Primary naive and interleukin-2-activated natural killer cells do not support efficient ectromelia virus replication

Area of Science:

• Immunology
• Virology

Background:

• Natural killer (NK) cells are crucial for antiviral defense and tumor surveillance.
• The susceptibility of NK cells to viral infection and the impact on their biology remain poorly understood.

Purpose of the Study:

• To investigate the susceptibility of NK cells to ectromelia virus (ECTV) infection.
• To determine the effects of ECTV infection on NK cell function and viability.

Main Methods:

• In vitro and in vivo infection of NK cells with ECTV.
• Analysis of NK cell proliferation, viability, and cytokine production (IFN-gamma).
• Detection of viral gene expression and particle formation within infected NK cells.

Main Results:

• ECTV successfully infected NK cells, leading to reduced gamma interferon (IFN-gamma) production.
• Infected NK cells exhibited decreased proliferation and viability.
• ECTV exhibited early and late gene expression and formed immature/mature virus particles, but no viable progeny virus was detected.
• Immunomodulatory viral proteins (IFN-gamma-binding protein, EMICE) were secreted, suggesting local environmental modulation.

Conclusions:

• NK cells can be infected by ECTV, resulting in impaired immune function and cell death.
• ECTV infection of NK cells is semi-permissive, allowing viral replication but not the production of infectious virions.
• Secreted viral proteins may modulate the local immune environment despite the lack of productive viral spread from NK cells.