of baby rat kidney cells with adenovirus 12 early region 1 DNA, into the syngeneic host. Antibodies to a protein of Mr 15200 as determined by SDS-PAGE, were detected in the sera from two rats bearing tumours. The 15K protein was identified as the viral structural component polypeptide IX by a number of criteria: (i) the protein was only observed in adenovirus 12-infected cells, (ii) it was produced at intermediate and late times after infection, (iii) it was immunoprecipitated from purified adenovirus 12 particles and (iv) it was immunoprecipitated from a purified protein preparation.