Novel Hepatitis C sub-type in a renal unit

Seroconversion for Hepatitis C virus (HCV) was detected on routine serological screening in a 75 year old haemodialysis (HD) patient. Serum collected three months previously was both seronegative and PCR negative. The man, DP, of Greek Cypriot origin, had been receiving HD for nine months. As he had received a blood transfusion six months previously, the blood donors were recalled for repeat HCV testing and were negative. No other risk factors for HCV were identified. To determine whether other patients had been infected, all 140 hospital HD patients were screened serologically for HCV infection at monthly intervals and amino transferase (ALT) levels measured weekly. HCV PCR was performed in patients with elevated ALT. No new cases of HCV infection were identified after six months follow-up. To identify a possible source of Hepatitis C infection for DP, genotyping was performed using PCR and restriction fragment length polymorphism (RFLP) analysis on sera from DP and the eleven HD patients previously known to have HCV infection. DP and two others (FJ and RK), both of Afro-Caribbean origin were found to be infected with type 2a. However sequence analysis of NS5 showed that all three patients were infected not with type 2a, but with a novel subtype tentatively called 2k. FJ was consistently dialysed on the same shift as DP and was therefore considered to be the more likely source of infection. Further sequence analysis is underway to establish whether transmission can be conclusively demonstrated.