B-cell characteristics define HCV reinfection outcome

Area of Science:

• Immunology
• Virology
• Vaccine Development

Background:

• Hepatitis C virus (HCV) reinfection is common in highly exposed individuals, making natural sterilizing immunity difficult to achieve.
• While most reinfections lead to persistent infection, a small subset spontaneously clear the virus, indicating potential natural protection mechanisms.

Purpose of the Study:

• To characterize the immune responses associated with rapid natural clearance of HCV reinfection.
• To identify correlates of immune protection crucial for developing an effective HCV vaccine.

Main Methods:

• Longitudinal examination of broad neutralizing antibodies (nAbs) and Envelope 2 (E2)-specific memory B cell (MBC) responses in 15 individuals with varied reinfection outcomes.
• Single-cell transcriptomic analyses of HCV-specific B cells.

Main Results:

• Broad nAb responses correlated with MBC recall but not with clearance of reinfection.
• HCV-specific B cells in cleared reinfections exhibited an activated transcriptomic profile with rapid expansion.
• Antigen imprinting was evident, with a highly Потом clonality and ongoing somatic hypermutation in the B-cell receptor repertoire.

Conclusions:

• The quality of MBC responses, rather than the breadth of nAb responses, is critical for protection against antigenically diverse HCV variants.
• These findings are encouraging for the development of a protective HCV vaccine.
• Humoral immune responses are vital, and for highly diverse viruses like HCV, exploring beyond antibodies as protection correlates is beneficial.