Enhancing genetic disease control by selecting for lower host infectivity and susceptibility

Area of Science:

• Animal genetics
• Epidemiology
• Quantitative genetics

Background:

• Infectious diseases significantly impact animal health, production, and welfare, as well as human health.
• Host genetics plays a crucial role in disease spread, influencing susceptibility and infectivity.
• While susceptibility has been a focus in livestock breeding, the genetic variation in host infectivity and its breeding potential remain underexplored.

Purpose of the Study:

• To assess the impact of genetic selection on both host susceptibility and infectivity on epidemic risk and severity.
• To evaluate the benefits of incorporating infectivity into breeding schemes for disease control.
• To determine the effectiveness of genetic selection in reducing infection incidence and epidemic potential.

Main Methods:

• Utilized a Susceptible-Infected-Recovered (SIR) epidemiological model.
• Integrated polygenic genetic variation for both susceptibility and infectivity.
• Combined with quantitative genetics selection theory to simulate 20 generations of selection in large populations.
• Analyzed selection schemes varying in accuracy and intensity.

Main Results:

• Genetic selection on susceptibility alone reduced the basic reproductive number (R0) from 7.64 to below 1 in seven generations.
• Including infectivity in the selection objective accelerated this decline to three generations.
• Selection on infectivity enhanced disease eradication, reduced outbreak risk more efficiently, and mitigated negative genetic correlations.

Conclusions:

• Host infectivity is a critical, yet often overlooked, trait for genetic selection in disease control.
• Integrating infectivity into breeding schemes offers significant advantages for accelerating disease eradication and reducing epidemic impact.
• Future genetic studies and breeding programs should prioritize targeting host infectivity for improved animal health and disease management.