TT virus in bone marrow transplant recipients

Area of Science:

• Virology
• Hepatology
• Hematology

Background:

• TT virus (TTV) is a transfusion-transmissible DNA virus potentially causing posttransfusion hepatitis.
• TTV was detected in 12% of Japanese blood donors, indicating its circulation in the population.

Purpose of the Study:

• To determine the prevalence of TTV infection in bone marrow transplant (BMT) recipients.
• To investigate the clinical impact and behavior of TTV in the context of BMT.

Main Methods:

• Sera from 25 BMT recipients were analyzed for TTV-DNA using seminested polymerase chain reaction (PCR).
• Serial samples were collected and analyzed for patients with detectable TTV-DNA.
• Nucleotide sequencing was used to classify novel TTV groups.

Main Results:

• A high prevalence of TTV-DNA was observed in 60% of BMT recipients post-transplant, compared to 10% of donors.
• TTV-DNA levels decreased significantly during myelosuppression in pre-transplant positive patients.
• A novel TTV group, G3, was identified based on nucleotide sequences.
• Median peak alanine aminotransferase (ALT) levels were similar in TTV-positive and negative recipients, suggesting TTV does not frequently cause severe hepatic injury.

Conclusions:

• TTV infection is highly prevalent in BMT recipients.
• TTV replication likely occurs in hematopoietic cells, and transfusion-transmitted TTV can lead to persistent infection.
• A new genetic group of TTV (G3) was discovered.
• While TTV generally does not cause frequent hepatic injury, one case suggested TTV-induced hepatitis.