Detection of dengue cell-surface antigens by peroxidase-labeled antibodies and immune cytolysis

Area of Science:

• Virology
• Immunology
• Cell Biology

Background:

• Dengue virus is a significant global health concern.
• Understanding viral antigen expression is crucial for vaccine development and antiviral strategies.
• LLC-MK(2) cells are a common model for studying viral infections.

Purpose of the Study:

• To investigate the temporal appearance and quantity of dengue-specific plasma membrane (DSPM) antigens in infected LLC-MK(2) cells.
• To compare the kinetics of DSPM antigen expression and immune cytolysis with viral release.
• To elucidate potential differences in viral plasma membrane antigen insertion mechanisms between dengue virus and Eastern equine encephalitis virus.

Main Methods:

• Utilized (51)Cr release assays for immune cytolysis.
• Employed peroxidase-labeled antibodies for ultrastructural analysis via electron microscopy.
• Monitored infectious virus release and cell surface antigen expression over time.

Main Results:

• DSPM antigen was detected in approximately 30% of cells by 36 hours, with no increase in the percentage of positive cells over time.
• Both surface staining and (51)Cr release assays indicated an increase in DSPM antigen quantity per cell over time.
• Immune cytolysis via (51)Cr release in dengue-infected cells occurred significantly later than peak infectious virus release.
• This contrasted with Eastern equine encephalitis virus, where viral release and (51)Cr release kinetics were identical.

Conclusions:

• Dengue virus infection leads to a time-dependent increase in DSPM antigen quantity per cell, despite a stable percentage of antigen-positive cells.
• The delayed immune cytolysis kinetics suggest distinct mechanisms of viral plasma membrane antigen insertion for dengue virus compared to Eastern equine encephalitis virus.
• These findings highlight differences in viral pathogenesis and host immune response modulation.