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: DISCUSSION : Our series of patients is representative of the spectrum of immunocompromised children at greatest risk for severe adenovirus disease , namely solid - organ and bone marrow transplant recipients , neonates , and children with immunodeficiency .
### Output Text:
DISCUSSION : Our series of patients is representative of the spectrum of immunocompromised children at greatest risk for severe adenovirus disease , namely solid - organ and bone marrow transplant recipients , neonates , and children with immunodeficiency . 