In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Available donor sera were examined for DNA polymerase ( DNAP ) and e antigen and antibody ( HBeAg ; anti - HBE ) .
### Output Text:
Available donor sera were examined for DNA polymerase ( DNAP ) and e antigen and antibody ( <span class="chemical">HBeAg</span> ; anti - HBE ) . 