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: Serological evidence for Epstein Barr Virus infection was found in 20 % of 65 cyclosporine patients studied .
### Output Text:
Serological evidence for Epstein Barr Virus infection was found in 20 % of 65 <span class="chemical">cyclosporine</span> patients studied . 