Human single chain-transbodies that bound to domain-I of non-structural protein 5A (NS5A) of hepatitis C virus

A safe and broadly effective direct acting anti-hepatitis C virus (HCV) agent that can withstand the viral mutation is needed. In this study, human single chain antibody variable fragments (HuscFvs) to conserved non-structural protein-5A (NS5A) of HCV were produced by phage display technology. Recombinant NS5A was used as bait for fishing-out the protein bound-phages from the HuscFv-phage display library. NS5A-bound HuscFvs produced by five phage transfected-E. coli clones were linked molecularly to nonaarginine (R9) for making them cell penetrable (become transbodies). The human monoclonal transbodies inhibited HCV replication in the HCVcc infected human hepatic cells and also rescued the cellular antiviral immune response from the viral suppression. Computerized simulation verified by immunoassays indicated that the transbodies used several residues in their multiple complementarity determining regions (CDRs) to form contact interface with many residues of the NS5A domain-I which is important for HCV replication complex formation and RNA binding as well as for interacting with several host proteins for viral immune evasion and regulation of cellular physiology. The human monoclonal transbodies have high potential for testing further as a new ramification of direct acting anti-HCV agent, either alone or in combination with their cognates that target other HCV proteins.

On-treatment outcome prediction and adjustment during chronic hepatitis B therapy: now and future

Studies published to date regarding on-treatment outcome prediction during chronic hepatitis B therapy were reviewed. Studies have shown that initial virological responses in terms of week 24 serum hepatitis B virus (HBV) DNA levels are associated with therapeutic outcomes of 1-year pegylated interferon-alpha and entecavir therapy, and weeks 52 or 104 of lamivudine and telbuvudine therapy. HBV DNA levels at week 48 are also associated with long-term adefovir therapy outcomes. Conceptual on-treatment adjustment and strategies have been proposed; however, this approach seems only necessary during therapy with nucleos(t)ide analogues with substantial risk of drug resistance. In addition, studies are needed to decide whether switching to or adding on a second drug, and with which drug, is the most cost-effective strategy.