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: A 46 - year old man with a chronic hepatitis C virus infection received triple therapy with ribavirin , pegylated interferon and telaprevir .
### Output Text:
A 46 - year old man with a chronic hepatitis C virus infection received triple therapy with <span class="chemical">ribavirin</span> , <span class="chemical">pegylated interferon</span> and <span class="chemical">telaprevir</span> . 