In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

Human sera were examined by immuno-blotting for antibodies to the reverse transcriptase of human hepatitis B virus (HBV) believed to be encoded in the P open reading frame (P-ORF). Sera from patients with self-limited (n = 58), acute (n = 23), and chronic (n = 8) hepatitis were analysed. One of the sera with markers of a prior infection and two sera of chronically infected patients reacted with a protein synthesized in E. coli that contains the middle part of the predicted polymerase. Other E. coli fusion proteins containing overlapping or different regions of P-ORF were used to localize antigenic domains. Antibody binding to two different domains representing the middle and the C-terminal region of P-ORF was obtained in the sera of chronically infected patients. Our findings are indirect evidence for the in vivo expression of the complete HBV polymerase reading frame.
Abstracts of Papers Presented at the Session of the Virology Section of the Deutsche Gesellschaft fiir Hygiene und Mikrobiologie