Waning immunity drives respiratory virus evolution and reinfection

Area of Science:

• Virology
• Immunology
• Epidemiology

Background:

• Respiratory viruses like influenza and coronaviruses exhibit frequent antigenic variation, leading to reinfections.
• Existing theories attribute this variation to viral immune escape.
• However, this doesn't fully explain the observed antigenic evolution patterns compared to viruses with systemic replication, such as measles.

Purpose of the Study:

• To propose and model a new primary driver for antigenic evolution in respiratory viruses.
• To explain the successive emergence and replacement of antigenic variants.
• To provide a novel framework for understanding respiratory virus evolution.

Main Methods:

• Development of a theoretical model.
• Analysis of immune waning dynamics in the respiratory tract.
• Modeling the invasion dynamics of immune escape variants in partially immune populations.

Main Results:

• Rapid waning of respiratory tract immunity is identified as the key driver of antigenic evolution.
• Partially immune hosts are susceptible to antigenically drifted variants, facilitating their invasion.
• Immune escape variants can invade even with fitness costs, potentially acquiring compensatory mutations.

Conclusions:

• Waning immunity provides a more comprehensive explanation for the antigenic evolution of respiratory viruses.
• This model accounts for the observed patterns of variant replacement.
• The findings offer a new perspective on controlling and predicting the evolution of viruses like influenza and coronaviruses.