Cell-mediated immune responses to BK virus in normal individuals

Area of Science:

• Immunology
• Virology

Background:

• BK virus (BKV) is a human papovavirus.
• Cell-mediated immunity (CMI) plays a role in viral infections.
• Assessing CMI to BKV is crucial for understanding host responses.

Purpose of the Study:

• To develop and validate a lymphoproliferative assay for measuring CMI to BKV.
• To compare CMI responses to BKV with humoral immunity (antibody titers).
• To determine the frequency of BKV-specific T cells in healthy individuals.

Main Methods:

• Developed a lymphoproliferative assay using ultraviolet-inactivated BKV antigen.
• Compared responses to BKV, mock antigen, and tetanus toxoid (TET).
• Measured humoral immunity via enzyme-linked immunosorbent assay (ELISA) and CMI via limiting dilution analysis (LDA).

Main Results:

• The assay demonstrated specificity, with no response to mock antigen.
• All seropositive individuals showed CMI to BKV, while neonates and seronegative children did not.
• CMI magnitude did not correlate with antibody titers; BKV-specific T cell frequency was lower than for TET.

Conclusions:

• The developed assay is a reliable tool for studying BKV-specific CMI.
• CMI to BKV is present in seropositive individuals.
• Lower BKV-specific T cell frequency may relate to antigen exposure differences.