Natural Killer Cells Are Dispensable for Virus Control in Rag2^-/- Mice During Primary RSV Infection.

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Respiratory syncytial virus (RSV) is a significant cause of severe lower respiratory tract infections.
• Immunocompromised individuals, including children and the elderly, face therapeutic challenges due to impaired adaptive immunity.
• T- and B-cell deficient Rag2^-/- mice offer a model to study protective mechanisms in immunocompromised hosts during RSV infection.

Purpose of the Study:

• To investigate the mechanisms of protection against RSV in immunocompromised hosts using T- and B-cell deficient Rag2^-/- mice.
• To determine the role of Natural Killer (NK) cells in controlling RSV infection in the absence of adaptive immunity.

Main Methods:

• RSV infection was induced in Rag2^-/- mice and wildtype controls.
• Lung and airway tissues were analyzed for disease symptoms and inflammation.
• NK cell recruitment, interferon-gamma (IFN-γ) production, and viral load were assessed.
• NK cells were depleted to evaluate their necessity for disease control.

Main Results:

• RSV-infected Rag2^-/- mice exhibited no disease symptoms or chronic lung inflammation, despite persistent infectious virus.
• NK cells were recruited earlier in Rag2^-/- mice lungs, leading to early IFN-γ production.
• Depletion of NK cells did not alter disease severity or viral load in these mice.

Conclusions:

• NK cells appear dispensable for controlling primary RSV infection in T- and B-cell deficient Rag2^-/- mice.
• These findings suggest that innate immune mechanisms beyond NK cells may mediate protection against RSV in immunocompromised individuals.