TT virus infection in haemodialysis patients

Background. The recent discovery of a new parenterally transmitted DNA viru s called TT virus (TTV) led us to investigate its prevalence in haemodialys is patients, a high-risk group for blood-borne infection, and to evaluate i ts role in liver disease. Moreover, we compared the TTV prevalence with the prevalence of other hepatitis virus coinfections. Methods. Serum samples of 78 patients on maintenance haemodialysis were tes ted for TTV-DNA, hepatitis G virus (HGV)-RNA, anti-E2, anti-hepatitis C vir us (HCV) and HCV-RNA. TTV-DNA was detected by semi-nested PCR using the pri mers from open reading frame 1 (ORF). HGV-RNA was detected by PCR using spe cific primers for the NS3 and the 5'-UTR genome regions while anti-E2 were checked by an enzyme immunological test. Anti-HCV was tested by the second generation Chiron RIBA HCV test system. HCV-RNA was evaluated by nested PCR with primers directed to the highly conserved 5' non-coding region of the HCV genome. Results. TTV prevalence in our patients was 19% ( 15/78) while the prevalen ce of HCV and HGV infection proved to be 20 and 15.4%, respectively. Among TTV positive patients HGV co-infection was present in five cases (33%), HCV in six cases (39.9%), while HBV co-infection was not present in any of the patients. Only three patients proved positive for all three viruses. ALT l evels were normal in most cases (13/15; 86%). In particular, patients with TTV infection alone showed normal ALT levels and HCV coinfection was found in the two patients with moderate ALT increases. Conclusions. TTV prevalence in haemodialysed patients is significant though the real clinical impact is still unclear. However, we must keep in mind t hat the epidemiological relevance of TTV infection is probably underestimat ed due to the impossibility in detecting the corresponding antibody.