Contact-number-driven virus evolution: A multi-level modeling framework for the evolution of acute or persistent RNA virus infection
Fig 1
Schematic illustration of multi-level disease transmission.
A schematic of our model is depicted in (A). The probability of infection ρ(t) of susceptible individuals from an infected hosts depends on their viral load Vi(t). At each time step (i.e., day), the focal infected individual has contacts with multiple susceptible individuals. Here the contact numbers C(t) are assumed to follow a negative binomial distribution, which does not depend on the viral load. The sum of newly infected individuals (i.e., [number of contacted individuals per day] × [probability of infection per contacted individual]) during the infectious period is calculated as RTP. The duration of the infectious periods for each parameter combination (p and ε) characterizing the proliferative ability and accuracy of viruses are calculated in (B) based on the virus infection model. The left panel corresponds to an infectious period of 713 days with a relatively low viral load, and the right panel represents an infectious period of 200 days with a high viral load. Examples of generated daily contact numbers characterizing environmental conditions are shown in (C). The contact numbers under a negative binomial distribution with k =100 and θ =0.03 (the mean and variance are 3.0 and 3.1) and k = 0.12 and θ = 10 (the mean and variance are 1.2 and 13.3) are shown in the top and bottom panels, respectively.