There are few reports regarding HEV seroprevalence in immunocompromised individuals. Superinfection with other hepatitis viruses is associated with progression of liver diseases, since multiple hepatotropic viruses infecting a single patient may amplify liver damage. In endemic areas, similar to hepatitis A infection, it has been described a high seroprevalence of HEV and a more severe hepatitis related to HEV infection in patients with pre-existing chronic liver disease due to hepatitis B virus or hepatitis C virus. Moreover, in USA, a significant association between HEV seropositivity and antibodies to HCV has been also reported. More recently, a study performed by Pischke et al revealed a high anti-HEV IgG rate in patients diagnosed with autoimmune hepatitis,MK204 suggesting that hepatitis E infection could have triggered immune events in those patients. Therefore, in order to better understand the clinical impact of HEV infection in these populations we have conducted a study determining IgG anti-HEV in a cohort of solid-organ transplant recipients, individuals with CLD including endstage liver disease, HIV-infected patients and healthy controls. In addition, epidemiological, clinical and analytical factors were analyzed in order to identify potential risk factors associated with HEV seropositivity. In this cross-sectional analysis,PK11007 the overall HEV seroprevalence was 6.3%. Concerning healthy controls, the IgG anti-HEV rate was very similar to that previously reported in blood donors from others European countries such as Switzerland or the north of France. Kidney-transplant recipients presented an anti-HEV seroprevalence of 3.5%, similar to the rate of the healthy donors. A study from France showed also similar seroprevalence rates in both blood donors and kidney transplantation. In regards to liver transplantation, the anti- HEV seroprevalence was 9.5%, a rate higher than previously reported in the Netherlands using the Genelabs assay or in Germany where the Abbot ELISA was used but is not currently commercialized. Regarding developed countries, hepatitis E seems to be related to zoonotic transmission of genotype 3 or 4 from an animal reservoir; however, the complete routes of transmissions and predictive factors of the development of acute and chronic infection are not totally understood, which hinders its prevention in non-epidemic settings.