Table 1

Clinical and immunologic characteristics of major viruses found in the intensive care unit
	Influenza	RSV	SARS-CoV	VZV	Adenovirus	CMV	VHF

Virus family	Orthomyxovirdae	Paramyxovirdae	Coronaviridae	Herpesvirdae	Adenoviridae	Herpesviridae	Filoviridae
Epidemiologic link	Seasonal epidemic	Seasonal epidemic, immunocompromised and transplant	Laboratory exposure on known infected individual	Contact with infected individual	Military camps, mental health facilities	Transplantation, immunosuppressive medications	Endemic area or contact with infected individual
Pulmonary clinical findings	Primary Alveolar Pneumonia	Upper respiratory tract infection, bronchiolitis, pneumonia	Rapid progressive pneumonia, ARDS	Primary alveolar pneumonia	Alveolar pneumonia with bronchiolitis	Interstitial pneumonitis, bronchiolitis	Alveolar edema
Lipid envelope	Yes	Yes	Yes	Yes	No	Yes	Yes
Major receptor for cell entry	Sialic acid	RSV glycoprotein G	CD209L ACE 2	Glycoprotein C and D	Coksackie-adenovirus receptor	Unknown, involves integrens	Folate receptor Alpha
Primary cell of infection	Type 1 respiratory epithelium	Type 1 respiratory epithelium	Type 1 respiratory epithelium	Macrophage and dendritic cells	Type 1 respiratory epithelium	Multiple	Macrophages and dendritic cells
Viremia	No	No	Yes	Yes	Yes	Yes	Yes
Primary host immunity	Humoral	Humoral	Unknown	Cellular	Cellular	Cellular	Humoral

ARDS, acute respiratory distress syndrome; CMV, cytomegalovirus; RSV, respiratory syncytial virus; SARS-CoV, severe acute respiratory syndrome-coronavirus; VHF, viral hemorrhagic fever; VZV, varicella-zoster virus.
Stollenwerk et al. Critical Care 2008 12:219 doi:10.1186/cc6917