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: We therefore systematically analyzed the functional impact of the most prevalent immune escape variants , the sG145R and sP120T mutants , on the viral replication efficacy and antiviral drug susceptibility of common treatment - associated mutants with resistance to lamivudine ( LAM ) and / or HBeAg negativity .
### Output Text:
We therefore systematically analyzed the functional impact of the most prevalent immune escape variants , the sG145R and sP120T mutants , on the viral replication efficacy and antiviral drug susceptibility of common treatment - associated mutants with resistance to <span class="chemical">lamivudine</span> ( <span class="chemical">LAM</span> ) and / or <span class="chemical">HBeAg</span> negativity . 