Autonomous Targeting of Infectious Superspreaders Using Engineered Transmissible Therapies

Metzger, Vincent T.; Lloyd-Smith, James O.; Weinberger, Leor S.

Contacts between individuals in the TIP population model are weighted by statistically independent transmission probabilities (b) which are calculated from steady-state HIV and TIP viral loads from the in vivo model (see Text S1 section: 'Calculation of Transmission-Rate Function'). There are six distinct transitions between infection classes in the TIP population model (see Table S3 in Text S1 for details). Briefly, contact between two individuals is represented by a contact function that considers asymmetric mixing of individuals among the four SACs: This contact function describes an individual in disease state X (and SAC i) becoming infected by an individual in disease state Y. The subscript j denotes SAC j, c j is the average number of sexual partners per year in SAC j, and N j is the sum of all sexually active individuals in SAC j. In the contact function, e is the degree of assortative mixing with e~1 corresponding to entirely assortative mixing and e~0 corresponding to entirely random mixing. The first term inside the brackets of the contact function describes assortative mixing in which infected individuals are encountered in proportion to their prevalence in SAC i. The second term describes random contacts in which infected individuals are encountered in proportion to their contribution to all of the sexual contacts being made in the entire population. We set the mixing parameter e equal to 0.37, as estimated in [12] .