Measles virus: immunomodulation and cell tropism as pathogenicity determinants

Area of Science:

• Virology
• Immunology

Background:

• Measles virus (MV) glycoproteins determine pathogenicity and cellular tropism.
• MV utilizes CD150 (SLAM) for entry; some strains also use CD46.
• Both CD150 and CD46 are down-regulated upon MV infection or H protein interaction.

Purpose of the Study:

• To investigate the role of MV glycoproteins in cellular tropism and immune modulation.
• To understand the consequences of CD46 and CD150 down-regulation by MV.
• To explore the mechanisms of MV-induced immunosuppression.

Main Methods:

• In vitro tropism studies using MV strains and target cells expressing CD150 and/or CD46.
• Analysis of CD46 and CD150 cell surface expression following MV infection or H protein exposure.
• Ex vivo assessment of lymphocyte proliferation in response to MV infection in animal models.
• Investigation of T cell activation pathways affected by MV glycoproteins.

Main Results:

• All MV strains bind CD150; certain strains (mainly vaccine) bind both CD150 and CD46.
• MV infection and H protein interaction lead to CD150 and CD46 down-regulation.
• CD46 down-regulation may enhance sensitivity to complement lysis, potentially an attenuation marker.
• Wild-type MV strains show tropism for dendritic cells and cause immunosuppression in cotton rats.
• Impaired lymphocyte proliferation ex vivo suggests MV inhibits T cell expansion.

Conclusions:

• MV glycoproteins play a critical role in viral pathogenicity and immune evasion.
• Down-regulation of CD46 and CD150 are key mechanisms employed by MV.
• Wild-type MV H protein interaction with immune cells, particularly dendritic cells, leads to immunosuppression.
• MV may inhibit T cell proliferation by disrupting S-phase entry pathways via surface contact.