Table 1.

Viruses studied in association with idiopathic pulmonary fibrosis.

Virus	Studies showing an association with IPF disease development or progression	Studies that do not support a specific association with IPF disease
HCV	Increased serum antibodies against HCV in IPF [28] IPF incidence increases with time post-HCV infection [30]	HCV more prevalent in all cases of lung disease (including IPF) than controls [29] No association between IPF and HCV prevalence [33]
TTV	Survival rate for IPF patients with TTV is lower [37]
Adenovirus		E1A gene product not detected at higher levels in IPF patients [40] No elevations in antiviral IgG in IPF [41]
HCMV	Increased HCMV in sera of IPF [45] Higher HCMV IgG in serum of IPF than controls [45] Increased HCMV serum IgG in IPF compared with controls [41] Increased HCMV DNA in lung tissue of IPF compared with controls [47]	No difference in prevalence of HCMV DNA in IPF and control patients [46]
EBV	Elevated titers of anti-IgG and -IgA in IPF compared with patients with fibrosis of known cause [48] Increased anti-IgA in BAL of IPF [49] Increased EBV DNA in IPF[47,49,50] lungs IPF patients with EBV LMP-1 in lung epithelial cells had worse prognosis [52] Increased presence or rearranged WZhet form of EBV in lung and buffy coat of IPF compared with controls [51]	No increased presence of EBV DNA in IPF patients compared with controls [57,58]

BAL: Bronchoalveolar lavage; EBV: Epstein–Barr virus; HCMV: Human cytomegalovirus; HCV: Hepatitis C virus; IPF: Idiopathic pulmonary fibrosis; membrane protein-1; TTV: TT virus.